Antimicrobial Efficacy of Methanolic fraction of Shea nut on selected Skin Pathogens and Characterization of the Bioactive Compounds

Abstract

This study aimed to investigate the antimicrobial activities of methanolic extracts of Vitellaria paradoxa nut against dermatophytes and characterize its bioactive compounds. Isolates used in this study were Candida albican ATCC14503, Trichophyton rubrum ATCC28188, Trichophyton mentagrophytes ATCC9533 and Staphylococcus aureus ATCC25925. Antimicrobial assay and minimum inhibitory concentration (MIC) were carried out using agar plug, agar well diffusion and broth dilution techniques. Bioactive compounds were characterized using Gas Chromatography-Mass Spectrometry (GC-MS). Phytochemical screening revealed alkaloids, tanins and saponins as active phytoconstituents of V. paradoxa's antimicrobial activity. Methanolic extract at 200 mg/ml showed mean clear zone of 25.0 mm and 29.0 mm against S. aureus and C. albican respectively. For T. rubrum, no growth observed after 14 days while T. mentagrophyte showed radial growth at day 12 of incubation. Highest activity of standard antibiotics against S. aureus was obtained with Meropenem (25.0 mm). Griseofulvin, itraconazole and fluconazole at 150, 25 and 100 mg/ml respectively inhibited T. rubrum while for T. mentagrophyte, at 350, 25 and 200 mg/ml respectively after 14 days incubation. MIC for S. aureus and C. albican were observed at 150 mg/ml and 100 mg/ml respectively. T. rubrum and T. mentagrophyte in comparison to conventional antifungals revealed Itraconazole among other antifungals exhibited lowest MIC value (25 mg/ml) against both fungi. However, MIC for extract was recorded at 150 mg/ml against T. rubrum while T. mentagrophyte did not indicate any MIC effect. Some bioactive compounds present in extract includes, E- 15 Heptadecenal, possess antifungal activity, Methyl palmitate possess anti-inflammatory, Palmitic acid possesses antifungal activities. The species of dermatophytes used in this present study has never been reported. Keywords: Antimicrobial, Dermatophytes, Bioactive, Antibiotics, Antifungal