This is a post-refereed version of the article published in:

Eur.Food Res.Tech. (2017) 243 (8), 1439-1445

Title: Comparison of the volatile antioxidant contents in the aqueous and methanolic extracts of a set of commercial spices and condiments

Authors: Rafael Estévez Britoa, José González-Rodríguezb, Mercedes Ruiz Montoyac, José Miguel Rodríguez Melladoa,*

aDepartamento de Química Física y Termodinámica Aplicada. Facultad de Ciencias. CeiA3, IUIQFN, Campus Universitario Rabanales, edificio Marie Curie. Universidad de Córdoba. E-14014-Córdoba (Spain)

bSchool of Chemistry. College of Science. University of Lincoln. Brayford Pool. Lincoln, LN6 7TS (United Kingdom)

cDepartamento de Ingeniería Química, Química Física y Ciencias de los Materiales. Facultad de Ciencias Experimentales. Campus de “El Carmen”. Universidad de Huelva. E-21071- Huelva (Spain)

*Corresponding author (Tel: +34 957218647; Fax: +34 957218618; e-mail: jmrodriguez@uco.es)

Acknowledgements

Financial support from Córdoba University within the framework of the “Ayudas puente para el desarrollo de proyectos de I+D precompetitivos XXI Programa Propio 2016”, and for the mobility grant of Dr. Estévez.

Abstract

Spices are of great interest because their aromatic properties and to preserve food, with no or low nutritional value, and also as components of a healthy diet. The composition of the methanolic and aqueous extracts of commercial samples of Basil, Cinnamon powder, Cinnamon sticks, Clove, Cumin, Turmeric, Ginger, Nutmeg, Oregano, Rosemary and Thyme was studied as a first step in the relation of their antioxidant activities with the composition. Methods used were Gas Chromatography coupled with Mass Spectrometry (GC-MS) and High Performance Liquid Chromatography (HPLC). Extracts were prepared with an amount of the sample suspended in ultrapure water preheated at 100 oC or methanol at 60 ºC, stirring at room temperature and filtering; for GC-MS the extracts were dried and re-dissolved in methanol. To solve the problem in GC-MS with the flash-points of some compounds, both techniques have been combined. The contents in antioxidants of the different species are compared finding spices having much higher antioxidant contents in the methanolic extract than in water, other with aqueous extracts much rich in antioxidants than the alcoholic extracts, and spices with low antioxidant content in both extracts. For Clove, Turmeric, Ginger, Cinnamon, Rosemary and Cumin, it is recommended the use of lipid and/or alcoholic fractions for the food preparation. For Basil, Oregano, Thyme and Nutmeg, to extract most of their antioxidant content only water must be used. Knowledge of the composition in antioxidants can aid the food industry in the design of healthy foods and food preparations.

Keywords

Antioxidant Content; Aqueous and methanolic extracts; GC-MS; HPLC; Spices

Introduction

Currently, a large part of society is concerned about the health effects of antioxidants. So, the antioxidant capacity of foods and products having potentially pharmaceutical activity is under study, especially in relation with their composition. Teas are a main target of such studies due to the extended consumption of these infusions [1-3], most of the research being centered in their high polyphenol content [4,5]. On the other hand, spices are commonly used in the diet because their aromatic properties and to preserve food, with null or low nutritional value [6], and also as components of a healthy diet. Spices extracts have been used as an alternative to the use of synthetic antioxidants by preserving oils [7] and meats, both unprocessed [6] and processed [9], in order to improve their acceptability. Knowledge of the composition in antioxidants can aid the food industry in the design of healthy foods and food preparations.

Pharmacological studies on spices revealed a wide range of biological activities, including, antioxidant, anti-tumor, immunomodulatory and antiradical activities [10-13]. Their antioxidant constituents are identified as the responsible of the health-promoting properties of spices, such as anti-atherosclerotic, anti-cancer, and anti-inflammatory activities [14, 15]. Indeed, a diet rich in spices reduces the negative responses of the organism to the consumption of high-fat meals, a blend of antioxidant spices in the diet increasing the antioxidant activity in the blood and decreasing insulin response [16].

Herbs and spices are sources of phytochemicals, many of which have antioxidant activity, though the published investigations were mainly focused on polyphenols [17]. There are many antioxidants in dietary plants as carotenoids and phenolics, which occur mainly in fruits and vegetables of human common consumption [18]. The antioxidant content of a wide number of spices was analysed by the FRAP assay. This assay allowed the quantification of most water- and fat-soluble antioxidants by measuring the antioxidant capacity [19], not by chemical analysis. But two samples having different antioxidant capacities not necessarily have different total antioxidant contents. Clove has the highest mean antioxidant value, followed by peppermint, cinnamon, oregano, thyme, sage and rosemary. The antioxidant activity of ethanol and water extracts of spices from China has been recently examined by the FRAP method [20]. In addition, some experimental data have been published for essential oils of spices [21].

The aim of this paper was to investigate the contents in antioxidants of spices made in aqueous and alcoholic (methanolic) media as a first step in the relation of their antioxidant activities, measured by different methodologies, with the composition.

Materials and methods

Samples, chemicals and standards

Spices analyzed were: Basil, Cinnamon powder, Cinnamon sticks, Clove, Cumin, Turmeric, Ginger, Nutmeg, Oregano, Rosemary and Thyme, all from Hacendado brand.

All the chemicals used were of chromatographic quality. Ultrapure water type I (resistivity 18.2 MΩ·cm at 25 OC) obtained from a MilliporeMilli Q system was used.

HPLC. For the Acid Mobile Phase: HCl (Merck) and Glycine (Sigma) and Ultrapure water filtered with a 0.45 µm filter. For the Methanolic Phase: Methanol (Merck-Millipore) filtered with a 0.45 µm filter.

GC-MS. Ultrapure water filtered with a 0.45 µm filter, for the aqueous extracts. Methanol (Merck-Millipore) filtered with a 0.45 µm filter, for the methanolic extracts and the injected samples.

Extracts preparation

For GC-MS, extracts were prepared with 0.4 g of the sample that was suspended in 10 mL ultrapure water preheated at 100 oC and stirred for 3 min at 300 r.p.m. at room temperature. The suspension was filtered through a 0.45 µm filter, 4 mL of the liquid were passed to vials and the solvent was totally evaporated by gently heating and passing a nitrogen stream on the surface. Then, 100 µL pure methanol were added and the samples were sonicated until total dissolution; these samples were introduced in the GC-MS. To prepare the methanolic extracts the procedure was the same but using 10 mL of pure methanol at 60 oC for the initial extraction.

For HPLC, extracts were produced by suspending 1 g of the sample in 10 mL ultrapure water preheated at 100 oC (or pure methanol at 60 oC) and stirring for 3 min at 300 r.p.m. at room temperature. The suspension was filtered through a 0.45 µm filter and 1.5 mL of the liquid were passed to the HPLC vials.

Methods

The GC-MS analyses were made on a Gas Chromatography-Mass Spectrum Perkin-Elmer Clarus 500 with auto-injector, a SLB-5ms (10 m x 0.1 mm x 0.1 µm) column, an injection volume of 0.5 µL, and with He as carrier. The method consisted of a temperature ramp from 100 oC to a 300 oC (in 4 minutes). This last temperature was constant during 6 minutes to ensure that all the components of the samples passed through both the column and the mass spectrometer.

HPLC analyses were performed using a High Performance Liquid Chromatography Perkin-Elmer Flexar with a diode array detector. The method used to improve the separation of the substances present in the samples was based mainly on their polarity. A fast method avoiding expensive and not easily accessible solvents was used, consisting of a mobile phase in two-component gradient formed by aqueous and methanolic parts. The stationary apolar phase was a C-18 column. The aqueous portion of the mobile phase, Acid Mobile Phase (AMP), was optimized according to pH, peak resolution and simplicity in composition, and consisted of a hydrochloric acid aqueous solution of 44·10–3 mol·L–1 and glycine 50·10–3 mol·L–1, being the final pH=2.01. Four methods were designed, depending on whether the samples were tea (measuring time, tm, 45 min), infusions (tm = 60 min), standards that showed a signal in less than 12 min (Gallic Acid), or standards that showed a signal before 42 min (Cinnamaldehyde). All methods needed a 5 min equilibration step previous to the run, with a composition of the mobile phase of a 60% AMP and 40% methanol. After this step the instrument automatically injected 10 μL of sample and the run steps began, the mobile phase gradually changing from a majority percentage in AMP to a majority percentage in methanol.

Results and discussion

The abundant information provided by GC-MS technique is limited by the thermal decomposition of some components of the samples. This happened in this work with some of the antioxidants most widespread in nature, and present in some samples, such as Cinnamaldehyde in Cinnamon, Vitamin E in many samples as cumin, turmeric, oregano and rosemary and other characteristic compounds such as Camphor in Sage and Rosemary. But, in compensation, many others interesting antioxidant compounds were monitored.

For Basil, the water extract showed in the chromatogram a main peak (more than 22% of the extract, denoted as “main” in figure 1) corresponding to the mixture of the 5-methylated isomers of 4-, 5- and 6-hydroxybenzaldehydes, which have contrasted antioxidant activity [22]. The three isomers of benzenediol, recognized natural antioxidants, were also found but in much lower proportion. The methanolic extract contained a great variety of aromatic compounds, among they α-bergamotene, a typical compound of Basil, and eugenol, one of the most ubiquitous natural antioxidants [22]. Non-aromatic antioxidants, as squalene [23], and some pro-oxidants as β-Sitosterol [24] were also found. The total phenolic content of water and ethanol extracts of basil was reported to be equivalent [22].

FIGURE 1

The three isomers of benzenediol and a very low quantity of eugenol were also found in the aqueous extract of powered cinnamon, in addition to cinnamaldhyde and cinnamic acid, characteristic of this spice, which provide high antioxidant capacity [22, 25, 26]. The most abundant compound extracted in water was coumarin (benzopiran-2-one) previously detected in Cinnamomum cassia but not reported in extracts of Cinnamomum zeylanucum [27]. Supporting the low solubility of coumarins in apolar media, it was reported that essential oil of cinnamon does not include coumarins [28]. In the methanolic extract the proportion of coumarin and cinnamic acid decrease with respect to the aqueous extract, while the proportion of cinnamaldehyde increases due to the lowering in polarity. For cinnamon sticks the extracts were of much lower concentration than those obtained for the powered spice because the ligneous character of the sample. Cinnamic acid was not found probably due to the absence of oxidation of cinnamaldehyde caused by the cellular rupture originated in the powdering process.

The ligneous character of clove is also the responsible for the low concentration of aqueous extracts, being eugenol the main compound found. In methanol the abundance of this antioxidant was higher than 90%. It was found that the content of redox-active compounds was much greater for powdered clove essential oil than for basil essential oil [22], supporting this finding.

For cumin, a variety of hydroxylated and polyhydroxylated aromatic compounds were found. The main compound found in methanol was 4-(1-methylethyl)-benzaldehyde, or cuminaldehyde, antioxidant typically found in cumin as major antioxidant [29, 30], which was also detected in water in this work but in very lower concentration due to its lower solubility in more polar solvents.

Turmeric extracts contained antioxidants as eugenol, thymol, Vitamin E, dihydroxy- and hydroxymethoxy- derivatives of benzaldehyde etc, but the main compounds extracted were Turmerone, Ar-Turmerone and curcumin (1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-Heptadiene-3,5-dione), three antioxidant compounds that act as superoxide radical eliminators and unactivators of molecular oxygen [31, 32]. As it can be seen in figure 1, the aqueous extract contains a greater number of compounds than the methanolic extract. Major components of the essential oils of turmeric rhizomes were ar-turmerone and α- and β-turmerone [31].

Ginger extracts contained a great variety of aromatic compounds, mainly phenolics, being the main antioxidant found gingerol, the active component of fresh ginger, as reported in the literature mainly for essential oils [30, 31, 33, 34]. In the methanolic extract it was also identified gingerone (also named zingerone) used as additive in spice oils and in perfume industry [35].

In the water extract of nutmeg the major component found is 2,6-dimethoxy-4-(2-propenyl)-phenol, the reduced form of 4-methoxy-6-(2-propenyl)- 1,3-Benzodioxol (myristicin), this last being the main compound in the extract in methanol together 1,2,3-trimethoxy-5-(2-propenyl)-Benzene (elemicin). Only low contents in myristicin and elemicin were reported in essential oils of nutmeg [36]. The structures of all these compounds ensure their antioxidant activity.

Oregano extracts have antioxidant, antifungal, antibacterial and antimicrobial properties as has been widely reported in the literature [8, 13, 14, 37]. Concerning antioxidant compounds, in this work stands out the high content in the three isomers of benzenediol, together carvacrol and Vitamin E in lower quantities. Due to the very low solubility in water of carvacrol and Vitamin E, these compounds appeared in higher proportions in the methanolic extracts. It was shown that hydroquinone is the responsible antioxidant compound in the ethyl acetate extract of Oregano [37].

For rosemary the aqueous extract was poor in compounds, whereas the alcoholic extract was more rich in antioxidants. The main compounds in this case were eucalyptol, camphor and β-pinene. Carnosol, carnosic acid rosmarinol and rosmarinic acid, found previously in the literature in essential oils as main components [26, 38], were not determined by GC-MS due to their high boiling points. However, totarol was quantified in the extract in methanol.

Finally, the main antioxidants identified for thyme were carvacrol and thymol that were extracted from this condiment by several methods including supercritical fluids [26, 33, 39]. In this work, these antioxidants were quantified in less proportion in water due to their lower solubility in this medium than in methanol. In the aqueous extract, hydroxy-benzaldehydes were also obtained.

Some interesting compounds do not reach the boiling point in the temperature range allowed by the equipment in GC-MS, this being a limitation and, in addition, many of them decomposed before reaching that point, causing errors by default. For this reason, HPLC was used to identify and quantify some compounds.

On the basis of GC-EM data and the standards used, the three isomers of benzenediol (1,2-benzenediol, resorcinol and hydroquinone) were measured from the HPLC peaks appearing in water (or methanol, but in this case in very low proportions) at 2-5 min retention times. This is illustrated in figure 2 with clove.

FIGURE 2

Cinnamaldehyde was quantified in the sample of powered cinnamon, obtaining 2.37·103 ppm in water and 12.68·103 ppm in methanol, the difference being due to the higher solubility in this medium. These values are around 500 ppm in water and 600 ppm in methanol for the cinnamon sticks. Nevertheless, the compositions of extracts in water and methanol are similar. This implies that the pulverization process improves the extraction of antioxidant compounds. Moreover, the quantity of cinnamaldehyde found was much higher than that found in GC-MS due to the thermal decomposition of this compound taking place at relatively low temperatures [40].

In agreement with the results mentioned above, eugenol was reported as the main compound of clove [41]. This compound was quantified using HPLC, the signal obtained for the extract in methanol showing much more intensity (see figure 2). This compound was also found in nutmeg and cinnamon, but in much lower proportion. The contents for clove were 1.21·103 ppm for the alcoholic extract and 540 ppm for the aqueous extract.

Cuminaldehyde was quantified for cumin [29, 30, 42], and curcumin for turmeric. For this last spice, before 10 min the signals are virtually inexistent, because the methanolic extract contains a very low proportion of aromatic alcohols and aldehydes. Gingerol is detected in both extracts of ginger but in much more quantity in methanol, as occurred in essential oils [30, 31, 33, 34]. Conversely to that observed for GC-MS, gingerone is observed in the aqueous extracts in addition to extracts in methanol.

The results for oregano strengthen the above said in the sense that they show a high content in the three isomers of benzenediol as main antioxidants. In addition, eucalyptol is one of the main components of the rosemary extracts. In the cases of both carvacrol and thymol, found in oregano and thyme, were found in much lower quantities in water than in methanol extracts, due to the higher solubility in polar media.

Because the strong differences found between the contents in antioxidants of the different spices, it is impossible to summarize the results in tables for the comparison. So, only the main characteristics of the extracts will be commented. Figure 3 presents the total antioxidant content of the extracts.

FIGURE 3

As it can be seen, the total antioxidants are very different from one spice to another. The main comments to these results are the following:

In some cases, the antioxidant content is much higher in the extract made in methanol than in the extract made in water due to the low solubility of the antioxidant compounds in water. This is the case of clove (the most extreme), which main antioxidant is eugenol, turmeric, with turmerone, Ar-turmerone and curcumin, and ginger, with gingerol and gingerone. It is also the case for cinnamon, both powered and in sticks, with cinnamaldehyde. Cinnamic acid is also found, being much more soluble in water, but present in much lower proportion than the aldehyde. In the case of cinnamon, the pulverization of the sample facilitates the extraction of their components. Finally, for rosemary the water extract is also less rich in antioxidants than the alcoholic extract.

Conversely to the preceding group, there is a second group of spices that have aqueous extracts much rich in antioxidants than the alcoholic extracts. This is due to the greater polarity of the antioxidants extracted. In this group are included basil, oregano and thyme, three green-leaved spices that have a great variety and quantity of hydroxyl-substituted aromatic compounds soluble in water. The most representative case is basil, being the content in antioxidants of the water extract c.a. sevenfold of the methanolic extract. Oregano present the higher antioxidant content in the aqueous extract of all the studied spices, being 2.5 times greater than the content of the alcoholic extract. In the case of thyme the difference between the two extracts is around a 20%.

Finally, the third group is integrated by spices that have low antioxidant contents in both extracts: cumin and nutmeg. In the case of cumin, the richest extract is that made in methanol whereas for nutmeg the case is the contrary. It must be taken in mind that a low antioxidant contents do not imply necessarily a low antioxidant activity.

So, it can be said that for spices as clove, turmeric, ginger, cinnamon, rosemary and cumin, if one wants to take advantage of their antioxidant properties, it is recommended to use alcohol in their food preparations, as wine, beer or whisky, for example, whereas for the other spices, basil, oregano, thyme, and nutmeg, it is enough to use water to extract the antioxidants to a greater extent.

Conclusions

Gas Chromatography coupled with Mass Spectrometry (GC-MS) and High Performance Liquid Chromatography (HPLC) allowed the determination of the composition of methanolic and aqueous extracts of commercial samples of Basil, Cinnamon powder, Cinnamon sticks, Clove, Cumin, Turmeric, Ginger, Nutmeg, Oregano, Rosemary and as a first step in the relation of their antioxidant activities with the composition. To solve the problem in GC-MS with the flash-points of some compounds, both techniques have been combined. The contents in antioxidants of the different species are compared finding three group of spices: i) those having much higher antioxidant contents in the methanolic extract than in water; ii) those with aqueous extracts much rich in antioxidants than the alcoholic extracts; iii) and those with low antioxidant content in both extracts. For Clove, Turmeric, Ginger, Cinnamon, Rosemary and Cumin, it is recommended the use of lipid and/or alcoholic fractions for the food preparation. For Basil, Oregano, Thyme and Nutmeg, to extract most of their antioxidant content only water must be used.

References

[1] Bramati L, Aquilano F, Pietta P (2003) Unfermented rooibos tea:  quantitative characterization of flavonoids by HPLC−UV determination of the total antioxidant activity. J Agric Food Chem 51:7472-7474.

[2] Stewart A, Mullen W, Crozier A (2005) On-line high-performance liquid chromatography analysis of the antioxidant activity of phenolic compounds in green black tea. Mol. Nutr. Food Res. 49:52-60.

[3] Turkmen, N, Velioglu, Y. S, Sari, F, Polat, G (2007) Effect of extraction conditions on measured total polyphenol contents antioxidant antibacterial activities of black tea. Molecules 12:484-496.

[4] Ho CT, Chen Q, Shi H, Zhang KQ, Rosen RT (1992) Antioxidative effects of polyphenol extract prepared from various chinese teas. Preventive Medicine 21:520-525.

[5] Sakakibara H, Honda Y, Nakagawa S, Ashida H, Kanazawa K (2003) Simultaneous determination of all polyphenols in vegetables, fruits, teas. J Agric Food Chem 51:571-581.

[6] Davidson A (1999) The Oxford Companion to Food. Oxford University Press, New York, USA.

[7] Dias LS, Menis MEC, Jorge N (2015) Effect of rosemary (Rosmarinus officinalis) extracts on the oxidative stability sensory acceptability of soybean oil. J Sci Food Agric 95:2021–2027.

[8] Hernández H, Franková A, Sykora T, Kloucek P, Kourimská L, Kucerová I, Banout J (2016) The effect of oregano essential oil on microbial load sensory attributes of dried meat. J Sci Food Agric DOI 10.1002/jsfa.7685 (2016).

[9] Jin S-K, Choi J-S, Jeong J-Y, Kim G-D (2016) The effect of clove bud powder at a spice level on antioxidant quality properties of emulsified pork sausage during cold storage, J Sci Food Agric 96:4089–4097.

[10] Cherng J, Chiang W, Chiang L (2008) Immunomodulatory activities of common vegetables spices of umbelliferae its related coumarins flavonoids. Food Chem 106:944-950.

[11] Ho S, Tang Y, Lin S, Liew Y (2010) Evaluation of peroxynitrite-scavenging capacities of several commonly used fresh spices. Food Chem 119:1102-1107.

[12] Madsen HL, Bertelsen G (1995) Spice as antioxidants, Trends Food Sci Technol 6:271-277.

[13] Erenler R, Sen O, Aksit H, Demirtas I, Yaglioglu AS, Elmastas M, Telci I (2016) Isolation identification of chemical constituents from Origanum majorana investigation of antiproliferative antioxidant activities J Sci Food Agric 96: 822–836.

[14] Bhalla Y, Gupta VK, Jaitak V (2013) Anticancer activity of essential oils: a review, J Sci Food Agric 93:3643–3653.

[15] Ringman JM, Frautschy SA, Cole GM, Masterman DL, Cummings JL (2005) Potential role of the curry spice curcumin in Alzheimer’s disease. Curr Alzheimer Res 2:131-136.

[16] Skulas-Ray AC, Kris-Etherton PM, Teeter DL, Chen CY, Vanden Heuvel J P, West SG (2011) A high antioxidant spice blend attenuates postprandial insulin triglyceride responses increases some plasma measures of antioxidant activity in healthy, overweight men. J Nutr 141:1451-1457.

[17] Paur I, Carlsen MH, Halvorsen BL, Blomhoff R (2011) In: Benzie, IFF, Wachtel-Galor S (eds) Herbal Medicine: Biomolecular Clinical Aspects. 2nd ed. Boca Raton (FL). CRC Press/Taylor & Francis Group. and references cited; chapter 2 p.11-35.

[18] Lindsay DG, Astley SB (2002) European research on the functional effects of dietary antioxidants-EUROFEDA. Mol Aspects Med 23:1–38.

[19] Carlsen MH, Halvorsen BL, Holte K, Bøhn SK, Dragland S, Sampson L, Willey C, Senoo H, Umezono Y, Sanada C, Barikmo I, Berhe N, Willett WC, Phillips KM, Jacobs DR, Blomhoff R (2010) The total antioxidant content of more than 3100 foods, beverages, spices, herbs supplements used worldwide. Nutr J 9:1-11.

[20] Ying L, Ying D, Liu-Juan Z, Xian-Jin L (2015) Antioxidant Activities of Nine Selected Culinary Spices from China. J Northeast Agric Univ 22:50-57.

[21] Tomaino A, Cimino F, Zimbalatti V, Venuti V, Sulfaro V, De Pasquale A, Saija A (2005) Influence of heating on antioxidant activity the chemical composition of some spice essential oils. Food Chem 89:549-554.

[22] Brewer MS (2011) Natural Antioxidants: Their sources, compounds, mechanism of action, potential applications. Compr Rev Food Sci Food Saf 10:221-247.

[23] Amarowicz R (2009) Squalene: A natural antioxidant? Eur J Lipid Sci Technol 111:411-412.

[24] Finotti E, D'Ambrosio M, Paoletti F, Vivanti V, Quaglia G (2000) Synergistic effects of α-tocopherol, β-sitosterol squalene on antioxidant activity assayed by crocin bleaching method. Nahrung 44:373-374.

[25] Arteaga JF, Ruiz-Montoya M, Palma A, Alonso-Garrido G, Pintado S, Rodríguez-Mellado, JM (2012) Comparison of the Simple Cyclic Voltammetry (CV) DPPH Assays for the Determination of Antioxidant Capacity of Active Principles. Molecules 17:5126-5138.

[26] Shan B, Cai YZ, Sun M, Corke H (2005) Antioxidant capacity of 26 spice extracts characterization of their phenolic constituents. J Agric Food Chem 53:7749-7759.

[27] Sproll C, Ruge W, Andlauer C, Godelmann R, Lachenmeier DW (2008) HPLC analysis safety assessment of coumarin in foods. Food Chem 109 (2008) 462-469.

[28] Brodowska KM, Brodowska AJ, Śmigielski K, Łodyga-Chruścińska E (2016) Antioxidant profile of essential oils and extracts of cinnamon bark (Cinnamomum cassia). Europ J Biol Res 6: 310-316

[29] Morshedi D, Aliakbari F, Tayaranian-Marvian A, Fassihi A, Pan-Montojo F, Pérez-Sánchez H (2015) Cuminaldehyde as the major component of Cuminum cyminum, a natural aldehyde with inhibitory effect on alpha-synuclein fibrillation cytotoxicity. J Food Sci 80:H2336-H2345.

[30] Rebey IB, Zakhama N, Karoui IJ, Marzouk B (2012) Polyphenol composition antioxidant activity of cumin (Cuminum Cyminum L.) seed extract under drought. J Food Sci 77:C734-C739.

[31] Gounder DK, Lingamallu J (2012) Comparison of chemical composition antioxidant potential of volatile oil from fresh, dried cured turmeric (Curcuma longa) rhizomes. Ind Crop Prod 38:124-131.

[32] Kumar GS, Nayaka H, Dharmesh SM, Salimath PV (2006) Free bound phenolic antioxidants in amla (Emblica officinalis) turmeric (Curcuma longa). J Food Compos Anal 19:446-452.

[33] Aeschbach R, Loliger J, Scott BC, Murcia A, Butler J, Halliwell B, Aruoma OI (1994) Antioxidant actions of thymol, carvacrol, 6-gingerol, zingerone, hydroxytyrosol, Food Chem Toxicol 32:31-36.

[34] Dugasani S, Pichika MR, Nadarajah VD, Balijepalli MK, Tandra S, Korlakunta JN (2010) Comparative antioxidant anti-inflammatory effects of [6]-gingerol, [8]-gingerol, [10]-gingerol [6]-shogaol. J Ethnopharmacol 127:515-520.

[35] Mc Gee H (2007) A survey of tropical spices. In: On Food Cooking: The Science Lore of the Kitchen. New York, NY, USA, Scribner, p. 426.

[36] Maya KM, Zachariah TJ, Krishnamoorthy B (2004) Chemical composition of essential oil of nutmeg (Myristica Fragans Houtt.) accessions. J Spices Aromat Crops 13:135-139.

[37] Charles DJ (2013) Sources of Natural Antioxidants Their Activities. In Frontier Natural Products Co-op, Antioxidant Properties of Spices, Herbs Other Sources. Springer New York, NY, USA, p. 449-459.

[38] Pérez-Fons L, Garzon MT, Micol V (2010) Relationship between the Antioxidant Capacity Effect of Rosemary (Rosmarinus officinalis L.) Polyphenols on Membrane Phospholipid Order. J Agric Food Chem 58:161-171.

[39] Villanueva Bermejo D, Angelov I, Vicente G, Stateva RP, Rodriguez García-Risco M, Reglero G, Ibañez E, Fornari T (2015) Extraction of thymol from different varieties of thyme plants using green solvents, J Sci Food Agric 95:2901-2907.

[40] Cinnamaldehyde properties in ChemSpider: http://www.chemspider.com/Chemical-Structure.553117.html?rid=75f28a7d-d685-45d5-9d27-4dbaf1b83857

[41] Gopalakrishnan N, Shanti PPV, Narayanan CS (1990) Composition of Clove (Syzygium aromaticum) Bud Oil Extracted Using Carbon Dioxide, J Sci Food Agric 50:111-117.

[42] Bettaieb I, Bourgou S, Sriti J, Msaada K, Limam F, Marzouk B (2011) Essential oils fatty acids composition of Tunisian Indian cumin (Cuminum cyminum L.) seeds: a comparative study, J Sci Food Agric 91:2100-2107.

Figures

Figure 1. GC-MS chromatograms of the aqueous and methanolic extracts of selected spices with the identification of some components.

Figure 2. HPLC chromatograms of the aqueous (up) and methanolic (down) extracts of clove.

Figure 3. Total antioxidant content of water and methanolic extracts of spices.

21