Purity >98%. AC-5216 is a high affinity agonist of the 18 kDa translocator protein (TSPO, previously called the peripheral benzodiazepine receptor) that exhibits a Ki value of 0.297 nM in rat whole brain and IC50 values of 2.73 and 3.04 nM, respectively, against human and rat glial TSPO. AC-5216 produces anxiolytic and antidepressant effects in various animal models, without inducing benzodiazepine-like adverse effects.