The monoterpene alkaloid cantleyine from Strychnos trinervis root and its spasmolytic properties

Author(s): da, S. , BA, Mukherjee, R.

Abstract: Cantleyine, a monoterpene alkaloid isolated from the root bark of Strychnos trinervis, was submitted to a broad spectrum pharmacological screening, in which the principal effect observed was a nonspecific relaxation of isolated smooth muscles. Cantleyine relaxed (IC50 2.1 x 10-4 M) the guinea-pig trachea, pre-contracted by carbachol and antagonized in a nonspecific manner; carbachol (IC50 2.1 x 10-4) and histamine (IC50 1.4 x 10-4 M) induced contractions in the guinea-pig ileum; and phenylephrine (IC50 3.8 x 10-4 M) responses in the rat aorta. Cantleyine antagonized (pD'2, 3.82) cumulative concentration response curves to histamine in the ileum in a noncompetitive, reversible (slope, 4.84) and concentration dependent manner. The tonic contractions induced by histamine and KCI were also inhibited in a concentration-dependent and reversible manner (IC50 7.2 x 10-5' and 1.8 x 10-4 M, respectively), suggesting that cantleyine should be acting on voltage-dependent Ca2+ channels. This hypothesis was confirmed by the observation that cantleyine inhibited (pD'2, 3.35), in a concentration dependent manner, the CaCI2 induced contraction in depolarizing medium. These results suggest that cantleyine produces nonspecific spasmolytic effects in smooth muscle and that in guinea-pig ileum this effect is, in part, due to the inhibition of Ca+2 influx through voltage-dependent Ca2+ channels.

Keyword(s): Strychnos trinervis

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