Lificiguat (YC-1) is an nitric oxide (NO)-independent activator of soluble guanylyl cyclase(sGC) and an inhibitor of Hypoxia-inducible factor-1alpha (HIF-1alpha).

YC-1 increases the catalytic rate of the soluble guanylyl cyclase (sGC) and sensitizes the enzyme toward its gaseous activators nitric oxide or carbon monoxide. YC-1 alone activates the enzyme only 10-fold, but it potentiates the CO- and NO-dependent activation of sGC, resulting in stimulation of the highly purified enzyme that may be several hundred- to several thousand-fold. It inhibits platelet aggregation and vascular contraction and also inhibits HIF-1 activity in vitro. YC-1 completely blocks HIF-1α expression at the post-transcriptional level and consequently inhibits the transcription factor activity of HIF-1 in hepatoma cells cultured under hypoxic conditions, suggesting that these effects of YC-1 are likely to be linked with the oxygen-sensing pathway and not with the activation of soluble guanylyl cyclase.

In experimental animals, YC-1 causes the inhibition of the platelet-rich thrombosis and a decrease of the mean arterial pressure. YC-1 effectively inhibits tumor growth in tumor-bearing mice. In mice, YC-1 inhibition of HIF-1 activity in tumors, and this is associated with blocked angiogenesis and an inhibition of tumor growth, while the anti-platelet aggregation effect of YC-1 does not appear to affect tumor growth.

Hep3B cells are plated in a six-well plate at a density of 1 × 105 cells/well in α-modified Eagle medium supplemented with 10% heat-inactivated FBS and incubated overnight. Cells are treated with YC-1 (0.01-10 μM) or vehicle (DMSO) for 5 minutes and are then subjected to normoxia or hypoxia for 24 hours. VEGF levels in the conditioned media are quantified by using the Quantikine human VEGF Immunoassay kit. The VEGF concentrations are quantified by comparison with a series of VEGF standard samples included in the assay kit.

Animal Models: Male nude (BALB/cAnNCrj–nu/nu) mice. Formulation: DMSO. Dosages: 30 μg/g. Administration: i.p.