Phytochemical Composition and Anti-microbial Properties of Petersianthus macrocarpus (P.Beauv.) Liben (Lecythidaceae) Stem Bark Extract and Fractions.

Petersianthus macrocarpus (Lecythidaceae) is commonly used in traditional medicine in southeastern part of Nigeria for treating infectious diseases. In the current study, qualitative and quantitative phytochemical composition, and antimicrobial properties of 95% aqueous methanolic stem bark extract, and various solvent fractions of P. macrocarpus, were evaluated. The total phenolics content (TPC) and total tannins content (TTC) were evaluated spectrophotometrically according to the Folin-Ciocalteu's protocol, while the total flavonoids content (TFC) was assessed according to the aluminum chloride colorimetric assay. The aqueous methanolic extract showed 706.61 ± 0.20 mg gallic acid equivalents GAE/g of extract, 131.42 ± 0.06 mg GAE/g of extract and 249.6 ± 0.14 mg quercetin equivalents QE/g of extract for TPC, TTC and TFC respectively. The ethyl acetate fraction showed higher TTC than the absolute methanol fraction but lower TPC and TFC. The antimicrobial properties of the extracts were evaluated against clinical strains of bacteria and fungi using the agar disc diffusion technique. All the evaluated samples showed inhibitory effect at 5.0 mg/mL against the tested bacteria and fungi, with the inhibition zone diameter (IZD) values ranging from 10 - 20 mm. The ethyl acetate fraction of the extract showed minimum inhibitory concentrations (MIC) of 0.81 mg/mL and 0.82 mg/mL against Aspergillus niger and Candida albicans respectively. P. macrocarpus stem bark is a rich source of phenolics, tannins and flavonoids which may be responsible for its ethno-medicinal use in treating microbial infections. [ABSTRACT FROM AUTHOR]