Abstract

IN VITRO ASSESSMENT OF THE ANTIBACTERIAL ACTIVITY OF THE METHANOLIC EXTRACTS OF OCHROCARPUS AFRICANUS BARK

Fannang Simone Veronique*, Manaoda Antoine Vayaraï, Dakam William, Nko’o Moïse Henri Julien, Nsalo Yann Henri, Ngoule Christian

Abstract

Introduction: Various secondary metabolites contained in medicinal plants have revealed many therapeutic potentials for diseases. Several studies conducted all over the world on plants belonging to the Clusiaceae family have shown that they are very rich in these metabolites. Species belonging to the genus Ochrocarpus are recognized as containing many compounds endowed with biological activity, especially the antibacterial activity. Therapeutic failures due to antibiotic resistance for the treatment of infections due to resistant bacteria call for finding other treatment alternatives. The present study was initiated with the aim of evaluating the activity and antibacterial sensitivity of methanolic extracts from the trunk bark of Ochrocarpus africanus. The methods of diffusion in agar medium and in liquid medium were used for the sensitivity test and the determination of the MIC and the MBC. The agar well diffusion method was used to determine antimicrobial activity. For phytochemical screening, several tests were used, namely the BORNSTRAGER, DRAGENDORFF, SHINODA, LIEBERMAN BURCHARD test and thin layer column chromatography was used for the separation. For the demonstration of the antibacterial activity, several strains were tested. The method used to assess the sensitivity of the bacteria in the different samples was the microdilution described in the ISO 20776-1, 2006 standard and amended by the Antibiogram Committee of the French Society of Microbiology. The result of the phytochemical screening carried out is the following: presence of flavonoids, saponins, polyphenols, terpenoids and steroids. During this study, 2 compounds from Ochrocarpus africanus (OA1 and OA2) were isolated by chromatography. We obtained 224.28 g of oily extract, red in color with an extraction yield of 5.57 %. The result of the sterility test shows that after inoculation of samples in Chapman, EMB, hektoen and sabouraud media, no germ growth was observed after 24 h (for Chapman, EMB, hektoen media) and 48 hours (for sabouraud medium). Conclusion: The in vitro evaluation of the antibacterial activity of methanolic extracts from the bark of the trunk of Ochrocarpus africanus showed that six major families of compounds were identified by phytochemical screening: polyphenols, anthraquinones, saponins, flavonoids, triterpenes and steroids. In addition, two compounds were isolated by chromatographic methods. Furthermore, the antibacterial activity results revealed that this extract is endowed with antibacterial activity against Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus.

Keywords: Ochrocarpus africanus, methanolic bark extracts, antimicrobial.