Design and Synthesis of Quinoxaline Hybrids as Modulators of HIF-1a, VEGF, and p21 for Halting Colorectal Cancer.

A library of 16 3-benzyl-N 1-substituted quinoxalin-2-ones was synthesized as N 1-substituted quinoxalines and quinoxaline-triazole hybrids via click reaction. These compounds were tested for their anticancer activity via MTT assay on HCT-116 and normal colonocyte cell lines to assess their cytotoxic potentials and safety profiles. Overall, compounds 6, 9, 14, and 20 were found to be promising anticolorectal cancer agents; they exhibited remarkable cytotoxicity (IC50 0.05-0.07 µM) against HCT-116 cells within their safe doses (EC100) on normal colon cells. Their pronounced anticancer activities were observed as severe morphological alterations and shrinkage of the treated cancer cells. Besides, qRT-PCR analysis was conducted showing the potential of the promising hits to downregulate HIF-1a, VEGF, and BCL-2 as well as their ability to enhance the expression of proapoptotic genes p21, p53, and BAX in HCT-116 cells. In silico prediction revealed that most of our compounds agree with Lipinski and Veber parameters of rules, in addition to remarkable medicinal chemistry and drug-likeness parameters with no CNS side effects. Interestingly, docking studies of the compounds in the VEGFR-2' active site showed significant affinity toward the essential amino acids, which supported the biological results.

Challenging the anticolorectal cancer capacity of quinoxaline-based scaffold via triazole ligation unveiled new efficient dual VEGFR-2/MAO-B inhibitors.

Monoamine oxidases (MAOs) and vascular endothelial growth factor receptor-2 (VEGFR-2) are promoters of colorectal cancer (CRC) and central signaling nodes in epithelial-mesenchymal transition (EMT) induced by activating hypoxia-inducible factors (HIFs). Herein, a novel series of rationally designed triazole-tethered quinoxalines were synthesized and evaluated against HCT-116 CRC cells. The tailored scaffolds combine the pharmacophoric themes of both VEGFR-2 inhibitors and MAO inhibitors. All the synthesized derivatives were screened utilizing the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay for their possible cytotoxic effects on normal human colonocytes, then evaluated for their anticancer activities against HCT-116 cells overexpressing MAOs. The hit derivatives 11 and 14 exhibited IC50 = 18.04 and 7.850 µM, respectively, against HCT-116cells within their EC100 doses on normal human colonocytes. Wound healing assay revealed their efficient CRC antimetastatic activities recording HCT-116 cell migration inhibition exceeding 75 %. In vitro enzymatic assays demonstrated that both 11 and 14 efficiently inhibited VEGFR-2 (IC50 = 88.79 and 9.910 nM), MAO-A (IC50 = 0.763 and 629.1 nM) and MAO-B (IC50 = 0.488 and 209.6 nM) with observed MAO-B over MAO-A selectivity (SI = 1.546 and 3.001), respectively. Enzyme kinetics studies were performed for both compounds to identify their mode of MAO-B inhibition. Furthermore, qRT-PCR analysis showed that the hits efficiently downregulated HIF-1α in HCT-116cells by 3.420 and 16.96 folds relative to untreated cells. Docking studies simulated their possible binding modes within the active sites of VEGFR-2 and MAO-B to highlight their essential structural determinants of activities. Finally, they recorded in silico drug-like absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiles as well as ligand efficiency metrics.

Halting colorectal cancer metastasis via novel dual nanomolar MMP-9/MAO-A quinoxaline-based inhibitors; design, synthesis, and evaluation.

Matrix metalloproteinase-9 (MMP-9) and monoamine oxidase-A (MAO-A) are central signaling nodes in CRC and promotors of distant metastasis associated with high mortality rates. Novel series of quinoxaline-based dual MMP-9/MAO-A inhibitors were synthesized to suppress CRC progression. The design rationale combines the thematic pharmacophoric features of MMP-9 and MAO-A inhibitors in hybrid scaffolds. All derivatives were initially screened via MTT assay for cytotoxic effects on normal colonocytes to assess their safety profiles, then evaluated for their anticancer potential on HCT116 cells overexpressing MMP-9 and MAO-A. The most promising derivatives 8, 16, 17, 19, and 28 exhibited single digit nanomolar IC50 against HCT116 cells within their safe doses (EC100) on normal colonocytes. They suppressed HCT116 cell migration by 73.32, 61.29, 21.27, 28.82, and 27.48%, respectively as detected by wound healing assay. Enzymatic assays revealed that the selected derivatives were superior to the reference MMP-9 and MAO-A inhibitors (quercetin and clorgyline, respectively). The nanomolar dual MMP-9/MAO-A inhibitor 19 was identified as the most potent and balanced dual inhibitor among the evaluated series with considerable selectivity against MAO-A over MAO-B. Besides, qRT-PCR analysis was conducted to explore the hit compounds' potential to downregulate hypoxia-inducing factor (HIF-1α) in HCT116 cells being correlated with MAO-A mediated CRC migration and invasion. The five above-mentioned compounds significantly downregulated HIF-1α by more than 5 folds. Docking simulations predicted their possible binding modes with MMP-9 and MAO-A and highlighted their essential structural features. Finally, they recorded drug-like in silico physicochemical parameters and ADMET profiles.

Design, synthesis, molecular modelling and in vitro screening of monoamine oxidase inhibitory activities of novel quinazolyl hydrazine derivatives.

A new series of N'-substituted benzylidene-2-(4-oxo-2-phenyl-1,4-dihydroquinazolin-3(2H)-yl)acetohydrazide (5a-5h) has been synthesized, characterized by FT-IR, NMR spectroscopy and mass spectrometry and tested against human monoamine oxidase (MAO) A and B. Only (4-hydroxy-3-methoxybenzylidene) substituted compounds gave submicromolar inhibition of MAO-A and MAO-B. Changing the phenyl substituent to methyl on the unsaturated quinazoline ring (12a-12d) decreased inhibition, but a less flexible linker (14a-14d) resulted in selective micromolar inhibition of hMAO-B providing insight for ongoing design.

Study of antileishmanial activity of 2-aminobenzoyl amino acid hydrazides and their quinazoline derivatives.

A new small library of 2-aminobenzoyl amino acid hydrazide derivatives and quinazolinones derivatives was synthesized and fully characterized by IR, NMR, and elemental analysis. The activity of the prepared compounds on the growth of Leishmania aethiopica promastigotes was evaluated. 2-Benzoyl amino acid hydrazide showed higher inhibitory effect than the quinazoline counterpart. The in vitro antipromastigote activity demonstrated that compounds 2a, 2b, 2f and 4a had IC50 better than standard drug miltefosine and comparable activity to amphotericin B deoxycholate, which indicates their high antileishmanial activity against Leishmania. aethiopica. Among the prepared compounds; 2-amino-N-(6-hydrazinyl-6-oxohexyl)benzamide 2f (IC50=0.051µM) has the best activity, 154 folds more active than reference standard drug miltefosine (IC50=7.832µM), and half fold the activity of amphotericin B (IC50=0.035µM). In addition, this compound was safe and well tolerated by experimental animals orally up to 250mg/kg and parenterally up to 100mg/kg.

Synthesis and evaluation of quinazoline amino acid derivatives as mono amine oxidase (MAO) inhibitors.

A series of quinazolinone amino acid ester and quinazolinone amino acid hydrazides were prepared under microwave irradiation as well as conventional condition. The microwave irradiation afforded the product in less reaction time, higher yield and purity. The structures of the synthesized compounds were confirmed by IR, NMR, and elemental analysis. The new synthesized compounds were studied for their monoamine oxidase inhibitory activity. They showed more selective inhibitory activity toward MAO-A than MAO-B. Compounds 7, 10, and 15 showed MAO-A inhibition activity (IC50=3.6×10(-9), 2.8×10(-9), 2.1×10(-9) M, respectively) comparable to that of the standard clorgyline (IC50=2.9×10(-9)M). 2-(2-(Benzo[d][1,3]dioxol-5-yl)-4-oxo-1,2-dihydroquinazolin-3(4H)-yl)acetohydrazide 15 showed selective MAO-A inhibition activity (SI=39524) superior to that of the standard clorgyline (SI=33793). The acute toxicity of the synthesized compounds was determined. In addition, computer-assisted simulated docking experiments were performed to rationalize the biological activity.

Exploring new selective 3-benzylquinoxaline-based MAO-A inhibitors: design, synthesis, biological evaluation and docking studies.

In this investigation, we searched for novel MAO-A inhibitors using a 3-benzylquinoxaline scaffold based on our earlier findings. Series of N'-(3-benzylquinoxalin-2-yl)acetohydrazide, 4a, N'-(3-benzylquinoxalin-2-yl)benzohydrazide derivatives 4b-f, N'-[2-(3-benzyl-2-oxoquinoxalin-1(2H)-yl)acetyl]benzohydrazide derivatives 7a-d, (9H-fluoren-9-yl)methyl 1-[2-(2-(3-benzyl-2-oxoquinoxalin-1(2H)-yl)acetyl)-hydrazinyl]-2-ylcarbamate derivatives 8a-c, 2-(3-benzyl-2-oxoquinoxalin-1(2H)-yl)-N'-benzylidene acetohydrazide derivatives 9a-h, and ethyl 2-(3-benzyl-2-oxoquinoxalin-1(2H)-yl)acetate derivatives 10a-e were synthesized and evaluated in vitro as inhibitors of the two monoamine oxidase isoforms, MAO-A and MAO-B. Most of the compounds showed a selective MAO-A inhibitory activity in the nanomolar or low micromolar range. Compounds 4e and 9g were the most potent derivatives with high MAO-A selectivity and their molecular docking studies were performed in order to rationalize the obtained biological result.

Synthesis and structure elucidation of novel fused 1,2,4-triazine derivatives as potent inhibitors targeting CYP1A1 activity.

Synthesis and structure elucidation of new series of novel fused 1,2,4-triazine derivatives 3a-3f, 4a-4i and 6a-6b and their inhibitory activities are presented. Molecular structures of the synthesized compounds were confirmed by (1)H NMR, (13)C NMR, MS spectra and elemental analyses. X-ray crystallographic analysis was performed on 2-acetyl-8-(N,N-diacetylamino)-6-(4-methoxybenzyl)-3-(4-methoxy-phenyl)-7-oxo-2,3-dihydro-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazine 3d and 2-acetyl-8-(N-acetylamino)-6-benzyl-3-(4-chlorophenyl)-3-methyl-7-oxo-2,3-dihydro-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazine 4e to secure their structures. The inhibitory effect of these compounds toward the CPY1A1 activity was screened to determine their potential as promising anticancer drugs. Our data showed that compounds 4e, 5a, 5b and 6b possess the highest inhibitory effects among all tested compounds. Furthermore, analysis of triazolotriazine derivatives docking showed that these compounds bind only at the interface of substrate recognition site 2 (SRS2) and (SRS6) at the outer surface of the protein. Amino-acids ASN214, SER216 and ILE462 participate in the binding of these compounds through H-bonds.

5-substituted pyrimidine L-2'-deoxyribonucleosides: synthetic, quantum chemical, and NMR studies.

As a part of an ongoing medicinal chemistry, we report here the synthesis and structure evaluation of 1-(2-deoxy-3,5-di-O-acetylpentofuranosyl)-5-[(3-methyl-5-oxo-1-phenyl-4,5-dihydro-4H-pyrazol-4-ylidene) pyrimidine-2,4(1H,3H)-dione 5 and 5-[bis(3-methyl-5-oxo-1-phenyl-4,5-dihydro-4H-pyrazol-4-yl)methyl-1-(2-deoxy-3,5-di-O-acetylpentofuranosyl)pyrimidine-2,4(1H,3H)-dione 6 derived from 3',5'-di-O-acetyl-5-formyl-2'-deoxy-ß-L-uridine 1. Base hydrolysis of compounds 1 and 6 furnished their deacetylated analogues in good yields, whereas hydrolysis of 5 was troublesome. Structural features of these molecules are discussed by NMR spectra analyses and density functional theory quantum chemical calculations. The newly synthesized L-analogues show no significant activity against vaccinia and cowpox viruses.

A regio- and stereo-controlled approach to triazoloquinoxalinyl C-nucleosides.

The synthesis of a new series of acyclic triazoloquinoxalinyl C-nucleosides and their transformation to their cyclic analogs are described following protection, activation, and deprotection with subsequent intramolecular nucleophilic substitution protocol. The antibacterial potency of the new compounds was determined using an inhibition zone diameter test. The results show that 3a and 2b exhibit good activity against Escherichiacoli and Candidaalbicans. On the other hand, the cyclic mesylated C-nucleoside 13 showed activity against the Gram-positive bacteria (Staphylococcusaureus) and antifungal activity against C. albicans.

Synthesis of new series of quinoxaline based MAO-inhibitors and docking studies.

A series of 2-benzyl-3-(2-arylidenehydrazinyl)quinoxalines 3, 4-benzyl-1-aryl-[1,2,4]triazolo[4,3-a]quinoxalines 4 and phenyl(1-aryl-[1,2,4]triazolo[4,3-a]quinoxalin-4-yl)methanones 5 analogues were synthesized and investigated for their monoamine oxidase (MAO) inhibitory property. The inhibition profile was found to be competitive for compounds 3k, 3m, 5f and 5n with MAO-A selectivity. Observation of the docked positions of these compounds revealed interactions with many residues previously reported to have an effect on the inhibition of the enzyme. The structural features of the new compounds have been determined from the microanalytical, IR, (1)H, (13)C NMR spectral studies and X-ray crystalography.

Synthesis of some pyridazinylacetic acid derivatives as a novel class of monoamine oxidase-A inhibitors.

A series of new pyridazinylacetic acid derivatives were synthesized and have been investigated for their ability to inhibit the activity of the A and B isoforms of monoamine oxidase (MAO). All compounds were found to be more selective to the MAO-A isoform with compound 5d having the highest SI values. Computational study performed with a docking technique indicated the potential of these compounds in pyridazine-based MAO-A inhibitor drug development.

Synthesis and antiviral activities of new acyclic and "double-headed" nucleoside analogues.

To develop an understanding of the structure-activity relationships for the inhibition of orthopoxviruses by nucleoside analogues, a variety of novel chemical entities were synthesized. These included a series of pyrimidine 5-hypermodified acyclic nucleoside analogues based upon recently discovered new leads, and some previously unknown "double-headed" or "abbreviated" nucleosides. None of the synthetic products possessed significant activity against two representative orthopoxviruses; namely, vaccinia virus and cowpox virus. They were also devoid of significant activity against a battery of other DNA and RNA viruses. So far as the results with the orthopoxviruses and herpes viruses, the results may point to the necessity for nucleoside analogues 5'-phosphorylation for antiviral efficacy.

Synthesis of 3-benzyl-2-substituted quinoxalines as novel monoamine oxidase A inhibitors.

A new series of 3-benzyl-2-substituted quinoxalines have been synthesized by means of microwave enhancement of nucleophilic substitution reaction involving the corresponding 2-chloroquinoxaline analogs and substituted amines or hydrazine. The synthesized compounds were evaluated for their monoamine oxidase A and B inhibitory activity by determination of their IC(50). All the newly synthesized compounds showed more selective inhibitory activity toward MAO-A than MAO-B. In addition, the acute toxicity of the synthesized compounds was determined. This work may be a fruitful matrix of the synthesis of a new series of novel MAO-A inhibitors with good safety margins.

Synthesis and antiviral activities of 1,2,3-triazole functionalized thymidines: 1,3-dipolar cycloaddition for efficient regioselective diversity generation.

Efficient regioselective synthesis of nucleoside conjugates was achieved by cycloaddition reaction of azides and alkynes using sodium ascorbate/ CuSO4 system as a catalyst. These 16 novel thymidine analogues were obtained in excellent yields (75-100%), employing mild reaction conditions with a broad scope of structural modification. For the compounds tested, no specific antiviral effects could be witnessed against a broad range of viruses.