Anti-Helicobacter pylori, anti-Inflammatory, and Antioxidant Activities of Trunk Bark of Alstonia boonei (Apocynaceae)

Abstract

An ulcer is an erosion of the gastric mucosa that occurs following an imbalance between the aggression and protective factors and/or an infection with Helicobacter pylori ( H. pylori ). About 90-100% of duodenal ulcers and 70-80% of gastric ulcers are caused by H. pylori . The objective of this work was to evaluate in vitro the anti- H. pylori activity and then the anti-inflammatory and antioxidant properties of aqueous and methanol extracts of Alstonia boonei . The anti- H. pylori tests (CMI and antiureasic activity) were determined using the agar well diffusion method, the microbroth dilution method, and the measurement of ammonia production by the indophenol method; the anti-inflammatory properties were evaluated by inhibition of proteinases, denaturation of albumin, production of NO by macrophages, cell viability, and hemolysis of red blood cells by heat; then, the antioxidant properties were evaluated by the FRAP method (ferric reducing antioxidant power) and the DPPH (1,1-diphenyl-2-picrylhydrazyl) test. The results show that the best trapping of the DPPH radical was obtained with the methanol extract (EC 50 = 8.91 μ g/mL) compared to the aqueous extract (EC 50 = 19.86 μ g/mL). The methanol extract also showed greater iron-reducing activity than the aqueous extract and vitamin C. Furthermore, at the concentration of 200 μ g/mL, the methanol extract showed a percentage (96.34%) strains of H. pylori higher than that of the aqueous extract (88.52%). The MIC 90 of the methanol extract was lower than that of the aqueous extract. The methanol extract showed a higher percentage inhibition (85%) of urease than the aqueous extract (73%). The methanol extract at a concentration of 1000 μ g/mL showed the greatest ability to inhibit proteinase activity, albumin denaturation, and red blood cell hemolysis; on the other hand, maximum cell viability and greater production of nitrite oxide by macrophages were obtained with the aqueous extract. Aqueous and methanol extracts of Alstonia boonei possess anti- H. pylori which would probably be linked to their antioxidant and anti-inflammatory properties.

A Study on Chemical Characterization and Biological Abilities of Alstonia boonei Extracts Obtained by Different Techniques

“…Methanol allows for the extraction of both hydrophilic and hydrophobic compounds from plant materials, and thus, we could gain more insights for plant extracts. It has been shown in the literature that methanol is commonly used and is more effective as an extraction solvent for Alstonia boonei [ 14 , 15 , 16 , 17 , 18 , 19 ]. With this in mind, methanol was selected as one solvent for the current study.…”