Antioxidative and antiapoptosis: Neuroprotective effects of dauricine in Alzheimer's disease models

Aims: Dauricine has been found that has significant neuroprotective effect on Alzheimer's disease (AD), but the mechanism is unclear, so we further investigated the possible mechanism of dauricine on AD. Main methods: Cell counting kit-8 (CCK8) was applied to measure the cytotoxicity of dauricine on SH-SY5Y cells that overexpress the Swedish mutant form of human beta-amyloid precursor protein (APPsw) and control cells (Neo). We used the Cu2+ to induce oxidative damage on APPsw cells, then tested the effect of dauricine on the damage and relative factors including reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and superoxide dismutase (SOD) activity. The secretion level of amyloid beta 1-42(A beta(1-42)), protein expression of apoptosis-related factors and the components of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway were determined by western blotting. A beta(1-42)-transgenic Caenorhabditis elegans GMC101, a model of AD, was applied to evaluate the neuroprotective effect of dauricine through the behavioral experiment and relative anti-oxidative tests. Key findings: In vitro, dauricine decreased the secretion level of A beta(1-42), significantly reduced the level of Cu2+-induced ROS, and restored MMP and SOD activity in APPsw cells. Meanwhile, dauricine could suppress the activation of caspase-3 and to upregulate the expression of Bcl-2. Dauricine also regulated the proteins levels of Nrf2, and Kelch-like ECH-associated protein 1 (Keap1) that is necessary for the activation of Nrf2 in APPsw cell. As oxidative stress induced by A beta or paraquat (PQ), dauricine showed protective effects in the survival experiment of GMC101 worms. Significance: Those data revealed that dauricine has the pharmacological activity of anti-oxidative and antiapoptosis, and shows the potential therapeutic value for AD.