Anti-histaminic and bronchodilatory activities of aqueous and methanol extracts of <i>Calotropis procera</i> (Ait) R.Br. root bark on allergic asthma in rodents

Abstract

The root bark of Calotropis procera (C. procera) (Asclepiadaceae) has been reported to be a part of herbal remedies for the management of allergic conditions including asthma. However, there is paucity of data on its anti-histaminic and bronhodilatory activity in asthma. This study therefore aimed to provide some pharmacological rationale for the ethnomedical use of C. procera as an anti-histamine and bronchodilator in asthma. The aqueous and methanol extracts of C. procera were investigated for anti-histaminic and bronchodilatory activities using histamine induced contraction of isolated guinea pig tracheal chain (at 0.5 ml, 1 ml and 2 ml, and stock concentration of 0.5 mg/ml), histamine induced contraction of isolated guinea pig ileum strip test (at 0.1, 0.2, 0.4, 0.8 and 1 ml, and stock concentration of 10 mg/ml), and haloperidol induced catalepsy test in rats (at 200 mg/kg and 300 mg/kg doses). Both extracts of C. procera significantly relaxed (p˂0.01) histamine induced contraction of isolated guinea pig trachea. The extracts also significantly inhibited (p˂0.001) histamine induced contraction of isolated guinea pig ileum. The aqueous extract did not significantly inhibit haloperidol-induced catalepsy. However, methanol extract significantly inhibited (p˂0.05) haloperidol-induced catalepsy at 300 mg/kg. The aqueous and methanol root bark extract of C. procera was found to poses anti-histaminic and bronchodilatory activities in in vivo and in vitro antiasthmatic test on animal models, with the methanol extract having greater activity than the aqueous extract, thus support the folkloric use of the plant in inflammatory and allergic conditions including asthma.

Keywords: Calotropis procera, Anti-histaminic, Bronchorelaxant, Anti-asthmatic, Histamine