ANTIOXIDATIVE AND ANTIBACTERIAL EFFECTS OF Ehretia asperula LEAVES EXTRACTS GROWN IN TAY NINH PROVINCE

Abstract

Ehretia asperula is a widely used as a medicinal plant in Vietnam. In the present study, leaves of Ehretia
asperula grown in Tay Ninh province were selected to evaluate their potential as antioxidant and
antibacterial agents. The antioxidant activities were determined by total antioxidant capacity, reducing
power, neutralize free radicals 2,2-diphenyl-1-picrylhydrazyl and 2,2’-azino-bis(3-ethylbenzothiazoline6-sulfonic aicd). The antibacterial activity was determined by determining the antibacterial ring
diameter, the minimum inhibitory concentration and the minimum bactericidal concentration of four
strains of Gram-negative bacteria and two strains of Gram-positive bacteria. The ethyl acetate fraction of
Ehretia asperula leaves had stronger antioxidant activity than the other extracts with EC50 values
ranging from 10 to 20 µg/mL. Ehretia asperula leaf extracts were more effective against Gram-positive
bacteria than Gram-negative bacteria. The results show that there is a direct correlation between
polyphenol content, antioxidant activity and antibacterial activity. Thus, the leaves of Ehretia asperula
grown in Tay Ninh showed good antioxidant and antibacterial activities.