Free radical scavenging and ferric reducing antioxidant properties of O.onites, T.vulgaris and O.basilicum from Greece and their rosmarinic acid content

摘要

This study determined the total phenol (TP), rosmarinic acid (RA) content and the free radical scavenging and ferric reducing antioxidant properties of acetone and methanol extracts of O.onites (oregano), T. vulgaris (thyme) and O. basilicum (basil) species (Crete, Greece). Oregano and thyme were higher in DPPH radical scavenging activity than basil (EC_(50): 0.489, 0.555, 1.16 mg/ml, resp.). In FRAP assay oregano was superior in reducing activity to thyme and basil (EC_(50): 0.04, 0.088 and 0.1452 mg/ml, resp.), as high as BHT (EC_(50): 0.0365 mg/ml). RA was stronger radical scavenger than BHT and a-tocopherol (EC_(50): 0.032, 0.083 and 0.123 mg/ml, resp.) and as strong reducing agent as ascorbic acid (EC_(50): 0.00216, 0.0033 mg/ml). Thyme was the highest source o f RA to oregano and basil (27.00, 20.15 and 14.05 mg/g, resp.). Oregano and thyme are more potent antioxidant sources than basil. The high positive correlations between TP, RA and DPPH activity (r= 0.854, r=0.924, p<0.05), indicate the significant contribution of o-dihydroxy-phenolic compounds to the antioxidant activity of the plant extracts.