Investigation of pharmacological properties of Ananas comosus extracts on uterine activity

In folklore medicine Ananas comosus (L.) Merr. is reputed to act as an abortifacient and in expectant women as a means of inducing labor. Several reports have claimed abortifacient property of A. comosus fruit (ripe or unripe) [1 – 2]. Scientific evidences supporting the efficacy of pineapple extracts in inducing uterine contractions is clearly lacking. This study investigated the pharmacological effects of different fractions of pineapple extract to identify the most potent uterotonic fraction. The ethanolic crude extracts of pineapple (edible part) were prepared and fractionated through a series of liquid-liquid partitions. Fractions were separately tested on isolated rat uterine muscle from virgin and pregnant SD female rats and human pregnant myometrium, which were cut into strips along the longitudinal axis of uterus, mounted vertically in organ baths (37 °C) and exposed to cumulative addition of fractions (0.1 – 10 mg.ml^-1), serotonin (0.05 – 5 µM) and different blockers to delineate the mechanism of action of the bioactive compounds. Following our initial finding that aqueous fraction (F4) possesses uterine stimulant property which was blocked by verapamil but unaffected by indomethacin and prazosin, the uterotonic activity induced by F4 was further characterized using antagonists of 5-HT (2A and 2C) receptors. Notably, ketanserin (10 µM), diminished the maximal contractile response (% of 120 mM KCl contracture) induced by both F4 and 5HT by 74.3% and 92.1% respectively, implicating the presence of 5HT or 5HT-like compound and serotonergic pathways in uterotonic activity of aqueous fraction of pineapple extract (Fig. 1).

Fig. 1: Representative traces of serotonin and F4 on spontaneously contracting rat uterine strips (late pregnant) in the absence (control) and presence of ketanserin

References:

[1] Yabesh JE, Prabhu S and Vijayakumar S. An ethnobotanical study of medicinal plants used by traditional healers in silent valley of Kerala, India. J Ethnopharmacol 2014; 154: 774 – 89

[2] Rahman AM. Ethno-gynecological study of traditional medicinal plants used by Santals of Joypurhat district, Bangladesh. J Biomed Biotechnol 2014; 2: 10 – 13