Dual Inhibition of Ca⁺² Influx and Phosphodiesterase Enzyme Provides Scientific Base for the Medicinal Use of Chrozophora prostrata Dalz. in Respiratory Disorders

The crude ethanolic extract of Chrozophora prostrata (Cp.Cr) was tested using in vivo and ex vivo assays for its possible bronchodilatory effects in order to validate its medicinal use in respiratory disorders, like asthma and cough. Cp.Cr exhibited dose-dependent inhibition of carbachol (CCh)-induced bronchospasm in anesthetized rats, similar to aminophylline. When tested on Guinea-pig tracheal preparations, Cp.Cr caused relaxation of both CCh (1 μM) and high K⁺ (80 mM)-induced contractions with comparable potencies, similar to papaverine, a dual inhibitor of phosphodiesterse (PDE) and Ca⁺² influx. Pre-treatment of the tracheal tissues with Cp.Cr resulted in potentiation of the inhibitory effect of isoprenaline on CCh-induced contractions, like that caused by papaverine indicative of PDE inhibitory activity, which was confirmed when Cp.Cr concentration dependently (1 and 3 mg/mL) increased intracellular cAMP levels of the tracheal preparations, like papaverine. Cp.Cr shifted concentrationresponse curves of Ca⁺² constructed in Guinea-pig tracheal preparation towards right with suppression of the maximum response, similar to both verapamil and papaverine. These data indicate bronchodilator activity of Chrozophora prostrata mediated possibly through dual inhibition of PDE and Ca⁺² influx, thus, showing therapeutic potential in asthma with effect enhancing and side-effect neutralizing potential.