Jai C. Tilak

A Study of Antioxidant Properties of Some Varieties of Grapes (Vitis vinifera L.)

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.

Evaluation of Antioxidant Activity of Selected Indian Mushrooms

Cellular damage caused by reactive oxygen species (ROS) has been implicated in several diseases, and hence antioxidants have significant importance in human health. In this study, five methods were used to test and compare the antioxidant activity at different levels involving formation and scavenging of free radicals by the extracts of four mushrooms that have medicinal values. The results were expressed as Trolox equivalent antioxidant capacity (TEAC) and ascorbic acid equivalent antioxidant capacity (AEAC). In the DPPH (1,1-diphenyl 2-picryl hydrazyl) assay, the ethyl acetate extract of Phellinus rimosus showed more potent activity than the methanolic extracts of Pleurotus florida, Pleurotus sajour-caju, and Ganoderma lucidum. The ethyl acetate extract of P. rimosus at a concentration of 0.1% showed a high TEAC value (12.488). In the ABTS (2,2-azobis-3-ethylbenzthiazoline-6-sulfonic acid) spectrophotometric assay, it possessed the most effective antioxidant activity (TEAC 4.84) compared to methanolic extracts of P. florida, P. sajour-caju, and G. lucidum. The extract of P. rimosus also possessed higher activity compared to other extracts in the ferric-reducing antioxidant power (FRAP) assay. In the pulse radiolysis studies and the ORAC (oxygen radical absorbance capacity) assay also, these mushrooms showed significant activities. Results of the DPPH, ABTS, FRAP, and ORAC assays indicate that all the four mushrooms examined showed significant antioxidant activities. Among these, P. rimosus extract seems to be the more effective antioxidant.