Kinetics on the DPPH· reaction with hydroalcoholic extracts from various pomegranate parts

Gabriela Sicoe, Claudia Izabela Oprinescu, Giulia Mădălina Golea, Adrian Riviş, Nicoleta G. Hădărugă

Volume 23, Issue 4;
Pages: 271-280; 2017
ISSN: 2069-0053 (print) (former ISSN: 1453-1399), Agroprint;
ISSN (online): 2068-9551
In the present study the antioxidant activity and kinetics on DPPH· (2,2-diphenyl-1-pycryl-hydrazyl) reaction in the presence of hydroalcoholic extracts from various pomegranate parts have been investigated. Pomegranate, the fruit of the small three Punica granatum L., is extensively used for obtaining food products, especially juices and alcoholic drinks, also having curative properties due to the presence of polyphenolic compounds and vitamin C. Pomegranate extracts were obtained from various fruit parts such as red or white internal shell, pulp, seeds and whole fruit, using ethanol 96% as solvent or the raw juice, at room temperature. The kinetic of the DPPH· reaction in the presence of pomegranate extracts (diluted at 1:50 and 1:100) was determined spectrophotometrically, measuring the variation of the absorbance at 518 nm during fifteen minutes. Consequently, the variation of DPPH· concentration during the reaction was determined using a calibration curve for the free radical. The mean DPPH· reaction rates were obtained for the pseudolinear intervals of 0-30 s, 30-90 s and 90-900 s. The mean DPPH· reaction rate for the first interval had values in a wide range of 0.17-3.03 μM/s, with maximum values for pomegranate red shell and pulp extracts and the lowest ones for seeds extracts. On the other hand, the corresponding values for the second interval were in a narrow range of 0.05-0.6 μM/s, with the same observation for the lowest values for pomegranate seeds extracts. The antioxidant activity of these extracts were significantly higher for the pomegranate red and white internal shell extracts, as well as for the pulp extracts (46.9-54.9%), in comparison with the pomegranate juice samples (7.9-18.4%) and only 3.9-5.1% for the seeds extracts, after 1½ minutes of evaluation by DPPH· method. This study demonstrates the value of the pomegranate red and internal white shell (generally considered as waste) from the antioxidant activity point of view and suggest the recovery and re-utilization of such by-products in the food, pharmaceutical or cosmetic fields.
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