Antimicrobial effect of aqueous extracts of Garcinia kola, Cymbopogan citratus and Bryophyllium pinnatum against sputum bacterial isolates from human subjects

Introduction: Garcinia kola, Cymbopogan citratus and Bryophyllium pinnatum are multipurpose plants used in diverse ways for medicinal and nutritional purposes across regions of the world, with their benefits yet to be fully exploited. Aim: This study investigated the antimicrobial effects of aqueous extracts of these plants against bacterial sputum isolates of consenting cough patients. Method: Isolates were identified based on colonial, morphological, gram staining, relevant biochemical and molecular characterization. Aqueous extracts of individual plants, binary, and ternary combinations were used for antimicrobial studies on four isolated bacterial species. The response of the bacterial isolates to aqueous extracts of the seeds of G. kola and leaves of B. pinnatum and C. citratus were determined using lactate dehydrogenase method and mean inhibitory concentrations (MIC) determined. Results: Streptococcus specie infection had the highest prevalence of 90% followed by Klebsiella pneumonia (85%), Staphylococcus aureus (80%), and E. coli (30%) among the cough patients. Co-bacterial infection was seen in 95% of the cases. Responses of the bacterial isolates to the plants’ aqueous extracts were dose-dependent. Dehydrogenase activities of the bacterial isolates were significantly and progressively inhibited by the aqueous extracts of the individual, binary and ternary combinations of the plants. However, MIC was significantly lowest in the ternary combination compared to the individual and binary extract formulations. Conclusion: The study revealed that individual, binary, and ternary combinations of the plant extracts have significant antibacterial properties, with ternary combination of 40% G. kola, 30% B. pinnatum and 30% C. citratus demonstrating the highest potency. The ternary combination of the extracts could potentially be exploited for treatment of bacterial-induced cough. However, more research is needed to further evaluate the plants’ safety and effectiveness for clinical use in humans.