Assessment of cytotoxic and genotoxic activity of alcohol extract of Polyscias filicifolia shoot, leaf, cell biomass of suspension culture and saponin fraction.

Some medicinal plants are the object of biotechnologists' special interest owing to their content of secondary metabolites, which have a strong pharmacological effect. Polyscias filicifolia is a plant known for long in traditional medicine of the Southeast Asia. Literature data suggest that it acts on the endocrine system, has adaptogenic and antiulcerative activity, shows bactericidal and insecticidal properties, restores the activity of the protein synthesis system in the conditions of long- and short-term anoxia, as well as reduces the effect of many mutagens in vitro. The purpose of the studies was to assess the cytotoxic and genotoxic effect of ethanol extracts from Polyscias filicifolia dry shoots and leaves obtained in vitro, as well as cell biomass from suspension culture. Saponin fraction from dried shoots was also tested. Initially, the cytotoxic effect was evaluated using the murine connective tissue cell line C3H/AN - L929. The genotoxic properties of the extracts were assessed using standard screening tests: the Ames test and the micronucleus test. Based on the obtained results it can be concluded that none of the extracts increases the number of revertants, both in tests with and without metabolic activation. The lack of in vitro genotoxic and mutagenic activity of tested shoot, dried leaf, cell biomass extracts, as well as the saponin fraction from dried shoots allows us to hope that Polyscias filicifolia could be used as a possible pharmaceutical raw material showing therapeutic properties.

Genotoxicity of alpha-asarone analogues.

The role of cholesterol in the formation of atherosclerotic lesions during hypercholesterolemia has been confirmed. alpha-Asarone is a substance of a potent hypolipidemic activity which is isolated from plants. We previously described the synthesis of several alpha-asarone analogues exhibiting hypolipidemic and antiplatelet activity. Genotoxic activity of four selected alpha-asarone analogues was theoretically evaluated based on quantum-mechanical method for calculation of enthalpy of carbocations formation (DeltaH(R)) according to the Testa's method. In the present paper, we evaluated the mutagenic and genotoxic activity of alpha-asarone isomers 2-5 based on the reference Ames test and micronucleus test. Results obtained in the study show that tested isomers were non-mutagenic, however, they exhibited growing cytotoxic activity. Relationship between the heat of formation of their putative metabolic intermediates and mutagenic/genotoxic activity was not confirmed.

OmpR negatively regulates expression of invasin in Yersinia enterocolitica.

Invasin, the major adhesion and invasion factor of Yersinia enterocolitica, is encoded by the inv gene, which is regulated by growth phase and in response to a variety of environmental conditions such as temperature, pH and osmolarity. So far, three proteins, RovA, H-NS and YmoA, have been identified as factors regulating the expression of the inv gene in enteropathogenic Yersinia. Here, data from inv' : : lacZYA chromosomal gene fusion studies are presented indicating that OmpR, the response regulator of the EnvZ/OmpR two-component system, acts to negatively regulate inv expression at the transcriptional level at 25 degrees C, and that high osmolarity enhances the inhibitory effect of this protein. In a strain lacking OmpR the expression of inv at 25 degrees C was increased sixfold, but at 37 degrees C, a temperature known to repress inv expression, this effect was not observed, suggesting that temperature regulation of inv is OmpR-independent. Furthermore, the expression of inv in the ompR background was no longer responsive to increased osmolarity. Complementation with the active ompR allele restored wild-type inv expression in the ompR mutant. In silico analysis of the Y. enterocolitica O : 9 inv promoter sequence revealed the presence of an OmpR consensus binding site located in the -15 to -33 region. OmpR was able to specifically bind to a fragment of the inv promoter containing this putative binding site in electrophoretic mobility shift assays. Thus, OmpR seems to be a repressor of inv in Y. enterocolitica.