Beauverolide Ka, a cyclotetradepsipeptide, is a metabolite of Beauveria bassiana fungus. Beauverolide Ka stimulates glucose uptake in cultured rat L6 myoblasts at 50 μM. Beauverolide Ka exhibits protecting effects on HEI-OC1 cells at 10 μM and shows dose-dependent activity in both L6 myoblasts and myotubes.