New orally bioavailable 5-(thiophen-2-yl)-substituted 2-aminobenzamide-series histone deacetylase inhibitors were synthesized. These compounds possess a morpholine or piperadine-derived moiety as an aqueous soluble functional group. Among them, 8b, having a 4-ethyl-2,3-dioxopiperazine-1-carboxamide group as a surface recognition domain, showed promising inhibitory activities against HCT116 cell growth and HDAC1/2. Notably, unlike MS-275, this compound did not induce apoptosis in the cell cycle tests. We therefore conducted antitumor tests of 8b and MS-275 against HCT116 cell xenografts in nude mice. Compound 8b reduced the volume of tumor mass to T/C: 60% and 47% at 45 and 80 mg/kg over 16 days, respectively. These values were comparable to the rate (T/C: 51% at 45 mg/kg) for MS-275. Furthermore, 8b, at neither 45 nor 80 mg/kg, induced the weight loss which was observed in the mice given MS-275 at 45 mg/kg.

We have designed cancer antiproliferative compounds, starting from aniline or phenol derivative, which comprise one or two nitrooxymethylphenyl groups as do the hybrid drugs NCX4040 and NCX530. Compound 2a with p-nitrooxymethylbenzoyl-oxy and -amino groups as well as 8a with a p-nitrooxymethylbenzoylamino group showed more promising effects than NCX4040 against human colon and breast cancer cells. Since 2a and 8a, but not NCX4040, arrested human colon carcinoma HCT116 cells in the M phase, the former two compounds may inhibit cell growth differently from NCX4040. Merged images of immunofluorescence-stained α-tubulin and Hoechst-stained nuclei in human fibrosarcoma HT1080 cells showed that 2a and 8a disrupted microtubule formation just as did vincristine, the tubulin polymerization inhibitor. In experiments in vivo, the intraperitoneal administration of 8a at 80 mg/kg/day reduced the growth of HCT116 xenografts in nude mice to T/C 55%.New compounds possessing a nitrooxymethylphenyl group were designed. Compounds 2a and 8a disrupted the formation of microtubules as did vincristine. The intraperitoneal administration (at 80 mg/kg) of 8a reduced the growth of HCT116 xenografts in nude mice to T/C 55%.

New 2-aminobenzamide-type histone deacetylase (HDAC) inhibitors were synthesized. They feature a sulfur-containing bicyclic arylmethyl moiety—a surface recognition domain introduced to increase in cellular uptake—and a substituted tert-amino group which affects physicochemical properties such as aqueous solubility. Compound 22 with a (2-hydroxyethyl)(4-(thiophen-2-yl)benzyl)amino group reduced the volume of human colon cancer HCT116 xenografts in nude mice to T/C 67% by oral administration at 45 mg/kg, which was comparable to the rate (T/C 62%) for a positive control, MS-275. Western blot analyses as well as cell cycle and TUNEL assays by flow cytometry suggested that the two compounds inhibited the growth of cancer cells via similar mechanisms.A sulfur-containing HDAC inhibitors were designed. Compound 22 reduced the growth of HCT116 xenografts in nude mice to T/C 67% by oral administration (at 45 mg/kg), which was similar to the value for MS-275.

Berberine chloride (1) and the structurally related compounds were assessed for the anti-human cytomegalovirus (HCMV) activity using the plaque assay. The anti-HCMV activity (IC50 0.68 μM) of 1 was equivalent to that (IC50 0.91 μM) of ganciclovir (GCV). The mechanism of action by which 1 inhibits the replication of HCMV is presumed to be different from that of GCV; 1 would interfere with intracellular events after virus penetration into the host cells and before viral DNA synthesis.Berberine chloride (1) inhibited the human cytomegalovirus replication at IC50 0.68 μM, which was equivalent to that (0.91 μM) for ganciclovir. The selectivity index of 1, the ratio of 50% cytotoxic concentration to IC50, was 110.

New series histone deacetylase inhibitors comprising a hydroxamic acid or 2-aminobenzamide group as a zinc-chelating function were synthesized and evaluated for antiproliferative activities against a panel of human cancer cells. The 2-aminobenzamide series inhibitors generally had the potency in cell growth inhibitions comparable to that of MS-275. Among them, the compound having a (3,4-difluorobenzyl)(2-hydroxyethyl)amino group at one end and a 2-aminobenzamide group at the other of molecule showed the most promising profile as an anticancer drug candidate, since it had a comparatively low toxicity as did MS-275 against a normal fibroblast cell CCD-1059SK. Additionally, the derivative exhibited a high recovery in human plasma stability test.

The screening tests of N-hydroxybenzamides for their HDAC-inhibitory activities led to the discovery of the promising compounds with a 2-naphthylcarbonyl group and with a 1,4-biphenylcarbonyl group. These compounds were further modified to optimize their physico-chemical profile. As a result, the inhibitor with a 6-amino-2-naphthylcarbonyl was obtained, which showed not only promising growth inhibitions against a panel of tumor cells, but also an improved water solubility. It exhibited the maximal 185% of survival rate (%T/C) in a in vivo experiment with P388 cell-inoculated mice.Histone deacetylase inhibitor 6g with the 6-amino-2-naphthylcarbonyl group showed a potent antitumor activity against the murine P388 model.

In order to seek promising cancer chemopreventive agents, we assessed the antitumor promoting activities of 3-O-octanoyl- or 3-O-(2-methyloctanoyl)-(−)-epigallocatechins, inhibiting markedly the activation of Epstein–Barr virus early antigen, in a two-stage mouse skin carcinogenesis assay. As a result, these derivatives inhibited a papilloma formation 1.3–1.6-fold more strongly than (−)-epigallocatechin gallate well established as anti-tumor promoter.(−)-Epigallocatechin derivatives possessing a 2-methyloctanoyl-chain inhibited papilloma formation more strongly than (−)-epigallocatechin gallate, well established antitumor promoter, in a two-stage mouse skin carcinogenesis assay.

Utilizing tranexamic acid as a starting material, a series of N-hydroxycarboxamides were synthesized in order to seek new histone deacetylase (HDAC) inhibitors. Further structure optimization involving the replacement of the 1,4-cyclohexylene group with the 1,4-phenylene group yielded the promising HDAC inhibitors which possess a terminal bicyclic aryl amide.Synthesis of the promising histone deacetylase inhibitors including 10a and 10e is reported. The terminal bicyclic aryl amide groups of these compounds played an important role in increment of their inhibitory activities.

As an exploratory investigation of antitumor promoting compounds, 3-O-acyl-(−)-epigallocatechins possessing a straight-, branched-, phenyl-inserted- or 1,4-phenylene-inserted-acyl chain of varying length from C4 to C18 were synthesized and evaluated their inhibitory effects against the activation of the Epstein–Barr virus early antigen (EBV-EA). It was indicated that the epigallocatechin derivatives having the straight- or branched-acyl chain of C8 to C11 carbon atoms achieve marked effects.