Phthalides from the rhizome of Ligusticum chuanxiong Hort. attenuate diabetic nephropathy in mice

In many famous formulas of traditional Chinese medicine (TCM), the rhizome of Ligusticum chuanxiong (L. chuanxiong) is commonly used as an ingredient for promoting blood circulation and resolving blood stasis to treat diabetic nephropathy. However, its material basis and mechanism of action still needed to be explored. The aim of this work is to elucidate the potential effective parts (phthalides) of L. chuanxiong responsible for renal protection and to explore the possible mechanism of renal protection. A method based on column chromatography of macroporous resin was established to enrich an effective part (LCE70), and the composition of LCE70 was identified by HPLC-UV and UPLC-MS/MS methods. DN mice model was induced by streptozotocin (STZ) to evaluate the protective effect of LCE70 on DN. In vitro, the suppressive effect of LCE70 on oxidative damage, inflammation and its mechanism were tested using immunoblot analysis, ELISA, etc. Cellular thermal shift assay (CETSA) was adopted to verify the interaction between the phthalides and the key targets involved in renal injury. LCE70 displayed therapeutic potential against metabolic disorders, renal dysfunction, and fibrosis in a DN model induced by STZ in mice. Furthermore, it markedly reduced oxidative stress of the kidney in DN mice by activating Nrf2 pathway. Z-ligustilide, the main component of LCE70, reacted with Keap1, and thus promoted Nrf2 dissociating from Keap1 to activate Nrf2 pathway. LCE70 improved hyperglycemia-induced renal function by enhancing the Nrf2 activation, reducing collagen deposition, suggesting its potential as a therapeutic agent for DN.