Constituents of the fruits of Rubus chingii Hu and their neuroprotective effects on human neuroblastoma SH-SY5Y cells

Rubi fructus (Rubus chingii Hu) is a fruit of Rubus genus and is used in medicine and food applications. In this study, eight new phenylpropanoids (1-8) and seven known compounds (9-15) were isolated from the dried fruits of Rubus chingii Hu, and their structures were characterized through high-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy. Electronic circular dichroism (ECD) experiments were performed, and the results were compared with ECD spectra. Compound 3 was characterized through extensive single crystal X-ray diffraction. Evaluation of the neuroprotective pharmacological activities revealed that compounds 6, 7, 9, and 14 exerted protective effects against H2O2-induced neurotoxicity by reducing the reactive oxygen species levels at concentrations of 50 and 100 μM. Moreover, the three compounds 6, 9, and 14 significantly inhibited the expression of the Casp3 gene at a concentration of 50 μM. Compounds 7 and 9 effectively repressed the expression of the MYC gene. Compounds 6 and 9 obviously upregulated the ratio of Bcl2/Bax in SH-SY5Y cells and inhibited cell apoptosis. The study results can be used as a reference for the development of R. chingii products to realize their neuroprotective functions in the future.