beta-Amyrin and alpha-amyrin acetate isolated from the stem bark of Alstonia boonei display profound anti-inflammatory activity

Abstract

Context: Alstonia boonei De Wild (Apocyanaceae) is used in ethnomedicine for the management of malaria, ulcer, rhematic pain, toothache, and inflammatory disorders. Objective: To investigate the anti-inflammatory potential of b-amyrin and a-amyrin acetate isolated from the stem bark of Alstonia boonei using animal models. Materials and methods: Chromatographic purification of the crude methanol extract led to the isolation and structure elucidation of b-amyrin and a-amyrin acetate. Their anti-inflammatory activities were evaluated in rodents using egg albumen-induced paw edema and xylene-induced ear edema models. The gastric ulcerogenic, in vivo leucocyte migration, and RBC membrane stabilization tests were also investigated. Results: a-Amyrin acetate at 100 mg/kg showed significant (p50.05) inhibition of egg albumen-induced paw edema with % inhibition of 40 at the 5th hour. Oral administration up to 100 mg/kg did not produce significant (p40.01) irritation of the gastric mucosa while significant (p50.01) ulceration was recorded for indomethacin at 40 mg/kg compared with the negative control. At 100 mg/mL, both b-amyrin and a-amyrin acetate inhibited heat-induced hemolysis to as much 47.2 and 61.5%, respectively, while diclofenac sodium (100 mg/mL) evoked only 40.5% inhibition. Both compounds at 100 mg/ear produced significant (p50.01)inhibition of ear edema in mice by 39.4 and 55.5%, respectively. Also at 100 mg/kg (p.o.) a-amyrin acetate evoked 60.3% reduction in total leucocyte count and significant (p50.05)suppression (47.9%) of neutrophil infiltration. Discussion and conclusion: This study generally provided evidence of profound anti-inflammatory activity of b-amyrin and a-amyrin acetate isolated from the Alstonia boonei stem bark.