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A vital approach of Fe(OTf)3 and MS3Å (molecular sieves 3Å) mediated one pot synthesis of 1,3-disubstituted imidazo[1,5-a]pyridines from dithioester, 2-methylaminopyridine and alcohol. This methodology involves the intramolecular cyclization and C–C bond formation under mild condition and operates in a single step yielding the products in good to excellent yields. This protocol was compatible to construct various 1,3-disubstituted imidazo[1,5-a] pyridines derivatives.

Small molecule inhibitors targeting DNA repair pathways in cancer cells is a novel and promising approach in cancer therapy, which can improve current therapeutic regimen. Although various attempts have been made for designing inhibitors against DNA damage response and repair proteins, reports on Nonhomologous End Joining (NHEJ) inhibitors are limited. Of the several chemical moieties identified, SCR7 and its oxidized form are novel and potent DNA Ligase IV inhibitors involved in the abrogation of DNA end joining thereby leading to cell death. In the present study, we have synthesized sodium salt of SCR7 to generate a water-soluble version of the molecule, referred to as water-soluble SCR7 (WS-SCR7). WS-SCR7 inhibits NHEJ in Ligase IV dependent manner, with a subtle effect on Ligase III at higher concentration. No effect on Ligase I mediated joining was observed. WS-SCR7 shows cytotoxicity in cancer cell lines, leading to induction of apoptosis in a dose-dependent manner.

A series of 2,5-disubstituted 1,3,4-thiadiazole was synthesized and evaluated for their antioxidant and molecular docking studies. These molecules were efficiently synthesized under mild and inexpensive starting material. Construction of these molecules developed using substituted aldehydes and substituted dithioesters in presence of NCS (N-Chorosuccinimide). The compounds 4a, 4b, 4c, 4f, and 4k showed good antibacterial and antioxidant activity among which, 4k possess excellent antibacterial and antioxidant activity. The results of antioxidant activity studies revealed that compound 4k manifested profound antioxidant potential. The molecular docking study was performed with respective newly synthesized compounds to ascertain the binding mode of 4k with respect to the critical proteins involved in biosynthesis and metabolic pathways.

A vital approach for the synthesis of a range of novel thioxotriaza-spiro derivatives is described. These new heterocyclic systems are obtained via oxalic acid catalyzed reaction of α,β-unsaturated ketones in the presence of 5,6-diamino-2-mercaptopyrimidine-4-ols; thus, spiro rings are constructed in one step. Notably, this transformation involves condensation of an amino group followed by enamine reaction with alkenes and subsequent reaction promoted by oxalic acid to afford spiro compounds with excellent regioselectivity.

Novel and convenient methodology for the construction of N-substituted amide derivatives have been developed from nitriles and alcohols using propylphosphonic anhydride (T3P®). This methodology is an alternate approach to the synthesis of amides via Ritter reaction, which is one of the classical methods for the synthesis of N-substituted amides from nitriles and alcohols. In this approach, first T3P® activates the alcohol which is then attacked by nitrile to form N-substituted amides. This methodology can also apply for the synthesis of benzhydryl ether. This developed protocol is one of the novel applications of T3P®.

There is an immense need to discover novel methods that would make diversely functionalized molecules available through atom-economical and environmentally friendly reactions that minimize the use of organic solvents. An efficient and facile synthesis of 2, 5-disubstituted 1, 3, 4-thiadiazoles via intramolecular cyclization from dithioesters and benzoic acid in presence of H2SO4 has been developed using dithioesters. The synthesized compound was characterized and confirmed by NMR analysis and single-crystal X-ray diffraction studies. The geometry (bond lengths and bond angles), and molecular properties were estimated by means of the density functional theory (DFT) at B3LYP/6-31G level of theory with no symmetry constraints. Frontier molecular orbital (HOMO and LUMO) was drawn using the optimized structures which elucidates the charge transfer collaboration and chemical stability of the compound. Good correlation coefficients were found (R2= 0.9629 and 0.9176,) between the experimental bond length & bond angles and theoretical values. The Hirshfeld surface (HS) analysis showed that oxygen and nitrogen atoms of the 5h compound may act as H-bond acceptors, some H-bonds contacts are expected to be shown as red spots on the HS of the molecule.

A new approach for the synthesis of novel bis(imidazol-1-yl)vinyl-1,2,4-oxadiazoles has been developed. This method operates in a single step giving the products in good to excellent yields. Antiproliferative efficiency of the synthesized compounds was tested against HCT116 (colon cancer) and A549 (lung cancer) cell lines. Among them, compounds 3m (IC50, 9.7 μM) and 3h (IC50, 20.3 μM) were found to be the best antiproliferative agents.

International audience; Nonhomologous DNA end joining (NHEJ) is the major DNA double-strand break (DSB) repair pathway in mammals. Previously, we have described a small molecule inhibitor, SCR7, which can inhibit NHEJ in a Ligase IV-dependent manner. Administration of SCR7 within the cells resulted in the accumulation of DNA breaks, cell death, and inhibition of tumor growth in mice. In the present study, we report that parental SCR7, which is unstable, can be autocyclized into a stable form. Both parental SCR7 and cyclized SCR7 possess the same molecular weight (334.09) and molecular formula (C18H14N4OS), whereas its oxidized form, SCR7-pyrazine, possesses a different molecular formula (C18H12N4OS), molecular weight (332.07), and structure. While cyclized form of SCR7 showed robust inhibition of NHEJ in vitro, both forms exhibited efficient cytotoxicity. Cyclized and oxidized forms of SCR7 inhibited DNA end joining catalyzed by Ligase IV, whereas their impact was minimal on Ligase III, Ligase I, and T4 DNA Ligase-mediated joining. Importantly, both forms inhibited V(D)J recombination, although the effect was more pronounced for SCR7-cyclized. Both forms blocked NHEJ in a Ligase IV-dependent manner leading to the accumulation of DSBs within the cells. Although cytotoxicity due to SCR7-cyclized was Ligase IV specific, the pyrazine form exhibited nonspecific cytotoxicity at higher concentrations in Ligase IV-null cells. Finally, we demonstrate that both forms can potentiate the effect of radiation. Thus, we report that cyclized and oxidized forms of SCR7 can inhibit NHEJ in a Ligase IV-dependent manner, although SCR7-pyrazine is less specific to Ligase IV inside the cell.

A new approach for the synthesis of novel bis(imidazol-1-yl)vinyl-1,2,4-oxadiazoles has been developed. This method operates in a single step giving the products in good to excellent yields. Antiproliferative efficiency of the synthesized compounds was tested against HCT116 (colon cancer) and A549 (lung cancer) cell lines. Among them, compounds 3m (IC50, 9.7 μM) and 3h (IC50, 20.3 μM) were found to be the best antiproliferative agents.

Poly(ADP-ribose) polymerase (PARP) is a critical nuclear enzyme which safeguards genome stability from genotoxic insults and helps in DNA repair. Inhibition of PARP results in sustained DNA damage in cancer cells. PARP inhibitors are known to play an important role in chemotherapy as single agents in many DNA repair pathway deficient tumor cells or in combination with several other chemotherapeutic agents. In the present study, we synthesize and characterize novel pyridazine derivatives, and evaluate their potential for use as PARP inhibitors. Results show that pyridazine derivatives inhibited the PARP1 enzymatic activity at the nanomolar range and showed anti-proliferative activity in leukemic cells. Interestingly, human leukemic cell line, Nalm6, in which PARP1 and PARP2 expression as well as intrinsic PARP activity are high, showed significant sensitivity for the novel inhibitors compared to other leukemic cells. Among the inhibitors, P10 showed maximum inhibition of intrinsic PARP activity and inhibited cell proliferation in Nalm6 cells. Besides P10 also showed maximum inhibition against purified PARP1 protein, which was comparable to olaparib in our assays. Newly synthesized compounds also showed remarkable DNA trapping ability, which is a signature feature of many PARP inhibitors. Importantly, P10 also induced late S and G2/M arrest in Nalm6 cells, indicating accumulation of DNA damage. Therefore, we identify P10 as a potential PARP inhibitor, which can be developed as a chemotherapeutic agent.