Pharmacological basis for the medicinal use of Psidium guajava leave in hyperactive gut disorders

Psidium guajava L. is reputed for its medicinal use in hyperactive gut disorders. This study was aimed to investigate mechanism responsible for its medicinal use in diarrhea and gut spasm. In castor oil-induced diarrheal model, the crude extract of P. guajava (100-1,000 mg/kg), provided 20.52-81.05% protection, similar to loperamide. In isolated rabbit jejunum preparations, crude extract was found more potent against high K+ than spontaneous pre-contractions, similar to verapamil, with EC50 values of 0.66 (0.44-0.97; n=8) and 2.28 mg/mL (1.43-3.62; n=8), respectively, suggests calcium channel blocking activity, as a possible mode of action. The Ca++ channel blocking activity was further confirmed when pre-treatment of tissue with crude extract (0.3-1 mg/mL) caused a rightward shift in the Ca++ concentration-response curves, similar to verapamil. Loperamide also inhibited spontaneous and high K+-induced contractions and shifted the Ca++ curves to the right. These data indicate that crude extract of P. guajava possesses Ca++ antagonist-like constituent(s), which explain its inhibitory effect on gut motility