Antioxidant characterization and in vitro DNA damage protection potential of some Indian fenugreek (Trigonella foenum- graecum) cultivars: effect of solvents

Indian fenugreek cultivars were characterized for their antioxidant properties and bioactive compounds were quantified using high performance liquid chromatography (HPLC). The extraction efficiencies were compared for two extraction solvents [aqueous ethanol (50%) and methanol]. The bioactive properties studied were total phenolic content (TPC), total flavonoids content (TFC), condensed tannin content (CTC), 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS⁺), 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, total antioxidant capacity (TAC), and reducing power activity (RPA). Aqueous ethanol extracts showed higher TPC, TFC, ABTS⁺, TAC and RPA as compared to methanol. However, methanolic extracts showed higher CTC and DPPH activity. Higher TPC [45.3 and 45.4 mg gallic acid equivalents (GAE)/g dry weight basis (dwb)], DPPH (93.0 and 93.2%), ABTS⁺ (98.3 and 98.5%), RPA [40.9 and 44.9 mg quercetin equivalents (QE)/g dwb], were observed for cv.RMT-143 and cv.RMT-365, respectively. TFC (20.5 mg catechin equivalents (CE)/g dwb) and CTC (9.3 mg CE/g dwb) were found the highest for cv. Kasoori methi. Quantification of phenolic compounds using HPLC revealed higher amount of gallic acid (in Kasoori methi), ascorbic and p-coumaric acid (HM-57), benzoic and cinnamic acid (RMT-143) and catechol (only in RMT-365). Significant (p < 0.05) protection against in vitro plasmid deoxyribonucleic acid (DNA) (pBR322) oxidative damage was observed for fenugreek extracts.