In vitro and in vivo safety of aqueous extracts of Graptopetalum paraguayense E. Walther

Ethnopharmacological relevance: Graptopetalum paraguayense E. Walther, a widely consumed vegetable in Taiwan, has many biological effects and has been used in folk medicine to alleviate hepatic disorders, exert diuretic effects, and relieve pain and infections. However, little data exist regarding its safety. Materials and methods: Two genotoxicity assays were performed: chromosomal aberration of Chinese hamster ovary (CHO-K1 cells) (in vitro) and micronucleus assay in mice (in vivo). Acute oral toxicity and 28-day repeated feeding toxicity tests were performed by oral gavage in Sprague-Dawley (SD) rats. Results: GWE did not increase micronucleus ratios in vivo, and by chromosome aberration assay, GWE was safe up to 1.2 mg/ml with regard to clastogenicity. Chromatid breakage was observed at high concentrations (2.5 and 5.0 mg/ml) of GWE. GWE had no acute lethal effect at the maximum dose (5 g/kg bw) in rats. In the 28-day study, there were no adverse effects on body weight, feed consumption, hematology, blood biochemical parameters, organ weight, or pathology. Conclusion: The acute toxicity study showed that the LD50 of GWE was greater than the tested dose (up to 1 g/kg bw) in SD rats. In the subacute toxicity study, the no observed adverse effect level (NOAEL) of GWE in rats was 1 g/kg bw. The in vivo study of mammalian erythrocyte micronuclei confirmed the Ames test results, demonstrating that GWE has no mutagenicity. High doses of GWE require further examination due to its clastogenic potential. (C) 2011 Elsevier Ireland Ltd. All rights reserved.