Phenolic constituents, antioxidant activity and neuroprotective effects of ethanol extracts of fruits, leaves and flower buds from Vaccinium dunalianum Wight

•Chlorogenic acid, quinic acid and 6'-O-caffeoylarbutin are the major phytochemicals.•Flower bud extract had strongest antioxidant activity than leaf and fruit extracts.•Flower buds extract showed a good inhibitory effect on oxidative stress.•Flower buds extract upregulated endogenous antioxidant enzymes expressions.•Flower buds extract exhibited cytoprotective effect via activating Nrf2 pathways. Vaccinium dunalianum Wight is an important healthy tea resource in China with health benefits. The chemical compositions and the possible bioactive substances in its fruits, leaves and flower buds extracts (FE, LE and FBE) were identified and characterized by UHPLC-HRMS/MS. Consequently, FE, LE and FBE were rich in phenolic and flavonoid compounds. Among them, 21 compounds were identified, and the main components were chlorogenic acid, quinic acid and 6′-O-caffeoylarbutin. Furthermore, their neuroprotection and mechanism on H2O2-induced neurotoxicity in PC12 cells were investigated. All the different concentrations of FE, LE and FBE were apparently inhibited the H2O2-induced ROS generation and apoptosis on PC12 cells. FBE showed stronger neuroprotective activity against H2O2-induced PC12 cell damage than those of FE and LE. The mechanism of neuroprotective effect might be related to the upregulation of endogenous antioxidant enzymes expressions and activation of the Nrf2/HO-1 signaling pathway.