Potent Protection Against MPP+-Induced Neurotoxicity via Activating Transcription Factor MEF2D by a Novel Derivative of Naturally Occurring Danshensu/Tetramethylpyrazine.

Danshensu (DSS) and tetramethylpyrazine (TMP) are active ingredients of Salvia miltiorrhiza Bge. and Ligusticum chuanxiong Hort that are widely used in oriental medicine. Structural combination of compounds with known biological activity may lead to the formation of a molecule with multiple properties or new function profile. In the current study, the neuroprotective effects of DT-010, a novel analogue in which TMP was coupled to DSS through an ester bond and two allyl groups at the carboxyl group, were evaluated in a cellular model of Parkinson's disease (PD). As evidenced by the increase in cell survival, as well as the decrease in the number of Hoechst-stained apoptotic nuclei and the level of intracellular accumulation of reactive oxygen species, DT-010 at 3-30 µM substantially protected against MPP+-induced neurotoxicity in both PC12 cells and primary cerebellar granule neurons, a protection that was more potent and efficacious than its parent molecules DSS and TMP. Very encouragingly, we found that DT-010, but not DSS or TMP, could enhance myocyte enhancer factor 2D (MEF2D) transcriptional activity using luciferase reporter gene assay. The neuroprotective effects of DT-010 could be blocked by pharmacologic inhibition of PI3K pathways with LY294002, or MEF2D pathway with short hairpin RNA-mediated knockdown of MEF2D. Furthermore, western blot analysis revealed that DT-010 potentiates Akt protein expression against MPP+ to down-regulate MEF2D inhibitor GSK3β. Taken together, the results suggest that DT-010 prevents MPP+-induced neurotoxicity via enhancing MEF2D through the activation of PI3K/Akt/GSK3β pathway. DT-010 may be a potential candidate for further preclinical study for preventing and treating PD.