Chronic toxicity, genotoxic assay, and phytochemical analysis of four traditional medicinal plants.

Four medicinal plants--Tecoma stans, Ligusticum porteri, Monarda austromontana, and Poliomintha longiflora, which are distributed in tropical and subtropical countries of the American continent--are widely used in folk medicine to treat diseases such as diarrhea and dysentery. In addition, T. stans and P. longiflora are extensively used as hypoglycemic agents, and M. austromontana and P. longiflora are used as condiments. The plants were collected, identified, dried, and pulverized. Solvent extraction was prepared by maceration of the plant samples, and the phytochemical composition of the extracts was determined by using standard analysis procedures. Phytochemical analysis showed the presence of triterpenoids/steroids, flavonoids, and phenols/tannins and, in L. porteri, traces of alkaloids. After the elimination of solvents in vacuo, the extracts were administrated to Drosophila larvae to test their toxicity and genotoxicity. Third instar larvae were chronically fed with the phytoextracts. The extract from L. porteri was toxic, whereas those from T. stans, P. longiflora, and M. austromontana were not. Genotoxic activities of the 4 plants were investigated by using the wing-spot assay of D. melanogaster. Mitomycin C was used as a positive control. No statistically significant increase was observed between treated sample series and a concurrent negative (water) or solvent control sample series.

Genotoxicity testing of Cecropia obtusifolia extracts in two in vivo assays: the wing somatic mutation and recombination test of Drosophila and the human cytokinesis-block micronucleus test.

Cecropia obtusifolia Bertol. (Cecropiaceae) is a tree that grows in secondary vegetation in the tropical rain forest along both coasts of Mexico. Its leaves are used in folk medicine for the treatment of diabetes mellitus type 2. The aim of the present studies was the evaluation of possible genotoxic effects of the aqueous extract from the leaves of Cecropia obtusifolia by means of two different experimental assay models: the wing somatic mutation and recombination test in flies and the micronucleus test from lymphocytes obtained from patients treated with the extract. No toxicity was found to be induced by the leaves of Cecropia obtusifolia. The Drosophila wing somatic mutation and recombination test (SMART) was applied in the standard version with basal biotransformation activity as well as in a variant version with increased cytochrome P450-dependent bioactivation capacity. The ranges of exposure concentrations for these genotoxicity experiments were between 0.82 and 13.32 mg/ml. The extract did not produce any genotoxic effect; however it showed a non significant antigenotoxic effect. The human micronucleus assay in vivo was performed with cultured lymphocytes obtained from six diagnosed type 2 diabetic patients treated daily with 13.5 g of the aqueous extract between 32 and 85 days. No statistically significant increases in cytotoxicity and/or genotoxicity between control and diabetic blood samples were observed.

A phytotherapeutic extract of Equisetum myriochaetum is not genotoxic either in the in vivo wing somatic test of Drosophila or in the in vitro human micronucleus test.

Equisetum myriochaetum is a Mexican plant used in folk medicine to treat kidney diseases and type 2 diabetes mellitus. The main constituents of the phytoextract are flavonol glycosides (kaempferol), phytoesterols and carbohydrates. In this study, phytotherapeutic extracts from Equisetum myriochaetum were investigated for genotoxicity in the in vivo wing spot test in Drosophila melanogaster and in the in vitro human micronucleus test. No acute toxicity of the phytoextract could be determined in Drosophila or in human lymphocytes in culture, ranging from 0.78 microg/ml to 3700 microg/ml for the wing assay and between 12.5 microg/ml and 500 microg/ml for the micronucleus test. The Drosophila wing somatic mutation and recombination test (SMART) was applied in the standard version with basal biotransformation activity as well as in a variant version with increased cytochrome P450-dependent bioactivation capacity. The ranges of exposure concentrations for these genotoxicity experiments were between 0.78 microg/ml and 500 microg/ml. The human micronucleus test in vitro was performed with cultured lymphocytes obtained from four healthy donors. The concentrations assayed for these experiments ranged from 12.5 microg/ml to 500 microg/ml. No statistically significant increase was observed between treated series when compared with a concurrent negative (water solvent) control series in either assay. The results demonstrate clearly that the phytotherapeutic extract from Equisetum myriochaetum, under the experimental conditions tested, is not genotoxic in the in vivo experiments or in the in vitro studies.

Genotoxic profile of inhibitors of topoisomerases I (camptothecin) and II (etoposide) in a mitotic recombination and sex-chromosome loss somatic eye assay of Drosophila melanogaster.

Genotoxic carcinogens which interact with DNA may produce double-strand breaks as normal intermediates of homologous mitotic recombination, and may give rise to structural chromosome aberrations and inter-chromosomal deletion-recombination. The genotoxic profile of two inhibitors of DNA topoisomerases were evaluated using an in vivo somatic w/w+ eye assay of Drosophila melanogaster for the detection of loss of heterozygosity (LOH) by homologous mitotic recombination, intra-chromosomal recombination and structural chromosomal aberrations. We studied camptothecin (CPT) as a topoisomerase-I-interactive agent and etoposide (ETOP) as a topoisomerase II inhibitor. These drugs act by stabilizing a ternary complex consisting of topoisomerases covalently linked to DNA at single-strand or at double-strand breaks, thereby preventing the relegation step of the breakage/rejoining reaction mediated by the enzyme. The genotoxic profiles were determined from the appearance of eye tissue in adult flies, in which LOH and expression of the reporter gene white produced light clones. The results demonstrated that both compounds were significantly genotoxic, with CPT being more effective than ETOP. Inter-chromosomal mitotic recombination was the major mechanism responsible for the induction of light spots by both compounds in XX females. Loss of the ring X chromosome (rX), was significantly enhanced by CPT, and this topoisomerase blocker also produced intra-chromosomal recombination (XY males).