Protective effect of diosmin on lipopolysaccharide-induced PC12 cell death

Background. Diosmin is a naturally occurring flavonoid glycoside that can be isolated from various plant sources or derived from the flavonoid hesperidin. Diosmin is considered to be a vascular-protecting agent used to treat chronic venous insufficiency, hemorrhoids, lymphedema, and varicose veins. As a flavonoid, diosmin also exhibits anti-inflammatory, free-radical scavenging, and antimutagenic properties. Lipopolysaccharide (LPS) by activating microglia causes the induction of harmful factors including nitric oxide and tumor necrosis factor alpha (TNFalpha). In the present study, LPS-injured PC12 cells were chosen as an in vitro model of Alzheimer's disease to investigate the possible preventive effect of diosmin on LPS induced PC12 cell death.;Methods. PC 12 Cells were treated with varying concentration of Diosmin (1 microM, 3 microM and 5 microM respectively) in the presence of 4 microg/ml Lipopolysachharide(IC 50) for 48 hours to assess anti-inflammatory effects, PC 12 Cell viability, and PC 12 cell death mechanisms. Cell viability was analysed by MTT assay. Anti-inflammatory effect was confirmed by Western blotting. Cell death mechanism was estimated by detecting DNA fragmentation using Agarose Gel Electrophoresis. Quantitative detection of Caspase-3 activity in cellular lysates after induction of apoptosis was determined by Caspase-3 Colorimetric Assay.;Results. Diosmin significantly reduced cell death caused by LPS. The cell protective effect of diosmin was exhibited in a concentration-dependent manner. Diosmin also suppressed dose-dependent LPS induced TNF-alpha expression. Diosmin (1, 3, and 5 microM), showed in a concentration-dependent manner gradual significant decrease in DNA fragmentation in comparison with LPS stimulated cells suggesting anti-apoptotic effects of diosmin. This anti-apoptotic effect of diosmin was confirmed by decrease in the expression of pro-apoptotic protein Bad and increase in the expression of anti-apoptotic protein Bcl2 on western blot analysis. Furthermore, LPS-induced caspase-3 activation was notably inhibited by diosmin. Thus, it is likely that diosmin prevents LPS-induced cell death by inhibiting caspase-3 activation in PC-12 cells.;Conclusion. The present study supports the notion that diosmin could be used as a neuroprotective agent for the treatment of neurodegenerative diseases such as Alzheimer's disease (AD).