Effects of extracts and phytochemicals of Carica papaya L. on pregnancy and uterine contraction

Abstract

Carica papaya L. (papaya) seeds extracted with 80% ethanol exhibited irreversible tocolytic activity and caused myometrial and endometrial degeneration of isolated rat uterus. Benzyl isothiocyanate was identified to be the bioactive compound responsible for the effect of papaya seed extract. Extracts and latex of unripe papaya fruit provoked strong contractions of isolated rat uterus. The oxytocic effect of papaya latex was found to be due to the proteolytic activity of papain and chymopapain and is possibly mediated by prostaglandin release from the uterus, independent of protease-activated receptors. Extracts of ripe papaya fruit had no effect on isolated rat uterus. Oral exposure of pregnant rats to ripe papaya fruit did not cause fetal or maternal toxicity. In contrast, oral exposure of pregnant rats to benzyl isothiocyanate caused severe maternal toxicity, low fetal and placental weights. It thus appears that consumption of ripe papaya fruit may not cause any significant adverse effect on pregnancy. However, benzyl isothiocyanate could be of reproductive/developmental toxicological importance, while papaya latex and its proteinases are strong oxytocic agents.