Marsupsin Isolated from Polyherbal Product ABPA Rejuvenates Insulin Resistance in L6 Skeletal Muscle Cell Line via IRS1‐PI3K‐AKT‐GLUT4 Signaling Pathway

Insulin resistance (IR) is one of the key characteristics of type 2 diabetes mellitus (T2DM) which impairs the insulin signal transduction pathway. It is typically caused by many factors including hyperglycemia, accumulation of advanced glycation end products (AGEs), chronic oxidative stress and hyperlipidemia. Hence, complementary medicine such as herbal medications have been widely used as a complement to allopathic medicine to facilitate its efficacy while minimizing its potential adverse effects. ABPA is a polyherbal formulation that consists several powerful antidiabetic agents such as Pterocarpus marsupium. Our previous study showed that ABPA exhibited strong antidiabetic effect and detected high expression of marsupsin through HPLC studies.The current study aims to elucidate the effect of marsupsin in rejuvenating insulin resistance through the IRS1-PI3K-AKT-GLUT4 insulin signaling pathway.L6 skeletal muscle cells were cultured and differentiated into L6 myotubes under standard conditions. The differentiated L6 myotubes were induced with high insulin to mimic insulin resistance and treated. Glucose uptake assay was also conducted to evaluate the effect of marsupsin on the rate of glucose uptake in the L6 cells. The cells were then lysed to extract the protein and RNA where the protein and differential gene expression of IRS1, PI3K, AKT and GLUT4 were analyzed using ELISA, qPCR, and Western Blot respectively.The rate of glucose uptake was higher in MAR-treated cells as compared to the negative control. This was further confirmed in the ELISA, qPCR and Western Blot analysis where MAR-treated cells showed an upregulation of IRS1, PI3K, AKT and GLUT4 proteins as compared to the vehicle control.Marsupsin rejuvenates insulin resistance in skeletal muscle cells by increasing the rate of glucose uptake through the activation of the IRS1-PI3K-AKT-GLUT4 pathway.