Evaluation of genotoxic and modulatory effects of Nyctanthes arbor-tristis calyx extract and the isolated crocin in Ames' assay

Flowers of the plant Nyctanthes arbor-tristis (NAT) are widely used in the traditional medicinal systems of several Asian countries. In the present study, potential genotoxicity and modulatory effects of ethanolic extract of NAT flower calyx (NAT FCE) and crocin, a carotenoid principle were evaluated employing standard Salmonella assay. Experiments evaluating the genotoxic potential of NAT FCE and crocin, with and without the S9-activation in TA 98, TA 100 and TA 102 showed a lack of increase in revertant mutants. Evaluation of modulatory effects of NAT FCE and crocin, without the S9, showed significant decrease in the number of 4-nitro-o-phenylenediamine-, sodium azide- and ethyl methanesulfonate-induced revertants. However, with S9, NAT FCE and crocin moderately increased the 2-aminoanthracene-induced revertants in TA 98; they moderately decreased revertants in TA 100 and TA 102. Both NAT FCE and crocin have been shown to be non-genotoxic and to be able to modulate responses of standard mutagens.