Bioactive compounds from Crataegus pinnatifida Bge. leaves: potential health benefits

The leaves of Crataegus pinnatifida Bge., a medicinal plant and a source of brewed tea, are often overlooked as a byproduct of fruit consumption. Despite this, these leaves have demonstrated significant cardiovascular protective and lipid-lowering properties. To further investigate their potential applications, nine novel compounds (1-9) and twelve known flavonoids were isolated from C. pinnatifida leaves. Their structures were elucidated through comprehensive spectroscopic analysis, including experimental and calculated electronic circular dichroism. The antioxidant capacities of these 21 compounds were assessed using DPPH˙ and ABTS˙⁺ assays. Notably, the newly identified biphenyl compounds 7 and 8 exhibited potent antioxidant activities, surpassing that of vitamin C in both assays. Additionally, the ABTS˙⁺ assay revealed that flavonoid O-glycosides generally possess stronger antioxidant activity compared to flavonoid C-glycosides. To evaluate their cytoprotective potential, compounds 12-14 and 18-20 were tested against H₂O₂-induced neurotoxicity in human neuroblastoma SH-SY5Y cells. At 100 μM, these compounds demonstrated significant protective effects. Furthermore, flavonoid C-glycosides exhibited stronger protective activity against alcohol-induced injury in BRL-3A hepatocytes than flavonoid O-glycosides. In conclusion, this study provides compelling evidence that C. pinnatifida leaves contain valuable bioactive compounds with potent antioxidant and cytoprotective properties. These findings further validate the traditional use of this plant and offer promising avenues for future research and potential therapeutic applications.