Tao Chen, Nan Mei and Peter P. Fu
Pyrrolizidine alkaloids (PAs) from many plants are toxic to livestock, wildlife and human. Many of them are genotoxic and tumorigenic. Upon metabolic activation, PAs produce DNA adducts, DNA cross-linking, DNA breaks, sister chromatid exchange, micronuclei, chromosomal aberrations, gene mutations, and chromosome mutations invivo and in vitro. The signature types of mutations are G : C T : A transversion and tandem base substitutions. Overall, PAs are mutagenic and their mutagenicity appears to be responsible for the carcinogenesis of PAs.