Toxicity of Aristolochia decoction: a relevant herbal in folk medicine

Ethnopharmacology studies report the use of Aristolochia (Aristolochiaceae) species as medicinal plants in various parts of the world. However, the acids aristolochic (AAs), secondary metabolites present in all species of Aristolochia, have cytogenotoxic activity and they are a potent carcinogen to rodents and humans. The aim of the current research was to perform to initial screening for the toxicity of Aristolochia labiata and Aristolochia triangularis decoctions through germination and growth rate, flow cytometry, mitotic index and cytogenetics analysis in Allium cepa. The decoctions were prepared from 2, 4, 8, 16 and 32 g L-1. Decoctions at concentrations 4 g to 16 g L-1 significantly reduced the germination rate of Allium cepa. Seeds exposed to 32 g L-1 decoctions did not germinate. All decoctions reduced the growth rate of onion seedlings. Decoctions at 4 g L-1 to 16 g L-1 inhibited mitotic index. Highest concentrations of decoctions (8 g L-1 and 16 g L-1 for Aristolochia labiata; 16 g L-1 for Aristolochia triangularis) showed statistically significant increase in frequency of Allium cepa nuclei in the G0/G1 phase. Both decoctions induced the formation of heteropycnotic nuclei. Qualitative phytochemical prospecting of decocts were performed and alkaloids secondary compounds were the largest presence in both species, indicating that the AAs may be related to the observed toxicity. Caution is recommended in the consumption of decoctions from Aristolochia labiata and Aristolochia triangularis stems.