Anti-apoptotic and cytoprotective effect of Enicostemma littorale against oxidative stress in Islets of Langerhans

Context Oxidative stress induces apoptosis within Islets of Langerhans in diabetes mellitus (DM). Enicostemma littorale blume, herb of the Gentianaceae family is used as an anti-diabetic agent across rural India. Objective This report demonstrates potent anti-apoptotic and cyto-protective activity of Enicostemma littorale MeOH extract (EL MeOH ext.) against 50 mu M H2O2 in isolated rat Islets. Materials and methods In this study, the whole plant methanolic extract of EL with doses 0.25-4 mg/mL each for the preincubation duration of 0.5-4 h against 50 mu M H2O2 were tested for optimum protective dose and time by Trypan blue dye exclusion assay. Islet intracellular reactive oxygen species (ROS) was quantified by DCFDA staining and cell death using PS/PI & FDA/PI staining. Further, comet assay, biochemical assessment of caspase-3 and antioxidant enzyme activities along with immunoblotting of PARP-1, caspase-3, TNF-alpha activation and p-P38 MapK (stress kinase) induction was performed. Results The optimized dose of EL MeOH ext. 2 mg/mL for 2 h was used throughout the study, which significantly decreased total Intracellular ROS and cell death. Further, caspase-3 activity, PARP-1 cleavage, p-P38 MapK (stress kinase) activation and TNF-a levels, which had been significantly elevated, were normalized. Antioxidant enzymes like catalase, superoxide dismutase, reduced glutathione and glutathione peroxidase, along with Comet assay, demonstrated that pretreatment with EL MeOH ext. can augment antioxidant enzyme activities and protect from DNA damage. Discussion and conclusions Significant anti-apoptotic and cyto-protective effects were mediated by EL with Islets of Langerhans subjected to oxidative stress-induced cell death.