Spasmolytic effect of Psidium guajava Linn. (Myrtaceae) leaf aqueous extract on rat isolated uterine horns

Abstract

Globally, primary dysmenorrhoea is one of the most frequent gynaecological disorders in young women. It is associated with increased uterine tone, and exaggerated contractility of uterine smooth muscles. In many rural African communities, a number of medicinal plants, including Psidium guajava Linn. (family: Myrtaceae), are used traditionally for the management, control and/or treatment of primary dysmenorrhoea. The present study was, therefore, undertaken to examine the spasmolytic effect of Psidium guajava leaf aqueous extract (PGE) on isolated, spontaneously-contracting and oestrogen-dominated, quiescent uterine horns of healthy, young adult, female Wistar rats. Graded, escalated concentrations of PGE (0.5-4.0 mg/ml) produced concentration-dependent and significant inhibitions of the amplitude of spontaneous phasic contractions of the isolated rat uterine horn preparations. In a concentration-related manner, PGE also significantly inhibited or abolished contractions produced by acetylcholine (ACh, 0.5-8.0 µg/ml), oxytocin (0.5-4.0 µU), bradykinin (2.5-10 ng/ml), carbachol (CCh, 0.5-8.0 µg/ml) or potassium chloride (K + , 10-80 mM) in quiescent uterine horn preparations isolated from the oestrogendominated rats. The spasmolytic effect of PGE observed in the present study lends pharmacological support to the traditional use of 'guava' leaves in the management, control and/or treatment of primary dysmenorrhoea in some rural African communities.

Effects of the aqueous extract of Pittosporum mannii Hook. f. (Pittosporaceae) stem barks on spontaneous and spasmogen-induced contractile activity of isolated rat duodenum

“…In this study, phytochemical analysis also shown that our plant extract contained more than 343.3728.8 mg/g of total polyphenolic content and it has been reported previously that phenolic compounds such as flavonoids and tannins have inhibitory effects on intestinal smooth muscle (Nguelefack et al, 2006;Aviello et al, 2010;Damabi et al, 2010;Kishore and Rahman, 2012;Yunita et al, 2012). Terpenoids and saponins have also been reported in other plant extracts to exhibit antispasmodic and vasodilatatory effects on smooth muscle preparations (Ghayur et al, 2005;Chiwororo and Ojewole., 2009;Dubravka et al, 2010). The presence of these bioactive compounds in the aqueous extract of P. mannii might explain at least in part the observed effects on rat duodenum.…”

“…Our results showed that PMAE partially but significantly inhibited in a concentration-dependent manner the contractile response elicited by carbachol or histamine on rat duodenum. Smooth muscles contraction, in response to histamine or carbachol is initiated by the increase of the cytoplasmic-free Ca 2 þ concentration.These agonists directly activate their specific receptors on the membrane of gastrointestinal smooth muscle cells (Rodriguez et al, 2006;Gilani et al, 2008), which results in activation of several intracellular pathways and production of second messengers (phospholipase C, inositol triphosphate, diacylglycerol, protein kinase C) which in turn stimulate the release of internal Ca 2 þ from sarcoplasmic reticulum stores and the Ca 2 þ influx through voltage-gated Ca 2 þ channels (Chiwororo et al, 2009;Desire et al, 2010;Dubravka et al, 2010;Hu et al, 2010). Therefore, the inhibitory effects of PMAE on carbachol-or histamine-induced contractions could be produced as a result of a blockage of muscarinic or histaminic receptors on the cell membrane, or a calcium channel blocking activity.…”

“…It causes smooth muscle contractions Q3 hrough opening voltage-dependent Ca 2 þ channels, thus allowing an influx of extracellular Ca 2 þ causing a contractile effect. A substance causing inhibition of high K þ -induced contractions is considered as a blocker of calcium influx (Gilani et al, 2008;Borgi and Chouchane, 2009;Chiwororo et al, 2009;Dubraska et al, 2010). Therefore, our results (the inhibitory effect exhibited by PMAE against high K þ contractions) suggest that PMAE might inhibit the Ca 2 þ influx through voltage-operated Ca 2 þ channels (Xia et al, 2008;Borgi and Chouchane, 2009;Chiwororo and Ojewole, 2009;Dubraska et al, 2010) to produce non-selective spasmolytic effects.…”

“…In another set of experiments, contraction was induced by increasing concentrations of KCl (10 À 3 -6.10 À 2 M) cumulatively administrated to the bath solution at 2 min interval and a reference concentration-response trace was recorded. Then, the preparation was pretreated with the extract (20, 40 or 80 mg/mL) for 10 min and the concentrationresponse curve to KCl was re-examined in the continuous presence of the extract (Rodriguez et al, 2006;Chiwororo et al, 2009). Verapamil (0.1 mM) was used as antagonistic positive control.…”

Effects of Sesamum Radiatum Aqueous Leaf Extract on Rhythmic Contractions of Uterine Smooth Muscle Bundles From Pregnant Rats

“…All drugs were dissolved and/or diluted in distilled water on each day of our experiments [28] . Drugs concentrations quoted in the text refer to final organ-bath concentration.…”