Efeito do acetato de taraxasterol isolado de Eupatorium ballotaefolium na resistência insulínica e no diabetes mellitus do tipo 2: um estudo in silico, in vitro e in vivo

Abstract

Type 2 Diabetes Mellitus (T2DM) is one of the most common metabolic disorders in the world, affecting about 400 million people across the globe. Currently, treatment for T2DM is carried out with several classes of drugs, but they are not free of adverse effects, which limits their clinical applications. In the search for new therapeutic options for the treatment of T2DM, pentacyclic triterpenes have been highlighted as promising in the regulation of glycemia and lipid metabolism. This study aimed to investigate the effect of taraxasterol acetate (TXA), a pentacyclic triterpene, isolated from Eupatorium ballotaefolium, on insulin resistance (IR) in C2C12, 3T3-L1 and HepG2 cells, evaluating glucose uptake, signaling of insulin, accumulation of triglycerides and intracellular lipids, oxidative stress and accumulation of glycogen. Together, the effect of TXA in a model of T2DM induced by a combination of a high-fat diet (HFD) and low doses of streptozotocin (STZ) in mice and its possible mechanisms of action on IR, glucose production and hepatic gluconeogenesis was evaluated. Additionally, a metabolomics analysis based on hydrogen nuclear magnetic resonance (1H-NMR) was carried out in the animals' serum. The results demonstrate that TXA (12.5 – 50 µM) increased glucose uptake in insulin resistant C2C12, 3T3-L1 and HepG2 cells by increasing the expression of IRS1, PI3K, Akt, mGLUT4 and AMPK. In addition, TXA (50 µM) prevented the inflammatory process, reducing the protein expression of JNK and NFκB, also preventing the formation of reactive oxygen species (ROS) and markers of oxidative stress (DCF-DA, nitrate/nitrite, MDA, GSH, catalase and SOD). In 3T3-L1 cells, TXA (12.5 - 50 µM) prevented TNFα-induced lipolysis, preserving lipid accumulation and reducing intracellular glycerol concentrations through basal regulation of PPARy, HSL, ATGL and perilipin mRNA expression, and the concentration of leptin and adiponectin. In T2DM in mice, the 4-week treatment with TXA (10 and 20 mg/Kg) restored the sustained glycemia observed in diabetic mice, in addition to improving blood parameters (IGTT, IITT, fasting glycemia, insulin, lipids, amylase and lipase) and liver (weight, glycogen synthesis, oxidative stress and histopathological changes). The effect of TXA on T2DM has, in part, been attributed to its ability to modulate hepatic insulin signaling pathways (IRS, PI3K and Akt); glucose production (GCK, GyS2 and GSK3β) and gluconeogenesis (PEPCK and G6Pase). In addition, metabolomic analysis showed that the effect of TXA in diabetic mice occurs in part through a glucose-related metabolic pathway with reduced α and β glucose and increased acetic acid concentration, which may be related to reduced appetite, AMPK activation and reduction of gluconeogenic and lipogenic genes. These findings suggest that TXA has an antidiabetic potential, modulating central insulin signaling pathways, carbohydrate and lipid metabolism.