In vitro antimicrobial activity of some phytochemical fractions of Euphorbia pulcherima L. (Poinsettia)

Abstract

The antimicrobial activities of aqueous and ethanolic extracts of flower, leaf, stem and whole plant of Euphorbia pulcherima were evaluated against bacteria and fungi by agar disc diffusion and macro broth dilution techniques. This was with the aim of substantiating the ethno medicinal use of the plant as anti-typhoid. The bacterial isolates showed sensitivity at discs concentrations of 1000 μg/disc to 1000 μg/disc. High sensitivity was shown by Salmonella typhiand Escherichia coli 0157:H7 on aqueous and ethanolic extracts as well as whole plant, but least on flower extract. The fungal isolates showed sensitivity at disc potencies of 2000 μg to 10,000 μg. High sensitivity was shown by Aspergillus niger to aqueous extract of leaves. Low sensitivity was shown by C. albicans. The minimum inhibitory concentration (MIC) for ethanol extract of leaves and the whole plant was 0.10, 100 and 10 mg/ml on S. typhi, S. paratyphi andE. coli 0157:H7 respectively. The values for flower ethanolic and aqueous extracts where 100 and > 1000 mg/ml respectively. Leaves and stem extracts contain active compounds against the test organisms. But the ethanolic extracts of flower were specifically antifungal on A. nigerand Trichophyton tonsurans. The minimum bactericidal concentration (MBC) test showed that the active fractions acted by bacteriostatic effect. The chemotherapeutic potential of the plant may be due to the presence of tannins, resins, steroids, glycoside, alkaloids, reducing sugars and sapoinins. Further biotechnological study on the pharmacological values of the plant is thus recommended. Key words: Euphorbia pulcherima, phytochemicals, antimicrobial, antitrichophyton, bacteriostatic.