Phenolic contents, antioxidant and antibacterial activities of Hymenocardia acida.

This study investigates the antioxidant and antibacterial activities of aqueous and methanolic extracts from Hymenocardia acida Tul. (Hymenocardiaceae). The inhibition values of the extracts and quercetin were found to be very close, with no significant differences at a concentration of 0.05 mg mL(-1) in their ability to inhibit 1,1-diphenyl-2-picrylhydrazyl (DPPH). Total proanthocyanidins for both water and methanol extracts were 20.2 +/- 0.01 and 30.6 +/- 0.51 mg g(-1) (catechin equivalent) while the total phenol contents were 20.0 +/- 0.52 and 35.6 +/- 1.42 mg mL(-1) (tannic acid equivalent), respectively. Positive correlations R(2) = 0.85, R(2) = 0.94, R(2) = 0.97 for DPPH, reducing power and 2'-azino-bis(3-ethylbenzo thiazoline)6-sulphonic acid (ABTS). Linear regression analysis also produced a high correlation coefficient with total proanthocyanidins (DPPH, R(2) = 0.69; ABTS, R(2) = 0.94). H. acida extracts showed low antibacterial activity (minimum inhibitory concentration (MIC) value >or=5.0 mg mL(-1)) against gram negative bacteria but significantly (MIC value