Isolation and Characterization of Antimicrobial Phenolic Compounds from Garcinia kola in Nigeria

Abstract

Garcinia kola is widely recognized for its medicinal value across Sub-Saharan Africa, yet there remains limited clarity on the specific phenolic constituents responsible for its antimicrobial effects. While previous studies have reported broad antibacterial and antifungal activity, the detailed characterization of bioactive compounds from Nigerian seeds remains incomplete. This study aimed to address this gap by extracting, isolating, and profiling phenolic constituents from seeds collected in Ibadan, Nigeria, and evaluating their antimicrobial potential. Seed powders were subjected to solvent extraction followed by chromatographic fractionation and purification. Isolated compounds were identified using FT-IR, MS, NMR, HPLC-DAD, and GC-MS. Antimicrobial activity was assessed using agar diffusion and broth microdilution assays against selected clinical and reference microorganisms. The extracts demonstrated substantial antibacterial and antifungal effects, with stronger activity against Gram-positive bacteria. Three major isolates were identified as cycloartenol, 24-methylenecycloartanol, and garcinianin, with the triterpenoids exhibiting the highest potency. The findings indicate that Nigerian G. kola seeds contain diverse phenolic and terpenoid compounds with promising antimicrobial properties, supporting traditional applications and highlighting their potential for drug development. Further research should investigate mechanisms of action, toxicity, and in vivo effectiveness to support future pharmacological use.