Synthesis and biological evaluation of novel tricyclic oxazine and oxazepine fused quinazolines. Part 2: Gefitinib analogs

Gefitinib derivatives and drug-resistance: A perspective from molecular dynamics simulations

Epidermal-growth factor receptor (EGFR) is a transmembrane tyrosine kinase (TK) with a significant role in cell survival. EGFR is upregulated in various cancer cells and known as a druggable target. Gefitinib is a first-line TK inhibitor used against metastatic non-small cell lung cancer (NSCLC). Despite initial clinical response, a conserved therapeutic effect could not be achieved due to the occurrence of resistance mechanisms. Point mutations in EGFR genes are one of the major causes of rendered tumor sensitivity. To aid in the development of more efficient TKIs, chemical structures of prevailing drugs and their target binding patterns are very important. The aim of the present study was to propose synthetically-accessible gefitinib congeners with enhanced binding fitness to clinically frequent EGFR mutants. Docking simulations of intended molecules identified 1-(4-(3-chloro-4-fluorophenylamino)-7-methoxyquinazolin-6-yl)-3-(oxazolidin-2-ylmethyl) thiourea (23) as a top-binder structure inside G719S, T790 M, L858R and T790 M/L858R-EGFR active sites. Superior docked complexes were subjected to the entire 400 ns molecular dynamics (MD) simulations. Analysis of data revealed the stability of mutant enzymes upon binding to molecule 23. All mutant complexes with the exception of a T790 M/L858R-EGFR, were majorly stabilized through cooperative hydrophobic contacts. Pairwise analysis of H-bonds proved Met793 as the conserved residue with stable H-bond participations as hydrogen bond donor (Frequency 63-96%). Amino acid decomposition analysis confirmed the probable role of Met793 in complex stabilization. Estimated binding free energies indicated the proper accommodation of molecule 23 inside target active sites. Pairwise energy decompositions of stable binding modes revealed the energetic contribution of key residues. Although wet lab experiments are required to unravel the mechanistic details of mEGFR inhibition, MD results provide structural basis for those events that are difficult to address experimentally. The outputs of the current study may assist to design small molecules with high potency to mEGFRs.

Synthesis, Antioxidant and Antiproliferative Actions of 4-(1,2,3-Triazol-1-yl)quinolin-2(1H)-ones as Multi-Target Inhibitors

The reaction of 4-azido-quinolin-2(1H)-ones 1a-e with the active methylene compounds pentane-2,4-dione (2a), 1,3-diphenylpropane-1,3-dione (2b), and K2CO3 was investigated in this study. This approach afforded 4-(1,2,3-triazol-1-yl)quinolin-2(1H)-ones 3a-j in high yields and purity. All newly synthesized products' structures were identified. Compounds 3a-j were tested for antiproliferative activity against a panel of four cancer cell lines. In comparison to the reference erlotinib (GI50 = 33), compounds 3f-j were the most potent derivatives, with GI50 values ranging from 22 nM to 31 nM. The most effective antiproliferative derivatives, 3f-j, were subsequently investigated as possible multi-target inhibitors of EGFR, BRAFV600E, and EGFRT790M. Compound 3h was the most potent inhibitor of the studied molecular targets, with IC50 values of 57 nM, 68 nM, and 9.70 nM, respectively. The apoptotic assay results demonstrated that compounds 3g and 3h function as caspase-3, 8, and Bax activators as well as down-regulators of the antiapoptotic Bcl2, and hence can be classified as apoptotic inducers. Finally, compounds 3g and 3h displayed promising antioxidant activity at 10 µM, with DPPH radical scavenging of 70.6% and 73.5%, respectively, compared to Trolox (77.6%).

Quinazolinone Synthesis through Base-Promoted SNAr Reaction of ortho-Fluorobenzamides with Amides Followed by Cyclization

A transition-metal-free synthesis of quinazolin-4-ones by Cs2CO3-promoted SNAr reaction of ortho-fluorobenzamides with amides followed by cyclization in dimethyl sulfoxide has been developed. The present procedure can provide efficient synthetic methods for the formation of both 2-substituted and 2,3-disubstituted quinazolin-4-one rings depending on the use of easily available starting materials and an efficient, one-pot protocol for the synthesis of the marketed drug product of methaqualone.

Synthesis of novel gefitinib-based derivatives and their anticancer activity

Drug latentiation is a process of modifying a drug molecule structurally to improve its binding affinity as well as increasing the drug-receptor interactions and potentiate its therapeutic potential. In the quest for discovering more potent epidermal growth factor receptor (EGFR) inhibitors, gefitinib-based derivatives were designed by simple structural modification at the secondary amine of gefitinib by N-alkylation. Three gefitinib derivatives (gefitinib-NB, -NP, and -NIP) were synthesized by N-alkylation and phase transfer catalysis. Structural characterization, physicochemical parameters such as solubility, log P, and p K _a were determined. Molecular docking studies were carried out to investigate the binding interactions at the active site. Further drug-bovine serum albumin (BSA) protein and drug-calf thymus (CT) DNA interactions were performed to understand the pharmacokinetics of the synthesized derivatives. All the compounds were screened for preliminary in vitro cytotoxic activity against A549, A431 lung, and MDA-MB-231 breast cancer cell lines by MTT assay. The gefitinib-NP and gefitinib-NB derivatives exhibited strong cytotoxic activity compared with gefitinib. They also showed higher drug-BSA and drug-DNA interactions. Molecular docking studies showed the orientation and binding interactions with the EGFR as well as with BSA and CT DNA. The results establish a strong correlation between the experimental and molecular docking studies. EGFR inhibition studies were also carried out for the derivatives and we identified the NP derivative of gefitinib as a potential lead compound. The gefitinib-based derivatives reported herein are cytotoxic agents and can be tested for further pharmacokinetic profiles and toxicity studies which might be helpful for designing more potent gefitinib-based derivatives in the future.

Synthesis and biological evaluation of 2-styrylquinolines as antitumour agents and EGFR kinase inhibitors: molecular docking study

A new series of 4,6-disubstituted 2-(4-(dimethylamino)styryl)quinoline 4a,b–9a,b was synthesized by the reaction of 2-(4-(dimethylamino)styryl)-6-substituted quinoline-4-carboxylic acids 3a,b with thiosemicarbazide, p-hydroxybenzaldehyde, ethylcyanoacetate, and 2,4-pentandione. In addition, the antitumour activity of all synthesized compounds 3a,b–9a,b was studied via MTT assay against two cancer cell lines (HepG2 and HCT116). Furthermore, epidermal growth factor receptor (EGFR) inhibition, using the most potent antitumour compounds, 3a, 3b, 4a, 4b, and 8a, was evaluated. The interpretation of the results showed clearly that the derivatives 3a, 4a, and 4b exhibited the highest antitumour activities against the tested cell lines HepG2 and HCT116 with IC₅₀ range of 7.7–14.2 µg/ml, in comparison with the reference drugs 5-fluorouracil (IC₅₀ = 7.9 and 5.3 µg/ml, respectively) and afatinib (IC₅₀ = 5.4 and 11.4 µg/ml, respectively). In vitro EGFR screening showed that compounds 3a, 3b, 4a, 4b, and 8a exhibited moderate inhibition towards EGFR with IC₅₀ values at micromolar levels (IC₅₀ range of 16.01–1.11 µM) compared with the reference drugs sorafenib (IC₅₀ = 1.14 µM) and erlotinib (IC₅₀ = 0.1 µM). Molecular docking was performed to study the mode of interaction of compounds 3a and 4b with EGFR kinase.