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Analysis of Carboxyatractyloside and Atractyloside in Xanthii Fructus (Cang'erzi)
The fruits of Xanthium sibiricum Patrin ex Widder (Asteraceae) are used in the Chinese traditional medicine for the treatment of sinusitis, nasal congestion and nasal discharge. However, they contain toxic diterpene glycosides, carboxyatractyloside and atractyloside, which are specific inhibitors of the mitochondrial oxidative phosphorylation and can induce apoptosis. For detoxification, Xanthium fruits are roasted so that carboxyatractyloside is decarboxylated to the less toxic atractyloside.
A new HPLC method has been developed to identify and analyse these toxic substances, using LC-DAD-MS/MS. The limit of detection was 1.464 ng/3 µl. Untreated fruits contained on 0.17% carboxyatractyloside. It was found that the average concentration of carboxyatractyloside in roasted fruits was much lower than in the untreated fruits, sometimes zero, while the atractyloside content was increased, indicating that the roasting process has in fact influence to reduce toxicity. A corresponding test for endpoint determination should be implemented when processing Cang'erzi.