Extracts of Trichilia heudelotii (Meliaceae) Planch, a Nigerian Medicinal Plant have Antibacterial and Antifungal Activity

Abstract

There is no overemphasizing the need for novel phytotherapeutic agents to combat the menace of drug resistance in microbial pathogens. Many plant species so far, have yielded some bioactive compounds with great promise for such drugs. Trichilia heudelotii (Meliaceae) is commonly used in traditional medicine in Nigeria for the treatment of many microbial infections ranging from gastrointestinal infections to gonorrhea. This study is thus designed to determine the phytochemicals present in T. heudeloti and evaluate the plant’s extracts' antimicrobial activity on some bacterial and fungal isolates. The phytochemical screening was done using standard procedures.  Soxhlet extracts using n-hexane and methanol were drying in vacuo. The methanol extract was partitioned into petroleum ether, chloroform, and aqueous fractions. The antibacterial and antifungal activity of the extracts determined using the agar-well diffusion method. The MICs were determined for the extracts using the agar dilution method. The qualitative phytochemical screening revealed the presence of tannins, saponins, alkaloids, cardenolides, and anthraquinones in the leaf, stem bark, and root bark of T. heudelotii. The extracts showed considerable activity against Gram-positive and Gram-negative organisms, and fungi with dermatophytes including Klebsiella spp, Escherichia coli, Proteus spp, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Neisseria gonorrhoeae, Mycobacterium smegmatis, Candida albicans, Aspergillus niger, Rhizopus stolonifer, Penicillium spp, Microsporium canis, and Trichophyton mentagrophytes. The mean diameter of zones of inhibition exhibited by the extracts ranged between 10mm+ 0.5 and 32+ 0.33mm. The methanol extracts compared favourably with the gentamycin (standard control). The minimum inhibitory concentration (MIC) ranged between 0.157mg/mL and 20mg/mL. The crude methanol extracts and methanol residue showed the highest activity of all the extracts while the hexane extract showed the lowest activity and the Petroleum ether fraction was inactive. These results showed the potential of T. heudelotii as a possible candidate for bioactive compounds for the discovery and development of new drugs for the treatment of diseases caused by test pathogens.