Preliminary phytochemical screening and in vitro anti-Helicobacter pylori activity of extracts of the leaves of Lippia javanica

Abstract

The antimicrobial activity of crude extracts of Lippia javanica was investigated against 31Helicobacter pylori strains by agar well diffusion. The minimum inhibitory concentration (MIC) was determined by spectrophotometric analysis at 620 nm using broth micro dilution method and the rate of kill by the broth dilution method. H. pylori standard strain NCTC 11638 was also included as a positive control. Metronidazole and amoxicillin were used as positive control antibiotics. The presence of phytochemicals qualitatively was also tested using standard methods. The strains were inhibited by all the extracts with inhibition zone diameter ranging from 0 to 36 mm and 0 to 35 mm for the control antibiotic, clarithromycin. Marked susceptibility of strains (100%) was observed for the acetone extract (P 0.05). Acetone extract completely inhibited PE369C at MIC (0.1 mg/ml) and 2 × MIC (0.2 mg/ml) in 18 h, at ½ × MIC (0.05 mg/ml) in 36 h. Strain PE466C was completely inhibited at 4 × MIC in 72 h. Qualitative phytochemical assay revealed the presence of alkaloids, tannins, flavonoids, saponins and steroids in the extracts. The present study results indicate that the acetone extract of the leaves of L. Javanica is a potential source of lead molecules for the design of new anti-H. pylori therapies. Key words: H. pylori, medicinal plant, antimicrobial activity, minimum inhibitory concentration, bactericidal activity.