Abstract

PHYTOCHEMICAL CONSTITUENTS, ANTIMICROBIAL ACTIVITY AND ACUTE ORAL TOXICITY STUDIES OF METHANOLIC EXTRACT OF VERNONIA AMYGDALINA LEAF

Nestor Tordzagla*, Francis Kwaku Dzideh Amankwah and Justice Dziedzom Amenu

ABSTRACT

Plant extracts offer a great potential for the development of newmedicinal agents against infectious diseases, which are burdensomeand difficult to treat. This study aimed to evaluate phytochemicalconstituents, antimicrobial activity and acute toxicity studies onmethanolic leaf extract of Vernonia amygdalina. The safety profile ofVernonia amygdalina extract was carried out in Sprague-Dawley rats(n⹀ 6). The antimicrobial assays were done using bacterial strains K.pneumomiae, S. typhi, S. aureus, MRSA, P. aeruginosa, N.gonorrhoeae, E. faecalis, E. coli ESLB, E. coli, E. faecalis, B. cereusand a fungal strain C. albicans. The determination of minimuminhibition concentrations (MIC) and minimum bactericidalconcentrations (MBC) were carried out by broth dilution method using96 well plates. The MIC values of the extract ranged from 1.562mg/mL to 3.125 mg/mL. Moreover, the MBC values obtained againstall the bacteria ranged from 50 mg/mL to 100 mg/mL. The synergistic effect of the extractplus ciprofloxacin was very remarkable against B. cereus, S. typhi and K. pneumomiae withMIC values of 0.390 μg/mL, 0.781 μg/mL and 0.781 μg/mL respectively. Preliminary acutetoxicity study of methanolic extract of Vernonia amygdalina leaves at doses of 500, 1000, 2000, 3000, and 5000 mg/kg indicated no serious adverse effects that could lead to death ofthe experimental animals. This means that the LD50 value of the extract could exceed 5000mg/kg, hence, the methanolic extract of Vernonia amygdalina leaves is nontoxic. Inconclusion, Vernonia amygdalina leaf is a potential source of a novel antibacterial agent.

Keywords: Vernonia amygdalina, phytochemicals, antimicrobial activity, toxicity studies.