The antioxidant activity of wheatgrass, which is consumed as a dietary supplement, was estimated at different levels. The methods employed include FRAP (ferric reducing antioxidant power), ABTS (2,2'-azobis-3-ethylbenzthiazoline-6-sulfonic acid) and DPPH (1,1'-diphenyl-2-picrylhydrazyl) assays. Aqueous and ethanol extracts of wheatgrass grown under different conditions over a period of 6, 7, 8, 10 and 15 days were used. Lipid peroxidation and oxygen radical absorbance capacity (ORAC) were determined and utilized to check the potency of a few selected extracts. Different conditions used for growth were (1) tap water, (2) tap water with nutrients, (3) soil and tap water, and (4) soil with nutrients. For comparison, a commercially available wheatgrass tablet was analysed. To explain the reasons behind the observed differences, the total phenolic and flavonoid contents of the extracts were measured. These contents increased with growth under all the conditions. The ethanol extracts were found to have a higher phenolic and flavonoid content than the aqueous extracts. The highest FRAP values occurred on day 15 of growth under condition 4, the values being 0.463 and 0.573 mmol of ascorbic acid and Trolox equivalents/100 g fresh wheatgrass for aqueous and ethanol extracts, respectively. In the aqueous extracts no specific trend was observed with the DPPH assay for the different conditions nor for the growth period. In the case of ethanol extracts, however, it increased with the growth period and the wheatgrass grown in condition 4 was found to be the most effective. These extracts were also found to inhibit significantly ascorbate-Fe2+ induced lipid peroxidation in rat liver mitochondria. The ORAC values of aqueous and ethanol extracts of day 10 with condition 4 were found to be 39.9 and 48.2, respectively, being higher than those reported for many natural extracts or vegetables.

Turmeric (Curcuma longa) has been used in Indian cooking, and in herbal remedies. Its possible mechanism of action was examined in terms of antioxidant availability during actual cooking conditions and in therapeutic applications using standardized extracts. The assays involve different levels of antioxidant action such as oxygen radical absorbance capacity (ORAC), radical scavenging abilities using 1,1-diphenyl-2-picryl hydrazyl (DPPH), 2,2'-azobis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS), ferric reducing antioxidant power (FRAP) and protection of membranes examined by inhibition of lipid peroxidation besides the content of phenols and total flavonoids. The aqueous and ethanol extracts of two major preparations of turmeric, corresponding to its use in cooking and medicine, showed significant antioxidant abilities. In conclusion, the studies reveal that the ability of turmeric to scavenge radicals, reduce iron complex and inhibit peroxidation may explain the possible mechanisms by which turmeric exhibits its beneficial effects in relation to its use in cooking and medicine.

Plumbago zeylanica (known as "Chitrak") is a useful Indian medicinal plant. The root of the plant and its constituents are credited with potential therapeutic properties including anti-atherogenic, cardiotonic, hepatoprotective and neuroprotective properties. To examine possible mechanisms of action of P. zeylanica (Chitrak), in relation to its reported beneficial properties, antioxidant effects of the aqueous/alcoholic extracts of root, corresponding to medicinal preparations, and the active ingredient, plumbagin, were studied. Methods used included: ferric reducing/antioxidant power (FRAP), radical scavenging of 1,1-diphenyl-2-picryl hydrazyl (DPPH) and 2,2'-azobis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS), lipid peroxidation in rat liver mitochondria induced by different agents, and estimating phenolic and flavonoid content. In FRAP/DPPH assays, boiled ethanolic extracts were the most effective, while in the ABTS assay boiled aqueous extracts were the most efficient. These extracts also significantly inhibited lipid peroxidation induced by cumene hydroperoxide, ascorbate-Fe(2+) and peroxynitrite and contained high amounts of polyphenols and flavonoids. To examine the mechanisms of action in detail, antioxidant and pulse radiolysis studies with plumbagin were conducted. The hydroxyl (.OH), alkyl peroxyl (CCl(3)OO.), linoleic acid peroxyl (LOO.), and glutathiyl (GS.) radicals generate a phenoxyl radical upon reaction with plumbagin. The bimolecular rate constants were: .OH, 2.03 x 10(9) dm(3)mol(-1)s(-1); CCl(3)OO., 1.1 x 10(9) dm(3)mol(-1)s(-1); LOO., 6.7 x 10(7) dm(3)mol(-1)s(-1); and GS., 8.8 x 10(8) dm(3)mol(-1)s(-1). In conclusion, our studies reveal that extracts of P. zeylanica and its active ingredient plumbagin have significant antioxidant abilities that may possibly explain some of the reported therapeutic effects.

Grapes (Vitis vinifera L.) are a major fruit crop in the world. Grapes seem to confer health benefits due to their antioxidant activity. We have evaluated the antioxidant potential of 11 grapes varieties from India and nearby Asian countries. The assays employed involve different levels of antioxidant action like ferric reducing antioxidant power, radical scavenging by 1,1-diphenyl-2-picrylhydrazyl, ferrylmyoglobin/2,2'-azobis-3-ethylbenzthiazoline-6-sulfonic acid, oxygen radical absorbance capacity (ORAC), and inhibition of lipid peroxidation. The total phenolic and flavonoids contents were also estimated. Our study indicates that cv. Mango is the most potent followed by Sharad Seedless. Ethanolic extracts were found to be more effective than aqueous extracts. Cv. Sharad Seedless, Mango, and Manikchaman also had high ORAC values. Their HPLC analysis showed the presence of various antioxidant polyphenols. In conclusion our studies identified some varieties of grapes with high antioxidant activities and showed that their high antioxidant potential may be due to their phenolic and flavonoid contents.

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