Synthesis, Antitumor Activity, and In Silico Drug Design of New Thieno[2,3-d]Pyrimidine-4-One Derivatives as Nonclassical Lipophilic Dihydrofolate Reductase Inhibitors.

Synthesis of a new series of 20 compounds bearing the thieno[2,3-d]pyrimidine-4-one scaffold was achieved. The inhibitory activity of these compounds was performed over 60 cell lines of human tumor at single and five dose concentrations. Compounds 20, 22, and 23 exhibited potent growth inhibitions toward the majority of the tested NCI 60 cell lines. Compounds 20 and 23 were the most active compounds with (MG-MID) TGI, GI50, and LC50 values of 16.2, 3.3, 50.1 and 67.7, 6.6, 100, respectively. Also, both compounds showed 7- and 4-fold better activity, respectively, than the standard antitumor agent 5-fluorouracil. Therefore, compounds 20 and 23 were selected to measure their ability to inhibit the dihydrofolate reductase enzyme (DHFR) in comparison to methotrexate (MTX) as a reference drug. Compound 20 was a more potent inhibitor of DHFR (IC50 = 0.20 µM) than MTX (IC50 = 0.22 µM). Molecular modeling studies were performed in the DHFR active site, and it showed compatibility with the results obtained from biological studies. Finally, the results showed that compound 20 is a strong antitumor agent and potent inhibitor of DHFR. In addition, this compound induced cell-cycle arrest in SNB-75 cells in the G2/M phase and the apoptosis process in the Pre-G phase. Compound 20 also increased the level of both caspases-3 and 9 by 11.8- and 50.3-fold, respectively.

Novel diaryl ether derivatives as InhA inhibitors: Design, synthesis and antimycobacterial activity.

A new series of triclosan (TCL)-mimicking diaryl ether derivatives 7-25 were synthesized and evaluated as inhibitors of enoyl acyl carrier protein reductase InhA enzyme. In addition, these derivatives were screened as inhibitors of drug-susceptible (DS), multidrug-resistant (MDR), and extensive drug-resistant (XDR) Mycobacterium tuberculosis (MTB) strains. Most compounds exihibted superior anti-TB activities and improved ClogP compared to TCL as a standard drug. The present work has led to the identification of compounds 14, 19 and 24 which possess remarkable activities against DS, MDR and XDR MTB strains with MIC values of 1.95, 3.9 and 15.63 µg/ml, respectively for compound 14, 1.95, 3.9 and 7.81 µg/ml, respectively for compound 19 and 0.98, 1.95 and 3.9 µg/ml, respectively for compound 24. Most compounds did not exhibit toxicity to HePG2 normal cell line. Compounds 14, 19 and 24, presenting the best MIC values, were further evaluated as inhibitors of InhA enzyme. They showed high binding affinities in the micromolar range with IC50 values of 1.33, 0.6, and 0.29 µM for compounds 14, 19, and 24, respectively. Furthermore, molecular docking approach was utilized to understand the difference in bioactivities between the new compounds. In particular, the results revealed strong binding interactions and high docking scores of compounds 14, 19 and 24, which could correlate with their high activities. Mainly, the molecular modelling study of compound 24 provides an excellent platform for understanding the molecular mechanism regarding InhA inhibition. Thus, compound 24 could be a lead compound for future development of new antitubercular drugs.

Dihydrofolate reductase inhibition effect of 5-substituted pyrido[2,3-d]pyrimidines: Synthesis, antitumor activity and molecular modeling study.

A new series of pyrido[2,3-d]pyrimidines 3-18 bearing substitution at C-5 position was synthesized. All compounds were tested for their in vitro antitumor activity against five human cancer cell lines namely; hepatocellular carcinoma (HePG2), breast carcinoma (MCF-7), human prostate carcinoma (PC3), colorectal carcinoma (HCT-116), and cervical carcinoma (Hela) using doxorubicin as a positive control. Compounds 3, 4, 9, 11, 13, 14, 15 and 17 exhibited the highest antitumor activity against the tested cell lines and were selected to screen their enzymatic inhibition against dihydrofolate reductase enzyme (DHFR) compared with the reference drug methotrexate (MTX), to explain the probable mechanism of action of the observed anticancer activity. Compound 11 displayed the highest inhibitory activity (IC50 = 6.5 µM) among the tested compounds in comparison with MTX (IC50 = 5.57 µM). Also, compounds 13 and 14 showed high inhibitory activity against DHFR with IC50 values 7.1 and 8.7 µM, respectively. Comparative molecular modeling study was performed between DHFR inhibitors 11, 13 and 14 of the highest activity and 10 of the lowest activity among the eight inhibitors against MTX. Docking studies into the active site of DHFR domain showed good agreement with the obtained biological results. Finally, compound 11 was found to be best antitumor, DHFR inhibitor, and it induced the process of apoptosis at Pre-G phase and cell cycle arrest at G2/M phase in MCF-7 cells.