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Title: Mechanisms of the oxytocic activity of papaya proteinases
Authors: Adebiyi, A.
Adaikan, P.G. 
Keywords: Carica papaya L.
Uterine contraction
Issue Date: Dec-2004
Citation: Adebiyi, A., Adaikan, P.G. (2004-12). Mechanisms of the oxytocic activity of papaya proteinases. Pharmaceutical Biology 42 (8) : 646-655. ScholarBank@NUS Repository.
Abstract: Crude papaya latex (CPL) and its proteinases, papain (PPN) and chymopapain (CPN), are strong uterine contractants. The current study was carried out to examine possible mechanisms of the uterine stimulating activity of the proteinases. Inactivation of the enzymatic activity of papaya proteinases reversibly abolished their uterine-stimulating effect, suggesting that enzymatic activity of the proteinases is a prerequisite for their oxytocic activity. Moreover, removal of Ca 2+ from the uterine bathing medium reversibly abolished the uterine-stimulating effect of the proteinases. Nifedipine and verapamil (Ca 2+ channel blockers) significantly and reversibly block CPL-, CPN-, and PPN-induced uterine contractions. Blockade of 5-hydroxytryptamine receptors did not prevent the oxytocic activity of papaya proteinases. However, uterine contractions induced by the proteinases were significantly and reversibly inhibited by meclofenamic acid (a cyclooxy-genase and prostaglandin inhibitor). At 0.3 and 1 mg/ml, CPL, CPN, and PPN caused a concentration-dependent increase in prostaglandin F 2α, production in cultured rat uterus, but only CPL (1 mg/ml) induced PGF 2α production by the cultured rat uterine tissues was statistically significant. The results of the current study suggest that prostaglandin release by Ca 2+ mobilization- and proteolysis-dependent activity of papaya latex and its proteinases could play a major role in their oxytocic activity. © 2004 Taylor & Francis Ltd.
Source Title: Pharmaceutical Biology
ISSN: 13880209
DOI: 10.1080/13880200490902608
Appears in Collections:Staff Publications

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