Design, synthesis and biological evaluation of 3,5-dimethylisoxazole and pyridone derivatives as BRD4 inhibitors.

Bromodomain-containing protein 4 (BRD4), a member of the bromodomain and extra-terminal (BET) family, has been recognized as an attractive candidate target for the treatment targeting gene transcription in several types of cancers. In this study, two types of novel compounds were designed, synthesized and evaluated as BRD4 inhibitors. Therein, pyridone derivatives were more effective against BRD4 protein and human leukemia cell lines MV4-11. Among them, compounds 11d, 11e and 11f were the most potential ones with IC50 values of 0.55 µM, 0.86 µM and 0.80 µM against BRD4, and exhibited remarkable antiproliferative activities against MV4-11 cells with IC50 values of 0.19 µM, 0.32 µM and 0.12 µM, respectively. Moreover, in western blot assay, compound 11e induced down-regulation of C-Myc, which is a significant downstream gene of BRD4. Cell cycle analysis assay also showed that compound 11e could block MV4-11 cells at G0/G1 phase. Taken together, our results suggested that compound 11e and its derivatives were a class of novel structural potential BRD4 inhibitors and could serve as lead compounds for further exploration.

Metabolism of SKLB-TB1001, a Potent Antituberculosis Agent, in Animals.

Tuberculosis is a major global health problem, and the emergence of multidrug-resistant and extensively drug-resistant strains has increased the difficulty of treating this disease. Among the novel antituberculosis drugs in the pipeline, decaprenylphosphoryl-beta-d-ribose-2-epimerase (DprE1) inhibitors such as BTZ043 and pBTZ169 exhibited extraordinary antituberculosis potency. Here, the metabolites of the new DprE1 inhibitor SKLB-TB1001 in vivo and its inhibition of cytochrome P450 isoforms and plasma protein binding (PPB) in vitro were studied. The results showed that rapid transformation and high PPB resulted in inadequate exposure in vivo and thus led to the moderate potency of SKLB-TB1001 in vivo This study provided explanations for the discrepant potency of this scaffold in vivo and in vitro Meanwhile, it also provides a rationale for lead optimization of this very promising scaffold of antituberculosis agents to prevent them from being metabolized, thus improving their exposure in vivo.

Synthesis and biological evaluation of 1,2,4-triazole and 1,3,4-thiadiazole derivatives as potential cytotoxic agents.

A series of new 3-amino-5-sulfanyl-1,2,4-triazole and 2-amino-5-sulfanyl-1,3,4-thiadiazole derivatives have been synthesized and their cytotoxicities were evaluated on a panel of human cancer cell lines (BxPC-3, H1975, SKOV-3, A875, HCT116, etc.). The best one (compound 5m) exhibited activities with IC50 values ranging from 0.04 to 23.6 µM against nine human cancer cell lines. Further biological evaluation indicated that DNA replication was blocked by treatment with compound 5m in HCT116 cells.

(E)-3-Dimethyl-amino-1-(1,3-thia-zol-2-yl)prop-2-en-1-one.

In the title compound, C8H10N2OS, the 3-(dimethyl-amino)-prop-2-en-1-one unit is approximately planar [give r.m.s. deviation] and the mean plane through the seven non-H atoms makes a dihedral angle of 8.88 (3)° with the thia-zole ring. The carbonyl and ring C=N double bonds adjacent to the carbonyl group are trans [N-C-C-O = 172.31 (15) °], while the conformation of the carbonyl and propene double bonds is cis [O-C-C-C = 2.2 (2)°]. In the crystal, short C-H⋯N and C-H⋯O inter-actions together with C-H⋯π inter-actions generate a three-dimensional network.

N-Methyl-4-(4-pivalamido-phenyl-sulfan-yl)picolinamide hemihydrate.

In the title compound, C(18)H(21)N(3)O(2)S·0.5H(2)O, the benzene ring makes dihedral angles of 88.59 (6) and 40.74 (8)° with the pyridine ring and the amide group, respectively. The water O atom lies on a twofold axis. In the crystal, the organic mol-ecules and the water mol-ecules are linked via O-H⋯O hydrogen bonds, while the organic mol-ecules are connected to each other via N-H⋯O hydrogen bonds, forming a three-dimensional network.

Design, synthesis, and biological evaluation of 4,5-dihydro-[1,2,4]triazolo[4,3-f]pteridine derivatives as novel dual-PLK1/BRD4 inhibitors.

Protein kinase inhibitors and epigenetic regulatory molecules are two main kinds of anticancer drugs developed in recent years. Both kinds of drugs harbor their own advantages and disadvantages in the treatment of cancer, and the development of small molecules which could target at kinases and epigenetic targets simultaneously can avoid the defects of drugs which only targets at kinases or epigenetic proteins. In this study, a series of 4,5-dihydro-[1,2,4]triazolo [4,3-f]pteridine derivatives were designed and synthesized based on the structure of PLK1 inhibitor BI-2536. Subsequent targets affinity screen and antiproliferative activity test led to the discovery of the most potent dual PLK1/BRD4 inhibitor 9b with good potency for both PLK1 (IC50 = 22 nM) and BRD4 (IC50 = 109 nM) as well as favorable antiproliferative activity against a panel of cancer cell lines. 9b could induce cell cycle arrest and apoptosis in acute myeloid leukemia cell line MV 4-11 in a concentration dependent manner. It could also downregulate the transcription of several proliferation-related oncogenes, including c-MYC, MYCN and BCL-2. Finally, in a MV4-11 mouse xenograft model, 9b exhibited favorable in vivo antitumor activity with 66% tumor growth inhibition (TGI) at a dose of 60 mg/kg while without obvious toxicity. This study thus provided us a start point for the development of new dual PLK1/BRD4 inhibitors as anticancer agents.

Design, synthesis and biological evaluation of novel 1-phenyl phenanthridin-6(5H)-one derivatives as anti-tumor agents targeting TOPK.

T-lymphokine-activated killer cell-originated protein kinase (TOPK) is a serine-threonine mitogen-activated protein kinase that is highly expressed in many types of human cancer. Due to its important role in cancer progression, TOPK is becoming an attractive target in chemotherapeutic drug design. In this study, a series of 1-phenyl phenanthridin-6(5H)-one derivatives have been identified as a novel chemical class of TOPK inhibitors. Some of them displayed very potent anti-cancer activity with IC50s less than 100 nM, superior than reference compound OTS964. The most potent compound, 9g suppressed the growth of cancer cells by apoptosis and specifically inhibited the activities of TOPK. Oral administration of 9g effectively suppressed tumor growth with TGI >79.7% in colorectal cancer xenograft models, demonstrating superior efficacy compared to OTS964. Pharmacokinetic studies reveal its good oral bioavailability. Our findings therefore show that 9g is a specific inhibitor of TOPK both in vitro and in vivo that may be further developed as a potential therapeutic agent against colorectal cancer.

Palladium-catalyzed intramolecular C-H arylation of 2-halo-N-Boc-N-arylbenzamides for the synthesis of N-H phenanthridinones.

A palladium catalyzed synthesis of N-H phenanthridinones was developed via C-H arylation. The protocol gives phenanthridinones regioselectively by one-pot reaction without deprotection. It exhibits broad substrate scope and affords targets in up to 95% yields. Importantly, it could be applied for the less reactive o-chlorobenzamides.

Identification of a new series of benzothiazinone derivatives with excellent antitubercular activity and improved pharmacokinetic profiles.

Nitrobenzothiazinone (BTZ) is a promising scaffold with potent activity against M. tuberculosis by inhibiting decaprenylphosphoryl-beta-d-ribose 2'-oxidase (DprE1). But unfavorable durability poses a challenge to further development of this class of agents. Herein, a series of BTZs bearing a variety of different substituents at the C-2 position were designed and synthesized. Compounds were screened for their antimycobacterial activity against Mycobacterium tuberculosis H37Ra and were profiled for metabolic stability, plasma protein-binding capacity and pharmacokinetics in vivo. In general, these new BTZs containing N-piperazine, N-piperidine or N-piperidone moiety have excellent antitubercular activity and low cytotoxicity. Several of the compounds showed improved microsomal stability and lower plasma protein-binding, opening a new direction for further lead optimization. And we obtained compound 3o, which maintained good anti-tuberculosis activity (MIC = 8 nM) and presented better in vitro ADME/T and in vivo pharmacokinetic profiles than reported BTZ compound PBTZ169, which may serve as a candidate for the treatment of tuberculosis.

A novel benzothiazinethione analogue SKLB-TB1001 displays potent antimycobacterial activities in a series of murine models.

New chemotherapeutic compounds and regimens are needed to combat multidrug-resistant Mycobacterium tuberculosis. Here, we used a series of murine models to assess an antitubercular lead compound SKLB-TB1001. In the Mycobacterium bovis bacillus Calmette-Guérin and the acute M. tuberculosis H37Rv infection mouse models, SKLB-TB1001 significantly attenuated the mycobacterial load in lungs and spleens. The colony forming unit counts and histological examination of lungs from H37Rv infected mice revealed that the benzothiazinethione analogue SKLB-TB1001 as a higher dose level was as effective as isoniazid. Moreover, in a multidrug-resistant (MDR)-TB mouse model, SKLB-TB1001 showed significant activity in a dose-dependent manner and was more effective than streptomycin. These results suggested that SKLB-TB1001 could be an antitubercular drug candidate worth further investigation.