Inhibiting PARP-1/2 offered an important arsenal for cancer treatments via interfering with DNA repair of cancer cells. Novel PARP-1/2 inhibitors were designed by capitalizing on methyl- or ethyl-substituted piperizine ring to capture the characteristics of adenine-ribose binding site (AD site), and their unique binding features were revealed by the cocrystal structures of compounds 4 and 6 in PARP-1. The investigation on structure-activity relationship resulted in compounds 24 and 32 with high enzymatic potency, binding selectivity, and significantly longer residence time for PARP-1 over PARP-2 (compound 24, PARP-1: IC50 = 0.51 nM, PARP-2: IC50 = 23.11 nM; compound 32, PARP-1: IC50 = 1.31 nM, PARP-2: IC50 = 15.63 nM). Furthermore, compound 24 was determined to be an attractive candidate molecule, which possessed an acceptable pharmacokinetic profile and produced remarkable antitumor activity in both breast cancer xenograft model and glioblastoma orthotopic model in mice, either alone or in combination treatment.

Novel quinazoline-2,4(1H,3H)-dione derivatives bearing a 3-amino pyrrolidine moiety were designed and synthesized as PARP-1/2 inhibitors. Structure-activity relationships were examined which revealed a number of potent PARP-1/2 inhibitors with moderate selectivity toward PARP-1 over PARP-2. These compounds had IC50 values against PARP-1 at the 10-9 M level and against PARP-2 at the 10-8 M level. Among all the synthesized compounds, compounds 10 and 11 displayed strong cytotoxicities which are either used as a single agent or in combination with temozolomide (TMZ) in MX-1 cells (10, IC50 < 3.12 μM, PF50 > 10; 11, IC50 = 3.02 μM, PF50 ≈ 10). In vivo tumor growth inhibition was investigated using compound 11 in combination with TMZ, and it was demonstrated that compound 11 could strongly potentiate the cytotoxicity of TMZ in a MX-1 xenograft tumor model. The co-crystal structure of compound 11 complexed with PARP-1 was achieved and demonstrated a unique binding mode.

The PARP-2 selective inhibitor is important for clarifying specific roles of PARP-2 in the pathophysiological process and developing desired drugs with reduced off-target side effects. In this work, a series of novel quinazoline-2,4(1H,3H)-dione derivatives was designed and synthesized to explore isoform selective PARP inhibitors. As a result, compound 11a (PARP-1 IC50=467nM, PARP-2 IC50=11.5nM, selectivity PARP-1/PARP-2=40.6) was disclosed as the most selective PARP-2 inhibitor with high potency to date. The binding features of compound 11a within PARP-1 and PARP-2 were investigated respectively to provide useful insights for the further construction of new isoform selective inhibitors of PARP-1 and PARP-2 by using CDOCKER program.

Pin1 (Protein interacting with NIMA1) is a peptidyl prolyl cis-trans isomerase (PPIase) which specifically catalyze the conformational conversion of the amide bond of pSer/Thr-Pro motifs in its substrate proteins and is a novel promising anticancer target. A series of new thiazole derivatives were designed and synthesized, and their inhibitory activities were measured against human Pin1 using a protease-coupled enzyme assay. Of all the tested compounds, a number of thiazole derivatives bearing an oxalic acid group at 4-position were found to be potent Pin1 inhibitors with IC50 values at low micromolar level. The detailed structure-activity relationships were analyzed and the binding features of compound 10b (IC50 5.38μM) was predicted using CDOCKER program. The results of this research would provide informative guidance for further optimizing thiazole derivatives as potent Pin1 inhibitors.

In our previous work,we found a new method by chance for the synthesis of thiazole derivatives with diversified substitutes on 2-and 5-positions of the thiazole scaffold which was published in Chinese Chemical Letters[2014,Vol.25 p.411].The structures were identified by ~1H NMR, 13 C NMR and HRMS as 2-alkoxy-4-amino-Narylthiazole-5-carboxamides,exemplified by compound 4a（Fig.1）.However,in our continuous research work,we found

Poly(ADP-ribose)polymerase-1 (PARP-1) plays significant roles in the DNA repair process by catalyzing the transfer of ADP-ribose from NAD+ to its receptors. It is a promising anticancer drug target and many PARP-1 inhibitors have been developed and used in the clinical trials. PARP-1 inhibitors could be used not only as chemo/ radiotherapy sensitizers, but also as single agents to selectively kill BRCA deficient cancer cells. In this review, 6 classes of PARP-1 inhibitors with distinct structure scaffold were described in terms of the structure-activity relationships and their binding modes within the catalytic domain of PARP-1.

A facile and efficient protocol was developed to access 2-alkoxy-4-amino-N-arylthiazole-5-carboxamides through a three-component one-pot reaction, which involved potassium methyl cyanimidodithiocarbonate, 2-halo-N-arylacetamides and alcohols. The easy availability and the broad structural diversity of substrates make the reaction useful for the construction of libraries in drug discovery.