COMPARATIVE STUDIES AND SYNERGISTIC EFFECT OF SENNA ALATA, RICINUS COMMUNIS LEAVES AND LANNEA BARTERI STEM BARK EXTRACTS AND THEIR FORMULATION ON PATHOGENIC BACTERIA AND FUNGUS

Abstract

Three medicinal plant parts, including the leaves of Senna alata, Ricinus communis and the stem bark of Lannea barteri were used for the current study. The aim was to investigate the antimicrobial effect of the crude extracts alone, their combinations and the crude extracts formulated individually with polyethylene glycol (PEG) and Shea butter, as well as phytochemical screening of the medicinal plants crude extracts. The microorganisms employed in this study were E. coli, S. aureus P. aeruginosa, K. pneumonia and C. albicans which are known to be associated with skin, wound and genitourinary infections. The phytochemicals screened showed the presence of tannins, saponins, reducing sugars, polyuronoids, terpenoids, flavonoids, alkaloids, and anthraquinones. The antimicrobial assay indicated that, all the microorganisms were susceptible to the crude extracts used at various concentrations. The crude extracts inhibited the test microorganisms in vitro with lower MIC values. The MBC and MFC values evaluated gave a range between 200 – 400 mg/ml of the respective extracts against the test microorganisms. The polyethylene glycol (PEG) and shea butter formulated ointments showed significant antimicrobial activity against the test microorganisms, with PEG ointment indicating higher activity than the Shea butter ointment at variable concentrations. The MIC values of PEG ointment was relatively lower compared with the Shea butter ointment. The MBC and MFC of the formulated ointment revealed that PEG based ointment showed both bactericidal and fungicidal activity whilst shea butter ointment showed only bacteriostatic activity up to a concentration of 400 mg/g. The combination studies revealed both synergistic and additive effects with no antagonistic effect against the test microorganisms. The MBC/MFC of the combined extract for the test microorganisms was recorded at 150 mg/ml. The findings of the current research using the plant extracts and their formulations against the test microorganisms reveal that, the respective parts of the stated plants could be used as antimicrobial agents.