TGase2-IN-1 (Compound 22) is an orally active inhibitor for TGase2 with an IC 50 of 1.12 μM. TGase2-IN-1 inhibits TGase2 in human retinal microvascular endothelial cells with an IC 50 of 0.07 μM. TGase2-IN-1 exhibits 74.6% oral bioavailability. TGase2-IN-1 inhibits retinal vascular leakage in mouse Streptozotocin -induced diabetic model.