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A series of novel thienopyridines and pyridothienoquinolines (3a,b–14) was synthesized, starting with 2-thioxo-1,2-dihydropyridine-3-carbonitriles 1a and 1b. All compounds were evaluated for their in vitro antimicrobial activity against six bacterial strains. Compounds 3a,b, 4a, 5b, 6a,b, 7a, 9b, 12b, and 14 showed significant growth inhibition activity against both Gram-positive and Gram-negative bacteria compared with the reference drug. The most active compounds (4a, 7a, 9b, and 12b) against Staphylococcus aureus were also tested for their in vitro inhibitory action on methicillin-resistant Staphylococcus aureus (MRSA). The tested compounds showed promising inhibition activity, with the performance of 12b being equal to gentamicin and that of 7a exceeding it. Moreover, the most promising compounds were also screened for their Escherichia coli DNA gyrase inhibitory activity, compared with novobiocin as a reference DNA gyrase inhibitor. The results revealed that compounds (3a, 3b, 4a, 9b, and 12b) had the highest inhibitory capacity, with IC50 values of 2.26–5.87 µM (that of novobiocin is equal to 4.17 µM). Docking studies were performed to identify the mode of binding of the tested compounds to the active site of E. coli DNA gyrase B.

A series of novel functionalized methyl 3-(hetero)arylthieno[3,2-b]pyridine-2-carboxylates 2a–2h were synthesized by C-C Pd-catalyzed Suzuki-Miyaura cross-coupling of methyl 3-bromothieno[3,2-b]pyridine-2-carboxylate with (hetero)aryl pinacol boranes, trifluoro potassium boronate salts or boronic acids. Their antitumoral potential was evaluated in two triple negative breast cancer (TNBC) cell lines—MDA-MB-231 and MDA-MB-468, by sulforhodamine B assay. Their effects on the non-tumorigenic MCF-12A cells were also evaluated. The results demonstrated that three compounds caused growth inhibition in both TNBC cell lines, with little or no effect against the non-tumorigenic cells. The most promising compound was further studied concerning possible effects on cell viability (by trypan blue exclusion assay), cell proliferation (by bromodeoxyuridine assay) and cell cycle profile (by flow cytometry). The results demonstrated that the GI50 concentration of compound 2e (13 μM) caused a decreased in MDA-MB-231 cell number, which was correlated with a decreased in the % of proliferating cells. Moreover, this compound increased G0/G1 phase and decreased S phases, when compared to control cells (although was not statistic significant). Interestingly, compound 2e also reduced tumor size using an in ovo CAM (chick chorioallantoic membrane) model. This work highlights the potential antitumor effect of a novel methyl 3-arylthieno[3,2-b]pyridine-2-carboxylate derivative.

3-Methyl-6-phenyl-2-thioxo-2,3-dihydrothieno[3,2-d]pyrimidin- 4(1H)-one (2), on treatment with phosphorous oxychoride, affored 4-chloro-3-methyl-6-phenyl -thieno[3,2-d]pyrimidine- 2(3H)-thione (3). A series of novel 6-phenyl-thieno[3,2-d]pyrimidine derivatives 4-9 bearing different functional groups were synthesized via treatment of compound 3 with different reagents. On the other hand, compound 2 was used to synthesize ethyl-[(3-methyl-6-phenyl-2-thioxo-2,3-dihydrothieno[ 3,2-d]pyrimidin-4-yl)-oxy]acetate (10), 2-hydrazinyl- -3-methyl-6-phenyl-thieno[3,2-d]pyrimidin-4(3H)-one (11), 3-methyl-2-(methyl-sulfanyl)-6-phenyl-thieno[3,2-d]pyrimidin- 4(3H)-one (12) and N-(phenyl)/4-chlorophenyl or methoxy- phenyl)-2-[(3-methyl-4-oxo-6-phenyl-3,4-dihydrothieno[ 3,2-d]pyrimidin-2-yl)-sulfanyl]-acetamide (13a-c). In addition, compound 12 was used to synthesize thieno[1,2,4] triazolopyrimidine derivatives 14 and 15 and 3-methyl-2-(methyl-sulfonyl)-6-phenyl-thieno[3,2-d]pyrimidin-4(3H)-one (16) through the reaction with the respective reagents. Moreover, the reaction of 16 with 4-phenylenediamine gave 2-[(4-aminophenyl)-amino]-3-methyl-6-phenyl-thieno[3,2-d] pyrimidin-4(3H)-one (17), which reacted with methanesulfonyl chloride to afford N-{4-[(3-methyl-4-oxo-6-phenyl-3H,4H- -thieno[3,2-d]pyrimidin-2-yl)-amino]phenyl}-methanesulfonamide (18). The majority of the newly synthesized compounds displayed potent anticancer activity, comparable to that of doxorubicin, on three human cancer cell lines, including the human breast adenocarcinoma cell line (MCF-7), cervical carcinoma cell line (HeLa) and colonic carcinoma cell line (HCT- 116). Compounds 18, 13b and 10 were nearly as active as doxorubicin whereas compounds 6, 7b and 15 exhibited marked growth inhibition, but still lower than doxorubicin.

Three aminodi(hetero)arylamines were prepared via a palladium-catalyzed C-N Buchwald-Hartwig coupling of methyl 3-aminothieno[3,2-b]pyridine-2-carboxylate with different bromonitrobenzenes, followed by reduction of the nitro groups of the coupling products to the corresponding amino compounds. The aminodi(hetero)arylamines thus obtained were evaluated for their growth inhibitory effect on four human tumor cell lines MCF-7 (breast adenocarcinoma), A375-C5 (melanoma), NCI-H460 (non-small cell lung cancer) and HepG2 (hepatocellular carcinoma). The toxicity to non-tumor cells was also evaluated using a porcine liver primary cell culture (PLP1), established by us. The aminodi(hetero)arylamine with the NH2 group in the ortho position and an OMe group in the para position to the NH of the di(hetero)arylamine, is the most promising compound giving the lowest GI50 values (1.30–1.63 µM) in all the tested human tumor cell lines, presenting no toxicity to PLP1 at those concentrations. The effect of this compound on the cell cycle and induction of apoptosis was analyzed in the NCI-H460 cell line. It was observed that it altered the cell cycle profile causing a decrease in the percentage of cells in the G0/G1 phase and an increase of the apoptosis levels.

Malaria causes hundreds of thousands of deaths every year, making it one of the most dangerous infectious diseases worldwide. Because the pathogens have developed resistance against most of the established anti-malarial drugs, new antiplasmodial agents are urgently needed. In analogy to similar antiplasmodial ketones, 4-arylthieno[2,3-b]pyridine-2-carboxamides were synthesized by Thorpe-Ziegler reactions. In contrast to the related ketones, these carboxamides are only weak inhibitors of the plasmodial enzyme PfGSK-3 but the compounds nevertheless show strong antiparasitic activity. The most potent representatives inhibit the pathogens with IC50 values in the two-digit nanomolar range and exhibit high selectivity indices (>100).

The rate of microbial resistance has continued to rise significantly as the availability of new antibiotics has declined. A new series of pyridine and thienopyridine derivatives were designed, synthesized and tested as antimicrobial agents. The reaction of 4-bromo acetophenone and vetraldehyde (3,4-dimethoxy benzaldehyde) in ethanol and sodium hydroxide solution afforded the corresponding chalcone which was used as a suitable precursor to prepare a new series of pyridine derivatives. The treatment of the latter chalcone with 2-cyanothioacetamide afforded the corresponding pyridinethione which was used as a precursor to synthesize the targeted thienopyridine derivatives in good to excellent yield by the reaction with 2-chloro- N -arylacetamide derivatives, α-haloketones, methyl iodide or chloroacetonitrile in one or two steps. The structure of the synthesized compounds was confirmed chemically by their preparations with other pathways and their spectral data. The newly synthesized pyridine and thienopyridine derivatives exhibited good to strong antimicrobial activity against microbial strains E. coli , B. mycoides and C. albicans . With maximal antimicrobial activity against B. mycoides (33 mm) and C. albicans (29 mm), respectively, compounds 12a and 15 demonstrated the highest inhibition zone. Compound 12a prevented the growth of E. coli , at MIC level of 0.0195 mg/mL, and B. mycoides and C. albicans at MIC level below than 0.0048 mg/mL, respectively. Additionally, compound 15 prevented the visible growth of E. coli , B. mycoides , and C. albicans at MIC values of >0.0048, 0.0098, and 0.039 mg/mL, respectively. The relation between the chemical structure of the synthesized pyridine and thienopyridine compounds and their antimicrobial properties was discussed in the SAR study.

The thienopyridines class of drugs used as P2Y12 receptor antagonists plays a vital role in antiplatelet therapy. To further optimized this compound class, we designed and synthesized a series of amino acid prodrugs of 2-hydroxytetrahydrothienopyridine. All compounds were then evaluated for their inhibitory effect on ADP-induced platelet aggregation in rats and then ED50 and bleeding time of the most potent compounds were compared with commercial drugs. The results showed compound 5c could be a potent and safe candidate for further research.

As a part of ongoing studies in developing new anticancer agents, novel 1,2-dihydropyridine , thienopyridine , isoquinolines , acrylamide , thiazolidine , thiazoles and thiophenes bearing a biologically active quinoline nucleus were synthesized. The structure of newly synthesized compounds was confirmed on the basis of elemental analyses and spectral data. All the newly synthesized compounds were evaluated for their cytotoxic activity against the breast cancer cell line MCF7. 2,3-Dihydrothiazole-5-carboxamides , , 4,5,6,7-tetrahydrobenzo[ ]thiophene-3-carboxamide ( ), 1,2-dihydroisoquinoline-7-carbonitrile ( ), 5,6,7,8-tetrahydro-4 -cyclohepta[ ]thiophene-3-carboxamide ( ), 1,2-dihydroisoquinoline-7-carbonitrile ( ), -cyano-3-(dimethylamino)- -(quinolin-3-yl)acrylamide ( ), 1,2-dihydroisoquinoline-7-carbonitriles ( ) and ( ) exhibited higher activity ( values of 27–45 μmol L ) compared to doxorubicin ( 47.9 μmol L ). LQ quinolin-3-yl)-1,2-dihydroisoquinoline-7-carbonitrile ( ), 2-thioxo-2,3-dihydrothiazole-5-carboxamide ( ) and quinolin-3-yl)-1,2-dihydroisoquinoline-7-carbonitrile ( ) show activity comparable to doxorubicin, while (quinolin-3-yl)-1,2-dihydroisoquinoline-7-carbonitrile ( ), 2,3-dihydrothiazole-5-carboxamide ( ), thieno [3,4- ] pyridine-4(5 )-one ( ), cyclopenta[ ]thiophene-3-carboxamide ( ) and (quinolin-3-yl)-6-stryl-1,2-dihydroisoquinoline-7-carbonitrile ( ) exhibited moderate activity, lower than doxorubicin.

Considering the thiophene unit as an electron-rich heterocycle, it is investigated with the aim of elucidating its potential efficiency for solar cell application. With the introduction of active substituents such as COOEt, CONH2 and CN into the thiophene segment, three novel thieno pyridine sensitizers (6a–c), based on donor-acceptor D-π-A construction, are designed and synthesized. The effect of the anchoring groups is investigated based on their molecular orbital’s (MO’s) energy gap (Eg). The electrostatic interaction between the synthesized dyes and metal nanoparticles, namely gold, silver and ruthenium, is believed to improve their performance as organic sensitizers. The dye-sensitized solar cells (DSSCs) are manufactured using the novel diazenyl pyridothiophene dyes, along with their metal nanoparticles conjugates as sensitizers, and were examined for efficiency improvement. Accordingly, using this modification, the photovoltaic performance was significantly improved. The promising results of conjugate (6b/AgNPs), compared with reported organic and natural sensitizers (JSC (1.136 × 10−1 mA/cm2), VOC (0.436 V), FF (0.57) and η (2.82 × 10−2%)), are attributed to the good interaction between the amide, methyl, amino and cyano groups attached to the thiophene pyridyl scaffolds and the surface of TiO2 porous film. Implementation of a molecular modeling study is performed to predict the ability of the thiophene moiety to be used in solar cell applications.

A series of 6-tosyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxamide analogues are synthesized by conventional techniques and characterized by elemental analysis, IR, MS,¹H, and¹³C NMR. These are tested for their antibacterial activity against Bacillus subtilis (abbreviated as BS), Staphylococcus aureus (abbreviated as SA), and Escherichia coli (abbreviated as EC). The synthesized compounds are able to inhibit the growth of the SA and EC. None of the compounds are effective against BS. All valence molecular orbital (abbreviated as MO) calculations with PM6 have been carried out for the molecules for which bioactivity data are available. Ciprofloxacin is taken as the standard antibiotics to compare activity with the molecules synthesized. It has been attempted to correlate the activity of the molecules with their electronic structure.