| Summary: | Herein, we determined whether α-Spinasterol, a stigmastane-type phytosterol isolated from <i>Aster pseudoglehnii</i>, potentially impacts glucose uptake and glucose-stimulated insulin secretion in skeletal muscle cells and pancreatic β-cells, respectively. We observed that <i>A. pseudoglehnii</i> and its fractions enhanced glucose uptake, with no toxic effects on C2C12 cells, with the <i>n</i>-hexane fraction exhibiting the most potent effect. α-Spinasterol, isolated from the <i>n</i>-hexane fraction, enhanced glucose uptake with no toxic effects on C2C12 cells. Additionally, α-Spinasterol increased the expression of associated proteins, including insulin receptor substrate-1, AMP-activated protein kinase, and glucose transporter type 4, as determined by Western blotting. Furthermore, α-Spinasterol enhanced insulin secretion in response to high glucose concentrations, with no toxic effects on INS-1 cells; this effect was superior to that demonstrated by gliclazide (positive control), commonly prescribed to treat type 2 diabetes (T2D). α-Spinasterol enhanced the expression of associated proteins, including insulin receptor substrate-2, peroxisome proliferator-activated receptor γ, and pancreatic and duodenal homeobox 1, as determined using Western blotting. The insulin secretory effect of α-Spinasterol was enhanced by a K<sup>+</sup> channel blocker and L-type Ca<sup>2+</sup> channel agonist and was suppressed by a K<sup>+</sup> channel activator and L-type Ca<sup>2+</sup> channel blocker. α-Spinasterol isolated from <i>A. pseudoglehnii</i> may improve hyperglycemia by improving glucose uptake into skeletal muscle cells and enhancing insulin secretion in pancreatic β-cells. Accordingly, α-Spinasterol could be a potential candidate for anti-T2D therapy.
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