Phytochemical investigation and evaluation of antimicrobial Activity of root extract of Vernonia hymenolepis

Abstract

Vernonia hymenolepis is a medicinal plant which has been known to be used for the treatments of various diseases including pneumonia, hypertension, toothache, diarrhea, jaundice, amoebiasis, malaria, typhoid, hepatitis, fever, stomach ache and constipation by different communities in Ethiopia. However, its phytochemical and biological information is very limited. Following its medicinal importance, the plant material was collected from Oromia regional state, East Wollega Zone Jimma Arjo woreda. The plant material was air dried and sequentially extracted with chloroform and methanol. The resulting crude extracts were in vitro assayed against four bacterial strains (Bacillus subtilis ATCC11778, Staphylococcus aureus ATCC25923, Escherichia coli ATCC25922, and Pseudomonas aeruginosa ATCC27853) and one fungal strain (Candida albicans) using disc diffusion method. The crude extracts showed promising antibacterial activities with the highest activity observed for chloroform extract against E. coli (18 mm) but lower than that of the reference drug gentamycin (25 mm). The methanol extract showed the highest activity (13 mm) against the fungal strain Candida albicans as compared to the reference drug, clotrimazole, (12 mm). The antimicrobial activity displayed by the root extracts of Vernonia hymenolepis validates the traditional use of this plant against bacterial infections. Finally, silica gel column chromatographic separation of the chloroform resulted in isolation of two compounds (1 and 2); betulinic acid (3β-hydroxy-lup-20(29)-en-28-oic acid) and 4-(α-hydroxyacrylic) phenol. The structures of the isolated compounds were established using 1H and 13C-NMR spectroscopic methods and comparison with literature reports.