Crude ethanolic extracts of Garcinia kola seeds Heckel (Guttiferae) prolong the lag phase of Helicobacter pylori: inhibitory and bactericidal potential.

Problems associated with current treatment regimens have generated a considerable interest in alternative approaches for the eradication of Helicobacter pylori infections using phytochemical compounds. In an attempt to identify potential sources of such compounds, the antimicrobial activity of five solvent extracts of Garcinia kola seeds were investigated against 30 clinical strains of H. pylori and a standard control strain, NCTC 11638, using standard microbiological techniques. Metronidazole and amoxicillin were included in these experiments as positive control antibiotics. All the extracts tested exhibited anti-H. pylori activity with zone diameters of inhibition between 0 and 25 mm. The ethanol extract demonstrated considerable anti-H. pylori activity with a percentage susceptibility of 53.3% and minimum inhibitory concentration for 50% susceptibility (MIC₅₀) values ranging from 0.63 to 5.0 mg/mL. Ranges of MIC₅₀ values for amoxicillin and metronidazole were 0.01-0.63 mg/mL and 0.04-5.0 mg/mL, respectively. The inhibitory activity of the ethanol extract was similar to that of metronidazole (P > .05) as opposed to amoxicillin (P < .05). The extract caused a 12-hour extension of the lag phase of H. pylori at 1.25 mg/mL. The same observations were recorded when this concentration was doubled and quadrupled alongside a killing rate of 80.1% and 93.7%, respectively, after 24 hours and of 100% after 30 hours. These results demonstrate that the ethanol extract of G. kola may contain therapeutically useful compounds against H. pylori.