Abstract
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 EC 50 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.
Highlights
Psidium guajava L. commonly known as “guava” is a native of tropical America and has long been naturalized in Southeast Asia
The following reference chemicals were obtained from the sources specified: acetylcholine chloride, loperamide hydrochloride, verapamil hydrochloride, potassium chloride (Sigma Chemical Company, U.S.A.) and castor oil (Karachi Chemical Industries, Pakistan)
Based on the medicinal use of P. guajava in hyperactive gut disorders, such as diarrhea and spasm (Lozoya et al, 1994; Duke, 2002; de Wet et al, 2010), its crude extract was screened for antidiarrheal effect in mice
Summary
Psidium guajava L. (family; Myrtaceae) commonly known as “guava” is a native of tropical America and has long been naturalized in Southeast Asia. Among the major constituents are quercetin, myricetin, luteolin and kaempferol (Gutierreza et al, 2008)
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