Extract of white sweet potato tuber against TNF-α-induced insulin resistant by activating the PI3K/Akt pathway in C2C12 myotubes

Abstract Background White sweet potato (WSP; I. batatas L. Simon No.1) has many potential beneficial effects on metabolic control and diabetes-related insulin resistance. The improvement of insulin resistance by WSP tuber extracts on glucose uptake were not investigated in C2C12 myoblast cells. Results WSP tuberous ethanol extract (WSP-E), partition with ethyl-acetate and water to got ethyl-acetate layer (WSP-EA) and water layer (WSP-EW) have highest total phenol contents and antioxidant activity respectively. After low concentration horse serum on differentiation inducement of C2C12 myoblasts into mature myotubes, treated with TNF-α to induce insulin resistant, WSP-EA and WSP-EW extracts increased the uptake of fluorescence glucose analogue (2-[N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl) amino]-2-deoxy-d-glucose, 2-NBDG) in a dose depend manner by flow cytometry. The WSP-EA enhanced glucose uptake by activation of phosphorylation of IR (pIR), IRS-1 (pIRS-1) and Akt (pAkt) involved in PI3K (phosphatidylinositol 3-kinase) / protein kinase B (Akt) pathway, also upregulated glucose transporter 4 (GLUT4) expression in myotubes. Conclusions WSP-EA enhanced the glucose uptake in C2C12 myotubes through upregulating the PI3K/Akt pathway. WSP tuber extracts has potential applications to improve insulin resistance in diabetes in vitro.