Phytochemical evaluation of Elaeodendron buchananii stem Bark for microbial activities

Abstract

Public health is under serious threat due to wide array of emerging and re-emerging infections as a result of resistance of microorganisms to first line drugs. Despite the wide availability of clinically useful antifungal and antibacterial drugs, there is’ need for search for effective antimicrobials with new strategies to replace those with limited antimicrobial spectrum. Plants that are used by traditional healers in the management of ailments could be sources of safe and effective drugs. Many communities in Africa use Elaeodendron buchananii stem bark to manage fungal and bacterial infections. Despite its extensive use to manage bacterial and fungal infections, there is no phytochemical evaluation on the stem bark. Previous phytochemical analyses on its fruits and root bark revealed the presence of steroids and terpenoids. The objectives of this research were to investigate the lethality of the extracts, determine in vitro antibacterial and antifungal assays on crude extracts and isolates and characterize, the active principles from stem bark of E. buchananii. The stem bark of E. buchananii was sequentially extracted using n-hexane, ethyl acetate and methanol. The extracts exhibited various degrees of activities, with ethyl acetate extract displaying highest lethality (LCso of 2.784 ug Iml). The isolated compounds were purified by crystallization. Structural elucidation of isolates revealed two coumarins, two sterols and five triterpenoids characterized by MS, IR and NMR. The n-hexane extract yielded Ju-Acetylamyrin (52), stigmasterol (53) and 3- Oxofriedooleonane (36) while ethyl acetate extract gave coumarin (54), ~-Sitosterol (55), , 30, -Hydroxyfriedooleonane (56), umbelliferone (57), camophyllol (38) and ursolic acid (58) in addition to those obtained from n-hexane extract. Methanol extract gave negligible isolates and were not analyzed. The ethyl acetate extract had strong antibacterial activities than the conventional gentamycin used as positive control, especially against Neisseria meningitidis while methanol extract displayed strong antifungal activities especially against Candida albicans. The n-hexane extract showed mild antimicrobial activities. Coumarin (54) and umbelliferone (57) Showed antifungal activities while 3-0xofriedooleonane and carnophyllol exhibited antibacterial activities. Ursolic acid (58) displayed antibacterial and antifungal activities. These nine compounds have been isolated from this plant for the first time. The biological activities established in this study explain in part the use of E. buchananii stem bark in folk medicine for the management of bacterial and fungal related ailments. This study justifies the use of stem bark of E. buchananii in folk medicine for the management of bacterial and fungal ailments and recommends the conservation of the plant.