Genotoxicity of an extract of Calendula officinalis L.

A fluid extract of Calendula officinalis L. displayed genotoxic properties when assayed for mitotic segregation in the heterozygous diploid D-30 of Aspergillus nidulans. The extract of Calendula exhibited dose-dependent toxicity and genotoxicity (both mitotic crossing-over and chromosome malsegregation being observed) to Aspergillus in the range of five plate concentrations from 0.1 to 1.0 mg of solids/ml assayed. Mutagenicity testing with the Salmonella/microsome assay in strains TA 1535, TA 1537, TA 98 and TA 100 was negative in a plate incorporation protocol, with concentrations ranging from 50 to 5000 microg/plate (+/- S9). The mouse bone marrow micronucleus test, where the extract was dosed orally up to 1 g/kg for 2 days, was also negative.

Activity of a nitroalkene derivative, 1-(5-bromofur-2-il)-2-bromo-2-nitroethene, in the Salmonella/microsome assay and the mouse bone marrow micronucleus test.

Mutagenicity of a substituted nitroalkene, 1-(5-bromofur-2-il)-2-bromo-2-nitroethene (BNF) was tested in the Salmonella/microsome assay using the strains TA 98, TA 100 and TA 100NR (nitroreductase deficient). BNF was a direct mutagen in TA 98 and TA 100; the response was lowered when exogenous metabolic activation (S9) was used. A further decrease in mutagenicity was observed in strain TA 100NR, as compared to the parental TA 100, which showed the involvement of nitroreduction in the overall response elicited by BNF. The micronucleus assay was carried out in Swiss male mice which were given a single i.p. dose of 10-20 mg/kg of BNF dissolved in peanut oil, bone marrow being sampled 24 and 48 h later. The micronucleated polychromatic erythrocyte counts (MNPCE) showed a weak response in the dose range of 10-17.5 mg/kg at the second sampling (48 h) and a significant rise for 20 mg/kg at 24 and 48 h.