Apigenin acts as a monoamine transporter activator, one of the few chemicals demonstrated to possess this property.[8] Apigenin is a weak ligand for central benzodiazepine receptors in vitro and exerts anxiolytic and slight sedative effects in an animal model.[9] Apigenin shows second-order positive modulatory activity at GABAA receptors.[10][11] It has also effects on adenosine receptors[12] and is an acute antagonist at the NMDA receptors (IC50 = 10 μM).[11] In addition, like various other flavonoids, apigenin has been found to possess nanomolar affinity for the opioid receptors (Ke = 410 nM, 970 nM, and 410 nM for the μ-, δ-, and κ-opioid receptors, respectively), acting as a non-selective antagonist of all three opioid receptors.[13]