Free radical scavenging activities of polyphenols from underutilized plant parts

Abstract

There is increasing concern to manage under-utilized plant parts and agri-horticultural waste to develop useful products and prevent environment pollution. Some selective under-utilized plant parts like fruits of Acacia nilotica, Cassia fistula, Trewia nudiflora, leaves of Curcuma zeoderia, Averrhoa carambola, Chamomilla recutita, Casuarina equisetifolia, flowers of Cassia fistula, leaves and rhizomes of Alpinia galanga, outer layer red peel of Allium cepa were studied for total phenolic content (TPC) and antioxidant activity (AOA). The fruits of A. nilotica (324.7 mg/g) and C. fistula (107.8 mg/g); leaves (105.8 mg/g) and fruits (98.8 mg/g GAE) of T. nudiflora were found to have high TPC. The AOA (%) in leaves (96.9), fruits (94.5) of T. nudiflora, A. carambola (95.1), A. cepa (peels, 80.7) and C. equisetifolia (90.2); fruits of C. fistula (86.9), leaves (96.9) were with high AOA. Plants with promising TPC and AOA were further investigated for FRSA and green fruit of A. nilotica, peels of A. cepa, C. equisetifolia, fruits and leaves of T. nudiflora showed very low IC50, EC50 measured by DPPH, ASE/ml 0.4 to 2.8, reasonably high values (8.5-76.9) of anti-radical power (ARP) close to reference standard quercetin. Promising plants showed significant reduction in the formation of nicked DNA and increased protection of native DNA. Extracts of T. nudiflora leaves and fruits, A. nilotica fruits, A. cepa peels and C. fistula fruits effectively prevented DNA nicking and mitigated oxidative stresses on susceptible biomolecules. Specific phenolic composition through HPLC and LC-MS/MS showed that fruits of A. nilotica and leaves of A. carambola were potential source of chlorogenic acid, fruits of A. nilotica and T. nudiflora of gallic acid, leaves of T. nudiflora for quercetin and C. equisetifolia of rutin.