Pharmacological basis for the folkloric uses of Buxus wallichiana in gastrointestinal, respiratory and vascular disorders

Abstract

<p><em>In vitro</em> study was carried out to explore the pharmacological basis of crude extract of <em>Buxus wallichiana </em>for its folkloric uses in gastrointestinal, respiratory and vascular disorders. In jejunum preparations, crude extract (0.03 ± 1.0 mg/mL) caused a transient spasmogenic effect followed by the spasmolytic effect at higher doses (3.0–10 mg/mL). In atropinized jejunum preparation, crude extract inhibited the spontaneous and K⁺(80 mM)-induced contraction, suggesting that spasmolytic effect is mediated through the Ca⁺²-channel blockade. The Ca⁺²-channel blockade effect was confirmed when pretreatment of tissue with extract produced a dose-dependent shift in Ca⁺²concentration-response curves to the right, similarly as verapamil. Furthermore, crude extract exhibited non-specific relaxant effect on carbachol- (1 µM) and K⁺(80 mM)-induced tracheal contractions, suggesting the coexistence of anticholi-nergic and Ca⁺²-antagonistic properties. Moreover, it relaxed the K⁺(80 mM)- and phenylephrine (1 µM)-induced contraction in rabbit aorta, suggesting the Ca⁺²-channel blockade. These findings may validate the folkloric uses of <em>B. wallichiana</em> in constipation, bronchitis, asthma and hypertension.</p>