Discovery of GABA(A) receptor modulator aristolactone in a commercial sample of the Chinese herbal drug "Chaihu" (Bupleurum chinense roots) unravels adulteration by nephrotoxic Aristolochia manshuriensis roots.
In a two-microelectrode voltage clamp assay using Xenopus laevis oocytes, a petroleum ether extract prepared from a commercial sample of the traditional Chinese herbal drug labelled as " Chaihu" (Bupleurum chinense DC. roots) enhanced the I(GABA) by 156 % ± 22 % when tested at 100 µg/mL. By means of HPLC-based activity profiling combined with high-resolution LC-MS and microprobe NMR, the germacranolide aristolactone was identified as one of the main active compounds (EC₅₀ 56.02 µM ± 5.09 µM). However, aristolactone has been previously reported only from the genus Aristolochia (Aristolochiaceae), suggesting a possible adulteration. With the aid of a validated HPTLC protocol for detection of aristolochic acids and with reference samples, the commercial sample was confirmed to be a mixture of Aristolochia manshuriensis root and Bupleurum chinense root. This finding was corroborated by macroscopic inspection of the drug. This case of adulteration with a highly nephrotoxic drug raises concerns about adequate quality control of TCM drugs commercialized in Europe.
PubMed ID: 22271081
Article link: Planta Med.