Microwave assisted, sequential two-step, one-pot synthesis of novel imidazo[1,2-a]pyrimidine containing tri/tetrasubstituted imidazole derivatives

Tailored Tetrasubstituted Imidazole Carrying the Benzenesulfonamide Fragments as Selective Human Carbonic Anhydrase IX/XII Inhibitors

A new series of tetrasubstituted imidazole carrying sulfonamide as zinc-anchoring group has been designed. The structures of the synthesized derivatives 5 a-l have been confirmed by spectroscopic analysis. These compounds incorporate an ethylenic spacer between the benzenesulfonamide and the rest of the trisubstituted imidazole moiety and were tested as inhibitors of carbonic anhydrases and for in-vitro cytotoxicity. Most of them act as effective inhibitors of the tumor-linked CA isoforms IX and XII, in nanomolar range. Also, different compounds have shown selectivity in comparable with the standard acetazolamide. Our IBS 5 d, 5 g, and 5 l (with Ki: 10.1, 19.4, 19.8 nM against hCA IX and 47, 45, 20 nM against hCA IX) showed the best inhibitory profile. In-vitro screening of all derivatives against a full sixty-cell-lined from NCI at a single dose of 10 μM offered growth inhibition of up to 45 %. Compound 5 b has been identified with the most potent cytotoxic activity and broad spectrum. Docking studies have also been implemented and were also in accordance with the biological outcomes. Our SAR analysis has interestingly proposed efficient tumor-related hCAs IX/XII suppression.

Synthesis of new imine-/amine-bearing imidazo[1,2-a]pyrimidine derivatives and screening of their cytotoxic activity

Imidazo[1,2-a]pyrimidine derivatives bearing imine groups (3a-e) were successfully synthesized in moderate to good yields using microwave-assisted heating. Corresponding amine derivatives (4a-e) were also obtained by the reduction reaction of the imine derivatives (3a-e). All synthesized products were characterized by FT-IR, 1H NMR, 13C NMR, and LC-MS spectroscopic techniques. In silico ADMET, Lipinski, and drug-likeness studies of the compounds were conducted and all were found to be suitable drug candidates. The cytotoxicity of the potential drug molecules was screened against the breast cancer cell lines MCF-7 and MDA-MB-231 and the healthy model HUVEC by the sulforhodamine B method. According to the antiproliferative studies, compounds 3d and 4d showed remarkable inhibition of MCF-7 cells with IC50 values of 43.4 and 39.0 μM and of MDA-MB-231 cells with IC50 values of 35.9 and 35.1 μM, respectively. In particular, compound 3d selectively inhibited the proliferation of MCF-7 1.6-fold and MDA-MB-231 2.0-fold relative to healthy cells. Moreover, the apoptotic mechanism studies indicated that compound 4d induced apoptosis by moderately increasing the ratio of Bax/Bcl-2 genes. Imidazo[1,2-a]pyrimidine derivative 3d, a promising cytotoxic agent, may be helpful in the discovery of new and more efficient anticancer agents for breast cancer treatment.

In-vitro anticancer evaluation of newly designed and characterized tri/tetra-substituted imidazole congeners- maternal embryonic leucine zipper kinase inhibitors: Molecular docking and MD simulation approaches

Our cascading attempt to develop new potent molecules now involves designing a series of imidazole derivatives and synthesizing two sets of 2,4,5- tri-substituted (4a-4d) and 1,2,4,5-tetra-substituted (6a-6d) imidazole by the principle of Debus-Radziszewski multicomponent synthesis reaction. The structures of the obtained compounds were confirmed by 1H/13C NMR, FT-IR, elemental analysis, purity and the retention time was analyzed by HPLC. Based upon the binding affinity in the molecular docking studies, we have synthesized different imidazole derivatives from which compound 6c have been found to show more anti-proliferative activity by inducing apoptosis at a higher rate than the other compounds corroborating the in-silico prediction. The structure and crystallinity of compound 4d have been confirmed by single XRD analysis. The synthesized molecules were screened for their in vitro anti-cancer properties in triple negative breast cancer cell line (MDA-MB-231), pancreatic cancer cell lines (MIA PaCa-2) and oral squamous cell carcinoma cell line (H357) and results indicated that all the compounds inhibited the cell proliferation in a concentration-dependent manner at different time points. The compounds 4b and 6d were found to be effective against the S. aureus bacterial strain whereas only compound 4d fairly inhibited the fungal strain of T. rubrum with a MIC 12.5 μg/mL. Molecular docking study reveals good interaction of the synthesized compounds with known target MELK involved in oncogenesis having high binding profiles. The lead compound 6c was further analyzed by the detailed molecular dynamics study to establish the stability of the ligand-enzyme complex.

Microwave-assisted rapid conjugation of horseradish peroxidase-dextran aldehyde with Schiff base reaction and decolorization of Reactive Blue 19

Microwave irradiation has become a routine technique in homogeneous and effective heating in organic synthesis. However, its application in enzyme-containing reactions is limited since it can cause denaturation of the enzyme. In this study, we have briefly investigated the effect of microwave heating on the conjugation reaction of horseradish peroxidase (HRP) with aldehyde derivative of dextran (D-CHO). The reaction was irradiated by microwave at 50 °C for 5 min. The conjugate was confirmed via GPC, in which the conjugates of HRP and D-CHO coexist with free unbound HRP molecules. Activity studies of HRP revealed that there is a small decrease in conjugate activity relative to the free enzyme after a short bioconjugation reaction with microwave irradiation. In decolorization studies of the textile dye Reactive Blue 19 (RB19), 99% of RB19 was decolorized through the free enzyme at 35 °C while the decolorization of the dye was 96% at 25-35 °C by the conjugate, which is a critical result showing clearly that the HRP conjugated via D-CHO is not denatured and still active after microwave-assisted reaction. This phenomenon is due to the multiple point conjugation of D-CHO on the surface of HRP and locking the 3D structure which may prevent changes in the secondary or tertiary structure of the enzyme. The results reveal that microwave irradiation can be used in production of covalently modified enzymes.