NCH 51 is a potent and novel inhibitor of histone deacetylase [1].

Histone deacetylases (HADC) are a series of enzymes that remove acetyl groups from an ε-N-acetyl lysine amino acid on a histone and make the histones to wrap the DNA more tightly, which prevent transcription.

NCH-51 inhibited cells growth with EC50 values of 2.1 and 4.4 μM in NCI-H460 cells and MDA-MB-231 cells, respectively. Also, it inhibited proliferation of various cancer cell lines with EC50 values of 1.1 - 9.5 μM [1][2]. In HCT 116 cells, NCH-51 increased levels of acetylated histone H4 and p21WAF1/CIP1 in dose-dependent way [2]. In a series of lymphoid malignant cell lines, NCH-51 induced apoptosis. In U266 cells, NCH-51 activated caspase-3, -8 and -9. Also, NCH-51 increased expression of p21 and reduced expression of anti-apoptotic molecules, such as survivin, bcl-w and c-FLIP. At the protein level, NCH-51 increased the levels of peroxiredoxin 1 and 2, glutathione S-transferase and reactive oxygen species (ROS) [3]. In HIV-1 latently infected-cells, NCH 51 increased histone hyperacetylation, reduced HDAC1 occupancy and recruited positive transcription factors at the HIV-1 promoter, which increased the expression of HIV-1 [4].

References:
[1].  Suzuki T, Hisakawa S, Itoh Y, et al. Identification of a potent and stable antiproliferative agent by the prodrug formation of a thiolate histone deacetylase inhibitor. Bioorg Med Chem Lett, 2007, 17(6): 1558-1561.
[2].  Suzuki T, Nagano Y, Kouketsu A, et al. Novel inhibitors of human histone deacetylases: design, synthesis, enzyme inhibition, and cancer cell growth inhibition of SAHA-based non-hydroxamates. J Med Chem, 2005, 48(4): 1019-1032.
[3].  Sanda T, Okamoto T, Uchida Y, et al. Proteome analyses of the growth inhibitory effects of NCH-51, a novel histone deacetylase inhibitor, on lymphoid malignant cells. Leukemia, 2007, 21(11): 2344-2353.
[4].  Victoriano AF, Imai K, Togami H, et al. Novel histone deacetylase inhibitor NCH-51 activates latent HIV-1 gene expression. FEBS Lett, 2011, 585(7): 1103-1111.