Neurotoxicity of Coscinium fenestratum stem, a medicinal plant used in traditional medicine.

Coscinium fenestratum is a common medicinal plant widely used in the Indochina region, but scientific data on its safety is very limited. This study aimed to observe the effect of this plant on neurotoxicity and neurobehavior. Oral administration of plant alcoholic extract at dosages of 5, 10 and 20 mg/kgBW for 14 days increased the rats body weight and decreased the neuron density in the cerebral cortex, hippocampus and striatum. The plant extract significantly increased stereotyped behavior in licking but did not cause anxiolytic activity, anti-depression, sensory motor co-ordination impairment and ataxia. It is concluded that the plant possesses neurotoxicity and is able to induce neurobehavioral changes in rats. Therefore, the application of this plant as either drug or supplementary food should be reconsidered.     

Hepatoprotective and antioxidant activities of Tetracera loureiri

Tetracera loureiri is one of the most valued herbs in Thai traditional medicine. In this study, we describe its in vitro and in vivo antioxidant and hepatoprotective activities. The ethanol extract of T. loureiri possessed potent antioxidant and strong free radical scavenging properties assayed using ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH), respectively. The cytoprotective effects of T. loureiri were demonstrated in ethanolic extracts of freshly isolated rat hepatocytes against the chemical toxicants paracetamol and tertiary-butylhydroperoxide. The cells pretreated with the extract maintained the GSH/GSSG ratio and suppressed lipid peroxidation in a dose dependent manner. Pretreating rats with the ethanol extract orally, one hour prior to intraperitoneal injection of toxic doses of paracetamol, significantly prevented elevations of plasma ALT and AST. These results suggest that T. loureiri may be of potential therapeutic value in some liver disorders.     

Anti-inflammatory isoflavonoids from the stems of Derris scandens

Fractionation of the aqueous extract of Derris scandens stems extract using tests for eicosanoid inhibition resulted in the isolation of three isoflavonoids, genistein, its 7- O-alpha-rhamno(1-->6)-beta-glucosyl glycoside, a new compound, and two known isoprenyl derivatives 3'-gamma,gamma-dimethylallylweighteone and scandenin. The isoprenylated compounds showed a high inhibitory effect on eicosanoid production in vitro but HPLC analysis showed that the genistein accounted for most of the activity of the total extract. Antioxidant studies showed that genistein and the isoprenylated compounds showed activity comparable to standard antioxidants. Genistein and its glycoside demonstrated no cytotoxicity in the MTT test but the prenylated compounds showed some toxicity and also increased LDH release from polymorphonucleocytes, at concentrations much greater than would be encountered in an aqueous extract of D. scandens.     

In vitro and in vivo anti-inflammatory potential of Cryptolepis buchanani

Cryptolepis buchanani Roem. & Schult. (Asclepiadaceae), a climbing tree, is used as folk medicine in southeast Asia. In Thailand, the stem of this plant is traditionally used for the treatment of inflammation, including arthritis, and muscle and joint pain. In the current study, the potential anti-inflammatory activity of a 50% ethanol extract of this plant was evaluated in a number of experimental models. For anti-acute inflammatory activity, results showed that the extract caused reduction of carrageenan-induced rat paw edema in addition to significant reduction of eicosanoid production from calcium ionophore A23187-stimulated rat peritoneal leukocytes. In a test for anti-chronic inflammatory potential utilizing the cotton thread-induced granuloma, the extract caused significant lowering of granulation tissue formation. The reduction of tumor necrosis factor-alpha (TNF-alpha) release from LPS-stimulated human monocytic cell line (THP-1) was also demonstrated in cells that were pre-incubated with the extract. An additional important feature of Cryptolepis buchanani is its low toxicity, especially by oral treatment, which significantly encourages clinical trials of this extract in the human. In conclusion, the results give scientific support to the traditional use of this plant for combating inflammation. Further investigations are required to identify the active constituents responsible for the anti-inflammatory activity of Cryptolepis buchanani. Subacute and chronic toxicological studies in animals are also needed before clinical trials.     

Using vaginal cytology to assess the estrogenic activity of phytoestrogen-rich herb

To assess the estrogenic activities of synthetic estrogen, synthetic phytoestrogen, Pueraria lobata and three distinct cultivars of Pueraria mirifica, a phytoestrogen-rich herb, a vaginal cytology assay in ovariectomized rats were used. Rats were ovariectomized and treated with DW, estradiol valerate (1 mg/kg BW), genistein (0.25-2.5 mg/kg BW), Pueraria lobata and Pueraria mirifica (10-1,000 mg/kg BW) for 14 days. The vaginal cytology was checked daily and the uteri were dissected and weighed at the end of treatment or post-treatment periods. The treatments of DW, genistein and Pueraria lobata did not influence the vaginal epithelium, but the injection of estradiol valerate induced a vaginal cornification from day-3 of treatment to day-14 of post-treatment period. The occurrence of vaginal cornification after treatment and the recovery after the cessation was dependent on dosages and cultivars of Pueraria mirifica. The increments of uterus weight in all rats agreed with the cornification of vaginal epithelium. Although both uterotropic and vaginal cytology assays can be used to assess the estrogenic activity of phytoestrogen-rich herb, however, using vaginal cytology assay has two advantages: (1) we do not need to kill the animals and (2) we can follow up the recovery after the cessation of treatment.