Author(s):

Jeannot Bako Razafindrakoto, Léa Herilala Rasoanaivo, Anne Wadouachi, Lalaina Rahajamanana, René Razafindrazaka, Louise Faramalala Rabemandroso and Amélie Raharisololalao

Abstract: Cynanchum ambositrense Choux (Asclepiadaceae) is used in Malagasy herbal medicine for diminishing teeth pain, enhancing lactation of childminder, also used against serious cough and for treating intestinal disorders and spasms. The ethanolic extract is efficient on isolated guinea pig trachea pre-contracted with histamine at 2.10^-5 M with a median effective concentration (EC₅₀) of 0.452 ± 0.127 mg / ml. Bioassay-guided fractionation using two models guinea pig isolated ileum contraction induced by histamine and isolated rat duodenum contracted with acetylcholine to monitor the activity led to the isolation of sesselin (pyranocoumarin) as the main active constituent from the most promising ethyl acetate extract obtained from partition of ethanolic extract of the aerial part of Cynanchum ambositrense. Indeed, sesselin induced a concentration-dependant relaxation on guinea pig ileum contracted by histamine and on rat duodenum contracted by acetylcholine with an IC₅₀ respectively of 0.027 ± 0.001 mg/ml and 0.023 ± 0.005 mg/ml. It inhibits the histamine spasm effect on the isolated ileum and the acetylcholine spasm effect on the isolated duodenum in a noncompetitive manner.

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