Etude bio-guidée de quelques plantes médicinales du Cameroun sur quelques facteurs de pathogénicité de Helicobacter pylori

Abstract

The treatment of H. pylori infection is of major Public Health problem, mainly because of multi-bacterial resistance. Among the solutions considered, natural substances from medicinal plants could therefore constitute a source of potential response to the fight against antibioticresistance.The objective of our work was to study the properties of extracts of some medicinal plants from Cameroon on the growth and pathogenicity factors of H. pylori (adhesion and virulence). The ethnopharmacological survey identified 41 plants used by the populations of Bafia (Center region), Bazou and Foumbot (West region) against gastric pain and digestive disorders. The anti-Helicobacter pylori, anti-ureasic and anti-adhesion activities of crude extracts obtained from a mixture of methylene chloride-methanol (1: 1 v / v) was studied, using the Hp12 and HpG27 strains of H. pylori. , the method of microdilution in liquid medium and the method of dilution on agar for the anti-Helicobacter pylori activity. The selected plant was subjected to bioguided fractionation. The anti-ureasic activity of the subfractions was also determined by spectrophotometry. The anti-adhesion activity was determined by the adhesion of H. pylori labelled with fluorescein isothiocyanate on sections of mouse gastric tissue. The extracts, fractions and subfractions which inhibited the culture of H. pylori were selected. The expression of the adhesins Blood group antigen binding adhesion (BabA), H. pylori outer membrane protein (HopZ) and the cytotoxin-associated gene A (CagA) were evaluated by western blot. The effect of these extracts was analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) on the babA and hopZ genes. In addition, the active fractions and subfractions of this extract were characterized by ultrahigh pressure liquid chromatography (HPLC) coupled to mass spectrometry. It emerges from these experiments that all the plants inhibited the culture of H. pylori with the minimum inhibitory concentration values of between 0.125 and 100 mg / ml. Extracts of Spathodea campanulata and Nicotina tabacum significantly inhibited H. pylori with MICs of 0.125 and 1 mg/mL, respectively. At these concentrations, these two extracts inhibited the expression of the BabA and HopZ proteins and genes. Based on its anti-H. pylori and anti-adhesion activities, the extract of S. campanulata was divided into 6 fractions and 11 sub-fractions. Fractions B and C with hexane / ethyl acetate 25% and 70% respectively and fraction E with ethyl acetate inhibited the culture of H. pylori with the inhibition diameters of 11.3; 10 and 12 mm at a concentration of 0.1 mg / mL. The subfractions SB1, SB2, SE1 and SE3 inhibited the culture of H. pylori with the inhibition diameters between 8 and 13 mm. The SB2 sub-fraction exhibited the highest anti-ureasic activity with an inhibitory concentration 50 (IC50) of 5.83mg / ml. Furthermore, the fraction E and its sub-fraction SE3 inhibited the expression of the adhesins BabA and HopZ, and the cytotoxin CagA. We have identified 6 compounds cited in the literature, namely: ursolic acid, kaempferol, spathodic acid, spathodol, tomentosolic acid, kaempferol-3-glucoside in fraction E. These results confirm the importance of the use of these plants in local traditional medicine and contribute to the promotion of these plants as a potential source for the treatment of H. pylori infections.