Antidiarrheal and antispasmodic activities of Vitex negundo are mediated through calcium channel blockade
Abstract
Vitex negundo has reputation in the traditional medicine in diarrhea and gut
spasm. This study was carried out to provide possible pharmacological basis
to its medicinal use in hyperactive gut disorders. In castor oil-induced
diarrheal model, the crude extract of V. negundo, caused a dose-dependent
protection (53-71%), similar to loperamide. In isolated rabbit jejunum preparation, V. negundo caused inhibition of spontaneous and high K+-induced
contractions, with EC50 values of 0.36 (0.22-0.61) and 1.30 mg/mL (0.27-5.89;
n=4-5), respectively, suggestive of spasmolytic activity, mediated possibly
through calcium channel blockade (CCB). The CCB activity was further
confirmed when pre-treatment of the tissue with V. negundo (0.03-0.3 mg/mL)
caused a rightward shift in the Ca++ concentration-response curves (CRCs),
similar to diltiazem or loperamide. These data indicate that the antidiarrheal
and spasmolytic effects of the crude extract of V. negundo are mediated
through the presence of CCB-like constituent(s).