PHYTOCHEMICAL INVESTIGATION AND EVALUATION OF ANTIMICROBIAL ACTIVITIES OF STEM BARK EXTRACTS OF Vernonia amygdalina

Abstract

Vernonia Amygdalina (VA) is a tropical African plant of the Asteraceae family and is occasionally cultivated for its medicinal uses, which include as a treatment for diarrhea, skin wounds, fever mastitis, body allergy and worms infection. The present study was intended to analyse phytochemicals as well as to evaluate antimicrobial activities of stem bark extracts of Vernonia amygdalina. The powdered stem barks of the plant were successively extracted with petroleum ether, chloroform/methanol (1:1) and methanol respectively. The methanol, chloroform/methanol (1:1) and petroleum ether extracts were subjected to phytochemical screening and the results of the screening revealed the presence of a diverse phytochemicals in reference to the solvents. The stem bark oil was extracted with n-hexane by using Soxhlet apparatus and its chemical compositions were characterized by GC-MS. The GC-MS analysis of n-hexane extract led to the identification of 25 compounds from Vernonia amygdalina representing 100.01% of the extracted oil. Among them, 9,12-octadecanoic acid, methyl ester (29.47%), hexadecanoicacid, methyl ester (14.75%), 9,12,15-octadecatrieneoic acid, Methyl ester, (Z, Z, Z) (8.77%), 1H-indole (6.53%) were the prevailing compounds. Antimicrobial activities of crude extracts, pure compound, and stem barks oil were performed against four bacterial and two fungal species. All the tested samples were active against all bacterial species at a dose of 20μg/mL. The crude extracts were also subjected to test their antitubercular activity and the results showed that the MeOH extract was very active at minimum concentration (3.12 MIC (μg/mL)) against M. tuberculosis. Therefore, the biological activities displayed by the extracts and isolated compounds from this plant corroborate the traditional uses of this plant by the local people against various diseases