Comparative antioxidant potential of some fruits and vegetables using DPPH method.
Rajnarayana K., Ajitha M., Gopireddy G., Giriprasad V. S.
Author Affiliation: Glukem Pharmaceutical (P) Ltd.Plot No: 205/2A, IDA, Phase-II, Cherlapally, Hyderabad - 500 051, India.
International Journal of Pharmacy and Technology 3 : 1952-1957
Abstract : An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions that damage cells. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions. DPPH (1, 1-diphenyl-2-picryl hydrazyl) a stable free radical can be used to determine the AOS of some photochemical and food materials. Antioxidant activity for all the fruits and vegetables that were investigated. Some of the flavonoids demonstrated greater activity than ascorbic acid. Green grapes showed greater AOS then black variety. Red onions have greater potential compared to white ones probably due to the presence of high concentrations of quercetin flavonoids in red variety. Carrots though they contain beta-carotinoids, which are antioxidants, did not showed good activity probably due to insoluble nature of the components in the methanol. Fresh fruits like green and black grapes, apples. Mangos, bananas. Oranges and pineapples. Vegetables like red & white onions, tomatoes, carrots, spices like garlic, dry and wet ginger, turmeric and others like tea, coffee and chyavanprash obtained from the local market of Warangal, were included in the study for comparing there antioxidant potential. Some pure flavonoids obtained as a gift samples from different phytochemical laboratories, like quercetin, rutin, luteolin, chrysin, 7,3?,5?-trihydroxyflavone, procumbentin, gossypin, diosmin, alfanapthoflavone, methyl-hesperidin were also included in the study for comparing their activity with standard antioxidant, ascorbic acid A suitable aliquot of extract, diluted to 2.8 ml with methanol. To this 0.2 ml of 0.005 Mm of DPPH (Sigma Chemical Company Inc., USA) was added before the absorbance was taken and mixed thoroughly. The change in the discoloration of DPPH solution was an index of the antioxidant activity that was measured at 517 nm wavelength.