Deoxycalyxin A exerts hypoglycemic effects through activating TGR5-induced GLP-1 secretion via TGR5/PKA/MEK/ERK pathway

DCA stimulated GLP-1 secretion in STC-1 and NCI-H716 cells. • DCA decreased fasting blood glucose levels by promoting GLP-1 secretion in db/db mice. • DCA ameliorated glucose intolerance and insulin resistance and lowered serum TC levels. • DCA promoted GLP-1 secretion through specific activation on TGR5/PKA/MEK/ERK pathway. Type 2 diabetes mellitus (T2DM) is a heterogeneous metabolic disorder characterized by insulin resistance and progressive β cell dysfunction. Deoxycalyxin A (DCA), a unique diarylheptanoid-chalcone hybrid isolated from Alpinia katsumadai , was identified as a novel stimulator of GLP 1 secretion in both STC-1 (EC 50 : 10.7 μM) and NCI-H716 (EC 50 : 13.4 μM) cells. Oral administration of DCA (40 and 80 mg/kg) in db/db mice significantly reduced fasting blood glucose, ameliorated glucose intolerance and insulin resistance by enhancing endogenous GLP-1 secretion, and lowered the total serum cholesterol levels. Mechanistic study demonstrated that DCA identify the TGR5 receptor, which induces a significant increase in intracellular cyclic AMP (cAMP) levels, which activates PKA with subsequent sequential phosphorylation of MEK1/2 and ERK activation, ultimately enhancing GLP-1 secretion. Our findings identify DCA as a novel TGR5 agonist to stimulate GLP-1 secretion via the TGR5/PKA/MEK/ERK pathway, which has the potential to be developed as a promising antidiabetic lead with a distinct mechanism of action. DCA, a unique diarylheptanoid-chalcone from Alpinia katsumadai , is a novel TGR5 agonist to stimulate GLP-1 secretion via PKA/MEK/ERK pathway, which has the potential to be developed as a promising antidiabetic candidate. Download: Download high-res image (123KB) Download: Download full-size image