Letters in Drug Design & Discovery - Volume 16, Issue 2, 2019

Background: With the approval of gefitinib, erlotinib, afatinib, and osimertinib for clinical use, targeting Epidermal Growth Factor Receptor (EGFR) has been intensively pursued. Similar to most therapies, challenges related to the treatment resistance against these drugs have emerged over time, so new EGFR Tyrosine Kinase Inhibitors (TKIs) need to be developed. This study aimed to investigate the potential use of a series of thiophene-bearing quinazoline derivatives as EGFR inhibitors. We designed and synthesized nine quinazolin derivatives, among which five compounds (5e, 5f, 5g, 5h, and 5i) were reported for the first time. Methods: Two cancer cell lines, A431 (overexpressing EGFR) and A549 (EGFR wild-type and Kras mutation), were treated by these compounds and subjected to MTT assay. The A431 cells were selected for further treatment (5e) and Western blot analysis. Results: Although the compounds exerted no obvious effects on the proliferation of A549 cells, seven out of the nine compounds significantly inhibited the growth of A431 cells. In particular, the IC50 values of 5e and erlotinib were nearly equal. Western blot results showed that 5e significantly inhibited EGFR autophosphorylation in A431 cells. Structure-activity relationships indicated that quinazolines bearing 6,7-side chains were more potent than those unsubstituted at the 6,7-positions. Moreover, electron-withdrawing hydrophobic groups on the 5-position of the thiophene were preferred, such as chlorine or bromine atom. Conclusion: Nine 4-aminoquinazolin derivatives were designed, synthesized, and evaluated against A431 and A549 cell lines. Seven compounds significantly inhibited the growth of A431 cells. In particular, 5e possessed similar antitumor potency to that of erlotinib.

Background: The synthesis of 2-[3/4-((6-substituted-1-oxo-2,3-dihydro-1H-inden-2- ylidene)methyl)phenoxy]-N-(heteroaryl)acetamide derivatives and the investigation of their anticancer activity were studied. Methods: 2-(3/4-Hydroxybenzylidene)-6-substituted-2,3-dihydro-1H-inden-1-ones were reacted with suitable 2-chloroacetamides to give 2-[3/4-((6-substituted-1-oxo-2,3-dihydro-1H-inden-2-ylidene) methyl)phenoxy]-N-(heteroaryl)acetamide derivatives. Results: The structure elucidation of the newly synthesised 16 compounds was performed by IR, 1H-NMR, mass spectroscopic data and elemental analyses. The anticancer screening was carried out in National Cancer Institute (NCI), USA. Conclusion: Compound 3e (2-(3-((6-chloro-1-oxo-2,3-dihydro-1H-inden-2-ylidene)methyl)phenoxy)- N-(thiazol-2-yl)acetamide), exhibited highest growth inhibition against the leukaemia (61.47%), non-small cell lung cancer (79.31%) and breast cancer (62.82%) cell lines.

Background: We report here an efficient synthesis of new Mannich products 4(a-m) in excellent yields via multi-component reaction for the condensation of 5-bromothiophene- 2-carboxaldehyde (5-BT-2C), 2,4-dihydroxybenzophenone (2,4-DHBP) and primary/secondary amine derivative using Ethyl Ammonium Nitrate (EAN) as ionic liquid, which is reusable and plays an important role as a catalyst under 800C. Methods: All synthesized compounds were characterized by FT-IR, 1H-NMR, 13C-NMR spectra. All compounds were screened for their in vitro antibacterial, antifungal and antituberculosis activity, in which we found compounds 4b, 4c, 4d, 4h, 4i, 4j showing good to very good activity against all gram-positive and gram-negative bacteria. Results & Conclusion: Molecular docking studies showed that some of the synthesized compounds showed good docking interactions.

Background: The impact of the ubiquitous dietary phenolic compound p-coumaric acid on human breast cancer cells was assessed, through a multidisciplinary approach: Combined biological assays for cytotoxicity evaluation and biochemical profiling by Raman microspectroscopic analysis in cells. Methods: Para-coumaric acid was shown to exert in vitro chemoprotective and antitumor activities, depending on the concentration and cell line probed: a significant anti-invasive ability was detected for the triple-negative MDA-MB-231 cells, while a high pro-oxidant effect was found for the estrogen- dependent MCF-7 cells. A striking cell selectivity was obtained, with a more noticeable outcome on the triple-negative MDA-MB-231 cell line. Results: The main impact on the cellular biochemical profile was verified to be on proteins and lipids, thus justifying the compound´s anti-invasive effect and chemoprotective ability. Conclusion: p-Coumaric acid was thus shown to be a promising chemoprotective/chemotherapeutic agent, particularly against the low prognosis triple-negative human breast adenocarcinoma.

Background: Aurora kinases perform important roles in mammals, mainly in cell cycle. Overexpression of these enzymes is related to tumor development and is indicative of worsening of clinical conditions. Aurora kinases are promising targets in the search for new anticancer drugs, in particular, Aurora B. Methods: This work was designed to study and understand the interactions between human Aurora B and several indolin-2-one derivatives, structurally similar to sunitinib. MVD software was utilized in docking analyses of indolin-2-one derivatives. Human Aurora B kinase was obtained from the PDB (4AF3) and redocked with hesperadin, which was used as a reference compound. The predicted model of the training group, considering 21 amino acid residues, performed in Chemoface, achieved an R2 of 0.945, suggesting that the binding conformations of the ligands with human Aurora B are reasonable and the data can be used to predict the interaction energy of other Aurora B inhibitors indolin-2-one derivatives. Results: MolDock Score energy for compound 1 showed more stable interaction energy (-225.90 kcal.mol-1) then the other inhibitors studied, while sunitinib was the least stable (-135.63 kcal.mol-1). Compounds 1-45, hesperadin and sunitinib, interacted with Glu171 (–NH from indolinonic moiety), and the majority of them with Ala173 (C=O from indolinonic moiety) via hydrogen bonds, thus these two residues are relevant for potency. Conclusion: Docking studies and biological activity in literature show subunits likely for structural optimizations, leading to four new proposed derivatives (IAF61, IAF63, IAF66, IAF79) as promising compounds for synthesis and biological evaluation against human Aurora B, validating and ratifying the docking studies.

Background: Acquired Immunodeficiency Syndrome (AIDS) caused by Human Immunodeficiency Virus (HIV) has seriously threatened human health, so development of new, selective and safe non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs) remains a high priority for medical research. Diaryltriazine (DATA) have been identified as a new class of potent nonnucleoside HIV-1 Reverse Transcriptase (RT) inhibitors. The study deals with Topomer CoMFA (Comparative Molecular Field Analysis) and molecular docking to explore the important features of DATA analogues for exerting potent HIV-1 RT inhibitors activity. Methods: In this work, 40 DATA analogues were studied using a combination of molecular modeling techniques including Three-Dimensional Quantitative Structure–Activity Relationship (3D-QSAR), molecular docking, and Topomer CoMFA were used to build 3D-QSAR models. Results: The results show that the Topomer CoMFA analysis has the cross-validation q2 = 0.800, SDCV = 0.45, the non-cross-validated r2 = 0.958, SD = 0.21, and the correlation coefficient of external validation Q2 ext = 0.965 showed that the model is reasonable and credible, and has a good predictive ability. Then binding mode pattern of the compounds to the binding site of enzyme was confirmed and the mechanism of drug and acceptor was studied by docking studies, the results showed that the drug and GLU138, LYS101, THR139 sites have an obvious function, these researches have provided an useful information for designing more effective HIV-1IN inhibitors. Conclusion: A series of 40 DATAs analogues was subjected to a 3D-QSAR study. Using Topomer CoMFA 3D-QSAR method built model, and the model has shown a good predictive and statistical validation. Substituent with low electronic density in the R5 and R3 positions and substituent with high electronic density in the R2 and C2 positions will increase the biological activity, small substituent on R4 positions and naphthyloxy as the spacer group C6 substituent hydrophobic will increase biological activity. This effect is supported by Topomer CoMFA contour map and docking results of HIV-1RT inhibition active site, the results of the 3D-QSAR and docking analyses have provided a guide for the synthesis of new putative inhibitors for HIV-1RT to improved inhibitory activity.

Background: 2,4-disubstituted-1,3-thiazole derivatives (2a–j), (3a–f) and (4a–f) were synthesized, characterized and screened for their potential as antimicrobial agents. In the preliminary screening against a panel of bacterial strains, nine compounds showed moderate to potent antibacterial activity (IC50 = 13.7-90.8 μg/ml). Methods: In the antifungal screening, compound (4c) displayed potent antifungal activity (IC50 = 26.5 μg/ml) against Candida tropicalis comparable to the standard drug, fluconazole (IC50 = 10.5 μg/ml). Based on in vitro antimicrobial results, compounds 2f, 4c and 4e were selected for further pharmacological investigations. Hemolytic activity using human red blood cells (hRBCs) and cytotoxicity by MTT assay on human embryonic kidney (HEK-293) cells revealed non-toxic nature of the selected compounds (2f, 4c and 4e). To ascertain their possible mode of action, docking studies with the lead inhibitors (2f, 4c and 4e) were performed using crystal structure coordinates of bacterial methionine aminopeptidases (MetAPs), an enzyme involved in bacterial protein synthesis and maturation. Results: The results of in vitro and in silico studies provide a rationale for selected compounds (2f, 4c and 4e) to be carried forward for further structural modifications and structure-activity relationship (SAR) studies against these bacterial infections. Conclusion: The study suggested binding with one or more key amino acid residues in the active site of Streptococcus pneumoniae MetAP (SpMetAP) and Escherichia coli MetAP (EcMetAP). In silico physicochemical properties using QikProp confirmed their drug likeliness.

Abstract: Background: Chlamydiae are widespread Gram-negative bacteria that cause a number of human diseases. Chlamydia trachomatis is the most prevalent sexually transmitted bacterial pathogen. Methods: Fourteen novel phenazine derivatives were efficiently synthesized via Buchwald-Hartwig cross coupling reaction and Suzuki reaction from 4-bromo-1-methoxyphenazine. All the derivatives displayed antichlamydial activity with IC50 values from 1.01-19.77 μM against Chlamydia trachomatis D and L2 for inhibiting progeny formation. Results: C-4 morpholinyl 8a and C-4 phenyl phenazine 9c exhibited stronger antichlamydial activity with no apparent cytotoxicity. Both phenazine derivatives inhibited chlamydial inclusions formation and growth in a dose-dependent manner. They inhibited Chlamydia infection by reducing elementary body infectivity and disturbing Chlamydia growth at the mid-stage of the chlamydial developmental cycle. Conclusion: Our findings suggest C-4 aryl and C-4 amino phenazine derivatives as promising lead molecules for antichlamydials development.

Background: Cancer caused nearly 8.8 million deaths in 2015. Limited efficacy, selectivity, drug resistance and toxicity are major complications associated with chemotherapy, potentiating the discovery of anticancer agents. Methods: A new series of N-(7-hydroxy-4-methyl-2-oxoquinolin-1(2H)-yl)acetamide/benzamide analogues (5a-j) was prepared from the precursor, 7-hydroxy-4-methyl-2H-chromen-2-one (3), as anticancer agent. The structural assignment of quinolone analogues (5a-j) was based on spectroscopic data analyses. The cytotoxicity was tested on breast cancer cell lines (MCF7 and MDA-MB- 231) by sulforhodamine B (SRB) assay and three dose-related parameters GI50, TGI, and LC50 were calculated. Results: 2-(2-chlorophenoxy)-N-(7-hydroxy-4-methyl-2-oxoquinolin-1(2H)-yl)acetamide (5a) showed the most potent cytotoxicity against the MCF7 and MDA-MB-231 cancer cell lines with GI50 of 18.7 and 48.1 μM respectively. The glide scores of the compounds, 5a-d were found to be related to the cytotoxicity profile and the emodel scores for ligands, 5a-j were found to be related to significant cytotoxicity. Conclusion: Compound 5a exhibited the most potent cytotoxicity and this report may provide some predictions to design more potent novel quinolines as cytotoxic agents.

Background: Polymorphonuclear neutrophils (PMNs) play a crucial role in the innate immune system's response to microbial pathogens through the release of reactive nitrogen species, including Nitric Oxide (NO). Methods: In neutrophils, NO is produced by the inducible Nitric Oxide Synthase (iNOS), which is regulated by various signaling pathways and transcription factors. N-nitrosodimethylamine (NDMA), a potential human carcinogen, affects immune cells. NDMA plays a major part in the growing incidence of cancers. Thanks to the increasing knowledge on the toxicological role of NDMA, the environmental factors that condition the exposure to this compound, especially its precursors- nitrates arouse wide concern. Results: In this article, we present a detailed summary of the molecular mechanisms of NDMA's effect on the iNOS-dependent NO production in human neutrophils. Conclusion: This research contributes to a more complete understanding of the mechanisms that explain the changes that occur during nonspecific cellular responses to NDMA toxicity.

Background: In attempts to discover new antiangiogenic entities, a novel series of thioethers derived from 6-thioxo-6,7-dihydro-1H-pyrazolo[3,4-d]pyrimidine-4(5H)ones was considered and designed. Methods: Virtual screening was carried out through docking of the compounds into the vascular endothelial growth factor and matrix metalloproteinase-9 binding sites. Molecular docking studies were performed using Lamarckian Genetic Algorithm. Compounds possessing lowest ligandprotein pairwise interaction energies were synthesized and screened for their antiproliferative activities against five cancer cell lines namely MHCC97H (liver), MDA-MB 231 (Breast), Colo205 (Colon), A549 (lung), A498 (kidney) and IC50 values were determined for the most potent compounds. Additionally, they were tested for their antiangiogenic activities by testing their ability to inhibit Human Umbilical Vein Endothelial Cell (HUVEC), cord formation and migration in response to chemoattractant. Results: Three compounds 2a, 2b and 5b showed significant antiangiogenic activities. The allyl thioether 2b was the most active with chemotaxis activity data nearly comparable to that of the positive control, TNP-470. Additionally, 2a, 2b and 5b, contrary to TNP-470, interfered with the migration of HUVECs in response to vascular endothelial growth factor rather than endothelial cells proliferation or cord formation. Compounds 2a, 2b and 5b were also investigated for their inhibitory effects on MMPs to investigate the relationship between their angiogenic activity and MMPs. Results revealed that compound 2b was the most effective MMP-9 inhibitor in this series. Additionally, compound 2b reduced the expression levels of VEGF and pERK1/2. Conclusion: Our results suggest that compound 2b is considered as a promising antiangiogenic agent by targeting VEGF and MMP-9.

Background: A new series of 1,2,3-triazol-nitrostyrene derivatives was designed, synthesized, and evaluated for cytotoxic activity against Hep-2 and L929 cell lines. Methods: The synthetic procedure started from the functionalization of 4-hydroxybenzaldehyde with propargyl bromide and a subsequent click reaction to give 1,2,3-triazole derivatives. Then, the reaction of the mentioned derivatives with nitromethane led to the formation of the title compounds in excellent yields. Results: Most of the compounds exhibited better cytotoxic activity with respect to the standard drug 5-fluorouracil. Among them, (E)-1-(3,4-dichlorobenzyl)-4-((4-(2-nitrovinyl)phenoxy)methyl)-1H- 1,2,3-triazole 6i (IC50 = 4.66 ± 1.3 μM) against the Hep-2 cell line and (E)-1-(2,3-dichlorobenzoyl)- 4-((4-(2-nitrovinyl)phenoxy)methyl)-1H-1,2,3-triazole 6g (IC50 = 5.18 ± 0.8 μM) against the L929 cell line exhibited the best cytotoxic effects. Conclusion: Moreover, the acridine orange/ethidium bromide double staining technique showed that the most potent compounds 6i and 6g could induce apoptosis in studied cancer cell lines.

Background: For the development of suitable lead molecules to different diseases is a highly challenging task for medicinal chemists. Nowadays, hybrid pharmacophore concept has developed as a useful structural modification tool in the drug design of new drug candidates for different diseases. Hybrid pharmacophore approach consists of combination of two or more pharmacophoric moieties from different biologically active compounds with complementary functions or different mechanisms of action into a single molecule. This often results in synergistic activity or enhanced drug efficacy. Objective: To develop the suitable leads for different diseases there will be a lot of scope to study the substitution of heterocyclic moieties on the different positions of isatin ring. The broad and potent activities of the isatin and their derivatives have been established them as pharmacologically significant scaffolds. In this review, an attempt has been made with specifically emphasizing the hybridization of Isatin with different derivatives of heterocyclic compounds on the different positions of the isatin ring (aryl ring, isatin nitrogen and C2/C3 carbonyl moieties). Conclusion: This review highlighted the recent advances of dual acting isatin-heterocyclic hybrids presenting various pharmacological activities viz., anticancer, antitubercular, anti-inflammatory and antimicrobial.