Synthesis and Biological Studies on (KLAKLAK)2-NH2 Analog Containing Unnatural Amino Acid β-Ala and Conjugates with Second Pharmacophore

(1) Background: Peptides are good candidates for anticancer drugs due to their natural existence in the body and lack of secondary effects. (KLAKLAK)₂ is an antimicrobial peptide that also shows good anticancer properties. (2) Methods: The Solid Phase Peptide Synthesis (Fmoc-strategy) was used for the synthesis of target molecules, analogs of (KLAKLAK)₂-NH₂. The purity of all compounds was monitored by HPLC, and their structures were proven using mass spectrometry. Cytotoxicity and antiproliferative effects were studied using 3T3 NRU and MTT tests, respectively. For determination of antimicrobial activity, the disc-diffusion method was used. Hydrolytic stability at three pH values, which mimic the physiological pH in the body, was investigated by means of the HPLC technique. (3) Results: A good selective index against MCF-7 tumor cell lines, combined with good cytotoxicity and antiproliferative properties, was revealed for conjugates NphtG-(KLAKLAK)₂-NH₂ and Caf-(KLAKLAK)₂-NH₂. The same compounds showed very good antifungal properties and complete hydrolytic stability for 72 h. The compound Caf-(KLβ-AKLβ-AK)₂-NH₂ containing β-Ala in its structures exhibited good antimicrobial activity against Escherichia coli K12 407 and Bacillus subtilis 3562, in combination with very good antiproliferative and cytotoxic properties, as well as hydrolytic stability. (4) Conclusions: The obtained results reveal that all synthesized conjugates could be useful for medical practice as anticancer or antimicrobial agents.     

Discovery of Novel 2,4-Dianilinopyrimidine Derivatives Containing 4-(Morpholinomethyl)phenyl and N-Substituted Benzamides as Potential FAK Inhibitors and Anticancer Agents

Focal adhesion kinase (FAK) is responsible for the development and progression of various malignancies. With the aim to explore novel FAK inhibitors as anticancer agents, a series of 2,4-dianilinopyrimidine derivatives 8a–8i and 9a–9g containing 4-(morpholinomethyl)phenyl and N-substituted benzamides have been designed and synthesized. Among them, compound 8a displayed potent anti-FAK activity (IC₅₀ = 0.047 ± 0.006 μM) and selective antiproliferative effects against H1975 (IC₅₀ = 0.044 ± 0.011 μM) and A431 cells (IC₅₀ = 0.119 ± 0.036 μM). Furthermore, compound 8a also induced apoptosis in a dose-dependent manner, arresting the cells in S/G2 phase and inhibiting the migration of H1975 cells, all of which were superior to those of TAE226. The docking analysis of compound 8a was performed to elucidate its possible binding modes with FAK. These results established 8a as our lead compound to be further investigated as a potential FAK inhibitor and anticancer agent.     

Synthesis and Biological Activity Evaluation of Coumarin-3-Carboxamide Derivatives

A series of novel coumarin-3-carboxamide derivatives were designed and synthesized to evaluate their biological activities. The compounds showed little to no activity against gram-positive and gram-negative bacteria but specifically showed potential to inhibit the growth of cancer cells. In particular, among the tested compounds, 4-fluoro and 2,5-difluoro benzamide derivatives (14b and 14e, respectively) were found to be the most potent derivatives against HepG2 cancer cell lines (IC₅₀ = 2.62–4.85 μM) and HeLa cancer cell lines (IC₅₀ = 0.39–0.75 μM). The activities of these two compounds were comparable to that of the positive control doxorubicin; especially, 4-flurobenzamide derivative (14b) exhibited low cytotoxic activity against LLC-MK2 normal cell lines, with IC₅₀ more than 100 μM. The molecular docking study of the synthesized compounds revealed the binding to the active site of the CK2 enzyme, indicating that the presence of the benzamide functionality is an important feature for anticancer activity.     

Antiproliferative and Antiangiogenic Properties of New VEGFR-2-targeting 2-thioxobenzo[g]quinazoline Derivatives (In Vitro)

A series of 3-ethyl(methyl)-2-thioxo-2,3-dihydrobenzo[g]quinazolines (1–17) were synthesized, characterized, and evaluated in vitro for their antiangiogenesis VEGFR-2-targeting, antiproliferative, and antiapoptotic activities against breast MCF-7 and liver HepG2 cells. Flow cytometry was used to determine cancer-cell cycle distributions, and apoptosis was detected using annexin-V-FITC (V) and propidium iodide (PI) dyes. Fluorescence microscopy, in combination with Hoechst staining was used to detect DNA fragmentation. Most of the tested benzo[g]quinazolines demonstrated promising activity (IC₅₀ = 8.8 ± 0.5–10.9 ± 0.9 μM) and (IC₅₀ = 26.0 ± 2.5–40.4 ± 4.1 μM) against MCF-7 and HepG2, respectively. Doxorubicin was used as a reference drug. Compounds 13–15 showed the highest activity against both cancer cell lines. Differential effects were detected by cell-cycle analysis, indicating similarities in the actions of 13 and 14 against both MCF7 and HepG2, involving the targeting of G1 and S phases, respectively. Compound 15 showed similar indices against both cells, indicating that its cytotoxicity toward the examined cancer cells could be unselective. Interestingly, 14 and 15 showed the highest apoptosis (30.76% and 25.30%, respectively) against MCF-7. The DNA fragmentation results agreed well with the apoptosis detected by flow cytometry. In terms of antiangiogenesis activity, as derived from VEGFR-2 inhibition, 13 and 15 were comparable to sorafenib and effected 1.5- and 1.4-fold inhibition relative to the standard sorafenib. A docking study was conducted to investigate the interaction between the synthesized benzo[g]quinazolines and the ATP-binding site within the catalytic domain of VEGFR-2.     

N-phenyl-6-chloro-4-hydroxy-2-quinolone-3-carboxamides: Molecular Docking,Synthesis, and Biological Investigation as Anticancer Agents

Cancer is a multifactorial disease and the second leading cause of death worldwide. Diverse factors induce carcinogenesis, such as diet, smoking, radiation, and genetic defects. The phosphatidylinositol 3-kinase (PI3Kα) has emerged as an attractive target for anticancer drug design. Eighteen derivatives of N-phenyl-6-chloro-4-hydroxy-2-quinolone-3-carboxamide were synthesized and characterized using FT-IR, NMR (¹H and ¹³C), and high-resolution mass spectra (HRMS). The series exhibited distinct antiproliferative activity (IC₅₀ µM) against human epithelial colorectal adenocarcinoma (Caco-2) and colon carcinoma (HCT-116) cell lines, respectively: compounds 16 (37.4, 8.9 µM), 18 (50.9, 3.3 µM), 19 (17.0, 5.3 µM), and 21 (18.9, 4.9 µM). The induced-fit docking (IFD) studies against PI3Kαs showed that the derivatives occupy the PI3Kα binding site and engage with key binding residues.     

Replacement of the Common Chromium Source CrCl3(thf)3 with Well-Defined [CrCl2(μ-Cl)(thf)2]2

CrCl₃(thf)₃ is a common starting material in the synthesis of organometallic and coordination compounds of Cr. Deposited as an irregular solid with no possibility of recrystallization, it is not a purity guaranteed chemical, causing problems in some cases. In this work, we disclose a well-defined form of the THF adduct of CrCl₃ ([CrCl₂(μ-Cl)(thf)₂]₂), a crystalline solid, that enables structure determination by X-ray crystallography. The EA data and XRD pattern of the bulk agreed with the revealed structure. Moreover, its preparation procedure is facile: evacuation of CrCl₃·6H₂O at 100 °C, treatment with 6 equivalents of Me₃SiCl in a minimal amount of THF, and crystallization from CH₂Cl₂. The ethylene tetramerization catalyst [iPrN{P(C₆H₄-p-Si(nBu)₃)₂}₂CrCl₂]⁺[B(C₆F₅)₄]⁻ prepared using well-defined [CrCl₂(μ-Cl)(thf)₂]₂ as a starting material exhibited a reliably high activity (6600 kg/g-Cr/h; 1-octene selectivity at 40 °C, 75%), while that of the one prepared using the impure CrCl₃(thf)₃ was inconsistent and relatively low (~3000 kg/g-Cr/h). By using well-defined [CrCl₂(μ-Cl)(thf)₂]₂ as a Cr source, single crystals of [(CH₃CN)₄CrCl₂]⁺[B(C₆F₅)₄]⁻ and [{Et(Cl)Al(N(iPr)₂)₂}Cr(μ-Cl)]₂ were obtained, allowing structure determination by X-ray crystallography, which had been unsuccessful when the previously known CrCl₃(thf)₃ was used as the Cr source.     

Bioactive Abietane-Type Diterpenoid Glycosides from Leaves of Clerodendrum infortunatum (Lamiaceae)

In this study, two previously undescribed diterpenoids, (5R,10S,16R)-11,16,19-trihydroxy-12-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranosyl-17(15→16),18(4→3)-diabeo-3,8,11,13-abietatetraene-7-one (1) and (5R,10S,16R)-11,16-dihydroxy-12-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranosyl-17(15→16),18(4→3)-diabeo-4-carboxy-3,8,11,13-abietatetraene-7-one (2), and one known compound, the C₁₃-nor-isoprenoid glycoside byzantionoside B (3), were isolated from the leaves of Clerodendrum infortunatum L. (Lamiaceae). Structures were established based on spectroscopic and spectrometric data and by comparison with literature data. The three terpenoids, along with five phenylpropanoids: 6′-O-caffeoyl-12-glucopyranosyloxyjasmonic acid (4), jionoside C (5), jionoside D (6), brachynoside (7), and incanoside C (8), previously isolated from the same source, were tested for their in vitro antidiabetic (α-amylase and α-glucosidase), anticancer (Hs578T and MDA-MB-231), and anticholinesterase activities. In an in vitro test against carbohydrate digestion enzymes, compound 6 showed the most potent effect against mammalian α-amylase (IC₅₀ 3.4 ± 0.2 μM) compared to the reference standard acarbose (IC₅₀ 5.9 ± 0.1 μM). As yeast α-glucosidase inhibitors, compounds 1, 2, 5, and 6 displayed moderate inhibitory activities, ranging from 24.6 to 96.0 μM, compared to acarbose (IC₅₀ 665 ± 42 μM). All of the tested compounds demonstrated negligible anticholinesterase effects. In an anticancer test, compounds 3 and 5 exhibited moderate antiproliferative properties with IC₅₀ of 94.7 ± 1.3 and 85.3 ± 2.4 μM, respectively, against Hs578T cell, while the rest of the compounds did not show significant activity (IC₅₀ > 100 μM).     

In Silico Approach Using Free Software to Optimize the Antiproliferative Activity and Predict the Potential Mechanism of Action of Pyrrolizine-Based Schiff Bases

In the current study, a simple in silico approach using free software was used with the experimental studies to optimize the antiproliferative activity and predict the potential mechanism of action of pyrrolizine-based Schiff bases. A compound library of 288 Schiff bases was designed based on compound 10, and a pharmacophore search was performed. Structural analysis of the top scoring hits and a docking study were used to select the best derivatives for the synthesis. Chemical synthesis and structural elucidation of compounds 16a–h were discussed. The antiproliferative activity of 16a–h was evaluated against three cancer (MCF7, A2780 and HT29, IC₅₀ = 0.01–40.50 μM) and one normal MRC5 (IC₅₀ = 1.27–24.06 μM) cell lines using the MTT assay. The results revealed the highest antiproliferative activity against MCF7 cells for 16g (IC₅₀ = 0.01 μM) with an exceptionally high selectivity index of (SI = 578). Cell cycle analysis of MCF7 cells treated with compound 16g revealed a cell cycle arrest at the G₂/M phase. In addition, compound 16g induced a dose-dependent increase in apoptotic events in MCF7 cells compared to the control. In silico target prediction of compound 16g showed six potential targets that could mediate these activities. Molecular docking analysis of compound 16g revealed high binding affinities toward COX-2, MAP P38α, EGFR, and CDK2. The results of the MD simulation revealed low RMSD values and high negative binding free energies for the two complexes formed between compound 16g with EGFR, and CDK2, while COX-2 was in the third order. These results highlighted a great potentiality for 16g to inhibit both CDK2 and EGFR. Taken together, the results mentioned above highlighted compound 16g as a potential anticancer agent.     

Involvement of the γ Isoform of cPLA2 in the Biosynthesis of Bioactive N-Acylethanolamines

Arachidonylethanolamide (anandamide) acts as an endogenous ligand of cannabinoid receptors, while other N-acylethanolamines (NAEs), such as palmitylethanolamide and oleylethanolamide, show analgesic, anti-inflammatory, and appetite-suppressing effects through other receptors. In mammalian tissues, NAEs, including anandamide, are produced from glycerophospholipid via N-acyl-phosphatidylethanolamine (NAPE). The ɛ isoform of cytosolic phospholipase A₂ (cPLA₂) functions as an N-acyltransferase to form NAPE. Since the cPLA₂ family consists of six isoforms (α, β, γ, δ, ɛ, and ζ), the present study investigated a possible involvement of isoforms other than ɛ in the NAE biosynthesis. Firstly, when the cells overexpressing one of the cPLA₂ isoforms were labeled with [¹⁴C]ethanolamine, the increase in the production of [¹⁴C]NAPE was observed only with the ɛ-expressing cells. Secondly, when the cells co-expressing ɛ and one of the other isoforms were analyzed, the increase in [¹⁴C]N-acyl-lysophosphatidylethanolamine (lysoNAPE) and [¹⁴C]NAE was seen with the combination of ɛ and γ isoforms. Furthermore, the purified cPLA₂γ hydrolyzed not only NAPE to lysoNAPE, but also lysoNAPE to glycerophospho-N-acylethanolamine (GP-NAE). Thus, the produced GP-NAE was further hydrolyzed to NAE by glycerophosphodiesterase 1. These results suggested that cPLA₂γ is involved in the biosynthesis of NAE by its phospholipase A₁/A₂ and lysophospholipase activities.     

Bio-Guided Fractionation of Stem Bark Extracts from Phyllanthus muellarianus: Identification of Phytocomponents with Anti-Cholinesterase Activity

A combination of flash chromatography, solid phase extraction, high-performance liquid chromatography, and in vitro bioassays was used to isolate phytocomponents endowed with anticholinesterase activity in extract from Phyllanthus muellarianus. Phytocomponents responsible for the anti-cholinesterase activity of subfractions PMF1 and PMF4 were identified and re-assayed to confirm their activity. Magnoflorine was identified as an active phytocomponent from PMF1 while nitidine was isolated from PMF4. Magnoflorine was shown to be a selective inhibitor of human butyrylcholinesterase—hBChE (IC₅₀ = 131 ± 9 μM and IC₅₀ = 1120 ± 83 μM, for hBuChE and human acetylcholinesterase—hAChE, respectively), while nitidine showed comparable inhibitory potencies against both enzymes (IC₅₀ = 6.68 ± 0.13 μM and IC₅₀ = 5.31 ± 0.50 μM, for hBChE and hAChE, respectively). When compared with the commercial anti-Alzheimer drug galanthamine, nitidine was as potent as galanthamine against hAChE and one order of magnitude more potent against hBuChE. Furthermore, nitidine also showed significant, although weak, antiaggregating activity towards amyloid-β self-aggregation.     

Cytotoxicity of Frutalin on Distinct Cancer Cells Is Independent of Its Glycosylation

Frutalin is a plant lectin with beneficial immunobiological action, although the access to its active form is still restricted. Moreover, there is a knowledge gap on isoform activity and glycosylation impact on its bioactivity, and recombinant production protocols were seen as ineffective. Here, a simpler and faster production and purification protocol was developed, attaining a yield of purified frutalin 3.3-fold higher than that obtained previously. Hemagglutination assays confirmed that this frutalin isoform could not agglutinate rabbit erythrocytes, while maintaining the native tetrameric structure, as indicated by DLS analysis, and strong interaction with methyl-alpha-galactose, in fluorescence spectroscopy studies. The cytotoxicity of the recombinant frutalin isoform was shown in a broad panel of human cancer cells: colon (HCT116), melanoma (A375), triple-negative breast cancer (MDA-MB-231), and ovarian (IGROV-1). Treatment with 8.5–11.8 μM TrxFTL reduced proliferation of all cancer cells to half in 48 h. This anti-proliferative effect encompasses the p53 pathway since it was significantly reduced in p53-null colon cancer cells (HCT116 p53^−/−; GI₅₀ of 25.0 ± 3.0 μM), when compared to the isogenic p53-positive cells (HCT116 p53^+/+; GI₅₀ of 8.7 ± 1.8 μM; p < 0.002). This recombinantly produced frutalin isoform has relevant cytotoxic effect and its biological activity is not dependent on glycosylation. The developed E. coli production and purification protocol generates high yield of non-glycosylated frutalin isoform with potent cytotoxic activity, enabling the development of novel anticancer p53-targeting therapies.     

Synthesis of Novel Biologically Active Proflavine Ureas Designed on the Basis of Predicted Entropy Changes

A novel series of proflavine ureas, derivatives 11a–11i, were synthesized on the basis of molecular modeling design studies. The structure of the novel ureas was obtained from the pharmacological model, the parameters of which were determined from studies of the structure-activity relationship of previously prepared proflavine ureas bearing n-alkyl chains. The lipophilicity (LogP) and the changes in the standard entropy (ΔS°) of the urea models, the input parameters of the pharmacological model, were determined using quantum mechanics and cheminformatics. The anticancer activity of the synthesized derivatives was evaluated against NCI-60 human cancer cell lines. The urea derivatives azepyl 11b, phenyl 11c and phenylethyl 11f displayed the highest levels of anticancer activity, although the results were only a slight improvement over the hexyl urea, derivative 11j, which was reported in a previous publication. Several of the novel urea derivatives displayed GI₅₀ values against the HCT-116 cancer cell line, which suggest the cytostatic effect of the compounds azepyl 11b–0.44 μM, phenyl 11c–0.23 μM, phenylethyl 11f–0.35 μM and hexyl 11j–0.36 μM. In contrast, the novel urea derivatives 11b, 11c and 11f exhibited levels of cytotoxicity three orders of magnitude lower than that of hexyl urea 11j or amsacrine.     

Alterations in β-Cell Sphingolipid Profile Associated with ER Stress and iPLA2β: Another Contributor to β-Cell Apoptosis in Type 1 Diabetes

Type 1 diabetes (T1D) development, in part, is due to ER stress-induced β-cell apoptosis. Activation of the Ca²⁺-independent phospholipase A₂ beta (iPLA₂β) leads to the generation of pro-inflammatory eicosanoids, which contribute to β-cell death and T1D. ER stress induces iPLA₂β-mediated generation of pro-apoptotic ceramides via neutral sphingomyelinase (NSMase). To gain a better understanding of the impact of iPLA₂β on sphingolipids (SLs), we characterized their profile in β-cells undergoing ER stress. ESI/MS/MS analyses followed by ANOVA/Student’s t-test were used to assess differences in sphingolipids molecular species in Vector (V) control and iPLA₂β-overexpressing (OE) INS-1 and Akita (AK, spontaneous model of ER stress) and WT-littermate (AK-WT) β-cells. As expected, iPLA₂β induction was greater in the OE and AK cells in comparison with V and WT cells. We report here that ER stress led to elevations in pro-apoptotic and decreases in pro-survival sphingolipids and that the inactivation of iPLA₂β restores the sphingolipid species toward those that promote cell survival. In view of our recent finding that the SL profile in macrophages—the initiators of autoimmune responses leading to T1D—is not significantly altered during T1D development, we posit that the iPLA₂β-mediated shift in the β-cell sphingolipid profile is an important contributor to β-cell death associated with T1D.     

A Cd(II) Luminescent Coordination Grid as a Multiresponsive Fluorescence Sensor for Cr(VI) Oxyanions and Cr(III), Fe(III), and Al(III) in Aqueous Medium

Hydro(solvo)thermal reactions of Cd(NO₃)₂, N-(pyridin-3-ylmethyl)-4-(pyridin-4-yl)-1,8-naphthalimide (NI-mbpy-34), and 5-bromobenzene-1,3-dicarboxylic acid (Br-1,3-H₂bdc) afforded a luminescent coordination polymer, {[Cd(Br-1,3-bdc)(NI-mbpy-34)(H₂O)]∙2H₂O}_n (1). Single-crystal X-ray diffraction analysis showed that 1 features a two-dimensional (2-D) gridlike sql layer with the point symbol of (4⁴·6²), where the Cd(II) center adopts a {CdO₅N₂} pentagonal bipyramidal geometry. Thermogravimetric (TG) analysis confirmed the thermal stability of 1 up to about 340 °C, whereas XRPD patterns proved the maintenance of crystallinity and framework integrity of 1 in CH₂Cl₂, H₂O, CH₃OH, and toluene. Photoluminescence studies indicated that 1 displayed intense blue fluorescence emissions in both solid-state and H₂O suspension-phase. Owing to the good fluorescent properties, 1 could serve as an excellent turn-off fluorescence sensor for selective and sensitive Cr(VI) detection in water, with LOD = 15.15 μM for CrO₄²⁻ and 14.91 μM for Cr₂O₇²⁻, through energy competition absorption mechanism. In addition, 1 could also sensitively detect Cr³⁺, Fe³⁺, and Al³⁺ ions in aqueous medium via fluorescence-enhancement responses, with LOD = 2.81 μM for Cr³⁺, 3.82 μM for Fe³⁺, and 3.37 μM for Al³⁺, mainly through an absorbance-caused enhancement (ACE) mechanism.     

Design and Synthesis of Non-Covalent Imidazo[1,2-a]quinoxaline-Based Inhibitors of EGFR and Their Anti-Cancer Assessment

A series of 30 non-covalent imidazo[1,2-a]quinoxaline-based inhibitors of epidermal growth factor receptor (EGFR) were designed and synthesized. EGFR inhibitory assessment (against wild type) data of compounds revealed 6b, 7h, 7j, 9a and 9c as potent EGFR^WT inhibitors with IC₅₀ values of 211.22, 222.21, 193.18, 223.32 and 221.53 nM, respectively, which were comparable to erlotinib (221.03 nM), a positive control. Furthermore, compounds exhibited excellent antiproliferative activity when tested against cancer cell lines harboring EGFR^WT; A549, a non-small cell lung cancer (NSCLC), HCT-116 (colon), MDA-MB-231 (breast) and gefitinib-resistant NSCLC cell line H1975 harboring EGFR^L858R/T790M. In particular, compound 6b demonstrated significant inhibitory potential against gefitinib-resistant H1975 cells (IC₅₀ = 3.65 μM) as compared to gefitinib (IC₅₀ > 20 μM). Moreover, molecular docking disclosed the binding mode of the 6b to the domain of EGFR (wild type and mutant type), indicating the basis of inhibition. Furthermore, its effects on redox modulation, mitochondrial membrane potential, cell cycle analysis and cell death mode in A549 lung cancer cells were also reported.     

Discovery of New Pyrazolopyridine,Furopyridine, and Pyridine Derivatives as CDK2 Inhibitors: Design,Synthesis, Docking Studies,and Anti-Proliferative Activity

New pyridine, pyrazoloyridine, and furopyridine derivatives substituted with naphthyl and thienyl moieties were designed and synthesized starting from 6-(naphthalen-2-yl)-2-oxo-4-(thiophen-2-yl)-1,2-dihydropyridine-3-carbonitrile (1). The chloro, methoxy, cholroacetoxy, imidazolyl, azide, and arylamino derivatives were prepared to obtain the pyridine-⁻C² functionalized derivatives. The derived pyrazolpyridine-N-glycosides were synthesized via heterocyclization of the C²-thioxopyridine derivative followed by glycosylation using glucose and galactose. The furopyridine derivative 14 and the tricyclic pyrido[3′,2′:4,5]furo[3,2-d]pyrimidine 15 were prepared via heterocyclization of the ester derivative followed by a reaction with formamide. The newly synthesized compounds were evaluated for their ability to in vitro inhibit the CDK2 enzyme. In addition, the cytotoxicity of the compounds was tested against four different human cancer cell lines (HCT-116, MCF-7, HepG2, and A549). The CDK2/cyclin A2 enzyme inhibitory results revealed that pyridone 1, 2-chloro-6-(naphthalen-2-yl)-4-(thiophen-2-yl)nicotinonitrile (4), 6-(naphthalen-2-yl)-4-(thiophen-2-yl)-1H-pyrazolo[3,4-b]pyridin-3-amine (8), S-(3-cyano-6-(naphthaen-2-yl)-4-(thiophen-2-yl)pyridin-2-yl) 2-chloroethanethioate (11), and ethyl 3-amino-6-(naphthalen-2-yl)-4-(thiophen-2-yl)furo[2,3-b]pyridine-2-carboxylate (14) are among the most active inhibitors with IC₅₀ values of 0.57, 0.24, 0.65, 0.50, and 0.93 µM, respectively, compared to roscovitine (IC₅₀ 0.394 μM). Most compounds showed significant inhibition on different human cancer cell lines (HCT-116, MCF-7, HepG2, and A549) with IC₅₀ ranges of 31.3–49.0, 19.3–55.5, 22.7–44.8, and 36.8–70.7 μM, respectively compared to doxorubicin (IC₅₀ 40.0, 64.8, 24.7 and 58.1 µM, respectively). Furthermore, a molecular docking study suggests that most of the target compounds have a similar binding mode as a reference compound in the active site of the CDK2 enzyme. The structural requirements controlling the CDK2 inhibitory activity were determined through the generation of a statistically significant 2D-QSAR model.     

Synthesis and Biological Evaluation of Amino Chalcone Derivatives as Antiproliferative Agents

Chalcone is a common scaffold found in many biologically active compounds. The chalcone scaffold was also frequently utilized to design novel anticancer agents with potent biological efficacy. Aiming to continue the research of effective chalcone derivatives to treat cancers with potent anticancer activity, fourteen amino chalcone derivatives were designed and synthesized. The antiproliferative activity of amino chalcone derivatives was studied in vitro and 5-Fu as a control group. Some of the compounds showed moderate to good activity against three human cancer cells (MGC-803, HCT-116 and MCF-7 cells) and compound 13e displayed the best antiproliferative activity against MGC-803 cells, HCT-116 cells and MCF-7 cells with IC₅₀ values of 1.52 μM (MGC-803), 1.83 μM (HCT-116) and 2.54 μM (MCF-7), respectively which was more potent than the positive control (5-Fu). Further mechanism studies were explored. The results of cell colony formatting assay suggested compound 10e inhibited the colony formation of MGC-803 cells. DAPI fluorescent staining and flow cytometry assay showed compound 13e induced MGC-803 cells apoptosis. Western blotting experiment indicated compound 13e induced cell apoptosis via the extrinsic/intrinsic apoptosis pathway in MGC-803 cells. Therefore, compound 13e might be a valuable lead compound as antiproliferative agents and amino chalcone derivatives worth further effort to improve amino chalcone derivatives’ potency.     

Novel Donepezil–Arylsulfonamide Hybrids as Multitarget-Directed Ligands for Potential Treatment of Alzheimer’s Disease

Alzheimer’s disease (AD) is one of the most devastating neurodegenerative disorders, characterized by multiple pathological features. Therefore, multi-target drug discovery has been one of the most active fields searching for new effective anti-AD therapies. Herein, a series of hybrid compounds are reported which were designed and developed by combining an aryl-sulfonamide function with a benzyl-piperidine moiety, the pharmacophore of donepezil (a current anti-AD acetylcholinesterase AChE inhibitor drug) or its benzyl-piperazine analogue. The in vitro results indicate that some of these hybrids achieve optimized activity towards two main AD targets, by displaying excellent AChE inhibitory potencies, as well as the capability to prevent amyloid-β (Aβ) aggregation. Some of these hybrids also prevented Aβ-induced cell toxicity. Significantly, drug-like properties were predicted, including for blood-brain permeability. Compound 9 emerged as a promising multi-target lead compound (AChE inhibition (IC₅₀ 1.6 μM); Aβ aggregation inhibition 60.7%). Overall, this family of hybrids is worthy of further exploration, due to the wide biological activity of sulfonamides.     

Synthesis and Antiviral Evaluation of (1,4-Disubstituted-1,2,3-Triazol)-(E)-2-Methyl-but-2-Enyl Nucleoside Phosphonate Prodrugs

A series of hitherto unknown (1,4-disubstituted-1,2,3-triazol)-(E)-2-methyl-but-2-enyl nucleosides phosphonate prodrugs bearing 4-substituted-1,2,3-triazoles were prepared in a straight approach through an olefin acyclic cross metathesis as the key synthetic step. All novel compounds were evaluated for their antiviral activities against HBV, HIV and SARS-CoV-2. Among these molecules, only compound 15j, a hexadecyloxypropyl (HDP)/(isopropyloxycarbonyl-oxymethyl)-ester (POC) prodrug, showed activity against HBV in Huh7 cell cultures with 62% inhibition at 10 μM, without significant cytotoxicity (IC₅₀ = 66.4 μM in HepG2 cells, IC₅₀ = 43.1 μM in HepG2 cells) at 10 μM.     

Cyclometalated Iridium(III) Complex–Cationic Peptide Hybrids Trigger Paraptosis in Cancer Cells via an Intracellular Ca2+ Overload from the Endoplasmic Reticulum and a Decrease in Mitochondrial Membrane Potential

In our previous paper, we reported that amphiphilic Ir complex–peptide hybrids (IPHs) containing basic peptides such as KK(K)GG (K: lysine, G: glycine) (e.g., ASb-2) exhibited potent anticancer activity against Jurkat cells, with the dead cells showing a strong green emission. Our initial mechanistic studies of this cell death suggest that IPHs would bind to the calcium (Ca²⁺)–calmodulin (CaM) complex and induce an overload of intracellular Ca²⁺, resulting in the induction of non-apoptotic programmed cell death. In this work, we conduct a detailed mechanistic study of cell death induced by ASb-2, a typical example of IPHs, and describe how ASb-2 induces paraptotic programmed cell death in a manner similar to that of celastrol, a naturally occurring triterpenoid that is known to function as a paraptosis inducer in cancer cells. It is suggested that ASb-2 (50 µM) induces ER stress and decreases the mitochondrial membrane potential (ΔΨ_m), thus triggering intracellular signaling pathways and resulting in cytoplasmic vacuolization in Jurkat cells (which is a typical phenomenon of paraptosis), while the change in ΔΨ_m values is negligibly induced by celastrol and curcumin. Other experimental data imply that both ASb-2 and celastrol induce paraptotic cell death in Jurkat cells, but this induction occurs via different signaling pathways.