Substitution between Aristolochia and Bryonia genus in North-Eastern Morocco: toxicological implications

Although acknowledged as toxic herbs, Aristolochia species are still widely used worldwide. The aristolochic acids (AA) they contain can induce the so-called "aristolochic acid nephropathy", leading to renal fibrosis and upper urinary tract cancer. Traditional Moroccan medicine still often uses Aristolochia species under the vernacular name of Bereztem for the treatment of numerous ailments, notably cancer, diabetes or digestive tract disorders. As the botanical identity and renal toxicity of used species remain unexplored, the safety of patients may be threatened.

Ethnopharmacological data were collected from herbalists from the provinces of Oujda and Berkane, located in North-Eastern Morocco. Samples of Bereztem were collected at herbalist shops and checked for their content in AA using TLC and LC-MS methods. The toxicity of crude methanolic extracts of each herb was assessed on a HK-2 cell-based in vitro model by measurement of the cell survival to evaluate cytotoxicity and by assessment of renal-specific toxicity via (i) the evaluation of genes (E-cadherin and α-smooth muscle actin) expression by RT-qPCR; (ii) the quantities of β-catenin and vimentin by immunofluorescence microscopy; (iii) the secretion of fibronectin; and (iv) the excretion of interleukin-6.

The survey indicated that, among 42 herbalists visited, 33 were retailers of Bereztem, which was generally sold as a cancer treatment. Botanical investigations revealed that Aristolochia longa was frequently substituted by Bryonia dioica, which was associated with a higher cytotoxicity. Parameters specific to renal toxicity were also found to be enhanced, as compared to Aristolochia baetica and A. longa: down-regulation of β-catenin and E-cadherin and up-regulation of vimentin and α-smooth muscle actin, and secretion of fibronectin and interleukin-6.

In accordance with the Moroccan regulations, the use of so-called Aristolochia species should be discontinued. On one hand, the correctly identified aristolochia contain nephrotoxic aristolochic acids; on the other hand, aristolochia are massively substituted in North-Eastern Morocco and adulterated by a well-known toxic herb, B. dioica. Our data indicate that the bryony renal toxicity may be deleterious in shorter time periods than aristolochia. Reinforced on-site controls are needed to remind herbalists and harvesters that these herbs should be prohibited.