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Aims: To evaluate the antimicrobial and antioxidant potentials of a biologically active compound isolated from the leaves of Ludwigia abyssinica A. Rich.
Study Design: Antimicrobial and antioxidant analysis of compound from the n-butanol fraction of plant leaf.
Place and Duration of Study: Chemistry and Microbiology Laboratories, Faculty of Science, Obafemi Awolowo University, Ile-Ife between November 2011 and September 2012.
Methodology: Chromatographic and nuclear magnetic resonance techniques were used to isolate and characterize the biologically active compound, respectively. Disc diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) measurements were used for antimicrobial test. 1, 1-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical scavenging assay was used for antioxidant test.
Results: The phenolic compound, 3,4,5-trihydroxybenzoic acid, also known as gallic acid was isolated from the n-butanol fraction of L. abyssinica leaf. It showed broad spectrum antimicrobial activities with zones of inhibition in the range 26.67±1.53 to 32.00±1.00 mm for the test bacteria and 6.67±1.15 to 30.33±0.58 mm for the test fungal strains. MIC and MBC values for gallic acid ranged from 12.5 to 200 µg ml-1 and 50 to 400 µg ml-1, respectively, comparing favourably with the standard reference drug used. DPPH radical scavenging activity for the compound was IC50 = 9.38 µg ml-1 compared with IC50 = 27.08µg ml-1 obtained for the standard ascorbic acid.
Conclusion: The results show that gallic acid from Ludwigia abyssinica leaves possesses In vitro antimicrobial and antioxidant properties and thus the plant has potentials as a source of natural health-giving products, given further investigations.