Chemical Constituents from the Rhizome of Ligusticum chuanxiong Hort. and Their Nrf2 Inducing Activity

The rhizome of Ligusticum chuanxiong Hort. has been widely used for the therapy of diabetic nephropathy (DN) in traditional Chinese medicine (TCM). The nuclear transcription factor erythroid 2-related factor (Nrf2) is a potential target for treating DN. The purpose of this research was to study the chemical constituents from the rhizome of L. chuanxiong, evaluate their Nrf2 inducing activity, and find the molecules with potential therapeutic effect against DN. In this study, two new phthalides (1-2) along with twenty-seven known constituents were obtained from the rhizome of L. chuanxiong. Their structures were elucidated through various spectroscopic methods. Twelve constituents, including eight phthalides (2, 5, 6,10-13, 14) and four other compounds (17, 18, 20,28), stimulated NAD(P)H: quinone reductase (QR) activity, suggesting that these bioactive constituents were potential Nrf2 activators. Among the isolated compounds, phthalide levistolide A (LA, 14) upregulated the protein levels of Nrf2, NQO1, and γ-GCS in a dose-dependent manner. Our results implied that the clinical application of the rhizome of L. chuanxiong as an anti-DN drug in TCM might be attributed to the Nrf2 inducing effect of phthalides. Thus, phthalides is a group of promising leading molecules for discovering anti-DN agents.