In vitro anti-Helicobacter pylori activity of aqueous extract from Persian Oak testa / 中草药·英文版

Objective: Growing problem of antibiotic resistance in Helicobacter pylori, as a common cause of chronic gastritis and even stomach cancer, demands searching for novel candidates of herbal sources. This study is aimed at assessing the antimicrobial activity of aqueous extract obtained from Quercus brantii var. persica seed coat (Testa) on H. pylori isolated from gastric biopsy specimens. Methods: Such specimens were collected from 100 patients presenting with endoscopic gastroduodenal findings. Testa extracts were prepared from Persian Oak forests in the province of Kohgiluyeh and Boyer-Ahmad, IRAN. H. pylori isolates were obtained by a series of standard bacteriology tests and cell culture, then were confirmed by PCR. The activity of testa extracts towards 25 H. pylori isolates was assessed by well diffusion method, microdilution assay, and a disk diffusion assay in vitro. Results were analyzed statistically by one-way ANOVA analysis. Results: Aqueous extract of testa demonstrated an antimicrobial activity with zone diameters of inhibition ranged from 0 mm to 40 mm. Its inhibitory activity increased simultaneously with increasing extract concentration. The lowest MIC and MBC were both recorded as 2 µg/mL. Anti-H. pylori activity of testa extract was approximately close to tetracycline and metronidazole and less than amoxicillin. A potent extract of testa possessed significant inhibitory activity (P < 0.05). Conclusion: Testa extract is suggested as a natural therapeutic source against the gastric H. pylori infection. However, evaluating the in vivo activity of this extract is necessary too.

Anti-Helicobacter pylori Compounds from Polygonum cuspidatum

Anti-Helicobacter pylori activity guided fractionation led to the isolation of five anthraquinones, two stilbenes and one naphthoquinone from the EtOAc fraction of Polygonum cuspidatum, using silica gel column chromatography, Sephadex-LH20, MPLC and recrystallization. The chemical structures were identified to be physcion (1), emodin (2), anthraglycoside B (3), trans-resveratrol (4), anthraglycoside A (5), polydatin (6), 2-methoxy-6-acetyl-7-methyljuglone (7) and citreorosein (8) by UV, ¹H-NMR, ¹³C-NMR and mass spectrometry. Anti-Helicobacter pylori activity including MIC values of each compound was evaluated. All of the isolates exhibited anti-H. pylori activity of which MIC values were lower than that of a positive control, quercetin. Compounds 2 and 7 showed potent growth inhibitory activity. Especially, a naphthoquinone, compound 7 displayed most potent antibacterial activity with MIC₅₀ value of 0.30 µM and MIC₉₀ value of 0.39 µM. Although anti-H. pylori activity of this plant was previously reported, this is the first report on that of compounds isolated from this species. From these findings, P. cuspidatum roots or its isolates may be useful for H. pylori infection and further study is needed to elucidate mechanism of action.

Anti-Helicobacter pylori Compounds from Maackia amurensis

Eight isoflavonoid compounds were isolated from the EtOAc fraction of Maackia amurensis which had shown the highest anti-Helicobacter pylori activity among the fractions, using medium pressure liquid chromatography and recrystallization. Based on the spectroscopic data including 1H-NMR, 13C-NMR, HMBC and MS data, the chemical structures of the isolates were determined to be (-)-medicarpin (1), afromosin (2), formononetin (3), tectorigenin (4), prunetin (5), wistin (6), tectoridin (7) and ononin (8). Anti-H. pylori activity of each compound was evaluated with broth dilution assay. As a result, (-)-medicarpin (1), tectorigenin (4) and wistin (6) showed anti-H. pylori activity. (-)-Medicarpin (1) exhibited the most potent growth inhibitory activity against H. pylori with the minimal inhibitory concentration (MIC)90 of 25 microM, and tectorigenin (4) with MIC90 of 100 microM ranked the second. This is the first study to show the anti-H. pylori activity of M. amurensis, and it is suggested that the stem bark of M. amurensis or the EtOAc fraction or the isolated compounds can be a new natural source for the treatment of H. pylori infection.