IC50: 9.5 μM

UCF 101 is an inhibitor of Omi/HtrA2.

Omi/HtrA2, a mitochondria serine protease with close homology to bacterial HtrA chaperones, is released from the mitochondria in response to apoptotic stimuli. Omi/HtrA2 has been reported to be able to induce cell death via a mechanism involving its protease activity.

In vitro: UCF 101 was identified in a HTS of a combinatorial library using Omi-(134-458) protease and fluorescein-casein as a generic substrate. UCF 101 exhibited specific activity against Omi/HtrA2 and very little activity against other serine proteases. UCF 101 showed a natural fluorescence that was used to monitor its ability to enter mammalian cells. In addition, when tested in caspase-9 (-/-) null fibroblasts, UCF 101 was able to inhibit Omi/HtrA2-induced cell death [1].

In vivo: In a previous study, rats were intraperitoneally administered UCF-101 at 1.5 micromol/kg 10 min prior to reperfusion. Results showed that UCF-101 treatment could significantly decrease cerebral infarct size by about 16.27% and also improve neurological behavior. Moreover, UCF-101 treatment was able to reduce TUNEL-positive cells in the cerebral cortex significantly. In addition, the upregulation in the expression of FasL and the cleavage products of active caspase-3 and caspase-8 induced by ischemia was attenuated in mice treated with UCF-101, while upregulation of FLIP levels was increased [2].

Clinical trial: So far, no clinical study has been conducted.

References:
[1] Cilenti, L. ,Lee, Y.,Hess, S., et al. Characterization of a novel and specific inhibitor for the pro-apoptotic protease Omi/HtrA2. The Journal of Biological Chemisty 278(13), 11489-11494 (2003).
[2] Su, D. ,Su, Z.,Wang, J., et al. UCF-101, a novel Omi/HtrA2 inhibitor, protects against cerebral ischemia/reperfusion injury in rats. Anat.Rec.(Hoboken) 292(6), 854-861 (2009).