Antimicrobial compounds and Antimicrobial Activity of Extracts of Thespesia garckeana F. Hoffm. on Candida albicans, Staphylococcus aureus and Escherichia coli

Abstract

Plant products as antimicrobials have received serious attention in the recent years. Herbal medicines form a significant role in African ethnomedicine. Thespesia garckeanaF. Hoffm.isan important herbal medicinal plant used to treat or manage human diseases and ailments such as chest pains, cough, infertility and sexually transmitted infections. However, its antimicrobial compounds and activity analysis has not been evaluated. This study aimed at evaluating the phytochemical and antimicrobial activities of compounds in Thespesia garckeanaleaves and bark extracts on growth of C. albicans, S. aureusand E. coli. The plant leaves and bark were collected from Mwingi, Kitui County of Kenyaand transported to Maseno University department of Botany laboratory, where they were dried separately and crushed to obtain a fine powder. Crude plant extraction was done using soxhlet method with methanol and water solvents. Thin layer chromatography was used to purify the extracts and phytochemical screening was done using standard methods to determine the compounds present in the extracts. Thin layer chromatography was carried on bark and leaves extracts of Thespesia garckeana. Thin layer chromatography plate surface was coated with silica gel, and n-Hexane and Ethyl acetate used as solvent systems in the ratio 2:3 and 3:7 respectively. Antimicrobial activity was performed ontest microorganisms using different concentrations of the plant extracts; 0 (distilled water), 90, 180, 270 and 360 mg/ml of the extract. Paper disc method was used for inoculation with three replications. Diameter of inhibition zones was measured using a transparent ruler. The data on growth inhibition was subjected to analysis ofvariance (ANOVA), and the treatments were separated and compared using LSD at p<0.05. The phytochemical compounds screening of leaves and stem bark extracts of Thespesia garckean revealed the presence of Tannins, Saponins, Cardiac glycosides, and Alkaloids. TLC using n-Hexane and Ethyl acetate ratio of 2:3 methanol leaves extracts produced 9 spots with Rf values of 0.94, 0.9, 0.81, 0.71, 0.35, 0.25, 0.2, 0.125 and 0.075 respectively. The stem methanol extracts produced 4 spots with Rf values of 0.99, 0.96,0.9, and 0.06 respectively. Leaf methanol extracts using n-Hexane and Ethyl acetate in the ratio of 3:7 produced 8 spots with Rf values of 0.95, 0.89, 0.78, 0.46, 0.36, 0.3, 0.19, and 0.1 respectively. The stem bark methanol extracts produced 2 spots withRf values of 0.97 and 0.94 respectively. Increase in extracts concentration of the leaves and stem bark of Thespesia garckeana, significantlyinhibited the growth of Candida albicans, Staphylococcus aureus and E. coli. Methanol leaf and bark extracts hadmore inhibitory activity compared to the water extracts. The results from this study confirm the use of Thespesia garckeana in herbal medicineby traditional herbalists.