Evaluation of cytotoxicity, phototoxicity and genotoxicity from Calceolaria chelidonioides (Scrophulariaceae) flowers ethanol extract

Calceolaria chelidonioides is an original Brazilian plant belonging to the Scrophulariaceae family, which is used in the Brazilian folk medicine for the treatment of several kinds of cancer. Its cytotoxicity, photoxicity and genotoxicity potential were evaluated in different methodologies in vitro using the flowers ethanol extract. The cytotoxicity and phototoxicity were evaluated by the neutral red dye assay using keratinocyte human cells (NCTC 2544). For the phototoxicity evaluation the cell culture containing the compounding test was submitted to UVA radiation (345nm) during 15 minutes. The assays showed the cell viability after the treatment with the extract and its metabolites formed by the UV radiation. The genotoxicity potential was evaluated by two different methods, both of them suggested in the „Genotoxicity: a standard battery for genotoxicity testing of pharmaceuticals“ guide [1]. The first one was the Comet assay [2,3] using keratinocyte human cells incubated for 1 hour with the extract, with and without metabolic activation using the S9 mix. The Comet assay is able to detect different kinds of DNA fragmentations caused by the genotoxic agents. The cells which DNA were damaged show an image comet like with a „head“ and a „tail“ that elongates proportionally to the DNA damages. The second method was the Ames' test [4] which is capable to detect compounds with carcinogenic and mutagenic properties using mutants Salmonella typhimurium strains to detect base substitution and frame shift point mutations. These tests were also evaluated with and without metabolic activation. The C. calceolaria flowers ethanol extract or even its metabolites didn't show any kind of toxicity in all tested models.

Acknowledgements: CAPES, CNPq

References: [1] ICH Harmonised Tripartite Guideline (1997) International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use. Brussels. [2] Rydberg B., Johanson K.J. (1978) DNA Repair Mechanisms. Academic Press. New York. [3] Östling O., Johanson K.J. (1984) Biochem Biophys Res Commun 123: 291–298. [4] Ames B.N., Maron D.O. (1983) Mutation Res 113: 173–215.