a uv radiation-absorbing pigment from kokum (garcinia indica) juice

21
Potential Biotechnological Applications of UV Absorbing pH Sensitive Pigments in Kokum (Garcinia indica Choicy) Nandkumar M. Kamat Department of Botany, Goa University, Taleigao, Goa.

Upload: nandkamat

Post on 10-Apr-2015

643 views

Category:

Documents


3 download

DESCRIPTION

Goa University research led by Dr. Nandkumar Kamat shows that fresh Kokum juice could be a potential souce for organic UV protection sunscreens

TRANSCRIPT

Page 1: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

Potential Biotechnological Applications of UV Absorbing pH Sensitive Pigments in

Kokum (Garcinia indica Choicy)

Nandkumar M. KamatDepartment of Botany, Goa University, Taleigao,

Goa.

Page 2: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

Garcinia indica Choisy

Page 3: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

INTRODUCTION• Plant Anthocyanins are pigments serving as UVscreen and may be present in entire fruit, juice orconfined only to skin (Goodwin, 1976).

• Garcinia indica Choisy or Kokum is a tropicalevergreen, slender ornamental tree havingcommercial importance with variety of culinary andmedicinal uses.

• Oval, ripe, dark red Kokum fruits containanthocyanin pigments like cyanidin-3-glucoside andcyanidin-3-sambubioside(http://www.hvfl.com/kokum.htm).

Page 4: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

♦ Strawberry anthocyanins have been found to beextremely sensitive to fluctuations in pH and athigher pH colour is lost (Goodwin, 1976).

♦ The pH buffering capacity of Kokum is wellknown (http://buyersguide.ift.org/cms).

♦ However, there is relatively poor knowledge of theeffect of changing pH on the colour of the kokumjuice.

♦ This work was aimed to assess the effect of theincreasing pH on the colour and the UV-visiblespectroscopic absorption profile of the Kokum juicein view of the possibility of the application of thefindings in biotechnology.

Page 5: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

Habit of Kokum Different stages of fruit maturation

Ripe red fruits Dry Kokum rind

Page 6: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

OBJECTIVES• To assess the impact of pH changeon the colour of the fresh Kokumjuice• To assess any correspondingchange in UV-Visible spectroscopicprofile• To identify distinct UV-Visiblespectral absorption peaks associatedwith the pH and /or colour change• To evaluate the potential of theresults for appropriate commercialand biotechnological applications

Page 7: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

MATERIALS AND METHODS Freshly harvested ripe Kokum fruits were washed thoroughly under tap water

Juice squeezed mechanically with muslin cloth

Centrifuged at 5000 rpm for 20 minutes

Five ml juice aliquot diluted to 25 ml with double distilled water

Original pH (Control Dynamics digital pH meter APX 175) and colour (Camel shade card) recorded

Titrated against 0.5 N NaOH till a distinct colour change appeared

pH, spectral profile for each colour change noted

Spectral profile was recorded using Shimadzu double beam UV spectrophotometer (Shimadzu) in range of 190-750 nm, in matched Quartz cuvettes with dist. water as ref.

Page 8: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

A sample of freshly extracted Kokum juice

Page 9: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

RESULTSTable 1: pH and colour change

Sr No. pH Colour change Colour code1 1.87 Alizarin crimson 0022 1.99 Vermilion hue 4493 2.85 Cadmium red 0414 4.70 Gold ochre transparent 1725 5.25 Raw sienna 3666 6.16 Raw sienna 3667 7.46 Venetian red 4478 8.47 Venetian red 4479 10.56 Venetian red 44710 13.00 Cadmium orange 039

♦ It was observed that the original red colour of the juice changed tocadmium orange within a pH range of 1.87-13.00

♦ pH 5.25 and 6.16 showed raw sienna with a slight variation in colour.Similarly for pH 7.46, 8.47 and 10.56.

♦ After pH 13.00 the colour did not change further.

Page 10: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

Flasks exhibiting some colours produced by change in the juice pH. Generally at lower pH the shades are closer to pink and with alkaline conditions these shift to Orange

Page 11: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

RESULTSTable 2: pH and spectral profile

Spectral peaksSr. No. pHWavelength(nm)

Absorbance

1 1.87 265.50208.50

1.1083.972

2 1.99 264.00193.00

0.2492.488

3 2.85 262.00193.00

0.2152.408

4 4.70 193.50 2.5685 5.25 194.00 2.5406 6.16 194.00 2.6197 7.46 194.00 2.6078 8.47 194.00 2.6559 10.56 194.50 2.64010 13.00 203.50 3.280

Page 12: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

RESULTS♦Two peaks are observed at pH 1.87, 1.99 and 2.85, each with one major peak in the range of 193.00 to 209.00 nm.

♦The minor peak with less absorption diminishes from pH 1.87 to 2.85 from 265.5, 264.00 to 262.00 nm respectively and completely disappears at higher pH.

♦pH 5.25 to 8.47 shows a common peak at wavelength 194.00 nm with slight variation in absorption.

♦There is sudden increase in wavelength at pH 13.00 from 194.50 nm (pH 10.56) to 203.50

Page 13: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

RESULTSTable 3. pH change, colour change and spectral profile

Sr. No pHchange

Colour change Spectral shift(nm)

1 1.87 Alizarin crimson 208.502 1.99 Vermilion hue 193.003 2.85 Cadmium red 193.004 4.70 Gold ochre transparent 193.505 5.25 Raw sienna 194.006 6.16 Raw sienna 194.007 7.46 Venetian red 194.008 8.47 Venetian red 194.009 10.56 Venetian red 194.5010 13.00 Cadmium orange 203.50

♦ With increase in pH there is distinct change in colour and the spectralcharacteristics of the juice

Page 14: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

Fig 1 a. shows two peaks. Major peak at 208.5 with 3.972 absorbance and minor peak at 265.5 nm with 1.108

1b. Shows two peaks. Major peak at 193.00 nm with 2.488 absorbance and second peak at 264.00 nm with very less absorbance of 0.249

1c. Shows two peaks. Major peak at 193.00 nm with 2.408 absorbance and second peak at 262.00 nm with very less absorbance of 0.215

Fig. 1 a Fig 1 b

pH 1.87 pH 1.99

Fig 1 c

pH 2.85

Page 15: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

Fig. 2 a Fig. 2b Fig. 2c

Fig. 2 a. shows only one prominent peak at 193.5 nm with absorbance of 2.568.

2 b & c. shows common peak at 194.00 nm with absorbances of 2.540 and 2.619 respectively.

pH 4.70 pH 5.25 pH 6.16

Page 16: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

Fig. 3 a

Fig. 3d

Fig. 3 b Fig. 3 c

Fig. 3. (a-c) display sharp peaks with high absorbance at a very narrow range 193-194.5 nm and a spectral shift occurs at high pH (d) at 203 nm with change of the colour from venetian red to cadmium orange

pH 7.46 pH 8.47 pH 10.56

pH 13.00

Page 17: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

DISCUSSION•Kokum juice at natural pH (1.87) does not show any absorbance between 600-700 nm. However there is a weak absorbance over a broad bandwidth of 400-600 nm which was found to diminish with higher pH.

•At the original pH there is a distinct absorption at 265 nm which diminishes in intensity with increasing pH and then disappears at pH 4.7 indicating a distinct chemical change.

•The absorbance of the solution gradually increases between 400-250 nm between 4.70-13.00 pH

Page 18: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

DISCUSSION

• At 13.00 pH the absorption profile is very smooth probably indicating presence of single chemical component with strong absorption in the UV range at 203.50 nm.

• Initially a slight change in pH shows a UV spectral shift between 208.50-193.00 nm. The absorbance peak remains almost constant from 1.99-10.56 pH.

• Between 10.56-13.00 pH the peak is shifted again from 194.50 nm to 203.50 nm.

Page 19: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

DISCUSSION

Potential applications of the UV absorbance capacity of the pigment :-

• The strong absorbance values ( 1.108-3.972) over 193 nm-265.5 nm range shows a UV protective function of the soluble pH sensitive pigment

• The Nucleic acids (DNA & RNA) are known to strongly absorb at 260 nm

Page 20: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

DISCUSSIONPotential of UV protectiveaction: -• The UV protective action of the Kokum

pigment may be useful in masking theskin from DNA damaging solar radiation.

• The natural juice could be an importantresource for developing cheap, organic,eco-friendly, UV-protecting sun-screens/ointments/lotions and couldhave immense potential in cosmeticsindustry

Page 21: A UV radiation-absorbing pigment from Kokum  (Garcinia  indica) juice

DISCUSSION• The Chromic shift associated with pH

change could be useful property forproducing either low cost pHindicator papers (for a pH range of 3-13) or pH sensitive opto-electronicbiosensors which can be employedunder highly alkaline bioreactorconditions

• The simple Kokum juice can thus serveto be a forerunner to new products andprocesses in cosmetics and biosensorindustry