Tulsi (Ocimum tenuiflorum) seeds: in vitro DNA damage protection, bioactive compounds and antioxidant potential

Abstract

Tulsi (Ocimum tenuiflorum) seeds (TS) were evaluated for bioactive compounds, antioxidant potential and DNA damage protection activity. TS were extracted with ethanol, methanol, acetone and chloroform at temperature 44.5 °C for 23.8 min in a water bath. Bioactive constituents and antioxidant properties were studied by TPC, CTC, DPPH, ABTS, TAC, RPA, HFRSA and FRAP assays. Two types of bioactive compounds with varying amount (mg/g dwb) were found. TPC in TS ranged from 0.03 to 1.02 (mg GAE/g dwb) whereas CTC was in range from 1.85 to 6.44 (mg CE/g dwb). Comparisons of antioxidant potential of different extracts of TS revealed that methanol extract (TSM) possess significantly (p < 0.05) higher value of DPPH (90.9%), ABTS (89.5%), TAC [0.73 mg ascorbic acid equivalent/g dry weight basis (mg AAE/g dwb)] and RPA (9.88 mg Quercetin equivalent/g dwb) as compared to other solvents. HFRSA value of ethanol extract (TSE) was, however, higher than others. Quantitative analysis of antioxidant compounds was performed using HPLC. Four bioactive compounds: gallic acid (0.38 mg), cinnamic acid (0.15 mg), p-coumaric acid (0.17 mg) and catechol (0.08 mg) were found when methanol extract (TSM) was used for their quantification. Correlation analysis also revealed relationships between TPC, CTC and different antioxidant assays. Among solvents used, methanol was found to be best extraction phase for the recovery of bioactive constituents with higher antioxidant potential.