Bio-Guided Fractionation of Cardamom Ethyl Acetate Fraction Promotes Glucose Uptake via GLUT4 Translocation through Insulin Signaling Pathway in the Skeletal Muscle

Regulation of skeletal muscle glucose uptake is an effective strategy for reducing postprandial hyperglycemia and improving whole-body glucose homeostasis in the management of type 2 diabetes. The present study investigated that cardamom enhances glucose uptake in skeletal muscle in vitro and improves glucose tolerance in vivo. Bioactivity-guided fractionation of cardamom identified an ethyl acetate fraction (Fr. A) and its subfraction (Fr. A-i) as potent stimulators of glucose uptake in L6 myotubes. Both fractions significantly promoted glucose uptake by enhancing glucose transporter type 4 (GLUT4) translocation to the plasma membrane. Mechanistic investigations revealed activation of the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway, accompanied by increased phosphorylation of Akt substrate of 160 kDa (AS160), a key regulator of GLUT4 vesicle trafficking, while no significant changes were observed in insulin receptor substrate-1 (IRS-1) or AMP-activated protein kinase (AMPK) phosphorylation. Fr. A induced a more pronounced effect on AS160 phosphorylation and was therefore selected for further evaluation. The antihyperglycemic potential of Fr. A was assessed in ICR mice using an oral glucose tolerance test. Oral administration of Fr. A (1 and 10 mg/kg body weight) significantly improved glucose tolerance and alleviated postprandial hyperglycemia. Cardamom in skeletal muscle and highlights its potential as a natural therapeutic candidate for the management of postprandial hyperglycemia.