Antioxidant and free radical scavenging activities of some promising wild edible fruits

In order to identify the potential sources of natural polyphenols with promising antioxidant (AOA) and free radical scavenging activities (FRSA) some under utilized edible fruits were studied for total phenolic contents (TPC), AOA and FRSA. The TPC varied from 7.3 (Ficus hookeri, fruits) to 119.2 mg/g GAE (Emblica officinalis, fruits), fruit pericarp of Castanopsis tribuloides (46.8 mg/g), fruits of Spondias axillaries (69.4 mg/g) and seeds of Emblica officinalis (81.5 mg/g) were found to have good amounts of TPC. The AOA varied from 8.6 (Citrullus colocynthus, seeds) to 80.3% (Emblica officinalis, fruits). The fruits of E. officinalis, Spondias axillaries and Baccaurea sapida were found to have good amounts of TPC and high AOA; low IC50, low EC50, reasonably good values of antiradical power (ARP) that support their effectiveness towards protection of DNA nicking and indicating strong FRSA. The IC50 values for inhibition of lipid per oxidation measured by ammonium thiocyanate assay ranged from 0.50 to 4.30 mg/ml; fruits (0.50 mg/ml) and seeds (0.92 mg/ml) of Emblica officinalis, fruits of Spondias axillaries (0.66 mg ml) and Baccaurea sapida (0.84 mg ml) showed better inhibition of peroxide formation compared to reference standard, quercetin (1.27 mg/ml). The ferrous ion-chelating capacity in terms of IC50 values varied from 0.28 (E. officinalis, fruits) to 2.83 mg/ml (Spondias axillaries, seeds). Further, the ferric ion chelating capacity of fruits of Baccaurea sapida (0.47 mg/ml) and E. officinalis (0.15 mg/ml) were observed to be better as compared to standard quercetin (0.66 mg/ml). Non enzymatic reactive oxygen species scavenging activity of the fruit extracts of E. officinalis (1.56 mg/ml), B. sapida (1.09 mg/ml) and S. axillaries (1.24 mg/ml) were found to be potent superoxide radical scavengers. Fruits of E.officinalis, B. sapida and S. axillaries showed reasonably good site specific inhibition of hydroxyl radical induced deoxyribose degradation on the other hand the non site specific inhibition exhibited IC50 values of 0.45 (E. officinalis, fruits) to 4.01 mg/ml (Cyphomandra betaceae, seeds). Promising samples were further assayed for their specific phenolic composition through HPLC and MS/MS which showed that fruits of E. officinalis were found to be potential source of caffeic acid; fruits of B. sapida of ellagic acid, fruits of S. axillaries and B. sapida of gallic acid.