Review of Literature

9

Glucosinolate profile as well as quantity is highly variable among different plant species

and even among different organs of the same plant. The majority of plants contain 2 to 5

glucosinolates, some contain only one, although as many as 23 different glucosinolates have

been identified in Arabidopsis thaliana (Hogge et al., 1988; Haughn et al., 1991). Research in

this field started with the endeavor to explore the pungent principle of the mustard oil present in

members of family Brassicaceae. Robiquet and Boutron (1831) tried to study this pungent

chemical component from seeds of Sinapis alba and isolated the first glucosinolate called

Sinalbin (4-hydroxybenzyl glucosinolate). A parallel investigation by Bussy (1840) led to the

search of one more related compound from seeds of Brassica nigra (black mustard). He isolated

this compound and named it potassium myronate which latter on known as ‘Sinigrin’ (2-

propenyl or allyl glucosinolate). These two compounds remained the sole representatives of the

glucosinolate family for nearly 80 years (Kjaer, 1964). Thereafter new members kept on adding

in the list owing to rapid progress made in this field. More than 120 glucosinolates have been

identified till date and most of them have been isolated from members of family Brassicaceae.

However, there are 15 more families of dicotyledonous angiosperms which are known to possess

glucosinolates. These include Bataceae, Bretschneideraceae, Capparaceae, Caricaceae,

Euphorbiaceae, Gyrostemonaceae, Limnanthaceae, Moringaceae, Pentadiplandraceae,

Phytolaccaceae, Pittosporaceae, Resedaceae, Salvadoraceae, Tovariaceae and Tropaeolaceae

(Fahey et al., 2001). In this review, attempt has been made to gather and compile information

regarding all the natural glucosinolates discovered till date from various plant sources (Table 1).

These plant secondary metabolites have gained substantial interest of researchers for many years.

Earlier studies were performed to reduce their content from plants because of their bitterness and

some antinutritional properties in animals. Exploration of the beneficial properties of hydrolytic

products emerging from their biological activities and medicinal uses shifted the whole scenario.

Extensive body of literature demonstrates that this group of compounds is important in various

pest control strategies, making them eligible contenders for integrated pest management.

However, another potential benefit of glucosinolates as cancer chemopreventive agents, deserves

further attention. Some of these compounds have also shown encouraging results in clinical trials

showing their strong potential in drug development against various cancers.

Table 1: Glucosinolates and their plant sources

S.No. Glucosinolate Common name R-group Identified sources Reference

1. AAllyl Sinigrin Arabidopsis thaliana Reichelt et al., 2002 (S)Armoracia lapathifolia Grob and Matile, 1980 (R); Birch et al., 1992

(R)Brassica alboglabra Rangkadilok et al., 2002 (S, Sp); Bennett et al.,

2004b (S)Brassica campestris var. pekinensis Bennett et al., 2004b (S)Brassica campestris var. rapifera Bennett et al., 2004b (S)Brassica nigra Bussy, 1840 (S); Rangkadilok et al., 2002 (S,

Sp); Bennett et al., 2004b (S)Brassica juncea Hanley et al., 1983 (S); Carlson et al., 1987

(A); Kaushik and Agnihotri, 1999 (S);Rangkadilok et al., 2002 (S, Sp); Bennett et al.,2004b (S); Song et al., 2006 (S)

Brassica napus Elfakir et al., 1992 (S); Birch et al., 1992 (R)Brassica oleracea var. acephala Carlson et al., 1987 (A); Bennett et al., 2004b

(S); Kushad et al., 2004 (A); Cartea et al., 2008(L); Sarikamis et al., 2008 (L)

Brassica oleracea var. botrytis Carlson et al., 1987(I); Rangkadilok et al., 2002(S, Sp); Tian et al., 2005 (I); Bellostas et al.,2007a (Sp, S); Lin et al., 2010 (S)

Brassica oleracea var. capitata Slominski and Campbell, 1989 (Bud); Kushadet al., 1999 (A); Rangkadilok et al., 2002 (S,Sp); Bennett et al., 2004b (S); Bellostas et al.,2007a (Sp, S); Cartea et al., 2008 (L); Lin et al.,2010 (S)

Brassica oleracea var. gemmifera Heaney and Fenwick, 1986 (Bud); Sones et al.,1984b (Bud); Carlson et al., 1987(A); VanDoorn et al., 1999; Kushad et al., 1999 (A);Rangkadilok et al., 2002 (S, Sp); Lin et al.,2010 (S)

Brassica oleracea var. italica Rangkadilok et al., 2002 (S, Sp); West, 2002(Sp); Tian et al., 2005 (Sp, I); Bellostas et al.,2007a (Sp, S)

Brassica rapa subsp. sylvestris Barbieri et al., 2008 (Sh+I)Capparis spinosa Romeo et al., 2007 (S, L)Dithyrea wislizenii Montaut et al., 2009 (F)Eruca sativa Cataldi et al., 2007 (L)Erysimum corinthium Al-Gendy et al., 2010 (S)Lepidium peruvianum Li et al., 2001 (S, Sp)Pachycladon cheesemanii Voelckel et al., 2010 (P)

Pachycladon novaezelandiae Voelckel et al., 2010 (P)Pringlea antiscorbutica Barillari et al., 2005c (S,L)

2. Benzyl Glucotropaeolin Arabidopsis thaliana Reichelt et al., 2002 (S)Brassica nigra Thies et al., 1988 (S)Cardamine hirsuta Bennett et al., 2004b (S)Cakile maritima Radwan et al., 2008 (A)Carica papaya Bennett et al., 2004b (S); Nakamura et al., 2007

(S); Rossetto et al., 2008 (Fr)Carica pentagona Bennett et al., 2004b (S)Descurainia sophia Chen and Guan, 2006 (S)Hutchinsia alpina Bennett et al., 2004b (S)Lepidium meyenii Gonzales et al., 2005(Sp)Lepidium peruvianum Li et al., 2001 (S, Sp)Lepidium sativum Hanley et al., 1983(S); Thies et al., 1988 (S);

Griffiths et al., 2001 (L); Bennett et al., 2004b(S); Radwan et al., 2007 (S); Sarikami andYanmaz, 2011 (P)

Pentadiplandra brazzeana De Nicola et al., 2012 (R)Pringlea antiscorbutica Barillari et al., 2005c (S,L)Raphanus raphanistrum Malik et al., 2010 (R, F)Tropaeolum majus Underhill and Wetter, 1969 (L); Lykkesfeldt

and Moller, 1993 (P); Griffiths et al., 2001 (L);Bennett et al., 2004b (S)

Tropaeolum pereginum Bennett et al., 2004b (S)Tropaeolum tuberosum Ortega et al., 2006 (P)

3. Butyl Armoracia lapathifolia Grob and Matile, 1980 (R)Brassica oleracea var. capitata MacLeod et al., 1989 (S)Capparis flexuosa Kjaer and Schuster, 1971 (L)Cardamine pratensis Bennett et al., 2004b (S)Dentaria pinnata Bennett et al., 2004b (S)Lepidium sativum Radwan et al., 2007 (P)Lunaria rediviva Bennett et al., 2004b (S)Pringlea antiscorbutica Barillari et al., 2005c (S,L)

4. Ethyl Glucolepidiin Cakile maritima Radwan et al., 2008 (A)Lepidium menziesii Kjaer and Larsen, 1954 (S)Raphanus sativus Li et al., 2008 (Sp, L, R)

5. n-Hexyl Eruca sativa Cataldi et al., 2007 (L)Isatis indigotica Lee et al., 2008 (R)Lepidium apetalum Lee et al., 2008 (S)Raphanus sativus Kjaer et al., 1978 (R)Brassica napus Kondo et al., 1985 (S)

6. n-Propyl Brassica oleracea var. capitata MacLeod and Nussbaum, 1977 (L)

7. n-Pentyl Brassica oleracea var. italica Lelario et al., 2012 (I)Armoracia lapathifolia Grob and Matile, 1980 (R)Brassica rapa Itoh et al., 1984 (L)Cardamine pratensis Bennett et al., 2004b (S)

8. ‘‘iso’’-HeptylCH3 ̶-CH2 ̶-CH2 ̶-CH2 ̶-CH2 ̶-

CH2 ̶-CH2 ̶ *Arabidopsis thaliana Bringmann et al., 2005 (S)

9. ‘‘iso’’-Hexyl Arabidopsis thaliana Bringmann et al., 2005 (S)

10. Methyl Glucocapparin Isomeris arborea Blua and Hanscom, 1986 (S)Cleome hassleriana Lazzeri and Manici, 2001 (P)Lepidium sativum Radwan et al., 2007 (P)Crataeva religiosa Ikeura et al., 2010 (P)Cleome viscosa Kjaer, 1960 (S), Hasapis et al., 1981 (S)Gynandropsis gynandra Kjaer, 1960 (S), Hasapis et al., 1981 (S)Capparis spinosa Schraudolf, 1989 (R), Matthaus and Ozcan,

2002 (S, I, Sh)Capparis ovate var. canescens Matthaus and Ozcan, 2002 (S, I, Sh)Boscia senegalensis Seck et al., 1993 (Fr, L)Isatis tinctoria Griffiths et al., 2001 (L)

11. 2- EthylbutylCH3 ̶ CH2 ̶ CH ̶ CH2 ̶ *

CH2 ̶ CH3

Lepidium sativum Radwan et al., 2007 (P)

12. 1-Methylpropyl/sec-Butyl/2-Butyl

Glucojiabutin/

Glucocochlearin

Brassica oleracea var. italica Lelario et al., 2012 (I)Brassica rapa Yang and Quiros, 2010 (L)Cochlearia officinalis Griffiths et al., 2001 (L)Cardamine cordifolia Rodman and Louda, 1985 (R, L, Sh)Sisymbrium loeselii Bainard et al., 2009 (R, Sh)

13. 2-Methylpropyl Isobutyl Brassica napus Brown and Morra, 1995 (S)Brassica oleracea var. capitata MacLeod et al., 1989 (S)Brassica oleracea var. italica Lelario et al., 2012 (I)Cardamine cordifolia Rodman and Louda, 1985 (R, L, Sh)Moringa peregrina Kjaer et al., 1979 (S)

14. 1-Methylethyl/ isopropyl Glucoputranjivin Brassica napobrassica Shaw et al., 1989 (R)Cardamine cordifolia Rodman and Louda, 1985 (R, L, Sh)Cochlearia officinalis Griffiths et al., 2001 (L)Putranjiva roxburghii Puntambekar, 1950 (S)Sisymbrium officinale Griffiths et al., 2001 (L)

15. 1-Methylbutyl Brassica oleracea var. italica Fisher et al., 2005 (I)

16. 2-Methylbutyl Armoracia lapathifolia Grob and Matile, 1980 (R)Brassica oleracea var. italica Lelario et al., 2012 (I)Cakile maritima Radwan et al., 2008 (A)

17. 3-Methylbutyl Arabidopsis thaliana Reichelt et al., 2002 (S)Armoracia lapathifolia Grob and Matile, 1980 (R)

18. 3-Methyl-3-butenyl Capparis linearis Kjaer and Wagnieres, 1965 (L)

19. 3-Methylpentyl Brassica oleracea var. italica Lelario et al., 2012 (I)Cardamine pratensis Agerbirk et al., 2010 (P)

20. 4-Methylpentyl Arabidopsis thaliana Reichelt et al., 2002 (S)Brassica oleracea var. italica Lelario et al., 2012 (I)Eruca sativa Cataldi et al., 2007 (L); Lelario et al., 2012 (L)

21. 2-Methyl-2-propenyl Brassica rapa Yang and Quiros, 2010 (L)Peltaria alliacea Daxenbichler et al., 1991 (S)

22. 3-butenyl Gluconapin Aurinia leucadea Blazevic et al., 2011 (A)Aurinia saxatilis Griffiths et al., 2001 (L)Brassica juncea Kaushik and Agnihotri, 1999(S)Brassica napus Griffiths et al., 2001 (L); Yasumoto et al., 2010

(S)Brassica oleracea var. botrytis Tian et al., 2005 (I)Brassica oleracea var. gemmifera Kushad et al., 1999 (A)Brassica oleracea var. italica Kushad et al., 1999; Rosa and Rodrigues, 2001

(I); Vallejo et al., 2002 (I); Du et al., 2008 (S)Brassica rapa subsp. sylvestris Barbieri et al., 2008 (Sh+I); Griffiths et al.,

2001 (L)Pachycladon novaezelandiae Voelckel et al., 2010 (P)Pringlea antiscorbutica Barillari et al., 2005c (S,L)

23. 1-Pentenyl Brassica juncea Tyagi, 2002 (S)

24. 4-Pentenyl Glucobrassicanapin Arabidopsis thaliana Reichelt et al., 2002 (S)Armoracia lapathifolia Grob and Matile, 1980 (R)Aurinia saxatilis Griffiths et al., 2001 (L)Brassica napobrassica Shaw et al., 1989 (R)Brassica napus Sang et al., 1984 (S); Koritsas et al., 1989 (L);

Birch et al., 1992 (R); Eberlein et al., 1998 (P);Griffiths et al., 2001 (L); Yasumoto et al., 2010(R)

Brassica oleracea var. italica Du et al., 2008 (S)Brassica oleracea var. capitata Cartea et al., 2008 (L)

Brassica rapa Carlson et al., 1987(L,R); Padilla et al., 2007(L)

Brassica rapa subsp. sylvestris Griffiths et al., 2001 (L); Barbieri et al., 2008(Sh+I)

Degenia velebitica De Nicola et al., 2011 (S)Lepidium peuvianum Li et al., 2001 (Sp)

25. 5-Hexenyl Armoracia lapathifoliaBrassica napusRaphanus sativus

Grob and Matile, 1980 (R)Kondo et al., 1985 (S)Kjaer et al., 1978 (S)

26. 6-Heptenyl Raphanus sativus Li et al., 2008 (Sp, L, R)

27.

2-Phenylethyl Gluconasturtiin/

phenethyl

Arabidopsis thaliana Reichelt et al., 2002 (S)Barbarea verna Barillari et al., 2001 (S)Barbarea vulgaris Griffiths et al., 2001 (L)Brassica oleracea var. italica Rosa and Rodrigues, 2001 (I)Brassica rapa Padilla et al., 2007 (L)Brassica rapa subsp. sylvestris Griffiths et al., 2001 (L); Barbieri et al., 2008

(Sh+I)Lepidium sativum Radwan et al., 2007 (S)

28. 3-Phenylpropyl Armoracia lapathifolia Grob and Matile, 1980 (R)

29. 4-Phenylbutyl Armoracia lapathifolia Grob and Matile, 1980 (R)

30. 3-(Methylsulfinyl)propyl Glucoiberin Brassica oleracea var. botrytis

Brassica oleracea var. acephala

Tian et al., 2005 (I); Bellostas et al., 2007a (Sp,S)Cartea et al., 2008 (L)

Brassica oleracea var. capitata Bellostas et al., 2007a (Sp, S); Cartea et al.,2008 (L)

Brassica oleracea var. gemmifera Tian et al., 2005 (Bud)Brassica oleracea var. italica Rosa and Rodrigues, 2001 (FH); West, 2002

(S); Vallejo et al., 2002 (I); Tian et al., 2005(Sp, I), Bellostas et al., 2007a (Sp, S); Du et al.,2008 (S)

Capparis spinosa Romeo et al., 2007 (S, L)Erysimum corinthium Al-Gendy et al., 2010 (S)Iberis amara Lazzeri and Manici, 2001 (P)Pachycladon exile Voelckel et al., 2010 (P)

31. 4-(Methylsulfinyl)butyl Glucoraphanin Arabidopsis thaliana Reichelt et al., 2002 (S)Brassica oleracea var. acephala Kushad et al., 2004; Cartea et al., 2008 (L);

Sarikamis et al., 2008 (L)Brassica oleracea var. botrytis

Brassica oleracea var. capitata

Tian et al., 2005 (C); Bellostas et al., 2007a (S,Sp)Cartea et al., 2008 (L)

Brassica oleracea var. gemmifera Tian et al., 2005 (A)Brassica oleracea var. italica Kushad et al., 1999 (I); Rosa and Rodrigues,

2001 (I); West, 2002 (S, Sp); Vallejo et al.,2002 (I); Fisher et al., 2005 (I); Tian et al.,2005 (Sp, I); Chuanphongpanich et al., 2006(S); Rochfort et al., 2006 (S); Trenerry et al.,2006 (S, I); Bellostas et al., 2007a (Sp); Du etal., 2008 (S); Barbieri et al., 2008 (Sh+I);Lelario et al., 2012 (I)

Cochlearia officinalis Griffiths et al., 2001 (L)Eruca sativa Cataldi et al., 2007 (S,L); Bennett et al., 2006

(L)Lepidium campestre Griffiths et al., 2001 (L)Pachycladon novaezelandiae Voelckel et al., 2010 (P)Pringlea antiscorbutica Barillari et al., 2005c (S,L)

32. 4-methylsulfinyl-3-butenyl Glucoraphenin Aurinia leucadea Blazevic et al., 2011 (A)Bunias orientalis Bennett et al., 2006 (S, R, L)Raphanus raphanistrum Griffiths et al., 2001 (L)Raphanus sativus Barillari et al., 2005b (Sp); Li et al., 2008 (Sp,

L, R)

33. 5-(Methylsulfinyl)pentyl Glucoalyssin Arabidopsis thaliana Reichelt et al., 2002 (S); Alvarez et al., 2008(Sp)

Aurinia leucadea Blazevic et al., 2011 (A)Aurinia saxatilis Griffiths et al., 2001 (L)Brassica oleracea var. botrytisBrassica oleracea var. capitata

Tian et al., 2005 (I)Cartea et al., 2008 (L)

Brassica oleracea gemmifera Tian et al., 2005 (Bud)Brassica oleracea var. italica Rosa and Rodrigues, 2001 (I); Vallejo et al.,

2002 (I); Tian et al., 2005 (Sp, I)Brassica rapa subsp. sylvestris Barbieri et al., 2008 (Sh+I)Degenia velebitica De Nicola et al., 2011 (A)Lepidium campestre Griffiths et al., 2001 (L)Lepidium peruvianum Li et al., 2001 (S, Sp)

34. 6-(Methylsulfinyl)hexyl Glucohesperin Arabidopsis thaliana Reichelt et al., 2002 (S); Brown et al., 2003 (S)Dithyrea wislizenii Montaut et al., 2009 (F)Hesperis matronalis Larsen et al., 1992 (P)Lepidium campestre Griffiths et al., 2001 (L)Pachycladon cheesemanii Voelckel et al., 2010 (P)Pachycladon exile Voelckel et al., 2010 (P)

35. 7-(Methylsulfinyl)heptyl Glucoibarin Arabidopsis thaliana Reichelt et al., 2002 (S); Brown et al., 2003 (S)Brassica oleracea var. italica Du et al., 2008 (S)Dithyrea wislizenii Montaut et al., 2009 (F)Pachycladon exile Voelckel et al., 2010 (P)Pachycladon cheesemanii Voelckel et al., 2010 (P)Pachycladon novaezelandiae Voelckel et al., 2010 (P)

36. 8-methylsulfinyloctyl- Glucohirustin Arabidopsis thaliana Brown et al., 2003 (S); Reichelt et al., 2002 (S);Alvarez et al., 2008 (Sp)

Pachycladon novaezelandiae Voelckel et al., 2010 (P)Rorippa indica Yamane et al., 1992 (R)Rorippa islandica Griffiths et al., 2001 (L)Rorippa silvestris Griffiths et al., 2001 (L)

37. 9-(Methylsulfinyl)nonyl Glucoarabin Arabis alpina Challenger, 1959 (S)Arabis nova Al-Shehbaz and Al-Shammary, 1987 (S)Camelina sativa Matthaus and Zubr, 2000 (S); Berhow et al.,

2008 (S)Drabopsis nuda Al-Shehbaz and Al-Shammary, 1987 (S)Rorippa indica Yamane et al., 1992 (R)Rorippa islandica Griffiths et al., 2001 (L)Rorippa silvestris Griffiths et al., 2001 (L)

38. 10-(Methylsulfinyl)decyl Glucocamelinin Arabis alpina Bennett et al., 2004b (S)Arabis arendsii Bennett et al., 2004b (S)Arabis caucasica Bennett et al., 2004b (S)Camelina sativa Kjaer et al., 1956b (S); Matthaus and Zubr,

2000 (S); Bennett et al., 2004b (S); Berhow etal., 2008 (S)

Rorippa indica Yamane et al., 1992 (R)

39. 11-(Methylsulfinyl)undecyl CH3SO(CH2)11 ̶ * Camelina microcarpa Daxenbichler et al., 1991 (S)Camelina sativa Matthaus and Zubr, 2000 (S); Berhow et al.,

2008 (S)

40. 3-(Methylsulfonyl)propyl Glucocheirolin Cochlearia species Dauvergne et al., 2006 (A)Erysimum corinthium Al-Gendy et al., 2010 (S, L)Rapistrum rugosum Lazzeri and Manici, 2001 (P)

41. 4-(Methylsulfonyl)butyl Glucoerysolin Erysimum corinthium Al-Gendy et al., 2010 (L, R)Erysimum allionii Bennett et al., 2004b (S)Erysimum perovskianum Bennett et al., 2004b (S)

42. 4-Methylsulfonyl-3-butenyl Raphanus sativus Cole, 1980 (S)

43. 5-(Methylsulfonyl)pentyl glucoerysihieracif-oliumin

Cakile maritima Rodman, 1976 (S)

44. 6-(Methylsulfonyl)hexyl Isatis microcarpa Emam and El-Moaty, 2009 (P)Pseuderucaria clavate Emam and El-Moaty, 2009 (P)Sisymbrium loeselii Bainard et al., 2009 (R, Sh)

45. 8-(Methylsulfonyl)octyl Brassica juncea Fabre et al., 1997 (S)Heliophila amplexicaulis Daxenbichler et al., 1991 (S)Sinapis arvensis Griffiths et al., 2001 (L)

46. 9-(Methylsulfonyl)nonyl Arabis turrita Daxenbichler et al., 1991 (S)Brassica juncea Fabre et al., 1997 (S)Heliophila amplexicaulis Daxenbichler et al., 1991 (S)Sinapis arvensis Griffiths et al., 2001 (L)Thlaspi arvense Lee et al., 2008 (P)

47. 10-(Methylsulfonyl)decyl Arabis turrita Daxenbichler et al., 1991 (S); Bennett et al.,2004b (S)

48. 6-methylsulfonyl-6-hydroxyhexyl

CH3SO2 ̶ CH(OH) ̶ (CH2)5 ̶ C ̶ * Isatis microcarpa Emam and El-Moaty, 2009 (P)

49. 2-(Methylthio)ethyl Glucoviorylin Armoracia lapathifolia Grob and Matile, 1980 (R)

50. 3-(Methylthio)propyl GlucoiberverinArabidopsis thalianaBrassica oleracea var. acephala

Reichelt et al., 2002 (S)Cartea et al., 2008 (L)

Brassica oleracea var. botrytis Bellostas et al., 2007a (S, Sp)Brassica oleracea var. capitata Sones et al., 1984a (I); Bellostas et al., 2007a

(S, Sp); Cartea et al., 2008 (L)Brassica oleracea var. italica West, 2002 (Sp); Bellostas et al., 2007a (S, Sp)Descurainia sophia Chen and Guan, 2006 (S)Pachycladon exile Voelckel et al., 2010 (P)Pachycladon novaezelandiae Voelckel et al., 2010 (P)

51. 4-(Methylthio)butyl Glucoerucin Arabidopsis thaliana Reichelt et al., 2002 (S)Brassica oleracea var. botrytis Tian et al., 2005 (I); Bellostas et al., 2007a (S,

Sp)Brassica oleracea var. capitata Bellostas et al., 2007a (S, Sp)Brassica oleracea var. italica West, 2002 (S, Sp); Tian et al., 2005 (S, I);

Chuanphongpanich et al., 2006 (S); Bellostas etal., 2007a (S, Sp)

Degenia velebitica De Nicola et al., 2011 (S)Diplotaxis spp. Bennett et al., 2006 (S, R, L)Eruca sativa Gmelin and Schluter, 1970 (S); Bennett et al.,

2006 (S, R); Cataldi et al., 2007 (S,L)Pachycladon novaezelandiae Voelckel et al., 2010 (P)Pringlea antiscorbutica Barillari et al., 2005c (S)Raphanus raphanistrum Malik et al., 2010 (R, F)

52. 5-(Methylthio)pentyl Glucoberteroin Arabidopsis thaliana Hogge et al., 1988 (S); Reichelt et al., 2002 (S);Alvarez et al., 2008 (Sp)

Brassica rapa Carlson et al., 1987(R)Cochlearia officinalis Griffiths et al., 2001 (L)Degenia velebitica De Nicola et al., 2011 (S, L)Dithyrea wislizenii Montaut et al., 2009 (F)Hesperis matronalis Daxenbichler et al., 1991 (S)Raphanus sativus Kjaer et al., 1978 (R)

53. 6-(Methylthio)hexyl Glucolesquerellin Arabidopsis thaliana Reichelt et al., 2002 (S)Alyssum lobularia procumbens Bennett et al., 2004b (S)Alyssum minimum Bennett et al., 2004b (S)Dithyrea wislizenii Montaut et al., 2009 (F)Hesperis matronalis Bennett et al., 2004b (S)Lepidium pedicillosum Bennett et al., 2004b (S)Lepidium strongylophyllum Bennett et al., 2004b (S)Lobularia maritima Bennett et al., 2004b (S)

54. 7-methylthioheptyl- Arabidopsis thaliana Brown et al., 2003 (S); Reichelt et al., 2002 (S);Alvarez et al., 2008 (Sp)

Pachycladon novaezelandiae Voelckel et al., 2010 (P)

55. 8-methylthiooctyl-Arabidopsis thaliana Brown et al., 2003 (S); Reichelt et al., 2002 (S);

Alvarez et al., 2008 (Sp)Arabis stelleri Bennett et al., 2004b (S)

56. 9-(Methylthio)nonylArabis alpina Bennett et al., 2004b (S)Arabis blepharophylla Bennett et al., 2004b (S)Arabis caucasia Bennett et al., 2004b (S)Arabis hirsuta Daxenbichler et al., 1991 (S)

57. 10-(Methylthio)decyl Arabis amplexicaulis Daxenbichler et al., 1991 (S)

58. 4-Methylthio-3-butenyl Dehydroerucin/

Glucoraphasatin

Raphanus sativus Barillari et al., 2005b (Sp); Li et al., 2008 (Sp,L, R)

Isatis microcarpa Emam and El-Moaty, 2009 (P)Pseuderucaria clavate Emam and El-Moaty, 2009 (P)Raphanus raphanistrum Griffiths et al., 2001 (L)

59. 2-(Benzoyloxy)ethyl Moricandia arvensis Daxenbichler et al., 1991 (S)

60. 3-(benzoyloxy)propyl- Glucomalcomiin Arabidopsis thaliana Brown et al., 2003 (S); Reichelt et al., 2002 (S);Alvarez et al., 2008 (Sp)

Malcomia maritima Bennett et al., 2004b (S)

61. 4-benzoyloxybutyl- Arabidopsis thaliana Brown et al., 2003 (S); Reichelt et al., 2002 (S);Alvarez et al., 2008 (Sp)

62. 5-(Benzoyloxy)pentyl Arabidopsis thaliana Hogge et al., 1988 (L, S); Reichelt et al., 2002(S)

63. 6-(Benzoyloxy)hexyl Arabidopsis thaliana Hogge et al., 1988 (L, S); Reichelt et al., 2002(S); Alvarez et al., 2008 (Sp)

64. 2-Benzoyloxy-1-ethylethyl Glucobenzsisaustr-icin

Sisymbrium austriacum Kjaer and Christensen, 1962b (S)

65. 2-Benzoyloxy-1-methylethyl

Glucobenzosisym-brin

Sisymbrium austriacum Kjaer and Christensen, 1961 (S); Daxenbichler

et al., 1991 (S)

66. 2-Hydroxyethyl Capparis masaikai Hu et al., 1989 (S)

67. 2-Hydroxypropyl Armoracia lapathifolia Grob and Matile, 1980 (R)

68. 3-Hydroxypropyl- Arabidopsis thaliana Brown et al., 2003 (S); Reichelt et al., 2002 (S);Alvarez et al., 2008 (Sp)

Erysimum hieracifolium Daxenbichler et al., 1980 (S)Malcolmia maritima Daxenbichler et al., 1980 (S)

69. 3-Hydroxybutyl Armoracia lapathifolia Grob and Matile, 1980 (R)Capparis flexuosa Kjaer and Schuster, 1971 (L)

70. 4-Hydroxybutyl- Arabidopsis thaliana Brown et al., 2003 (S); Reichelt et al., 2002 (S);Alvarez et al., 2008 (Sp)

71. 2-Hydroxybenzyl Reseda odorata Olsen and Sorensen, 1979 (S)

72. 3-Hydroxybenzyl Glucolepigramin Lepidium peuvianum Li et al., 2001 (Sp)Lepidium vesicarium Daxenbichler et al., 1991 (S)Reseda media Olsen and Sorenson, 1979 (S, L)Limnanthes floccosa Velasco et al., 2011 (S)

73. 4-Hydroxybenzyl Sinalbin Brassica juncea Fabre et al., 1997 (S)Bunias orientalis Bennett et al., 2006 (S, R, L)Cardamine pratensis Agerbirk et al., 2010 (P)Lepidium peuvianum Li et al., 2001 (Sp)Sinapis alba Robiquet and Boutron, 1831 (S)Sinapis arvensis Griffiths et al., 2001 (L)Tropaeolum majus Griffiths et al., 2001 (L)Tropaeolum tuberosum Ortega et al., 2006 (P)

74. 2-hydroxy-2-methylbutyl Glucocleomin Dentaria laciniata Daxenbichler et al., 1991 (S)Capparis ovate var. palaestina Ahmed et al., 1972 (P)Capparis spinosa Kjaer and Thomsen, 1962 (S); Romeo et al.,

2007 (S,L)Cleome chelidonii Songsak and Lockwood, 2002 (S)Cleome hassleriana Lazzeri and Manici, 2001 (P)

75. 1-Methyl-2-hydroxyethyl Glucosisymbrin Coluteocarpus vesicaria Al-Shehbaz and Al-Shammary, 1987 (S)Dentaria laciniata Daxenbichler et al., 1991 (S)Euclidium syriacum Al-Shehbaz and Al-Shammary, 1987 (S)Torularia torulosa Al-Shehbaz and Al-Shammary, 1987 (S)

76. 1-Ethyl-2-hydroxyethyl Glucosisaustricin Cleome diandra Daxenbichler et al., 1991 (S)Sisymbrium austriacum Kjaer and Christensen, 1962a (S)

77. 1-(Hydroxymethyl)propyl Cardamine pratensis Agerbirk et al., 2010 (P)Coluteocarpus vesicaria Al-Shehbaz and Al-Shammary, 1987 (S)

78. 2-Hydroxy-2-methylpropyl Glucoconringiin Bretschneidera sinensis Boufford et al., 1989 (L)Cochlearia officinalis Challenger, 1959 (S); Griffiths et al., 2001 (L)Conringia orientalis Challenger, 1959 (S)Erysimum orientale Kjaer, 1960 (S)Moringa stenopetala Mekonnen and Drager, 2003 (S)

79. 2-Hydroxy-4-pentenyl Gluconapoleiferin Brassica napobrassica Shaw et al., 1989 (R)Brassica napus Sang et al., 1984 (S, L, R); Koritsas et al., 1989

(L); Birch et al., 1992 (R); Elfakir et al., 1992(S); Hrnc et al., 1998 (S); Eberlein et al., 1998(P)

Brassica rapa Padilla et al., 2007 (L)Brassica rapa silvestris Griffiths et al., 2001 (L)Brassica oleracea var. italica Kushad et al., 1999 (I)

80. 2(R)-2-Hydroxy-2-phenylethyl

Glucosibarin Barbarea australis Agerbirk and Olsen, 2011 (S)Barbarea bracteosa Agerbirk and Olsen, 2011 (S)Barbarea intermediata Agerbirk and Olsen, 2011 (S)Barbarea plantaginae Agerbirk and Olsen, 2011 (S)Barbarea stricta Agerbirk and Olsen, 2011 (S)Barbarea verna Agerbirk and Olsen, 2011 (S)Barbarea vulgaris Griffiths et al., 2001 (L); Bennett et al., 2004b

(S); Agerbirk and Olsen, 2011 (S)Brassica oleracea var. italica Rosa and Rodrigues, 2001 (I)Reseda luteola Bennett et al., 2004b (S)

81. 2(S)-2-Hydroxy-2-phenylethyl

Glucobarbarin Barbarea australis Agerbirk and Olsen, 2011 (S)Barbarea bracteosa Agerbirk and Olsen, 2011 (S)Barbarea intermediata Agerbirk and Olsen, 2011 (S)Barbarea plantaginae Agerbirk and Olsen, 2011 (S)Barbarea stricta Agerbirk and Olsen, 2011 (S)Barbarea verna Agerbirk and Olsen, 2011 (S)Barbarea vulgaris Bennett et al., 2004b (S); Agerbirk and Olsen,

2011 (S)Reseda luteola Bennett et al., 2004b (S)

82. 2(S)-2-Hydroxy-3-butenyl Epiprogoitrin Brassica oleracea var. acephalaBrassica oleracea var. capitataCrambe abyssinica

Cartea et al., 2008 (L)Cartea et al., 2008 (L)Lazzeri and Manici, 2001 (P)

Pachycladon cheesemanii Voelckel et al., 2010 (P)Pachycladon novaezelandiae Voelckel et al., 2010 (P)Radix isatidis Xie et al., 2011 (P)Raphanus sativus Li et al., 2008 (Sp, L, R)

83. 2(R)-2-Hydroxy-3-butenyl ProgoitrinArabidopsis thaliana Reichelt et al., 2002 (S)Brassica napus VanEtten and Daxnbichler, 1971 (L); Yasumoto

et al., 2010 (S); Griffiths et al., 2001 (L)Brassica oleracea Zhou et al., 2005 (S)Brassica oleracea var. acephalaBrassica oleracea var. capitata

Kushad et al., 2004; Cartea et al., 2008 (L)Cartea et al., 2008 (L)

Brassica oleracea var. gemmiferra Heaney and Fenwick, 1980 (Bud); Mc Milan etal., 1986 (Bud); Slominski and Campbell, 1989(Bud); Van Doorn et al., 1999; Tian et al., 2005(Bud)

Brassica oleracea var. italica Slominski and Campbell, 1989 (I); West, 2002(Sp); Vallejo et al., 2002 (I); Tian et al., 2005(Sp, I); Bellostas et al., 2007a (S, Sp)

Brassica rapa Carlson et al., 1987; Griffiths et al., 2001 (L)Crambe abyssinica VanEtten and Daxnbichler, 1971 (L)Eruca sativa Cataldi et al., 2007 (L)Erysimum corinthium Al-Gendy et al., 2010 (R)Radix isatidis Xie et al., 2011 (P)

84. 4-Hydroxyindol-3-ylmethyl 4-Hydroxyglucobrassic-in

Arabidopsis thaliana Reichelt et al., 2002 (S)Aurinia saxatilis Griffiths et al., 2001 (L)Azima tetracantha Bennett et al., 2004a (R)Brassica oleracea var. acephala

Brassica oleracea var. capitata

Cartea et al., 2008 (L); Sarikamis et al., 2008(L)Cartea et al., 2008 (L)

Brassica oleracea var. italica Rosa and Rodrigues, 2001 (I); Vallejo et al.,2002 (I); Chuanphongpanich et al., 2006 (S)

Brassica rapa subsp. silvestris Griffiths et al., 2001 (L)Eruca sativa Cataldi et al., 2007 (L)Pachycladon cheesemanii Voelckel et al., 2010 (P)Pachycladon novaezelandiae Voelckel et al., 2010 (P)Raphanus sativus Li et al., 2008 (Sp, L, R)

85. 1-Sulfo-indol-3-ylmethyl Glucobrassicin-1-sulfate

Isatis tinctoria Elliott and Stowe, 1970 (Sp)

86. 3,4-Dihydroxybenzyl Glucomatronalin Hesperis matronalis Larsen et al., 1992 (P)Bretschneidera sinensis Boufford et al., 1989 (L)

87. 3,4-Dimethoxybenzyl Heliophila longifolia Daxenbichler et al., 1991 (S)Hesperis matronalis Larsen et al., 1992 (P)Pentadiplandra brazzeana De Nicola et al., 2012 (L)

88. 2-Methoxybenzyl Lepidium peruvianum Li et al., 2001 (S, Sp)

89. 3-Methoxybenzyl Glucolimnanthin Limnanthes alba Velasco et al., 2011 (S)Limnanthes douglasii Kjaer, 1960 (S)Limnanthes floccosa Velasco et al., 2011 (S)Limnanthes gracilis Velasco et al., 2011 (S)Limnanthes montana Velasco et al., 2011 (S)Pentadiplandra brazzeana De Nicola et al., 2012 (R)Tropaeolum tuberosum Ortega et al., 2006 (P)

90. 4-Methoxybenzyl Glucoaubrietin Aubrietia hybrida Kjaer et al., 1956a (L, S)Degenia velebitica De Nicola et al., 2011 (S)Lepidium peuvianum Li et al., 2001 (Sp)Pentadiplandra brazzeana De Nicola et al., 2012 (R,S)Tropaeolum tuberosum Ramallo et al., 2004 (T)

91. 2-(4-Methoxyphenyl)-2,2-dimethylethyl

Pentadiplandra brazzeana De Nicola et al., 2012 (S)

92. 2-(4-Methoxyphenyl)-2-hydroxyethyl

Arabis hirsuta Daxenbichler et al., 1991 (S); Kjaer andSchuster, 1972 (S)

93. 1-Methoxyindol-3-ylmethyl Neoglucobrassicin Arabidopsis thaliana Reichelt et al., 2002 (S); Alvarez et al., 2008(Sp)

Azima tetracantha Bennett et al., 2004a (R,S)Brassica oleracea var. acephala

Brassica oleracea var. capitata

Cartea et al., 2008 (L); Sarikamis et al., 2008(L)Cartea et al., 2008 (L)

Brassica oleracea var. italica Rosa and Rodrigues, 2001 (I); Vallejo et al.,2002 (I); Tian et al., 2005 (Sp, I);Chuanphongpanich et al., 2006 (S); Barbieri etal., 2008 (Sh+I)

Brassica rapa subsp. sylvestris Barbieri et al., 2008 (Sh+I)Capparis spinosa Ahmed et al., 1972 (R)Pachycladon novaezelandiae Voelckel et al., 2010 (P)Raphanus sativus Li et al., 2008 (Sp, L, R)

94. 4-Methoxyindol-3-ylmethyl 4-methoxy-

glucobrassicin

Arabidopsis thaliana Reichelt et al., 2002 (S); Alvarez et al., 2008(Sp)

Aurinia saxatilis Griffiths et al., 2001 (L)Barbarea vulgaris Griffiths et al., 2001 (L)Brassica oleracea var. acephala Sarikamis et al., 2008 (L)Brassica oleracea var. botrytisBrassica oleracea var. capitata

Tian et al., 2005 (I)Cartea et al., 2008 (L)

Brassica napus Griffiths et al., 2001 (L)Brassica oleracea var. capitata Song et al., 1984 (Bud)Brassica oleracea gemmifera Tian et al., 2005 (Bud)Brassica oleracea var. italica Rosa and Rodrigues, 2001 (I); Vallejo et al.,

2002 (I); Tian et al., 2005 (Sp, I);Chuanphongpanich et al., 2006 (S); Barbieri etal., 2008 (Sh+I)

Brassica rapa subsp. sylvestris Griffiths et al., 2001 (L); Barbieri et al., 2008(Sh+I)

Capparis spinosa Ahmed et al., 1972 (R)Eruca sativa Cataldi et al., 2007 (S, L)Lepidium peruvianum Li et al., 2001 (S, Sp)Raphanus raphanistrum Griffiths et al., 2001 (L)Rorippa silvestris Griffiths et al., 2001 (L)

95. 3-Methoxycarbonylpropyl Glucoerypestrin Erysimum aucherianum Al-Shehbaz and Al-Shammary, 1987 (S)Erysimum filifolium Al-Shehbaz and Al-Shammary, 1987 (S)Erysimum rupestre Kjaer, 1960 (S); Chisholm, 1973 (L)

96. 1-Acetyl-indol-3-ylmethyl 1-Acetyl-

glucobrassicin

Brassica oleracea var. acephala Kushad et al., 2004

97. 3-Hydroxy-6-(methylsulfinyl)hexyl

Erysimum rhaeticum Kjaer and Schuster, 1973 (S)

98. 3-Hydroxy-5-(methylsulfinyl)pentyl

Descurainia sophiaErysimum virgatum

Chen and Guan, 2006 (S)Kjaer and Schuster, 1970 (S)

99. 3-Hydroxy-6-(methylsulfonyl)hexyl

Erysimum rhaeticum Kjaer and Schuster, 1973 (S)

100. 3-Hydroxy-5-(methylsulfonyl)pentyl

Descurainia sophia Chen and Guan, 2006 (S)Erysimum virgatum Kjaer and Schuster, 1970 (S)

101. 3-Hydroxy-6-(methylthio)hexyl

Erysimum rhaeticum Kjaer and Schuster, 1973 (S)

102. 3-Hydroxy-5-(methylthio)pentyl

Erysimum hieracifolium Kjaer and Schuster, 1970 (S)Armoracia lapathifolia Grob and Matile, 1980 (R)

103. 3-(hydroxymethyl)pentyl Cardamine pratensis Agerbirk et al., 2010 (S)

104. 4-mercaptobutyl Diplotaxis spp. Bennett et al., 2006 (L)Eruca sativa Bennett et al., 2002 (L); Kim and Ishii, 2006

(L); Cataldi et al., 2007 (L)

105. Indol-3-ylmethyl Glucobrassicin Arabidopsis thaliana Brown et al., 2003 (S); Reichelt et al., 2002 (S);Alvarez et al., 2008 (Sp)

Barbarea vulgaris Griffiths et al., 2001 (L)Brassica napus Yasumoto et al., 2010 (R)Brassica oleracea var. acephala Kushad et al., 1999; Cartea et al., 2008 (L);

Sarikamis et al., 2008 (L)Brassica oleracea var. botrytis Tian et al., 2005 (I)Brassica oleracea var. capitata Slominski and Campbell, 1989 (Bud); Sones et

al., 1984a (Bud); Sang et al., 1984 (S); Carteaet al., 2008 (L)

Brassica oleracea var. gemmifera Tian et al., 2005 (Bud)Brassica oleracea var. italica Kushad et al., 1999 (I); Rosa and Rodrigues,

2001 (I); Vallejo et al., 2002 (I); Tian et al.,2005 (S, I); Barbieri et al., 2008 (Sh+I)

Brassica rapa subsp. sylvestris Barbieri et al., 2008 (Sh+I); Griffiths et al.,2001 (L)

Capparis spinosa Ahmed et al., 1972 (R)Cleome spinosa Griffiths et al., 2001 (L)Isatis tinctoria Griffiths et al., 2001 (L)Lepidium campestre Griffiths et al., 2001 (L)Lepidium peruvianum Li et al., 2001 (S, Sp)Pentadiplandra brazzeana De Nicola et al., 2012 (L)Raphanus raphanistrum Griffiths et al., 2001 (L)Raphanus sativus Li et al., 2008 (Sp, L, R)Reseda luteola Griffiths et al., 2001 (L)Tropaeolum majus Griffiths et al., 2001 (L)

106. 4-Oxoheptyl Glucocapangulin/glucopangulin

Capparis ovate var. palaestina Ahmed et al., 1972 (P)Capparis salicifolia Kjaer and Thomsen, 1963a (S)Capparis spinosa var. aegyptia Ahmed et al., 1972 (P)Capparis spinosa var. deserti Ahmed et al., 1972 (P)

107. 5-Oxoheptyl Gluconorcappasalin Capparis ferruginea Brown and Staurt, 1968 (P)Capparis flexuosa Brown and Staurt, 1968 (P)Capparis salicifolia Kjaer and Thomsen, 1963b (S)

108. 5-Oxooctyl Glucocappasalin Capparis salicifolia Kjaer and Thomsen, 1963a (S)Descurainia sophia Chen and Guan, 2006 (S)

109. 4-Oxopentyl/ 3-(Methylcarbonyl)propyl

Erysimum corinthium Al-Gendy et al., 2010 (L)

110. 3,4,5-Trimethoxybenzyl Coronopus squamatus Daxenbichler et al., 1991 (S); Bennett et al.,2004b (S)

Lepidium hyssopifolium Kjaer et al., 1971 (P)Lepidium sordidum Kjaer and Wagniere, 1971 (P)

111. 4,5,6,7-Tetrahydroxydecyl Capparis grandis Gaind et al., 1975 (R)

112. 2-(α-L-Rhamnopyranosyloxy)benzyl

Reseda lutea Bennett et al., 2004b (S)Reseda odorata Olsen and Sorensen, 1979 (F)

113. 4-(α-L-Rhamnopyranosyloxy)benzyl

Moringa oleifera Bennett et al., 2003 (S, R, B)Moringa stenopetala Asres, 1995 (L)Thlaspi perfoliatum Al-Shehbaz and Al-Shammary, 1987 (S)

114. 3-O-Apiosylglucomatronalin

Hesperis matronalis Larsen et al., 1992 (P)

115. 3-O-Apiosylglucomatronalin3,4-dimethoxybenzoyl ester

Hesperis matronalis Larsen et al., 1992 (P)

116. 4-(4’

-O-Acetyl-α -L-rhamnopyranosyloxy)benzyl

Moringa peregrina Kjaer et al., 1979 (S)

117. 2-( α-L-Arabinopyranosyloxy)-2-phenylethyl

Sesamoides canescens Olsen et al., 1981 (L)

118. 4-(β-D-Glucopyranosyldisulfanyl)butyl

Eruca sativa Kim et al., 2004 (L)Eruca sativa Cataldi et al., 2007 (L)

119. 6’-isoferuloyl-(R)-2-hydroxy-2-phenylethyl

R' = (R)-2-hydroxy-2-phenylethyl

Barbarea vulgaris subsp. arcuata Agerbirk and Olsen, 2011 (S, L, F)Barbarea vulgaris subsp. vulgaris Agerbirk and Olsen, 2011 (S)

120. 6’-isoferuloyl-(S)-2-hydroxy-2-phenylethyl

R' = (S)-2-hydroxy-2-phenylethyl

Barbarea vulgaris subsp. arcuata Agerbirk and Olsen, 2011 (S)Barbarea vulgaris subsp. vulgaris Agerbirk and Olsen, 2011 (S)

121. 6’-isoferuloyl-phenethyl

R' = phenylethyl

Barbarea vulgaris subsp. arcuata Agerbirk and Olsen, 2011 (S)Barbarea australis Agerbirk and Olsen, 2011 (S)Barbarea bracteosa Agerbirk and Olsen, 2011 (S)Barbarea plantaginae Agerbirk and Olsen, 2011 (S)Barbarea verna Agerbirk and Olsen, 2011 (S)

122. 6’-isoferuloyl-indol-3-yl-methyl

R' = indol-3-yl-methyl

Barbarea plantaginae Agerbirk and Olsen, 2011 (S)Barbarea vulgaris subsp. arcuata Agerbirk and Olsen, 2011 (S)

▪ A: Aerial plant parts; B: Bark; F: Flowers; Fr = Fruit, I: Inflorescence; L: Leaves; P: Whole Plant; R: Roots; S: Seeds; Sh: Shoot; Sp: Sprouts; T: Tubers▪ Structures of glucosinolates 114 and 115 are not available in literature*Represents the core structure of glucosinolate:

Review of Literature

10

2.1 Hydrolytic products of glucosinolates

Numerous explorations have been focused on the glucosinolate composition of

cruciferous seeds (Daxenbichler et al., 1991). However, the information in current literature

regarding the kinds and contents of isothiocyanates (ITCs) in seeds is somewhat ambiguous

(You et al., 2008). The reason might be the high volatility of these hydrolytic products.

However, some researchers have extracted different hydrolytic products of glucosinolates using a

variety of non-polar solvents like n-hexane, methanol, ethyl acetate, dimethyl sulfoxide,

dimethylformamide, acetonitrile, ether and dichloromethane etc. (Clapp et al., 1959; Kyung et

al., 1995; Fahey et al., 1997; Nakamura et al., 2001; Al-Gendy and Lockwood, 2003; Vaughn

and Berhow, 2005; Jiang et al., 2006). Liang et al. (2005) tested four different solvents viz.

methylene chloride, ethyl acetate, chloroform and hexane for extraction of sulforaphane from

Brassica oleracea seeds. The largest amount of sulforaphane was extracted by methylene

chloride, followed by ethyl acetate. Hexane could not extract detectable amount of sulforaphane.

However, extraction with ethyl acetate showed the least amount of contaminants. You et al.

(2008) attempted to study the isothiocyanate profile of seeds of some Chinese Brassica species.

They used the defatted seedmeal, which was extracted with phosphate buffer and

dichloromethane. Allyl ITC (2-propenyl), 3-butenyl ITC, iberverin (3-methylthiopropyl), erucin

(4-methylthiobutyl), iberin (3-methylsulphinylpropyl), sulforaphane (4-methylsulphinyl-butyl),

phenethyl ITC, dehydroerucin (4-methylthio-3-butenyl) and goitrin (L-5-vinyloxazolidine-2-

thione) were the major isothiocyanates detected in different cultivars of Brassica. Some nitriles

and other chemicals that degraded from these isothiocyanates were also observed.

High hydrostatic pressure (HHP) treatment, a fast growing nonthermal technology, is a

promising approach to obtain more ITCs in Brassica crops as it brings the myrosinase and

glucosinolate in contact with each other more effectively (Van Eylen et al., 2007). The study

conducted by Van Eylen et al. (2009) showed that treating broccoli with high pressure (100 to

500 MPa) at moderate temperatures (20 to 40°C), promotes the conversion of glucosinolates into

ITCs, which can be then extracted with suitable solvents. Amplification of allyl isothiocyanate in

red cabbage using HHP treatment was performed at four different pressures (100, 200, 300, and

400 MPa) for 10 minutes, followed by incubation and extraction with n-hexane. Amount of allyl

ITC was found to be 39.6 µmol/kg of fresh weight with 400 MPa HHP treatment, which was 6.4

Review of Literature

11

times higher than that from HHP-untreated controls (Koo et al., 2011a). Similar study was done

for amplifying the sulforaphane content of broccoli (Koo et al., 2011b). The highest quantity of

sulforaphane was found to be 99.7 µmol/kg fresh weight at 400 MPa HHP treatment followed by

standing at 60°C. HHP treatment and incubation temperature were found to be crucial for the

improvement of sulforaphane content.

Supercritical fluid extraction (SCFE) is another commonly used method for extraction

of ITCs. Kim et al. (2007) attempted to extract allyl isothiocyanate from freeze dried wasabi

(Wasabia japonica), using supercritical CO2 with ethanol as co-solvent. Instability of allyl ITC in

ethanol was the major drawback of this method. Li et al. (2010a) tried to extract allyl

isothiocyanate from roots, stem and leaves of Wasabia japonica using ethanol, hexane and ether

as trapping solvents. Hexane was found to be the best solvent in which, allyl ITC remained intact

for 2 weeks. They reported the yields of 368, 39 and 11 mg/100g of roots, stem and leaves,

respectively at 35°C and 20 MPa pressure. Wu et al. (2009) compared the hydrodistillation and

SCFE for extraction of allyl ITC from Armoracia rusticana, and observed no significant

difference for allyl ITC extraction rate between these two methods.

The highly electrophilic central carbon atom of the N=C=S group can undergo

successive nucleophilic additions, with reagents containing two sulfhydryl groups on adjacent

carbon atoms to form a cyclic thio-carbonyl product. This releases the nitrogen atom as a

primary amine (Zhang et al., 1992). This property of ITCs has been utilized for their

determination from different sources. Zhang et al. (1996) employed 1,2-benzenedithiol as the

vicinal dithiol reagent and measured the final cyclocondensation product i.e. 1,3-Benzodithiole-

2-thione by HPLC with photodiode array detection. Various analytical methods have been used

for the quantitative determination of these hydrolytic products like analytical HPLC (Matthaus

and Fiebig, 1996; Liebes et al., 2001; Sivakumar et al., 2007; Campas-Baypoli et al., 2010),1HNMR,13CNMR, elemental analysis and mass spectrometry (Combourieu et al., 2001; Song et

al., 2006), LC-MS/MS (Ji and Morris, 2003; Yan and Morris, 2003), GC-MS (Al-Gendy and

Lockwood, 2003; Rohloff and Bones, 2005; Blazevic and Mastelic, 2009) and micellar

electrokinetic capillary chromatography (Bellostas et al., 2006).

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12

2.2 Biological activities

Glucosinolates comprise a distinctive group of bioactive compounds, possessing a wide

array of bioactivities. They are not only important to plants as they act as their major defense

system but also to humans in many ways. Natural products are in demand nowadays for the

control of pathogens due to the detrimental effects of synthetic chemicals and orthodox practices.

Hydrolytic products of glucosinolates are a preferred choice among farmers for the control of

pathogens as they are safer fumigants in pest control. These natural products are considered to be

fully biodegradable and non-toxic, encouraging their use as potential allelochemicals in

agriculture. However, their potential as a significant alternative in cancer management has

become a subject of active research leading to many analytical explorations. A brief review of

the biological activities of glucosinolates derived products is presented below:

2.2.1 Bactericidal

Glucosinolate-myrosinase system plays an important defensive role against a wide range

of pathogenic microorganisms. Primarily, reports regarding bactericidal activity of ITCs were

restricted to human pathogens. Benzyl ITC has been used as an antibiotic to treat infections of

respiratory and urinary tracts (Mennicke et al., 1988). There are many reports in literature, which

show that ITCs have the capacity to kill multiple strains of Helicobacter pylori, which causes

peptic ulcers and stomach cancer (Normark et al., 2003). Fahey et al. (2002) demonstrated that

purified sulforaphane, hydrolytic product of glucoraphanin, inhibited the growth and killed

multiple strains of Helicobacter pylori in the test tube and in tissue culture, including antibiotic

resistant strains. Haristoy et al. (2003) reported that sulforaphane administration for 5 days

eradicated H. pylori from 8 out of 11 xenografts of human gastric tissue implanted in immune-

compromised mice. Efficacy of 12 different ITCs was tested on 25 strains of this bacterium by

Haristoy et al. (2005). Almost, all the ITCs showed promising effect against H. pylori, indicating

their potential for eradication of this bacterial strain.

Fenwick et al. (1983) and Smelt et al. (1989) reported that gram negative bacteria are

generally less susceptible than gram positive bacteria to ITCs. Jang et al. (2010) investigated

antibacterial activities of 4 ITCs (3-butenyl ITC, 4-pentenyl ITC, 2-phenylethyl ITC and benzyl

Review of Literature

13

ITC) against some Gram-positive bacteria (Bacillus cereus, Bacillus subtilis, Listeria

monocytogenes, and Staphylococcus aureus) and Gram-negative bacteria (Aeromonas

hydrophila, Pseudomonas aeruginosa, Salmonella choleaesuis, Salmonella enterica, Serratia

marcescens, Shigella sonnei, and Vibrio parahaemolyticus). Benzyl and 2-phenylethyl ITCs

exhibited higher activity against most of the pathogenic bacteria than 3-butenyl and 4-pentenyl

ITCs. The ITCs were found to be more effective against Gram-positive bacteria as compared to

Gram-negative bacteria. Sofrata et al. (2011) evaluated the effects of root extracts of Salvadora

persica, containing benzyl ITC and commercially available benzyl ITC against various Gram-

positive and Gram-negative bacterial strains. They observed that benzyl ITC was very effective

against Gram-negative oral pathogens involved in periodontal disease. The toxicity and range of

activity of hydrolytic products of glucosinolate vary with the type of organism. Brassica napus

seed meal extracts inhibited the growth of Aphanomyces euteiches (Smolinska et al., 1997) but

slightly enhanced the growth of propionibacterium (Rutkowski et al., 1972). Ammonium

thiocyanate inhibits bacterial growth in soil but stimulates fungi at concentrations > 250 µg g-1

(Smith et al., 1945).

The bactericidal effects of allyl ITC has been well documented against a number of

pathogenic bacteria (Inoue et al., 1983; Isshiki et al., 1992; Delaquis and Sholberg, 1997; Lin et

al., 2000; Shin et al., 2004; Pires et al., 2009; Wang et al., 2010). Escherichia coli O157:H7, an

important pathogen responsible for causing serious disease in humans including hemolytic

uremic syndrome and hemorrhagic colitis (Chacon et al., 2006), can be effectively inhibited by

allyl ITC (Park et al., 2000; Nadarajah et al., 2005; Chacon et al., 2006; Luciano and Holley,

2009). Delaquis and Mazza (1995) proposed that allyl ITC might cause inactivation of various

intracellular enzymes of the pathogen, by oxidative breakdown of –S-S- bridges present in the

enzymes. In an attempt to study the antibacterial mechanism of allyl ITC, Lin et al. (2000)

compared the allyl ITC with streptomycin, penicillin G, and polymyxin B, antibiotics with

known antibacterial mechanisms. Allyl ITC caused metabolite leakages, measurable increases in

3-galactosidase activity and reduction of viable bacteria in the similar way as polymixin B.

Consequently, allyl ITC was hypothesized to show its bactericidal effect by damaging the

bacterial cell membrane and causing leakage of essential cellular metabolites.

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14

2.2.2 Fungicidal

Chan and Close (1987); Vierheilig and Ocampo (1990); Gamliel and Stapleton (1993);

and Angus (1994) demonstrated that members of family Brassicaceae have the ability to control

the growth of phytopathogenic fungi. Walker et al. (1937) reported the antifungal activity of

mustard oils and of cruciferous plant extracts containing allyl and phenethyl ITCs, which was

confirmed by Hooker et al. (1943). In addition, Greenhalgh and Mitchell (1976), Gamliel and

Stapleton (1993) reported that ITCs released from cabbage tissues are toxic towards Pernospora

parasitica, Pythium ultimum and Sclerotium rolfsii. Latter on in 1994, Angus reported that

volatile compounds from macerated Brassica root tissue inhibited the fungal pathogen of wheat,

Gaeumannomyces graminis. Mari et al. (1993, 1996) reported the protective effect of enzymatic

hydrolysis products of glucosinolates against some post harvest pathogenic fungi and thus

increasing the shelf life of fruits.

Eleven glucosinolates and their enzymatic hydrolysis products were tested in vitro

against Fusarium culmorum (Manici et al., 1997). The results showed that parent glucosinolates

showed no fungitoxic activity whereas their hydrolytic products, in particular ITCs with sulphate

side chain (mainly degradation products of glucoiberin, glucoerucin, glucoheirolin and

glucotropaeolin), inhibited growth of Rhizoctonia solani, Sclerotinia sclerotiorum, Diaporthe

phaseolorum and Pythium irregulare with different inhibitory responses depending upon the

chemical nature of the hydrolytic product. Smith et al. (1999) reported that incorporation of

canola root residues caused reduction in the infection of wheat seedlings by several root fungal

pathogens. Manici et al. (2000) indicated that ITCs produced by the hydrolysis of

thiofunctionalized glucosinolates such as glucoiberin and glucoerucin are more fungitoxic

against Pythium irregulare and Rhizoctonia solani than hydrolysis products of alkenyl

glucosinolates. Dandurand et al. (2000) attempted to control fungal pathogens using Brassica

napus cv. Dwarf Essex, seed meal. A 100% reduction of myceliogenic germination of

Sclerotinia sclerotiorum was observed. Lazzeri and Manici (2001) performed the field trails of

three glucosinolate containing plants (Iberis amara, Rapistrum ruggosum, Cleome hassleriana)

against Pythium. Fresh plant material was incorporated into soil naturally infected by Pythium

species. All green manure treatments suppressed Pythium sp. and also induced an increase in

total soil microbial activity. Kurt et al. (2011) studied the in vitro and in vivo antifungal activity

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of some ITCs against Sclerotinia sclerotiorum. Benzyl ITC exhibited the highest inhibitory

effect on sclerotial germination, with an EC50 value of 75.1 µmol l−1. However, in case of in vivo

assay, only allyl and 2-phenylethyl ITCs showed reduced disease incidence (by 76.7% and 70%,

respectively) at low concentrations.

Different hydrolysis products of glucosinolates respond differently to the microbial

population but ITCs are the major inhibitors of microbial activity (Mayton et al., 1996). The

toxicity and range of activity also vary with changes in the isothiocyanate R- Group. Greater

toxicity is often related to increased volatility (Lewis and Papavizas, 1971). Biofungicides may

act in different ways. They might work by triggering the plant’s defense mechanism, by

producing the toxins that kill the target organism or by producing a defensive barrier around the

roots of the host plant and preventing the harmful fungi to enter the host and thus protecting it

from the detrimental effects of fungi. Kojima and Oawa (1971) tried to elucidate the particular

biochemical mechanism of fungicigal activity of several ITCs using three different strains of

Saccharomyces cerevisiae (yeast). They reported that ITCs act by inhibiting the oxygen uptake

by yeast through the uncoupler action of oxidative phosphorylation in mitochondria of yeast i.e.

inhibiting the coupling between the electron transport and phosphorylation reactions and thus

eventually hindering the ATP synthesis.

2.2.3 Effects on insects and other invertebrates

Insecticidal activity of several ITCs has been demonstrated, especially for aromatic

compounds (Lichtenstein et al., 1962, 1964; Seo and Tang, 1982; Ahman, 1986; Chew, 1988;

Wadleigh and Yu, 1988; Borek et al., 1995). Borek et al. (1995) demonstrated that aromatic

ITCs are most toxic to the eggs of the black vine weevil, Otiorhynchus sulcatus. Matthiessen and

Shackleton (2000) reported that methyl ITC is toxic to whitefringed weevil larvae (Naupactus

leucoloma). Chen et al. (2011) studied the effect of essential oil of Armoracia rusticana

containing allyl ITC as major product (97.81%), against different life stages of Plodia

interpunctella and Sitophilus zeamais. They hypothesized that high fumigant effect of A.

rusticana volatile oil on P. interpunctella and S. zeamais might be due to its high pungent odour

because of the presence of allyl ITC in the volatile oil. The volatile oil might be able to block the

spiracles of the insects by impairing breathing and thereby choking them to death. The organic

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thiocyanates have also been used as insecticides to control weevils in grain and to cause rapid

eradication of flying insects such as houseflies (Beekhuis, 1975; Wood, 1975). Nitriles also

possess insecticidal activity e.g. 3-indolylacetonitrile has been known to inhibit the growth of

insects (Smissman et al., 1961).

The capacity of glucosinolates and their degradation products to keep nematodes in soil

under control has also been reported by various workers. Winkler and Otto (1980) reported that

rotational plantings of mustard in strawberries controlled the spread of nematode, Pratylenchus

penetrans. Johnson et al. (1992) demonstrated that incorporating the rapeseed tissue as green

manure in soil reduced the populations of Meloidogyne incognita and Meloidogyne javanica.

Papaya seed extracts and benzyl ITC isolated from them have been reported to have strong

nematicidal activity against Caenorhabditis elegans and Meloidogyne incognita (Nagesh et al.,

2002). Zasada and Ferris (2003) identified the lethal concentrations (LC) of several purified ITCs

to Tylenchulus semipenetrans and Meloidogyne javanica. They further used these LC values to

select suitable plant material containing the glucosinolate precursors of these nematicidal ITCs.

The biomass application rates were selected on the basis of glucosinolate profiles of the plant

sources and LC values of their corresponding ITCs, with an aim to develop chemistry-based

experiment for consistent and repeatable nematode suppression (Zasada and Ferris, 2004). Wu et

al. (2011) studied the effect of different ITCs against root-knot nematode, Meloidogyne javanica.

They reported that in in vitro experiments allyl, ethyl, benzyl, 1-phenylethyl, 2-phenylethyl ITCs

along with benzyl thiocyanate showed irreversible nematicidal activity against M. javanica, at 5

µgml−1. Similar results were obtained with allyl ITC in the pot experiments (1.0 ml/ kg of soil)

and field trials (1.0 kg/ha). Appropriate selection of the glucosinolate containing plant biomass

or pure hydrolytic product seems to be the key factor for effective and efficient biocidal activity.

Glucosinolates get broken down in soil to their biologically active compounds so plant

tissues containing these compounds are incorporated into soil for controlling soil-borne pests.

Different mechanisms have been proposed for their mode of action against pests. They work

either by inactivating the thiol group of essential enzymes of the pest or by alkylating the

nucleophillic groups of biopolymers like DNA or as uncouplers they affect the respiration of pest

and eventually lead to their death (Tsao et al., 2002). Uncouplers kill pests by enhancing the

respiration and not by inhibiting normal electron transport of the respiratory chain. Respiratory

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control is lost due to uncoupling between the respiratory chain and phosphorylation, the electron

transport along the respiratory chain occurs at full pace without producing ATP. Respiration is

accelerated which needs more ATP as source of energy and at the same time ATP production is

blocked. This causes exhaustion of stored energy sources which finally leads to death of the pest.

2.2.4 Bioherbicidal potential

Glucosinolates may represent a viable source of allelochemical control for variety of

weeds. Germination bioassays were conducted by Brown and Morra (1995) with Lactuca sativa

seeds in the presence of defatted meal of Brassica napus. Only tissues containing glucosinolates

produced volatiles which inhibited germination. The results suggested that this type of control

may contribute to the reduction in synthetic weedicide usage, if weed seeds are targeted. This

effect recently had been referred to as biofumigation. Biofumigation potential of Brassica

species in term of environmental effects and ontogeny on glucosinolate production, and in vitro

toxicity of ITCs to soil-borne fungal pathogen has been described by Sarwar and Kirkegaard,

(1998) and Sarwar et al. (1998).

Some species of the Brassicaceae family showed potential for use as green manure

(incorporating green plant material into the soil) crops (Al-Khatib et al., 1997; Krishnan et al.,

1998; Buhler et al., 2001). Petersen et al. (2001) analyzed the allelopathic potential of ITCs

released by turnip–rape mulch (Brassica rapa-Brassica napus). They reported that ITCs were

strong suppressants of germination of Sonchus asper (spiny sowthistle), Matricaria inodora

(scentless mayweed), Amaranthus hybridus (smooth pigweed), Echinochloa crusgalli (barnyard

grass), Alopecurus myosuroides (black grass) and Triticum aestivum (wheat). Norsworthy et al.

(2005) reported the potential of Brassicaceae green manures as weed suppressants in Vigna

unguiculata. Herbicidal activity of individual ITCs has also been rationally explored. A

greenhouse study conducted by Norsworthy and Meehan (2005) ascertained the herbicidal

potential of ITCs against Texas panicum, large crabgrass and sicklepod. Effectiveness of ITCs

varied among species. Propyl ITC and allyl ITC were most effective in suppressing Texas

panicum, while aromatic ITCs reduced large crabgrass, more effectively. Sicklepod was

effectively inhibited by allyl, benzyl, 3-methylthiopropyl, and phenyl ITCs. Soil treatment with

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glucosinolate containing plant materials as well as with purified ITCs, offer a more efficient and

harmless alternative for weed control.

Seed meals or residues left after extraction of oil from seeds, is the favored choice for

controlling the weed populations. The effectiveness of glucosinolate containing seedmeals

against wide range of weeds has been well documented by various laboratory and field

experiment. Vaughn et al. (2006) analyzed defatted seedmeals from fifteen glucosinolate-

containing plant species for bioherbicidal activity. They reported that at 0.1 % rate, seed meals of

Brassica juncea (Brown mustard), Lunaria annua (Money plant) and Thlaspi avense (Field

Pennycress) inhibited the germination of Triticum aestivum, while at 1% rate, eight of the seed

meals (Brassica juncea, Thlaspi avense, Eruca vesicaria, Erysimum cheiri, Erysimum allionii,

Lepidium sativum, Lobularia maritima, and Matthiola longipetala) were completely inhibitory

for Senna obtusifolia. Intact glucosinolates as well as their corresponding hydrolysis products

were identified in the active seedmeals. The chemical characterization of seedmeals revealed that

allyl ITC was the major hydrolytic product in Brassica juncea seedmeal, allyl thiocyanate and

allyl ITC were major products in Thlaspi arvense seedmeal, erucin (4-methylthiobutyl

isothiocyanate) in Eruca sativa, 3-butenyl isothiocyanate and lesquerellin (6-methylthiohexyl

isothiocyanate) in Lobularia maritima, and isopropyl isothiocyanate in Lunaria annua seed

meal. More recently, Handiseni et al. (2011) proposed that the soil treatment with a blend of

Indian mustard and white mustard seed meals could effectively control both grass and broadleaf

weeds.

The exact mechanisms of weed control by ITCs are not known, however evidence

suggests that they inhibit seed germination by interfering with protein synthesis and processes

involved in the formation of phosphorylated sugars or inhibition of plant enzyme activity

(Leblova-Svobodova and Kostir, 1962). In order to take advantage of these compounds in weed

suppression and to protect the main crop from their germination inhibiting effects, a complete

knowledge of biochemical mechanism involved in suppression of target weed is required as they

act in host specific manner.

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2.2.5 Antioxidative potential

Vitamin C, Vitamin E and carotenoids are direct antioxidants as they neutralize free

radicals before they can harm cells. Glucosinolates and their hydrolytic products are considered

as indirect antioxidants, as they are known to modulate the activity of xenobiotic metabolizing

enzymes (Phase I and Phase II enzymes), that trigger the long lasting antioxidant activity. ITCs

are powerful electrophiles, because of the reactivity of central carbon atom of the N=C=S group,

which reacts readily with sulfur, nitrogen and oxygen-based nucleophiles (Barton and Ollis,

1979). However, there are very less evidences regarding the participation of these compounds in

oxidation or reduction reactions like direct-acting antioxidants under physiological conditions.

Plumb et al. (1996) examined the free radical scavenging properties of some glucosinolates from

cruciferous vegetables by means of deoxyribose, ABTS (2,2'-azino-bis(3-ethylbenzthiazoline-6-

sulphonic acid) and bleomycin assays. They reported that glucosinolates are unlikely to have

direct antioxidant activity. Purified glucosinolates such as p-hydroxybenzyl glucosinolate, but-3-

enyl glucosinolate and 3-methylsulfinylpropyl glucosinolate were found to have only weak

antioxidant activity in their assay system. Intraperitoneal administration of allyl ITC and phenyl

ITC was found to inhibit the lipid peroxidation (allyl ITC- 47.4%, phenyl ITC- 25.9%) in mice

liver homogenate. Both ITCs also scavenged hydroxyl radicals in vitro (Manesh and Kuttan,

2003). Barillari et al. (2005a) reported that glucoerucin and its hydrolytic product, erucin

effectively decomposed hydrogen peroxide and alkyl hydroperoxides, thereby acting as a

peroxide-scavenging antioxidant. However, erucin did not show any chain-breaking antioxidant

activity. While studying this hydroperoxide scavenging property, they made an interesting

observation that glucoerucin and erucin upon reaction with hydroperoxides, produced

glucoraphanin and sulforaphane, respectively. Haina et al. (2010) reported that the antioxidant

activity of sulforaphane was approximately one tenth to one fifth of that of ascorbic acid.

However, no direct antioxidant activity was found for benzyl ITC in vitro, indicating that the

N=C=S group was not essential for the antioxidant activity of sulforaphane. Direct antioxidant

activity of these compounds needs to be scrupulously elucidated, to present a more

comprehensible depiction.

Glucosinolate derived products, especially ITCs have gained attention as potent

modulators of phase I and phase II enzymes which are important in the detoxification of

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electrophiles and protection against oxidative stress (Prestera et al., 1993). Phase I enzymes

(cytochrome P450 enzymes) generally increase the reactivity of fat soluble compounds and as a

consequence of this process, some reactive molecules are produced which may be more toxic

than the parent molecule. While, Phase II enzymes (glutathione-S-transferase, aldehyde

reductase, S-methyl transferase, N-acetyltransferase etc.) increase water solubility and promote

the excretion of these metabolites from the body. Hence, inhibition of phase I and induction of

phase II enzymes is necessary for the protection of cells against DNA damage by carcinogens

and reactive oxygen species. Sulforaphane (4-methylsulfinylbutyl ITC) is considered as the most

active phase II enzyme inducer. Sulforaphane has been attributed to have indirect antioxidant

activity which would arise from induction of glutathione transferases, quinine reductase,

glutathione peroxidase, NAD(P)H:quinone oxidoreductase-1, thioredoxin reductase and heme

oxygenase (Fahey and Talalay, 1999; Brooks et al., 2001; Misiewicz et al., 2004; Angeloni et

al., 2009). In a dose escalation trial on human subjects, it was observed that the oral

administration of sulforaphane doses contained in a standardized broccoli sprout homogenate,

safely and effectively induced mucosal phase II enzyme expression in the upper airway of human

subjects (Riedl et al., 2009). Leoncini et al. (2011) demonstrated that sulforaphane influenced

the expression and activity of glutathione reductase, glutathione-S-transferase, thioredoxin

reductase, and NAD(P)H:quinone oxidoreductase-1 through phosphatidylinositol 3-kinase

(PI3K)/Akt pathway.

Other hydrolytic products of glucosinolates have also been reported to modulate the

activity of Phase I (CYP family) and phase II enzymes. Nho and Jeffery (2001) reported that,

indole-3-carbinol (I3C) alone and with crambene (1-cyano-2-hydroxy-3-butene, a nitrile) caused

significant induction of CYP1A activity and CYP1A1 mRNA levels. Crambene and I3C also

caused induction of glutathione S-transferase (GST) and quinone reductase (QR) activity. Benzyl

ITC has also been reported to inhibit rat CYP2B1 (Goosen et al., 2000), and human CYP2B6

and CYP2D6 (Goosen et al., 2001). Nakajima et al. (2001) reported phenethyl ITC, as an

inhibitor of human CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and

CYP3A4. Konsue and Ioannides (2008) studied the effects of different doses of phenethyl ITC

on xenobiotic-metabolising systems and observed that the responses are dose and tissue

dependent, with the liver being the most sensitive compared to lung and kidney. Phenethyl ITC

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was found to be more effective in stimulating detoxification enzymes such as quinone reductase

and GST rather than cytochrome P450 inhibition. Phenethyl ITC modulated the cytochrome

P450 enzymes, but most effects were observed at doses much higher than dietary intake.

The hydrolytic products of glucosinolates have also been shown to increase the activity

of phase II enzymes by increasing the transcription of genes that contain ARE (antioxidant

response element). This action is mediated by nuclear factor-erythroid 2 p45 related factor-2,

which binds to ARE and regulate the transcriptional induction of phase II enzymes. (Holst and

Williamson, 2004). Prawan et al. (2008) demonstrated that the ITCs are involved in the

activation of ARE-mediated HO-1 gene transcription through Nrf2/ARE signaling pathway,

depending on the chemical structure. Indole-3-carbinol and its acid condensation products,

particularly 3,3-diindolylmethane and indole[3,2-b]carbazole (ICZ), can bind to the aryl

hydrocarbon receptor (Ahr) in the cytoplasm (Aggarwal and Ichikawa, 2005). This facilitates the

entry of Ahr into the nucleus where it forms a complex with AhR nuclear translocator protein

(Arnt). This complex binds to xenobiotic response elements (XRE) and enhances their

transcription (Safe, 2001).

2.2.6 Antimutagenic and antiproliferative activity

Chemopreventive agents, on the basis of the mechanism through which they exert

anticancer effects, can be divided into two groups: antimutagenic and antiproliferative (Steele,

2003). In concentrations, not dangerous to human and animal health, ITCs also have shown an

inhibitory effect against cancer (Nastruzzi et al., 1996). Dietary glucosinolates exhibit

anticarcinogenicity by blocking formation of endogenous or exogenous carcinogens, thus

inhibiting the formation of neoplastic cells. However, ITCs are also capable of eliminating

established cancer cells through interplay of different molecular mechanisms.

Nakamura et al. (2001) reported the antimutagenic activity of 4-(methylthio)-3-butenyl

ITC in UV-induced mutation assay of E. coli B/r WP2. Shishu et al. (2003) reported strong

antimutagenic abilities of sulforaphane against group of heterocyclic amines viz. 2-amino-3-

methyl-3H-imidazo- (4,5-f) -quinoline (IQ), 2-Amino-3,4-dimethylimidazo [4,5-f] quinoline

(MeIQ) and 2-Amino-3,8-dimethylimidazo [4,5-f] quinoxaline (MeIQx). Murugan et al. (2007)

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investigated the antimutagenic effect of broccoli flower head by the Ames Salmonella reverse

mutation assay. They reported that ethanol extracts of broccoli flower head at 46 mg/plate

suppressed the mutagenic effect induced by the corresponding mutagens on all the tester strains

TA98, TA102 and TA1535. Antimutagenic potential of phenethyl ITC was evaluated against

indirect-acting mutagens and carcinogens, aflatoxin B1 (AFB1) and IQ as well as direct-acting

mutagen and carcinogen N-nitroso-N-methylurea (MNU) using Ames assay, comet assay and in

vivo micronucleus test (Smerak et al., 2009). Phenethyl ITC was found to exhibit strong

antimutagenicity against these mutagens.

Chemoprotective properties of hydrolysis products of glucosinolates against chemical

carcinogens have been well demonstrated. They block the initiation of tumours in a variety of

tissues like liver, bladder, pancreas, colon and small intestine. It was reported that the hydrolytic

products of methyl sulphinyl glucosinolate are the most potent inducers of phase II enzymes,

which detoxify carcinogens. Wattenberg (1983) demonstrated, by using animal models, that

induction of phase II enzymes directly or indirectly reduces the risk of carcinogenesis.

Epidemiological data suggested that dietary intake of cruciferous vegetables may protect against

the risk of various types of cancers (Verhoeven et al., 1996; Cohen et al., 2000; Zhang, et al.,

2000 and Ambrosone et al., 2004). ITCs have been found to impose significant protection against

cancer in animal models induced by a variety of chemical carcinogens (Wattenberg, 1977; Stoner

et al., 1991; Morse et al., 1989, 1991; Jiao et al., 1997; Hecht, 2000; Talalay and Fahey, 2001,

Conaway et al., 2002; Yang et al., 2002).

Many studies have indicated sulforaphane as potent anticancer compound (Fimognari et

al., 2002; Kim et al., 2003; Rosea et al., 2005; Choi et al., 2008; Ramirez and Singletary, 2009;

Li et al., 2010b). Sulforaphane as well as its N-acetylcysteine conjugate, administered during the

post-initiation period, significantly inhibited azoxymethane-induced colonic aberrant crypt foci

formation in rats (Chung et al., 2000). In another study, conducted by Singh et al. (2004)

sulforaphane was found to inhibit proliferation of cultured PC-3 human prostate cancer cells by

inducing apoptosis. This compound has also shown profound activity against breast cancer cells.

Sulforaphane treatment was found to inhibit cell growth, induce G2-M cell cycle block, increase

the expression of cyclin B1, and oligonucleosomal DNA fragmentation in the four human breast

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cancer cell lines, MDA-MB231, MDA-MB-468, MCF-7, and T47D (Pledgie-Tracy et al., 2007).

In a pre-clinical and clinical trail conducted by Cornblatt et al. (2007), it was demonstrated that

the orally administered sulforaphane reached mammary gland and increased the detoxification

enzyme activity. Sulforaphane can suppress angiogenesis and metastasis by downregulating

vascular endothelial growth factor, HIF-1a, matrix metalloproteinase-2 and matrix

metalloproteinase-9 (Zhang and Tang, 2007). Li et al. (2010b) reported that sulforaphane

inhibited breast cancer stem cells and downregulates the Wnt/ß-catenin self-renewal pathway.

Indole-3-carbinol, another widely studied hydrolytic product is known to have potent

antiproliferative effects against human breast cancer cells and also has the potential to decrease

metastatic spread of tumors. Brew et al. (2009) demonstrated that indole-3-carbinol induced the

stress fibers and peripheral focal adhesions in a rho kinase-dependent manner that leads to

inhibition of motility in human breast cancer cells.

ITCs work against various cancer cells by induction of antioxidant and detoxifying

enzymes such as glutathione-S-transferases and UDP-glucuronosyl transferase, by inhibition of

carcinogen-activating enzymes such as cytochrome P450 or altering steroid hormone

metabolism. Apoptosis induction through various signal transduction pathways is another mode

of action of these compounds. Sulforaphane-induced apoptosis was found to be associated with

upregulation of BAX (promoter of apoptosis), down-regulation of BCL-2 (suppressor of

apoptosis) and activation of caspases-3, -9 and -8 (executers of apoptosis) (Singh et al., 2004).

Rosea et al. (2005) reported that 4-methysulfinylbutyl and 7-methylsulphinylheptyl ITCs derived

form Brassica oleracea var. italica (broccoli) and Rorripa nasturtium aquaticum (watercress),

inhibited metalloproteinase-9 (extracellular endopeptidase that selectively degrade the

components of various extracellular matrixes) activities and also suppressed the invasive

potential of human MDA-MB-231 breast cancer cells in vitro. The surgically resected colon

tissue from three human volunteers treated with sulforaphane for 2 hours showed a strong

induction of p21 (cyclin-dependent kinase inhibitor) in cancer tissue but not in normal tissues in

two out of three volunteers (Traka et al., 2005). ITCs have been known to inhibit the activation

of NFκB, a transcription factor involved in the expression of genes, which have been shown to

suppress apoptosis, induce cellular transformation, proliferation, invasion, metastasis,

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chemoresistance and inflammation (Baldwin, 2001). Srivastava and Singh (2004) reported that

benzyl ITC caused inhibition of NFκB activation in human pancreatic cancer cell line (BxPC-3).

Microtubules that play a vital role in mitosis and cytokinesis are excellent targets for

development of anticancer drugs. Azarenko et al. (2008) observed that the sulforaphane have the

potential to arrest mitosis, possibly by affecting spindle microtubule function in breast cancer

cells (MCF7). They reported that this ITC modified microtubule organization in arrested spindles

without modulating the spindle microtubule mass in a manner similar to that of much more

powerful antimitotic drugs.