Amentoflavone is a biflavonoid originally isolated from Selaginella. It has a wide variety of biological effects including antibacterial, antioxidant, antiviral, antidiabetic, and neuroprotective activities.^1,2,3,4 Amentoflavone has antiviral activity against the influenza A subtypes H1N1 and H3N2, influenza B, and herpes simplex virus 1 (EC50s = 3.1 and 4.3, 0.56, and 17.9 µg/ml, respectively).⁵ It has antidiabetic effects such that it dose-dependently increases insulin receptor phosphorylation and activation and inhibits hydrolysis of p-nitrophenyl phosphate (p-NPP) catalyzed by protein tyrosine phosphatase 1B (PTP1B; IC50 = 7.3 µM).⁶ Amentoflavone reduces the time mice spend immobile in the forced swim test, a measure of antidepressant efficacy, in a dose-dependent manner.⁷