Six undescribed Daphniphyllum alkaloids from Daphniphyllum calycinum and their protective effects against OGD/R-induced injury in H9c2 cells.

Six undescribed Daphniphyllum alkaloids, daphcalycines E-J (1-6), possessing structurally diverse skeletal frameworks, were isolated from the seeds of Daphniphyllum calycinum. Their structures and relative configurations were elucidated by comprehensive spectroscopic analysis, including extensive 2D NMR techniques and single-crystal X-ray diffraction. Compounds 1-6 were evaluated in vitro for cytotoxicity and for their effects on oxygen-glucose deprivation/reoxygenation (OGD/R)-induced injury in H9c2 cells. None of the compounds showed detectable cytotoxicity at 10 μM. Under the OGD/R conditions, compound 4 (Daphcalycine H) significantly increased cell viability at 10 μM, indicating a measurable protective effect in this ischemia-reperfusion-like cell model, with an EC50 value of 4.862 μM. Further ROS analysis showed that compound 4 attenuated OGD/R-induced ROS accumulation in H9c2 cells.