Synthesis and Evaluation of Salicylanilide Derivatives as Potential Epidermal Growth Factor Receptor Inhibitors

Two series of novel salicylanilide were synthesized as potential epidermal growth factor receptor (EGFR) inhibitors. The enzyme inhibitory activity against EGFR of all compounds was carried out, and their antiproliferative activities against the A549 and A431 cell lines were also evaluated. Of the compounds studied, majority of them exhibited high antiproliferative activities compared with gefitinib; especially, 12a and 12b exhibited stronger inhibitory activity against EGFR with IC₅₀ values of 10.4 ± 2.25 and 15.4 ± 2.33 nm , respectively, which were comparable to the positive control of gefitinib (IC₅₀ = 12.1 ± 2.21 nm ). Compound 12b also showed outstanding inhibitory activity against A431 and A549 cell lines with the IC₅₀ values of 0.42 ± 0.43 μm and 0.57 ± 0.43 μm , which was better than the positive controls. In the molecular modeling study, compound 12b was bound into the active pocket of EGFR with two hydrogen bond and with minimum binding free energy ▵G_b = −25.1125 kcal/mol. The result also suggested that compound 12b could bind the EGFR kinase well.     

Design,synthesis, and evaluation of novel Akt1 inhibitors based on an indole scaffold

A new series of potential Akt1 inhibitors with indole scaffold were designed and synthesized. The antiproliferative activity against PC‐3 cell line and enzyme inhibitory activity against Akt1 were evaluated. Among them, some compounds showed much more potent antiproliferative activity and stronger Akt1 inhibitory activity compared to the positive control of GSK690693. In particular, compound 19b exhibited the most potent inhibitory activity against Akt1 with inhibition rate of 70.3% at a concentration of 10 nm . Furthermore, compound 19b could dose dependently reduce the phosphorylation of the downstream GSK3β protein in the PC‐3 cell line and displayed fivefold higher antiproliferative activity against PC‐3 cell line with IC₅₀ value of 3.1 ± 0.1 μm than positive control (15.5 ± 0.4 μm ). Herein, compound 19b may serve as a promising lead for further optimization and development of novel Akt1 inhibitors based on an indole scaffold.     

Design,synthesis, and biological evaluation of some novel naphthoquinone-glycine/β-alanine anilide derivatives as noncovalent proteasome inhibitors

A series of novel noncovalent glycine/β-alanine anilide derivatives possessing 2-chloronaphthoquinone structure as a pharmacophoric unit were designed, synthesized, and evaluated for their antiproliferative and antiproteasomal activities against MCF-7 cell line, in vitro. According to biological activity results, all the target compounds showed antiproliferative activity in the range of IC₅₀ = 7.10 ± 0.10–41.08 ± 0.14 μM and most of them exhibited inhibitory efficacy with varying ratios against the three catalytic subunits (β1, β2, and β5) presenting caspase-like (C-L), trypsin-like (T-L) and chymotrypsin-like (ChT-L) activities of proteasome. The antiproteasomal activity evaluations revealed that compounds preferentially inhibited the β5 subunit compared with β1 and β2 subunits of the proteasome. Among the compounds, compounds 7 and 9 showed the highest antiproliferative activity with an IC₅₀ value of 7.10 ± 0.10 and 7.43 ± 0.25 μM, respectively. Additionally, compound 7 displayed comparable potency to PI-083 lead compound in terms of β5 antiproteasomal activity with an inhibition percentage of 34.67 at 10 μM. This compound showed an IC₅₀ value of 32.30 ± 0.45 μM against β5 subunit. Furthermore, molecular modeling studies of the most active compound 7 revealed key interactions with β5 subunit. The results suggest that this class of compounds may be beneficial for the development of new potent proteasome inhibitors.     

Identification of Novel Selective Lysine‐Specific Demethylase 1 (LSD1) Inhibitors Using a Pharmacophore‐Based Virtual Screening Combined with Docking

Lysine‐specific demethylase 1 (LSD1) plays an important role in regulating the lysine methylation at residues K4 and K9 on histone H3. High levels of LSD1 expression have been observed in several malignant tumors. In this study, we presented a pharmacophore‐based virtual screening of a moderate database of 171 143 small molecules. A pharmacophore of LSD1 inhibitors was constructed for the first time and then used to screen the compound library combined with validated molecular docking tools followed by biochemical assays, led to the identification of 9 novel LSD1 inhibitors, showing their IC₅₀ values in a range of 2.41–101 μm . Furthermore, compound XZ 09 exhibited less inhibition against the homologous monoamine oxidase A (MAO‐A) and B (MAO‐B) displaying its moderate selectivity. Our study provides an effective virtual screening method to identify new LSD1 inhibitors and XZ09 represents a potent and selective lead compound to deserve further optimization for the treatment of LSD1 overexpressing cancers.     

Identification of Dipeptidyl Peptidase IV Inhibitors: Virtual Screening,Synthesis and Biological Evaluation

Inhibition of dipeptidyl peptidase IV is an important approach for the treatment of type‐2 diabetes. In this study, we reported a multistage virtual screening workflow that integrated 3D pharmacophore models, structural consensus docking, and molecular mechanics/generalized Born surface area binding energy calculation to identify novel dipeptidyl peptidase IV inhibitors. After screening our in‐house database, two hit compounds, HWL‐405 and HWL‐892, having persistent high performance in all stages of virtual screening were identified. These two hit compounds together with several analogs were synthesized and evaluated for in vitro inhibition of dipeptidyl peptidase IV. The experimental data indicated that most designed compounds exhibited significant dipeptidyl peptidase IV inhibitory activity. Among them, compounds 35f displayed the greatest potency against dipeptidyl peptidase IV in vitro with the IC₅₀ value of 78 nm . In an oral glucose tolerance test in normal male Kunming mice, compound 35f reduced blood glucose excursion in a dose‐dependent manner.     

Synthesis and docking studies of N-(5-(alkylthio)-1,3,4-oxadiazol-2-yl)methyl)benzamide analogues as potential alkaline phosphatase inhibitors

A series of N-(5-(alkylthio)-1,3,4-oxadiazol-2-yl)methyl)benzamides 6a–i were synthesized as alkaline phosphatase inhibitors. The intermediate 5-substituted 1,3,4-oxadiazole-2-thione 4 was synthesized starting with hippuric acid. Hippuric acid in the first step was converted into corresponding methyl ester 2 which upon reaction with hydrazine hydrate furnished the formation of hydrazide 3 . The hippuric acid hydrazide was then cyclized into 5-substituted 1,3,4-oxadiazole-2-thione 4 . The intermediate 4 was then reacted with alkyl or aryl halides 5a–5i to afford the title compounds N-(5-(methylthio)-1,3,4-oxadiazol-2-yl)methyl)benzamides 6a–i . The bioassay results showed that compounds 6a–i exhibited good to excellent alkaline phosphatase inhibitory activity. The most potent activity was exhibited by the compound 6i having IC₅₀ value 0.420 μM, whereas IC₅₀ value of standard (KH₂PO₄) was 2.80 μM. Molecular docking studies was performed against alkaline phosphatase enzyme (PDBID 1EW2) to check binding affinity of the synthesized compounds 6a–i against target protein. The docking results showed that three compounds 6c , 6e , and 6i have maximum binding interactions with binding energy values of −8 kcal/mol. The compound 6i displayed the interactions of oxadiazole ring nitrogen with amino acid His265 having a binding distance 2.13 Ǻ. It was concluded from our results that synthesized compounds, especially compound 6i may serve as lead structure to design more potent inhibitors of human alkaline phosphatase.     

Synthesis,in vitro evaluation and molecular docking studies of novel coumarin‐isatin derivatives as α‐glucosidase inhibitors

This study synthesized a series of novel coumarin‐isatin derivatives and evaluated them for α‐glucosidase inhibitory activity. The majority of the screened compounds exhibited excellent inhibition activities with IC₅₀ values of 2.56 ± 0.08–268.79 ± 3.04 μm , when compared to acarbose. Among the newly derivatives, compound 5p was found to be the most active compound in the library of coumarin‐isatin derivatives. Furthermore, enzyme kinetic studies showed that compound 5p is a non‐competitive inhibitor with a K_i of 2.14 μm . Molecular docking analysis revealed the existence of hydrophobic and hydrogen interactions between compound 5p and the active site of α‐glucosidase. Our results indicate that coumarin‐isatin derivatives as a new class of α‐glucosidase inhibitors.     

Design,synthesis, biological evaluation,and docking study of 4‐isochromanone hybrids bearing N‐benzyl pyridinium moiety as dual binding site acetylcholinesterase inhibitors (part II)

A series of novel 4‐isochromanone compounds bearing N‐benzyl pyridinium moiety were designed and synthesized as acetylcholinesterase (AChE) inhibitors. The biological evaluation showed that most of the target compounds exhibited potent inhibitory activities against AChE. Among them, compound 1q possessed the strongest anti‐AChE activity with an IC₅₀ value of 0.15 nm and high AChE/BuChE selectivity (SI > 5,000). Moreover, compound 1q had low toxicity in normal nerve cells and was relatively stable in rat plasma. Together, the current finding may provide a new approach for the discovery of novel anti‐Alzheimer's disease agents.     

Synthesis and Anticholinergic Activity of 4‐hydroxycoumarin Derivatives Containing Substituted Benzyl‐1,2,3‐triazole Moiety

A series of 4‐hydroxycoumarin‐derived compounds 8a‐p containing N‐benzyl‐1,2,3‐triazole motif were designed as AChE inhibitors. The title compounds were obtained conveniently using multicomponent click reaction. The in vitro anticholinesterase evaluation of synthesized compounds against AChE and BuChE showed that some of them are potent and selective inhibitors of AChE. Among them, 2‐chlorobenzyl derivative 8k showed the most potent activity against AChE (IC₅₀ = 0.18 μm ). Its activity was also superior to that of standard drug tacrine. The kinetic study and molecular docking simulation of the most potent compound 8k were also described.     

Design,synthesis, and preliminary bioactivity evaluation of N1‐hydroxyterephthalamide derivatives with indole cap as novel histone deacetylase inhibitors

Histone deacetylases inhibitors (HDACIs) have been widely recognized as significant therapeutic approach to cancers. In our efforts to develop novel histone deacetylases inhibitors (HDACIs) as potential anticancer agents, a series of N¹‐hydroxyterephthalamide derivatives with an indole cap group were designed and synthesized. Compound 12m was identified to be the most potent one (IC₅₀ = 0.074 μm against HeLa nuclear extract ) and showed higher inhibitory activity than the positive control SAHA (IC₅₀ = 0.131 μm ), which was also verified by further molecular docking studies into active site of HDAC2. The results of selectivity on the inhibition of HDACs exhibited 12m being with similar isoform selective profile with PXD101. In addition, the representative compounds (8d, 12d, 12j, 12m) based on the outcomes of preliminary tumor cell screening demonstrated more potent or comparable to SAHA in the next antiproliferative activity assays. Collectively, the results encouraged further development of this chemical template to provide more potent analogs as HDACIs.     

3D‐quantitative structure‐activity relationship study for the design of novel enterovirus A71 3C protease inhibitors

A three‐dimensional quantitative structure‐activity relationships model of enterovirus A71 3C protease inhibitors was constructed in this study. The protein‐ligand interaction fingerprint was analyzed to generate a pharmacophore model. A predictive and reliable three‐dimensional quantitative structure‐activity relationships model was built based on the Flexible Alignment of AutoGPA. Moreover, three novel compounds ( I – III) were designed and evaluated for their biochemical activity against 3C protease and anti‐enterovirus A71 activity in vitro. III exhibited excellent inhibitory activity (IC₅₀ = 0.031 ± 0.005 μM, EC₅₀ = 0.036 ± 0.007 μM). Thus, this study provides a useful quantitative structure‐activity relationships model to develop potent inhibitors for enterovirus A71 3C protease.     

Discovery of New 4‐Alkoxyquinazoline‐Based Derivatives as Potent VEGFR2 Inhibitors

VEGFR2 has been proved to play a major role in the regulation of tumor angiogenesis. Twenty‐one 4‐alkoxyquinazoline‐based derivatives have been designed and synthesized as vascular endothelial growth factor receptor 2 (VEGFR2) inhibitors, and their biological activities were evaluated. Among these compounds, compound 3h exhibited the most potent inhibitory activities against VEGFR2 tyrosine kinase and cell proliferation, with the IC₅₀ values of 2.89 nm (for VEGFR2) and 0.25  μ m (for MCF‐7), which were comparable with the control compound. Docking simulation was performed to position compound 3h into the 4ASE active site, and the result showed that compound 3h could bind well at the 4ASE active site.     

Pharmacophore‐based virtual screening,molecular docking,molecular dynamics simulation,and biological evaluation for the discovery of novel BRD4 inhibitors

Bromodomain is a recognition module in the signal transduction of acetylated histone. BRD4, one of the bromodomain members, is emerging as an attractive therapeutic target for several types of cancer. Therefore, in this study, an attempt has been made to screen compounds from an integrated database containing 5.5 million compounds for BRD4 inhibitors using pharmacophore‐based virtual screening, molecular docking, and molecular dynamics simulations. As a result, two molecules of twelve hits were found to be active in bioactivity tests. Among the molecules, compound 5 exhibited potent anticancer activity, and the IC₅₀ values against human cancer cell lines MV4‐11, A375, and HeLa were 4.2, 7.1, and 11.6 μm , respectively. After that, colony formation assay, cell cycle, apoptosis analysis, wound‐healing migration assay, and Western blotting were carried out to learn the bioactivity of compound 5 .     

Design and synthesis of 4′‐((5‐benzylidene‐2,4‐dioxothiazolidin‐3‐yl)methyl)biphenyl‐2‐carbonitrile analogs as bacterial peptide deformylase inhibitors

Herein, we report the synthesis and screening of 4′‐((5‐benzylidene‐2,4‐dioxothiazolidin‐3‐yl)methyl)biphenyl‐2‐carbonitrile analogs 11(a–j) as bacterial peptide deformylase (PDF) enzyme inhibitors. The compounds 11b (IC₅₀ value = 139.28 μm ), 11g (IC₅₀ value = 136.18 μm ), and 11h (IC₅₀ value = 131.65 μm ) had shown good PDF inhibition activity. The compounds 11b (MIC range = 103.36–167.26 μg/mL), 11g (MIC range = 93.75–145.67 μg/mL), and 11h (MIC range = 63.61–126.63 μg/mL) had also shown potent antibacterial activity when compared with standard ampicillin (MIC range = 100.00–250.00 μg/mL). Thus, the active derivatives were not only PDF inhibitors but also efficient antibacterial agents. To gain more insight on the binding mode of the compounds with PDF enzyme, the synthesized compounds 11(a–j) were docked against PDF enzyme of Escherichia coli and compounds exhibited good binding properties. The results suggest that this class of compounds has potential for development and use in future as antibacterial drugs.     

Design,synthesis, in silico and antiproliferative evaluation of novel pyrazole derivatives as VEGFR‐2 inhibitors

As the blockade of the VEGFR‐2 signaling pathway is a viable approach in cancer therapy, the present study focuses on a series of pyrazole based VEGFR‐2 inhibitors that were designed on the basis of the hybridization approach, supported by docking and in silico computational studies. The designed compounds were synthesized through facile synthetic methods and the structures were confirmed by ¹H NMR, ¹³C NMR, MS and elemental analysis. The compounds were screened for in vitro antiproliferative activity against the HT‐29 (human colon cancer) and MCF‐7 (human breast cancer) cell lines by MTT assay. The compounds were also studied for in vitro inhibitory activity against VEGFR‐2 kinase. Among all the tested compounds, compound 6h emerged as a potent agent in the antiproliferative study against HT‐29 and MCF‐7 cells, with IC₅₀ values of 2.36 and 6.59 μM, respectively. Moreover, the same compound exhibited the highest VEGFR‐2 inhibitory activity with an IC₅₀ value of 1.89 μM. In docking studies, the designed compounds showed similar and essential key interactions as those of known VEGFR‐2 inhibitors. The present study may lead to new molecules in the development of anticancer agents targeting VEGFR‐2.     

Synthesis and Biological Evaluation of Strictosamide Derivatives with Improved Antiviral and Antiproliferative Activities

A series of novel derivatives of strictosamide were synthesized and biologically evaluated. Most of the new compounds exhibited improved activities than the parent compound strictosamide. Among them, compounds Ib and If possessed antiviral activities against influenza A virus (A/Jinan/15/90) with IC₅₀ values of 4.12 and 12.35 μg/mL, respectively. Compound Ie possessed antiviral activity against respiratory syncytial virus (RSV) with an IC₅₀ value of 9.58 μg/mL. Both compounds IIc and IId had moderate antiproliferative effects against five human cancer cell lines. The preliminary structure‐activity relationships were also concluded. This study provides a promising new template with potential antiviral activity.     

Synthesis,enzyme inhibitory kinetics,and computational studies of novel 1‐(2‐(4‐isobutylphenyl) propanoyl)‐3‐arylthioureas as Jack bean urease inhibitors

In this article, synthesis of a novel 1‐(2‐(4‐isobutylphenyl)propanoyl)‐3‐arylthioureas ( 4a–j) as jack bean urease inhibitors has been described. Freshly prepared 2‐(4‐isobutylphenyl) propanoyl isothiocyanate was treated with substituted aromatic anilines in one pot using anhydrous acetone. The compounds 4e, 4h, and 4j showed IC₅₀ values 0.0086 nm , 0.0081 nm , and 0.0094 nm , respectively. The enzyme inhibitory kinetics results showed that compound 4h inhibit the enzyme competitively while derivatives 4e and 4j are the mixed type inhibitors. The compound 4h reversibly binds the urease enzyme showing Ki value 0.0012 nm . The Ki values for 4e and 4j are 0.0025 nm and 0.003 nm , respectively. The antioxidant activity results reflected that compounds 4b, 4i, and 4j showed excellent radical scavenging activity. Moreover, the cytotoxic activity of the target compounds was evaluated using brine shrimp assay and it was found that all of the synthesized compounds exhibited no cytotoxic effects to brine shrimps. The computational molecular docking and molecular dynamic simulation of title compounds were also performed, and results showed that the wet laboratory findings are in good agreement to the dry laboratory results. Based upon our results, it is proposed that compound 4h may act as a lead candidate to design the clinically useful urease inhibitors.     

Evaluation of multifunctional synthetic tetralone derivatives for treatment of Alzheimer's disease

Neurodegeneration, a complex disease state, comprises several pathways that contribute to cell death. Conventional approach of targeting only one of these pathways has not been proven to be entirely successful and has demanded a hypothetical change as to how researchers design and develop new drugs. In this study, effects of a series of α, β‐unsaturated carbonyl‐based tetralone derivatives against Alzheimer's disease (AD) were investigated. Moreover, their activity toward amyloid β‐induced cytotoxicity was also studied. Six compounds including 3f , 3o , 3u , 3ae , 3af , and 3ag were discovered to be most protective against Aβ‐induced neuronal cell death in PC12 cells. The findings of in vitro experiment revealed that most of these compounds exhibited potent inhibitory activity against MAO‐B, AChE, and self‐induced Aβ_1–42 aggregation. The compound 3f exhibited best AChE (IC₅₀ = 0.045 ± 0.02 μm ) inhibitory potential in addition to potent inhibition of MAO‐B (IC₅₀ = 0.88 ± 0.12 μm ). Furthermore, compound 3f disassembled the Aβ fibrils produced by self‐induced Aβ aggregation by 78.2 ± 4.8%. Collectively, these findings suggest that some compounds from this series have potential to be promising multifunctional agents for AD treatment.     

Design,synthesis, and anticancer evaluation of N6-hydrazone purine derivatives with potential antiplatelet aggregation activity

In our research on novel anticancer agents, a series of N⁶-hydrazone purine derivatives were designed and synthesized by analysis of a pharmacophore model for ATP-competitive inhibitors. The activities screening results showed that N⁶-hydrazone purine derivatives 21 and 26 not only showed potential antiproliferative activity against the A549 and MCF-7 cell lines comparable to Vandetanib as a positive control but also had moderate antiplatelet aggregation activity. In order to investigate the possible targets, a molecular docking study was carried out on the fourteen kinases associated with anticancer and antiplatelet aggregation activities. The results indicated that compounds 21 and 26 had the potential activity to target VEGFR-2, PI3Kα, EGFR, and HER2 kinases. The inhibition of the kinases assay showed that compound 26 could target VEGFR-2, PI3Kα, and EGFR (IC₅₀ = 0.822, 3.040 and 6.625 μM). All results indicated that compound 26 will be an encouraging framework as potential new multi-target anticancer agent with potential antiplatelet aggregation activity.