Phytochemical Constituents, Antimicrobial activities and Isolation of Eupatorin from the Seed Extract of <i>L. inermis</i> LINN

Abstract

In low- and middle-income countries like Nigeria, traditional medicine practitioners use seeds, roots, stem barks or the whole plant to cure some ailments, hence, the need to scientifically analyze these ethnobotanical claims. The extracts of L. inermis revealed the presence of cardiac glycosides, saponins, flavonoids tannins, triterpenes, steroid and alkaloids. The antimicrobial screening and activities of the crude extracts were observed against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, Klebsiella pneumonia with a zones of inhibition ranging from 12-26 mm which were however lower than the standard drug (Ciprofloxacin) with 28-30 mm. The MIC/MBC  measurement against those microbes was found to be between 3.125 mg/ml to 50 mg/ml. The ethyl acetate extract was purified using column chromatography and eluted with ethyl acetate and ethanol solvents in various ratios. From the fractions obtained, the compound eupatorin (3’,5-dihydroxy-4’,6,7-trimethoxyflavone) was isolated and characterized using IR, 1D and 2D NMR. The eupatorin was found to show significant microbial activity against P. vulgaris, S. typhi, E. coli, S. pneumonia and S. pyogenes when compared with standard antibiotics used against these microbes. The results from this research have supported the ethnomedicinal uses of this plant in the treatment of skin infections, abdominal disorders, leprosy, rheumatalgia, edema and as a cough and cold remedy.

Keywords: Lawsonia inermis, phytochemicals, antimicrobial screening, Eupatorin