Danshen has been widely used for the treatment of central nervous system diseases. We investigated the effect of dihydroisotanshinone I (DT), a compound extracted from Danshen, as well as the corresponding mechanisms in an in vitro-based 6-OHDA-induced Parkinson's disease (PD) model. SH-SY5Y human neuroblastoma cell lines were pretreated with 6-hydroxydopamine (6-OHDA) and challenged with DT. Subsequently, the cell viability and levels of reactive oxygen species (ROS) and caspase-3 were analyzed. The effect of DT on the 6-OHDA-treated SH-SY5Y cells and the expression of the core circadian clock genes were measured using a real-time quantitative polymerase chain reaction. Our results indicated that DT attenuated the 6-OHDA-induced cell death in the SH-SY5Y cells and suppressed ROS and caspase-3. Moreover, DT reversed both the RNA and protein levels of BMAL1 and SIRT1 in the 6-OHDA-treated SH-SY5Y cells. Additionally, the SIRT1 inhibitor attenuated the effect of DT on BMAL1 and reduced the cell viability. The DT and SIRT1 activators activated SIRT1 and BMAL1, and then reduced the death of the SH-SY5Y cells damaged by 6-OHDA. SIRT1 silencing was enhanced by DT and resulted in a BMAL1 downregulation and a reduction in cell viability. In conclusion, our investigation suggested that DT reduces cell apoptosis, including an antioxidative effect due to a reduction in ROS, and regulates the circadian genes by enhancing SIRT1 and suppressing BMAL1. DT may possess novel therapeutic potential for PD in the future, but further in vivo studies are still needed.
Keywords: 6-OHDA; BMAL1; Danshen; Dihydroisotanshinone I; Idiopathic Parkinson’s disease; ROS; SIRT1; reactive oxygen species.