Norlignans and Phenolics from Curculigo capitulata and Their Neuroprotection Against Glutamate-Induced Oxidative Injury in SH-SY5Y Cells

Abstract

The herb Curculigo capitulata (Lour.) Ktze is widely distributed in southern and southwestern China. The Curculigo genus and its primary chemical constituents exhibit remarkable antidepressant activities. To investigate the chemical constituents and potential health benefits of C. capitulata, a phytochemical study was conducted. In this study, seven new compounds (capitugenin A–G), including three new norlignans (1–3), a new chalcone dimer (4), a new hemiacetal (5), two novel pyrrolidine-based compounds (6 and 7), including one identified as a natural product (7), and nineteen known compounds (8–26), were isolated from C. capitulata. The chemical structures and absolute configurations of Compounds 1–7 were elucidated via comprehensive spectroscopic data analyses. The neuroprotective effects of Compounds 1–26 against glutamate-induced cell death were tested in the human neuroblastoma cell line SH-SY5Y. Compounds 1, 3, 6, 8, 11, and 17 showed significant neuroprotective effects, with protection rates ranging from 29.4 to 52.8% at concentrations ranging from 5 to 40 μM. Western blot analysis indicated that Compound 3 exerted a protective effect by regulating the expression of Nrf2/HO-1.