Fermentation of Aristolochia debilis by six different medicinal fungi and identification of aristolochic acid derivates in their products by HPLC-ESI-TOF-MS.

To analyze the content change of the nephrotoxic substances, aristolochic acid derivates (AAs) in the roots of Aristolochia debilis and the products generated from the solid-state fermentation of six different medicinal fungi by HPLC-ESI-TOF-MS, the chromatographic separation was carried out on C18 column at 30°C with the DAD detector. The elution was performed using the mobile phase of acetonitrile (A) and 0.2% acetic acid (B). Several new peaks were found in the scale of 0-20 min elution of HPLC diagram in the fermentation products. The ESI-MS detection (negative ion mode) was carried out by post-column flow splitting method following the automatic injection. Seven AAs in the fermentation products and A. debilis were deduced, which were recognized as AAIa or IIIa (1), AAVIa (2), AAIVa, Va, VIIa or VIIIa (3); AAII (4); AAIII (5); AAI (6); AAIV or VII (7). The areas of almost all these seven components existing originally in the corresponding crude drug decreased after the fermentation process, suggesting that fermentation is an effective way of lowering the nephrotoxicity induced by AAs in Chinese medicines similar with A. debilis. In addition, Optimized HPLC-MS method is helpful to AAs content identification.