The Effects of Watermelon (Citrullus lanatus) Extracts and l-Citrulline on Rat Uterine Contractility

Abstract

In uterine smooth muscle, the effects of watermelon and its citrulline content are unknown. The aims of this study were therefore, to determine the effects of watermelon extract and citrulline on the myometrium and to investigate their mechanisms of action. The effects of extracts of watermelon flesh and rind and L-citrulline (64 μmol/L) were evaluated on 3 types of contractile activity; spontaneous, those elicited by potassium chloride (KCl) depolarization, or oxytocin (10 nmol/L) application in isolated rat uterus. Inhibitors of nitric oxide (NO) and its mechanisms of action, N ω-Nitro-L-arginine methyl ester hydrochloride (L-NAME, 100 μmol/L), LY83583 (1 μmol/L), and tetraethylamonium chloride (5 mmol/L), as well as Ca signaling pathways, were determined. Both flesh and rind extracts significantly decreased the force produced by all 3 mechanisms, in a dose-dependent manner. The extracts could also significantly decrease the force under conditions of sustained high Ca levels (depolarization and agonist) and when the force was produced only by sarcoplasmic reticulum (SR) Ca release. L-citrulline produced the same effects on force as watermelon extracts. With submaximal doses of extract, the additive effects of L-citrulline were found. The inhibitory effects of extracts and L-citrulline were reversed upon the addition of NO inhibitors, and pretreatment of tissues with these inhibitors prevented the actions of both extracts and L-citrulline. Thus, these data show that watermelon and citrulline are potent tocolytics, decreasing the force produced by calcium entry and SR release and arising by different pathways, including oxytocin stimulation. Their major mechanism is to stimulate the NO-cyclic guanosine monophosphate (cGMP) relaxant pathway.

The effects of Ginseng Java root extract on uterine contractility in nonpregnant rats

“…The electrical signal from the transducer was amplified and converted to a digital signal and recorded on a computer using Chart software, as detailed elsewhere (Munglue et al. ).…”

Finding new agents in medicinal plants to act on the myometrium

“…We have therefore chosen to synthesize data from our studies of four plants used in menstruation-, pregnancy-and birth-related problems and to compare mechanisms, in order to obtain insights into directions for future studies. We have focused on pomegranate (Punica granatum L., Punicaceae; Promprom et al 2010), wild ginger (Costus speciosus (Koen) Smith, Costaceae; Lijuan et al 2011), ginger (Zingiber officinale Roscoe, Zingiberaceae; Buddhakala et al 2008) and watermelon (Citrulus lantanus, Cucurbitaceae; Munglue et al 2013). Different plant parts, such as the rhizomes and fruits, were freshly…”

“…) and watermelon ( Citrulus lantanus , Cucurbitaceae; Munglue et al . ). Different plant parts, such as the rhizomes and fruits, were freshly collected when they were seasonally available.…”

“…; Munglue et al . ). All separated compounds were identified from the recorded mass spectra by comparing the mass spectra from the The National Institute of Standards and Technology and Wiley libraries.…”

“…Oil (ginger) was obtained by hydrodistillation. The quantitative phytochemical screening of the plant extracts were analysed by gas chromatography-mass spectrometry (Buddhakala et al 2008;Promprom et al 2010;Lijuan et al 2011;Munglue et al 2013). All separated compounds were identified from the recorded mass spectra by comparing the mass spectra from the The National Institute of Standards and Technology and Wiley libraries.…”