Alocasia sakonakhonensis (Araceae), a new species from northeastern Thailand.

Alocasia sakonakhonensis Chatan & Promprom (Araceae), a new species from northeastern Thailand, is described and illustrated. It is clearly different from other previously known species by leaves, spathe, ovary, sterile interstice, synandria, and appendix. Color illustrations, and a distribution map are provided, as well as comparative morphological characters about its similar species. The preliminary conservation status assessment of the new species was presented.

Finding new agents in medicinal plants to act on the myometrium.

This report summarizes work investigating the effects of some medicinal plants on uterine contraction. As there is a clinical need to find better drugs to help control uterine activity, and novel compounds are sought, the mechanisms whereby the medicinal plants exert their effects, as well as their major compounds, are discussed. By identifying the plants, major constituents and mechanisms, this review also illustrates the potential for development of new drugs, so that better ways to treat uterine disorders will be available to women worldwide.

The effects of watermelon (Citrullus lanatus) extracts and L-citrulline on rat uterine contractility.

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.