GNF-PF-3777 (8-Nitrotryptanthrin) is a potent human indoleamine 2,3-dioxygenase 2 (h IDO2 ) inhibitor which significantly reduces IDO2 activity with K i of 0.97 μM. In Vitro The typtanthrin derivative GNF-PF-3777 (8-Nitrotryptanthrin; Compound 5i) is found to be a potent hIDO2 inhibitor with superior efficiency far better than that of the most frequently-used inhibitor L-1-MT. The IC 50 values show that all nine tryptanthrin compounds display hIDO2 inhibitory activities, GNF-PF-3777 demonstrates much stronger inhibition (1.87 μM) than both L-1-MT (82.53 μM) and D-1-MT (262.75 μM). GNF-PF-3777 exhibits significant antitrypanosomal activity with EC 50 of 0.82 μM. GNF-PF-3777 (8-Nitrotryptanthrin) has a microplate Alamar Blue assay (MABA) minimum inhibitory concentration (MIC) value of 0.032 μg/mL. GNF-PF-3777 also has a LORA MIC value of 2.4 μg/mL, while the majority of analogues lack LORA activity. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:rhIDO2 1.8 μM (IC 50 ) rhIDO2 0.97 μM (Ki)