'Preliminary assessment of the cytotoxicity and genotoxicity of an association Aristolochia baetica - Magnolia officinalis'

Introduction:
Herbal medicines are widely used around the world, either for primary health care or as complementary medicine. These herbal medicines are generally considered as safe and reliable. However, herbs can sometimes cause serious health troubles. For example, the aristolochic acid nephropathy (AAN), a progressive renal interstitial fibrosis frequently associated with urothelial malignancies, was reported in a Belgian cohort after the intake of slimming pills inadvertently containing an Aristolochia species, rich in nitro-polyaromatic compounds, aristolochic acids (AA). Numerous studies confirmed that AAs are genotoxic through the generation of aristolactams which yield highly persistent and non- or poorly-repaired DNA adducts. Interestingly, the Belgian cases are remarkable by the rapid onset of the pathology. Available records indicate that supposedly slimming pills prescribed especially contained Stephania, that was adulterated by the roots of an Aristolochia species (probably A. fangchi), and also bark of Magnolia. The presence of Aristolochia was blamed for the pathologies and, to the best of our knowledge, the prescription itself has not been further investigated.
Material and methods:
The goal of the present study is to evaluate on a FHs 74 Int human intestinal epithelial cell line the cytotoxicity and genotoxicity of Aristolochia baetica and Magnolia officinalis aqueous and methanolic extracts alone or in combination. Cytotoxicity of the Aristolochia - Magnolia combination is studied by a MTT cell viability assay and the genotoxicity by the detection and quantification of the phosphorylated histone γ-H2AX (whole cell ELISA and Immunocytochemistry) and by an Ames test on four different Salmonella typhimurium strains (TA98, TA100, TA1535, TA1537).
Results:
The genotoxicity of the association of Aristolochia baetica and Magnolia officinalis extracts is significantly higher compared to the individual plant extracts.
Discussion:
The high potentiation of AAs genotoxicity by Magnolia officinalis could then be an explanatory factor for the 'Chinese herbs nephropathy' case, observed in Belgium in the 1990s. Although this would be a very interesting example of indirect genotoxicity, this observation warrants further studies to establish the precise role of the Magnolia officinalis extracts and to identify the compounds responsible for the observed co-genotoxicity.