Mutagenicity of Pueraria mirifica Airy Shaw & Suvatabandhu and antimutagenicity of Thunbergia laurifolia Linn.

Thunbergia laurifolia Linn has been reputed to have antitoxic effects for all toxic substances. In this present study, we evaluated its effect against the mutagenicity induced by aqueous extracts from Pueraria mirifica Airy Shaw & Suvatabundhu in male rats. The formation of micronuclei in polychromatic erythrocytes was induced by oral administration of an aqueous extract of P. mirifica at the doses of 400, 600, and 800 mg/kg to the rats for 30 days. The results were that the extracts of P. mirifica at doses of 600 and 800 mg/kg acted as a mutagenic agent by inducing higher frequencies of micronuclei as compared to the controls. For the antimutagenic test, P. mirifica extract at a dose of 600 mg/kg (minimal effective dose) was mixed with fresh and dried extracts of T. laurifolia in proportions of 7:3 and 1:1, respectively. The results of 4-week-treatment indicated that aqueous extracts of T. laurifolia, prepared by both fresh and dry methods, could significantly inhibit the induction of micronuclei as induced by P. mirifica. It could be concluded from the results that, under certain circumstances, T. laurifolia exhibits a significant antimutagenic activity. The use of P. mirifica and T. laurifolia as fusion herbal medicines is suggested.

Anti-diabetic effect of Thunbergia laurifolia Linn. aqueous extract.

Several kinds of medicinal plants have been used to treat diabetes mellitus. In the present study, Thunbergia laurifolia Linn. (purple flower strain) were tested for hypoglycemic activity in rats. The effects on the reproductive system and the histology of the pancreas were also investigated. The hypoglycemic properties of the aqueous extract from the leaves (60 mg/ml/day) were evaluated in normoglycemic and alloxan-induced diabetic rats. The results showed that high blood glucose levels of diabetic rats were associated with severe destruction of beta-cells (insulin-secreting cells) in the islet of Langerhans. The 15-day-treatment of T. laurifolia extract decreased levels of blood glucose in diabetic rats. The recovery of some beta-cells was found in diabetic rats treated with the extract, although not completely normal. Whether T. laurifolia leaf contains insulin-like substance(s) which directly act as hypoglycemic agents, or contains substances that induce the regenerative process of beta-cells remains to be further investigated. Alteration of the reproductive system was also observed in diabetic rats, but it was not improved by treatment with T. laurifolia extract.

The toxicology of Butea superba, Roxb.

A study to determine the primary toxicological effects of Red Gwow Kreur (Butea superba, Roxb.) dry powder by micronucleus and dominant lethal tests was undertaken. Aqueous solution of Red Gwow Kreur dry powder in doses of 2, 20, 200 and 1,000 mg/kg/day were fed to male rats for 9 weeks. The results showed that 1,000 mg/kg/day of Red Gwow Kreur solution was significantly more effective in inducing the formation of micronuclei in polychromatic erythrocytes than the control (p<0.01), whereas dominant lethal test indicated that none of the doses had a toxic effect on male reproduction. There were no abnormal changes in the number of implantation sites and the number of dead fetuses produced by females that had mated with Red Gwow Kreur treated males in comparison with the controls. In addition, the Red Gwow Kreur solutions had no effect on the body weights of the treated rats.

Dominant lethal test in rats treated with some plant extracts.

The present study was undertaken to investigate the toxic effect of aqueous extracts of Aegle marmelos (AM), Stevia rebaudiana (SR), Pouteria cambodiana (PC) and Clausena excavata (CE) on rats by dominant lethal test. The data of 8-week treatment suggested that none of the extracts adversely affected male body and testicular weights as well as cauda epididymal sperm counts. No notable changes in sperm morphology and motility were observed. On the other hand, sperm count in the CE group was significantly higher as compared to both control and other treatment groups. There were no abnormal changes in the number of implantation sites, number of viable fetuses and number of dead fetuses in females mated with plant extract-treated males relative to controls. Based on these results, it could be concluded that all the investigated plant extracts have no toxic effect on male rat reproduction and progeny outcome.