Anti-amyloidogenic and disaggregating effects of Salvia officinalis in vitro: a strategy to reduce the insulin amyloid fibrils due to repeated subcutaneous injections in diabetic patients

Background: Recently, there has been growing efforts to elucidate the molecular mechanism of amyloid formation and investigating effective compounds for inhibiting of amyloid structures. Investigation of the fibrillation process through its induction and inhibition using specific compounds such as aromatic derivatives provide useful information for stabilizing the protein structure. In the present study, the in vitro anti-amyloidogenic and destabilizing effects of Salvia officinalis were investigated using bovine insulin as a model protein. Materials and Methods: To induce fibrillation, the bovine pancreatic insulin was incubated for 10 days in 50 mM glycine buffer at pH = 2.2 at 57° C. Amyloid formation was examined using CR absorption spectroscopy, ANS and THT fluorescence and Field-emission Scanning Electron Microscope (FE-SEM) methods. Then, the effect of different concentrations of Salvia officinalis extract (ratios of 0.1, 1, and 5 extracts to 1 protein) on inhibition of fibrillation and destabilization of pre-formed insulin fibrils was investigated. Results: Results indicated a significant decrease in the accumulation of amyloid fibrils in drug-incubated samples compared to control. It also found that Salvia officinalis extract in all concentrations, especially in the 1: 1 ratio of drug to protein, has a strong inhibitory effect on fibrillation and defibrillation of insulin protein. Conclusion: The results of this study showed that by purification and isolation of effective compounds of Salvia officinalis and its effect on amyloid fibrils, this plant could probably be used to treat amyloid diseases.