ANTIMICROBIAL ACTIVITY AND PHYTOCHEMICAL SCREENING OF CRUDE EXTRACTS OF MEDICINAL PLANTS GROWN IN EASTERN ETHIOPIA

Abstract

The aim of my research was to screen secondary metabolites and antimicrobial activities of methanolic extracts of the leaves Vernonia amygdalina and Plantago lanceolata, and acetone extracts of the leaves Rosmarinus officinalis and Thymus schimperi against two bacteria (Staphylococcus aureus and Escherichia coli) and two fungi (Aspergillus niger and Fusarium oxysporum) using paper disc diffusion method. Phytochemical screening of the extracts revealed the presence of alkaloids, flavonoids, saponins, steroids, tannins, phenolic compounds, anthraquinones, cardiac glycosides and triterpenes in the plants investigated. The plant extracts were found to be more effective on bacteria than fungi. The bioassay has indicated that the inhibition effect of the extracts was proportional to the concentration. The acetone leaf extracts of Rosmarinus officinalis possess higher antibacterial properties than Vernonia amygdalina, Plantago lanceolata and Thymus schimperi. Phytochemical investigation results showed that the highest antibacterial potential of Rosmarinus officinalis may be attributed to flavonoids, phenolic compounds and triterpenes.