Wei-Qiong Zuo

Synthesis and structure–activity relationships evaluation of benzothiazinone derivatives as potential anti-tubercular agents

N-Alkyl and heterocycle substituted 1,3-benzothiazin-4-one (BTZ) derivatives were synthesized. The anti-mycobacterial activities of these compounds were evaluated by determination of minimal inhibitory concentration (MIC) for Mycobacterium tuberculosis H37Ra and M. tuberculosis H37Rv. It was found that an extended or branched alkyl chain analog could enhance the potency, and activities of N-alkyl substituted BTZs were not affected by either nitro or trifluoromethyl at 6-position. Trifluoromethyl plays an important role in maintaining anti-tubercular activity in the piperazine or piperidine analogs. Compound 8o, which contains an azaspirodithiolane group, showed a MIC of 0.0001 μM against M. tuberculosis H37Rv, 20-fold more potent than BTZ043 racemate. These results suggested that the volume and lipophilicity of the substituents were important in maintaining activity. In addition, compound 8o was nontoxic to Vero cells and orally bioavailable in a preliminary pharmacokinetics study.

Discovery of imidazo[2,1-b]thiazole HCV NS4B inhibitors exhibiting synergistic effect with other direct-acting antiviral agents.

The design, synthesis, and SAR studies of novel inhibitors of HCV NS4B based on the imidazo[2,1-b]thiazole scaffold were described. Optimization of potency with respect to genotype 1b resulted in the discovery of two potent leads 26f (EC50 = 16 nM) and 28g (EC50 = 31 nM). The resistance profile studies revealed that 26f and 28g targeted HCV NS4B, more precisely the second amphipathic α helix of NS4B (4BAH2). Cross-resistance between our 4BAH2 inhibitors and other direct-acting antiviral agents targeting NS3/4A, NS5A, and NS5B was not observed. For the first time, the synergism of a series of combinations based on 4BAH2 inhibitors was evaluated. The results demonstrated that our 4BAH2 inhibitor 26f was synergistic with NS3/4A inhibitor simeprevir, NS5A inhibitor daclatasvir, and NS5B inhibitor sofosbuvir, and it could also reduce the dose of these drugs at almost all effect levels. Our study suggested that favorable effects could be achieved by combining 4BAH2 inhibitors such as 26f with these approved drugs and that new all-oral antiviral combinations based on 4BAH2 inhibitors were worth developing to supplement or even replace current treatment regimens for curing HCV infection.

Nifuroxazide exerts potent anti-tumor and anti-metastasis activity in melanoma.

Melanoma is a highly malignant neoplasm of melanocytes with considerable metastatic potential and drug resistance, explaining the need for new candidates that inhibit tumor growth and metastasis. The signal transducer and activator of the transcription 3 (Stat3) signaling pathway plays an important role in melanoma and has been validated as promising anticancer target for melanoma therapy. In this study, nifuroxazide, an antidiarrheal agent identified as an inhibitor of Stat3, was evaluated for its anti-melanoma activity in vitro and in vivo. It had potent anti-proliferative activity against various melanoma cell lines and could induce G2/M phase arrest and cell apoptosis. Moreover, nifuroxazide markedly impaired melanoma cell migration and invasion by down-regulating phosphorylated-Src, phosphorylated-FAK, and expression of matrix metalloproteinase (MMP) -2, MMP-9 and vimentin. It also significantly inhibited tumor growth without obvious side effects in the A375-bearing mice model by inducing apoptosis and reducing cell proliferation and metastasis. Notably, nifuroxazide significantly inhibited pulmonary metastases, which might be associated with the decrease of myeloid-derived suppressor cells (MDSCs). These findings suggested that nifuroxazide might be a potential agent for inhibiting the growth and metastasis of melanoma.

Synthesis and antitubercular evaluation of 4-carbonyl piperazine substituted 1,3-benzothiazin-4-one derivatives

Tuberculosis (TB) remains a major human health problem. New therapeutic antitubercular agents are urgent needed to control the global tuberculosis pandemic. We synthesized a new series of 4-carbonyl piperazine substituted 1,3-benzothiazin-4-one derivatives and evaluated their anti-mycobacterial activities against Mycobacterium tuberculosis H37Ra as well as their druggabilities. The results showed that most of these derivatives, especially the compounds with simple alkyl side chains, exhibited good antitubercular activities and favorable aqueous solubilities with no obvious cytotoxicity. It suggested that the 4-carbonyl piperazine substituents in benzothiazinone scaffold were well tolerated, in which the compound 8h, with an antitubercular activity of MIC 0.008 μM, exhibited an excellent aqueous solubility of 104 μg/mL, which was 100-fold better than the potent DprE1 inhibitor Comp.1 (BTZ038), also more soluble than PBTZ169.

Discovery and structure–activity relationships study of novel thieno[2,3-b]pyridine analogues as hepatitis C virus inhibitors

Current treatment for hepatitis C is barely satisfactory, there is an urgent need to develop novel agents for combating hepatitis C virus infection. This study discovered a new class of thieno[2,3-b]pyridine derivatives as HCV inhibitors. First, a hit compound characterized by a thienopyridine core was identified in a cell-based screening of our privileged small molecule library. And then, structure activity relationship study of the hit compound led to the discovery of several potent compounds without obvious cytotoxicity in vitro (12c, EC50=3.3μM, SI >30.3, 12b, EC50=3.5μM, SI >28.6, 10l, EC50=3.9μM, SI >25.6, 12o, EC50=4.5μM, SI >22.2, respectively). Although the mechanism of them had not been clearly elucidated, our preliminary optimization of this class of compounds had provided us a start point to develop new anti-HCV agents.

Benzothiazinethione is a potent preclinical candidate for the treatment of drug-resistant tuberculosis.

New chemotherapeutic compounds are needed to combat multidrug-resistant Mycobacterium tuberculosis (Mtb), which remains a serious public-health challenge. Decaprenylphosphoryl-β-D-ribose 2′-epimerase (DprE1 enzyme) has been characterized as an attractive therapeutic target to address this urgent demand. Herein, we have identified a new class of DprE1 inhibitors benzothiazinethiones as antitubercular agents. Benzothiazinethione analogue SKLB-TB1001 exhibited excellent activity against Mtb in the Microplate Alamar blue assay and intracellular model, meanwhile SKLB-TB1001 was also highly potent against multi-drug resistant extensively and drug resistant clinical isolates. Importantly, no antagonism interaction was found with any two-drug combinations tested in the present study and the combination of SKLB-TB1001 with rifampicin (RMP) was proved to be synergistic. Furthermore, benzothiazinethione showed superb in vivo antitubercular efficacy in an acute Mtb infection mouse model, significantly better than that of BTZ043. These data combined with the bioavailability and safety profiles of benzothiazinethione indicates SKLB-TB1001 is a promising preclinical candidate for the treatment of drug-resistant tuberculosis.

ZLD1122, a novel EZH2 and EZH1 small molecular inhibitor, blocks H3K27 methylation and diffuse large B cell lymphoma cell growth

The histone methyltransferase enhancer of zeste homolog 2 (EZH2) has been reported to be overexpressed in a variety of cancers and is associated with tumor malignancy. This is mainly because EZH2 catalyzes the hypertrimethylation of histone 3 at lysine 27 (H3K27) at the promoter of target genes, leading to the silencing of downstream tumor suppressor genes. Hence, blocking its catalytic function may be a therapeutic strategy for the treatment of tumors which over-express or have a gain-of-function mutation in EZH2, such as lymphomas. Here, we reported a novel, selective, small-molecule inhibitor of EZH2 and EZH1 synthesized by us, ZLD1122, which inhibited both EZH1 and wild type and mutant EZH2 activities with nanomolar potency. ZLD1122 significantly inhibited intracellular H3K27 trimethylation without affecting the levels of H3, H3K9me3, and H3K4me3, indicating its selective inhibition of polycomb repressive complex 2 (PRC2) methyl catalytic function. Moreover, ZLD1122 induced G0/G1 phase arrest in diffuse large B cell lymphoma (DLBCL) cells in a dose-dependent manner via downregulation of cyclinE and CDK4 as well as upregulation of p21 and cyclinD1. Furthermore, it induced apoptosis and loss of mitochondrial membrane potential (Δψm), and elevated the levels of cleaved caspase-9 in Su-DHL-6 and Pfeiffer cells, suggesting that ZLD1122 suppresses the viability of DLBCL cells by inducing caspase-mediated intrinsic apoptosis. Taken together, these data demonstrated that ZLD1122, owing to its pharmacologically inhibitory activity against EZH2, could be a promising agent for the treatment of lymphomas with EZH2 gain-of-function mutations.

A novel small-molecule YLT256 inhibits proliferation and induces apoptosis both in vitro and in vivo in solid tumors

Pancreatic carcinoma is a still unsolved health problem all over the world with poor prognosis and high mortality rate. YLT256, a novel synthesized chemical small inhibitor, displays potent antineoplastic activities via inducing apoptosis both in vitro and in vivo. In this study, we found that YLT256 showed growth inhibition against a broad spectrum of human cancer cell lines and pancreatic cancer cell line BxPc-3 was the most sensitive with an IC50 of 0.42μM. We also found YLT256 could induce apoptosis of BxPc-3 cells in a dose-dependent manner. Western blot analysis revealed that the occurrence of its apoptosis was associated with activation of caspases-3 and -9, up-regulation of pro-apoptotic Bak, and down-regulation of anti-apoptotic Bcl-2. Moreover, YLT256-treated resulted in changes of mitochondrial membrane potential (Δψm), and generation of reactive oxygen species (ROS). Furthermore, our data also revealed that YLT256 suppressed the growth of established tumor-bearing xenograft models without obvious side effects. Immunohistochemical analyses and TUNEL assay revealed an increase in cleaved caspase-3-positive cells and TUNEL-positive cells, a decrease in Ki67-positive cells upon YLT256. Together, all the results of present study provided evidence demonstrating that YLT256 could be a promising potential drug candidate for pancreatic cancer therapy.

Synthesis and biological evaluation of N-(3-oxo-3,4-dihydro-2H-benzo[b][1,4]oxazin-7-yl)benzenesulfonamide derivatives as new BET bromodomain inhibitors for anti-hematologic malignancies activities

The bromodomain and extra-terminal proteins (BETs), in particular BRD4, has been reported to play important roles in cancer, inflammation, obesity, cardiovascular disease, and neurological disorders. In this paper, a series of benzomorpholinone derivatives were synthesized and biologically evaluated as BETs inhibitors. Detailed structure–activity relationship studies led to the discovery of several new potent compounds, of which 15h and 15i displayed