Risk characterization of botanical extracts containing hydroxyanthracenes as determined by a validated micronucleus in vitro assay

Extracts of Rheum palmatum L., Rhamnus purshiana DC., Rhamnus frangula L., and Cassia senna L. are used in traditional medicine thanks to their beneficial properties. These species contain hydroxyanthracene derivatives, considered genotoxic and possibly related to colorectal cancer development. This research aimed to study, using a micronucleus assay in vitro, the genotoxic potential of Rheum palmatum L., Rhamnus purshiana DC., Rhamnus frangula L. (bark), and Cassia senna L. (leaves and fruits) extracts. The extracts were evaluated at different concentrations: from 0 to 2000 µg/mL for Rhamnus purshiana DC, from 0 to 2500 µg/mL for Rheum palmatum L. and Rhamnus frangula L., and from 0 to 5000 µg/mL for Cassia senna L. The cytokinesis-block proliferation index was calculated to analyse if the used concentrations showed cytotoxicity. The hydroxyanthracene content varied between 0.06% and 0.23% for aloe-emodin, and between 0.07% and 0.16% for emodin and rhein. No cytotoxic effect was detected at any of these concentrations. Micronucleus analyses showed a lack of genotoxicity for all the extracts tested. These results show that Rheum palmatum L., Rhamnus purshiana DC, Rhamnus frangula L., and Cassia senna L. extracts do not induce genotoxicity since no increase in micronuclei formation in human lymphocytes in vitro was detected.