The extract of Mucuna pruriens possesses histamine activity

Abstract

Objective To investigate the activity of the active principle in the spines of the seed pods of Mucuna pruriens using contraction of guinea pig ileum as index of pharmacological activity. Methods The active principle was extracted with 0.0015 M NaCl. Muscle strips of guinea pig ileum were prepared and contractile responses were measured using a Kymograph. Two sets of experiment were conducted: (1). The contraction of the ileum in presence of different concentrations of histamine, 2-methylhistamine and the extract of Mucuna pruriens. (2). The contractile response of the ileum in presence of different concentrations of the extract and antagonists including diphenhydramine, atropine and methysergide. Results (1) The extract of Mucuna pruriens hair, 2-methylhistamine and histamine produced dose dependent contraction of guinea pig ileum (Extract ED 50 = 13.0 μg/mL, 2-methylhistamine ED 50 = 8.5 μg/mL and histamine ED 50 = 10.0 μg/mL). (2) Diphenhydramine, an H 1 antagonist competitively blocked the contractile response of the Mucuna pruriens extract. (3) Coadminstration of the Mucuna pruriens extract either with different doses of antimuscarinic agent atropine or 5-hydroxytryptamine blocking agent methysergide did not alter the extract induced contractile response of the guinea pig ileum. Conclusion These results demonstrate that the spines of Mucuna pruriens possess histamine activity which may contribute to its itching and painful irritation effects.