Studies on the toxicity of Aristolochia manshuriensis (Guanmuton)

Aims: (1) To study the acute and chronic toxicity of stem of Aristolochia manshuriensis (AMA Guanmuton) which is a Chinese medicinal herb in order to provide basis for safe clinical use. (2) To investigate the possibility of reducing toxicity of the herb combined with Rhizoma Coptidis (Huanglian). Methods: The 70% ethanol extract of the herb was fed to mice via gastric tube for 8 weeks. The blood was collected to assess liver and renal functions. The tissue samples of the liver, kidney and bladder were collected from executed animals for pathology examination. Results: The LD₅₀ with a 95% average trustable probability (P=0.95) of AMA from Hanzhong (HZ) is 29.2±3.71 g/kg. The weight of animals in the treatment group at a dose of 4 g/kg raw drug, equivalent to 40 times of normal human dose in clinical prescription, remained the same as the control group (P>0.05). On pathological examination, there were no morphological changes under light microscope in the liver and bladder. For the kidney, the renal toxicity was significantly reduced after using ethanol extract of R. coptidis to process HZ AMA in that there were no interstitial inflammation, formation of hyaline cast or regeneration of renal tubules.