Lignan and Phthalide Derivatives from the Rhizome of Ligusticum chuanxiong ( Rhizoma chuanxiong ) and Evaluation of Their anti -Xanthine Oxidase Activities.

The previous research results showed that the extracts of ethyl acetate of the rhizome of Ligusticum chuanxiong ( Rhizoma chuanxiong ) possessed significant antigout effects in model mice. To explore the active ingredients responsible for the effects, phytochemical studies were performed, which led to the isolation of three rare 8', 9-linked neolignans, ligusticumins A-C ( 1 - 3 ), together with two novel phthalide-phenylpropanoid heterodimers, ligusticumalides A-B ( 4 and 5 ). It is noteworthy that 4 possesses an unprecedented 7-styryl phthalide skeleton. The structures and absolute configurations of 1 - 5 were elucidated by one-dimensional (1D) and two-dimensional (2D) NMR spectroscopy and electron-capture detector (ECD) spectroscopic methods. The bioassay results showed that compounds 1 , 2 , 3 , and 5 presented moderate inhibitory activities against xanthine oxidase (XO) and 4 possessed a significant XO inhibitory effect with an IC 50 value of 93.88 μM. This is the first time to investigate the anti -XO active ingredients of R. chuanxiong , which provides valuable information for searching for new antigout agents from natural products.