Acetylshikonin stimulates glucose uptake in L6 myotubes via a PLC-β3/PKCδ-dependent pathway

Acetylshikonin, a naphthoquinone derivative derived from Lithospermum erythrorhizon, has been shown to have various pharmacological activities; however, its effect on diabetes has rarely been reported. We investigated the hypoglycemic effect of acetylshikonin and found that it decreased blood glucose to a greater extent than insulin and improved glucose tolerance in mice. It also increased glucose uptake in L6 myotubes by inducing the expression and translocation of glucose transporter 4 via decomposition of phosphatidylinositol, increased generation of diacylglycerol, and activation of protein kinase C delta cascades; this is an insulin-, reactive oxygen species-, and AMP-activated protein kinase-independent pathway for glucose uptake. Our findings highlight the antidiabetic potential of acetylshikonin via a possible novel pathway for glucose uptake in L6 myotubes.