Design,synthesis and biological evaluation of novel 4-anilinoquinazolines with C-6 urea-linked side chains as inhibitors of the epidermal growth factor receptor

A novel series of anilinoquinazoline compounds with C-6 urea-linked side chains was designed and synthesized as reversible inhibitors of epidermal growth factor receptor (EGFR) based on the structure–activity relationships (SARs) of anilinoquinazoline inhibitors. All compounds demonstrated good inhibition of EGFR wild type (EGFR wt) (IC₅₀ = 0.024–1.715 μM) and inhibited proliferation of A431cell line (IC₅₀ = 0.116–22.008 μM). The binding mode of compounds 8a, 8d, 8k and 8o was consistent with the biological results. Moreover, compounds 8k and 8l almost completely blocked the phosphorylation of EGFR in A431 cell line at 0.01 μM. Interestingly, all of the compounds also demonstrated moderate inhibition of EGFR/T790M/L858R (IC₅₀ = 0.049–5.578 μM). In addition, compounds 8f and 8h blocked the autophosphorylation of EGFR in NCI-H1975 cells at high concentration (10 μM), and compound 8f was confirmed to be an irreversible inhibitor through the dilution method. Importantly, the compounds with C-6 urea-linked side chains which did not contain Michael acceptors demonstrated moderate to strong irreversible EGFR inhibition.     

Design,synthesis and biological evaluation of new 2,3-diarylquinoline derivatives as selective cyclooxygenase-2 inhibitors

A new group of 2,3-diarylquinoline derivatives possessing a methylsulfonyl COX-2 pharmacophore at the para-position of the C-2 phenyl ring were synthesized and evaluated as selective COX-2 inhibitors. In vitro COX-1/COX-2 structure–activity relationships were determined by varying the substituents on the C-4 quinoline ring. Among the 2,3-diarylquinolines, 2-(4-(methylsulfonyl) phenyl)-3-phenylquinoline-4-carboxylic acid (8) exhibited the highest potency and selectivity for COX-2 inhibitory activity (COX-2 IC₅₀ = 0.07 μM; selectivity index = 687.1) that was more selective than the reference drug celecoxib (COX-2 IC₅₀ = 0.06 μM; selectivity index = 405). A molecular modeling study where 8 was docked in the binding site of COX-2 indicated that the p-MeSO₂ COX-2 pharmacophore group on the C-2 phenyl ring is oriented in the vicinity of the COX-2 secondary pocket (Arg⁵¹³, Phe⁵¹⁸ and Val⁵²³) and the carboxylic acid substituent can interact with Ser⁵³⁰. The structure activity data acquired indicate that the size and nature of the C-4 quinoline substituent are important for COX-2 inhibitory activity.     

Design,synthesis and evaluation of N-substituted saccharin derivatives as selective inhibitors of tumor-associated carbonic anhydrase XII

A series of N-alkylated saccharin derivatives were synthesized and tested for the inhibition of four different isoforms of human carbonic anhydrase (CA, EC 4. 2.1.1): the transmembrane tumor-associated CA IX and XII, and the cytosolic CA I and II. Most of the reported derivatives inhibited CA XII in the nanomolar/low micromolar range, hCA IX with K_Is ranging between 11 and 390 nM, whereas they were inactive against both CA I (K_Is >50 μM) and II (K_Is ranging between 39.1 nM and 50 μM). Since CA I and II are off-targets of antitumor carbonic anhydrase inhibitors (CAIs), the obtained results represent an encouraging achievement for the development of new anticancer candidates without the common side effects of non-selective CAIs. Moreover, the lack of an explicit zinc binding function on these inhibitors opens the way towards the exploration of novel mechanisms of inhibition that could explain the high selectivity of these compounds for the inhibition of the transmembrane, tumor-associated isoforms over the cytosolic ones.     

Design,synthesis and biological evaluation of 3-benzyloxy-linked pyrimidinylphenylamine derivatives as potent HIV-1 NNRTIs

A novel series of 3-benzyloxy-linked pyrimidinylphenylamine derivatives (8a–8s) was designed, synthesized and evaluated for their in vitro anti-HIV activity in MT-4 cell cultures. Most of the compounds inhibited wild-type (wt) HIV-1 replication in the lower micromolar concentration range (EC₅₀ = 0.05–35 μM) with high selectivity index (SI) values (ranged from 10 to >4870). In particular, 8h and 8g displayed excellent antiretroviral activity against wt HIV-1 with low cytotoxicity (EC₅₀ = 0.07 μM, CC₅₀ >347 μM, SI >4870; EC₅₀ = 0.05 μM, CC₅₀ = 42 μM, SI = 777, respectively), comparable to that of the marked drug nevirapine (EC₅₀ = 0.113 μM, CC₅₀ >15 μM, SI >133). In order to confirm the binding target, 8h was selected to perform the anti-HIV-1 RT assay. Additionally, preliminary structure activity relationship (SAR) analysis and molecular docking studies of newly synthesized compounds were also discussed, as well as the predicted physicochemical properties.     

Design,synthesis and evaluation of 2,4-disubstituted pyrimidines as cholinesterase inhibitors

A group of 2,4-disubstituted pyrimidine derivatives (7a–e, 8a–e and 9a–d) that possess a variety of C-2 aliphatic five- and six-membered heterocycloalkyl ring in conjunction with a C-4 arylalkylamino substituent were designed, synthesized and evaluated as cholinesterase (ChE) inhibitors. The steric and electronic properties at C-2 and C-4 positions of the pyrimidine ring were varied to investigate their effect on ChE inhibitory potency and selectivity. The structure–activity relationship (SAR) studies identified N-benzyl-2-thiomorpholinopyrimidin-4-amine (7c) as the most potent cholinesterase inhibitor (ChEI) with an IC₅₀ = 0.33 μM (acetylcholinesterase, AChE) and 2.30 μM (butyrylcholinesterase, BuChE). The molecular modeling studies indicate that within the AChE active site, the C-2 thiomorpholine substituent was oriented toward the cationic active site region (Trp84 and Phe330) whereas within the BuChE active site, it was oriented toward a hydrophobic region closer to the active site gorge entrance (Ala277). Accordingly, steric and electronic properties at the C-2 position of the pyrimidine ring play a critical role in ChE inhibition.     

Design,synthesis, and docking studies of afatinib analogs bearing cinnamamide moiety as potent EGFR inhibitors

Two series of afatinib derivatives bearing cinnamamide moiety (10a–n and 11a–h) were designed, synthesized and evaluated for the IC₅₀ values against four cancer cell lines (A549, PC-3, MCF-7 and Hela). Two selected compounds (10e, 10k) were further evaluated for the inhibitory activity against EGFR and VEGFR2/KDR kinases. Seven of the compounds showed excellent cytotoxicity activity and selectivity with the IC₅₀ values in single-digit μM to nanomole range. Three of them are equal to more active than positive control afatinib against one or more cell lines. The most promising compound 10k showed the best activity against A549, PC-3, MCF-7 and Hela cancer cell lines and EGFR kinase, with the IC₅₀ values of 0.07 ± 0.02 μM, 7.67 ± 0.97 μM, 4.65 ± 0.90 μM and 4.83 ± 1.28 μM, which were equal to more active than afatinib (0.05 ± 0.01 μM, 4.1 ± 2.47 μM, 5.83 ± 1.89 μM and 6.81 ± 1.77 μM), respectively. Activity of compounds 10e (IC₅₀ 9.1 nM) and 10k (IC₅₀ 3.6 nM) against EGFR kinase were equal to the reference compound afatinib (IC₅₀ 1.6 nM). Structure–activity relationships (SARs) and docking studies indicated that replacement of the aqueous solubility 4-(dimethylamino)but-2-enamide group by cinnamamide moiety didn’t decrease the antitumor activity. The results suggested that methoxy substitution had a significant impact on the activity and methoxy substituted on C-4 or C-2,3,4 position was benefit for the activity.     

Synthesis,characterization and biological studies of diosgenyl analogues

A series of optical amino acid diosgenyl esters and diosgenyl salicylate conjugates were designed and synthesized to develop new anticancer and anti-inflammatory agents. The analogue 9c that contains an 6-aminohexanoic acid residue at C-3 of diosgenin exhibits higher potency against all three tumor cell lines with IC₅₀ values ranging from 4.7 μM in C26 cells to 14.6 μM in Hep G2 cells. In addition, seven of newly synthesized compounds significantly inhibit xylene-induced ear edema and exhibit comparable or better anti-inflammatory activities than those of diosgenin and aspirin. Furthermore, preliminary structure–activity relationship studies demonstrate that diosgenyl salicylate conjugates have stronger anti-inflammatory activities than amino acid diosgenyl esters.     

Synthesis,biological evaluation and molecular modeling of 1,3,4-thiadiazol-2-amide derivatives as novel antitubulin agents

A series of 1,3,4-thiadiazol-2-amide derivatives (6a–w) were designed and synthesized as potential inhibitors of tubulin polymerization and as anticancer agents. The in vitro anticancer activities of these compounds were evaluated against three cancer cell lines by the MTT method. Among all the designed compounds, compound 6f exhibited the most potent anticancer activity against A549, MCF-7 and HepG2 cancer cell lines with IC₅₀ values of 0.03 μM, 0.06 μM and 0.05 μM, respectively. Compound 6f also exhibited significant tubulin polymerization inhibitory activity (IC₅₀ = 1.73 μM), which was superior to the positive control. The obtained results, along with a 3D-QSAR study and molecular docking that were used for investigating the probable binding mode, could provide an important basis for further optimization of compound 6f as a novel anticancer agent.     

Synthesis and biological evaluation of heterocyclic ring-substituted maslinic acid derivatives as novel inhibitors of protein tyrosine phosphatase 1B

A series of maslinic acid derivatives have been synthesized by introducing various fused heterocyclic rings at C-2 and C-3 positions. Their inhibitory effects on PTP1B, TCPTP and related PTPs are evaluated. Most of the compounds exhibited a dramatic increase in inhibitory potency and selectivity, the two most potent PTP1B inhibitors 20 (IC₅₀ = 0.61 μM) and 29 (IC₅₀ = 0.64 μM) showed about 10-fold more potent than lead compound maslinic acid. More importantly, 29 possesses the best selectivity of 6.9-fold for PTP1B over TCPTP.     

Novel thienopyridine derivatives as specific anti-hepatocellular carcinoma (HCC) agents: Synthesis,preliminary structure–activity relationships,and in vitro biological evaluation

Novel thienopyridine derivatives 1b–1r were synthesized, based on a hit compound 1a that was found in a previous cell-based screening of anticancer drugs. Compounds 1a–1r have the following features: (1) their anticancer activity in vitro was first reported by our group. (2) The most potent analog 1g possesses hepatocellular carcinoma (HCC)-specific anticancer activity. It can specifically inhibit the proliferation of the human hepatoma HepG2 cells with an IC₅₀ value of 0.016 μM (compared with doxorubicin as a positive control, whose IC₅₀ was 0.37 μM). It is inactive toward a panel of five different types of human cancer cell lines. (3) Compound 1g remarkably induces G₀/G₁ arrest and apoptosis in HepG2 cells in vitro at low micromolar concentrations. These results, especially the HCC-specific anticancer activity of 1g, suggest their potential in targeted chemotherapy for HCC.     

Design,synthesis, and docking studies of phenylpicolinamide derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety as c-Met inhibitors

Four series of phenylpicolinamide derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety (12a–e, 13a–f, 14a–f and 15a–i) were designed, synthesized and evaluated for the IC₅₀ values against three cancer cell lines (A549, PC-3 and MCF-7) and c-Met kinase. Five selected compounds (13b, 15b, 15d, 15e and 15f) were further evaluated for the activity against HepG2 and Hela cell lines. Eighteen of the compounds showed excellent cytotoxicity activity and selectivity with the IC₅₀ valuables in single-digit μM to nanomole range. Seven of them are equal to more active than positive control Foretinib against one or more cell lines. The most promising compound 15f showed superior activity to Foretinib, with the IC₅₀ values of 1.04 ± 0.11 μM, 0.02 ± 0.01 μM and 9.11 ± 0.55 μM against A549, PC-3 and MCF-7 cell lines, which were 0.62 to 19.5 times more active than Foretinib (IC₅₀ values: 0.64 ± 0.26 μM, 0.39 ± 0.11 μM, 9.47 ± 0.22 μM), respectively. Structure–activity relationships (SARs) and docking studies indicated that replacement of quinoline nucleus of the previous active compounds with 1H-pyrrolo[2,3-b]pyridine moiety maintained even improved the potent cytotoxic activity. The results suggested that the introduction of fluoro atoms to the aminophenoxy part of target compounds or the phenyl group of pyrimidine substituted on C-4 position was benefit for the activity.     

Synthesis of isothiazol-3-one derivatives as inhibitors of histone acetyltransferases (HATs)

High-throughput screening led to the identification of isothiazolones 1 and 2 as inhibitors of histone acetyltransferase (HAT) with IC50s of 3 μM and 5 μM, respectively. Analogues of these hit compounds with variations of the N-phenyl group, and with variety of substituents at C-4, C-5 of the thiazolone ring, were prepared and assayed for inhibition of the HAT enzyme PCAF. Potency is modestly favoured when the N-aryl group is electron deficient (4-pyridyl derivative 10 has IC₅₀ = 1.5 μM); alkyl substitution at C-4 has little effect, whilst similar substitution at C-5 causes a significant drop in potency. The ring–fused compound 38 has activity (IC₅₀ = 6.1 μM) to encourage further exploration of this bicyclic structure. The foregoing SAR is consistent with an inhibitory mechanism involving cleavage of the S–N bond of the isothiazolone ring by a catalytically important thiol residue.     

Design,synthesis and cytotoxic activity of novel sulfonylurea derivatives of podophyllotoxin

Three series of novel sulfonylurea podophyllotoxin derivatives were designed, synthesized, and evaluated for in vitro cytotoxicity against four tumor cell lines (A-549, DU-145, KB and KBvin). Compounds 14c (IC₅₀: 1.41–1.76 μM) and 14e (IC₅₀: 1.72–2.01 μM) showed superior cytotoxic activity compared with etoposide (IC₅₀: 2.03 to >20 μM), a clinically available anticancer drug. Significantly, most of the compounds exhibited comparable cytotoxicity against the drug-resistant tumor cell line KBvin, while etoposide lost activity completely. Preliminary structure–activity relationship (SAR) correlations indicated that the 4′-O-methyl functionality in podophyllotoxin analogues may be essential to maintain cytotoxic activity, while an arylsulfonylurea side chain at podophyllotoxin’s 4β position can significantly improve cytotoxic activity.     

Synthesis and evaluation of novel ligands for the histamine H4 receptor based on a pyrrolo[2,3-d]pyrimidine scaffold

Starting from a known H₄R ligand based on a pyrimidine skeleton, a series of novel analogues based on a pyrrolo[2,3-d]pyrimidine scaffold have been prepared. Whereas the original pyrimidine congener shows good affinity at hH₄R (K_i = 0.5 μM), its lacks selectivity with a K_i value for the hH₃R of 1 μM. Within the newly synthesized pyrrolo[2,3-d]pyrimidines, several congeners show K_i values of less than 1 μM at the hH₄R and show a much improved selectivity profile. Therefore, these series represent an interesting starting point for the discovery of novel hH₄R ligands.     

Carbonic anhydrase inhibitors. Inhibition of the human cytosolic isoforms I and II and transmembrane,tumor-associated isoforms IX and XII with boronic acids

A series of aromatic, arylalkenyl- and arylalkyl boronic acids were assayed as inhibitors of four physiologically relevant carbonic anhydrase (CA, EC 4.2.1.1) isoforms, the cytosolic human (h) hCA I and II, and the transmembrane, tumor-associated hCA IX and XII. The best hCA I and II inhibitor was biphenyl boronic acid with, a K_I of 3.7–4.5 μM, whereas the remaining derivatives showed inhibition constants in the range of 6.0–1560 μM for hCA I and of 6.0–1050 μM for hCA II, respectively. hCA IX and XII were effectively inhibited by most of the aromatic boronic acids (K_Is of 7.6–12.3 μM) whereas the arylalkenyl and aryl–alkyl derivatives generally showed weaker inhibitory properties (K_Is of 34–531 μM). The nature of the moiety substituting the boronic acid group strongly influenced the CA inhibitory activity, with inhibitors possessing low micromolar to millimolar activity being detected in this small series of investigated compounds. This study proves that the B(OH)₂ moiety represents a new zinc-binding group for the generation of effective CA inhibitors targeting isoforms with medicinal chemistry applications. The boronic acids probably bind to the Zn(II) ion within the CA active site leading to a tetrahedral geometry of the metal ion and of the B(III) derivative.     

Synthesis,biological evaluation,and docking studies of novel heterocyclic diaryl compounds as selective COX-2 inhibitors

Three novel series of diaryl heterocyclic derivatives bearing the 2-oxo-5H-furan, 2-oxo-3H-1,3-oxazole, and 1H-pyrazole moieties as the central heterocyclic ring were synthesized and their in vitro inhibitory activities on COX-1 and COX-2 isoforms were evaluated using a purified enzyme assay. The 2-oxo-5H-furan derivative 6b was identified as potent COX inhibitor with selectivity toward COX-1 (COX-1 IC₅₀ = 0.061 μM and COX-2 IC₅₀ = 0.325 μM; selectivity index (SI) = 0.19). Among the 1H-pyrazole derivatives, 11b was found to be a potent COX-2 inhibitor, about 38 times more potent than Rofecoxib (COX-2 IC₅₀ = 0.011 μM and 0.398 μM, respectively), but showed no selectivity for COX-2 isoform. Compound 11c demonstrated strong and selective COX-2 inhibitory activity (COX-1 IC₅₀ = 1 μM, COX-2 IC₅₀ = 0.011 μM; SI = ～92). Molecular docking studies of compounds 6b and 11b–d into the binding sites of COX-1 and COX-2 allowed to shed light on the binding mode of these novel COX inhibitors.     

Effect of mercury and gold on growth,nutrient uptake,and anatomical changes in Chilopsis linearis

Plants of Chilopsis linearis were grown with 0, 50, 100, and 200 μM Hg [as Hg(CH₃COO)₂] and 0 and 50 μM Au (as KAuCl₄) in hydroponics. The results showed that seedling grown with 50 μM Au + 50 μM Hg and 50 μM Au + 100 μM Hg had roots 25 and 55% shorter than control roots, respectively. The element uptake determination using ICP/OES demonstrated that Hg at 50 and 100 μM (with and without Au) significantly increased (p < 0.05) the S concentration in leaves. On the other hand, the concentration of Fe significantly increased in roots of plants treated with Au–Hg. In addition, the stems of plants treated with Hg at 100 μM, with and without Au, had 239 and 876 mg Hg/kg dry biomass (d wt), respectively. Also, at 50 μM Hg, with and without Au, stems accumulated 375 and 475 mg Hg/kg d wt. The Hg concentration in leaves (287 mg Hg/kg d wt) was higher (p < 0.05) for the treatment containing 50 μM Au + 100 μM Hg. Without Au, the Hg concentration in leaves decreased to 75 mg Hg/kg d wt. Toxicity symptoms induced by Hg in cortex cells and the vascular system were lower in plants exposed to 50 μM Au + 50 μM Hg compared to plants exposed to 50 μM Hg only. Further, the SEM micrographs revealed deposition of Au–Hg particles inside the root. Although the concentrations of Hg used in this study showed different degree of toxicity, the plants displayed good agronomic value.     

Synthesis and carbonic anhydrase inhibitory properties of sulfamides structurally related to dopamine

A series of novel sulfamides incorporating the dopamine scaffold were synthesized. Reaction of amines and tert-butyl-alcohol/benzyl alcohol in the presence of chlorosulfonyl isocyanate (CSI) afforded sulfamoyl carbamates, which were converted to the title compounds by treatment with trifluoroacetic acid or by palladium-catalyzed hydrogenolysis. Inhibition of six α-carbonic anhydrases (CAs, EC 4.2.1.1), that is, CA I, CA II, CA VA, CA IX, CA XII and CA XIV, and two β-CAs from Candida glabrata (CgCA) and Mycobacterium tuberculosis (Rv3588) with these sulfamides was investigated. All CA isozymes were inhibited in the low micromolar to nanomolar range by the dopamine sulfamide analogues. K_is were in the range of 0.061–1.822 μM for CA I, 1.47–2.94 nM for CA II, 2.25–3.34 μM for CA VA, 0.041–0.37 μM for CA IX, 0.021–1.52 μM for CA XII, 0.007–0.219 μM for CA XIV, 0.35–5.31 μM for CgCA and 0.465–4.29 μM for Rv3588. The synthesized sulfamides may lead to inhibitors targeting medicinally relevant CA isoforms with potential applications as antiepileptic, antiobesity antitumor agents or anti-infective.     

Synthesis,biological evaluation of novel 4,5-dihydro-2H-pyrazole 2-hydroxyphenyl derivatives as BRAF inhibitors

A series of novel 4,5-dihydropyrazole derivatives (3a–3t) containing hydroxyphenyl moiety as potential V600E mutant BRAF kinase (BRAF^V600E) inhibitors were designed and synthesized. Docking simulation was performed to insert compounds 3d (1-(5-(5-chloro-2-hydroxyphenyl)-3-(p-tolyl)-4,5-dihydro-1H-pyrazol-1-yl)ethanone) and 3m (1-(3-(4-chlorophenyl)-5-(3,5-dibromo-2-hydroxyphenyl)-4,5-dihydro-1H-pyrazol-1-yl)ethanone) into the crystal structure of BRAF^V600E to determine the probable binding model, respectively. Based on the preliminary results, compound 3d and 3m with potent inhibitory activity in tumor growth may be a potential anticancer agent. Results of the bioassays against BRAF^V600E, MCF-7 human breast cancer cell line and WM266.4 human melanoma cell line all showed several compounds had potent activities IC₅₀ value in low micromolar range, among them, compound 3d and compound 3m showed strong potent anticancer activity, which were proved by that 3d: IC₅₀ = 1.31 μM for MCF-7 and IC₅₀ = 0.45 μM for WM266.5, IC₅₀ = 0.22 μM for BRAF^V600E, 3m: IC₅₀ = 0.97 μM for MCF-7 and IC₅₀ = 0.72 μM for WM266.5, IC₅₀ = 0.46 μM for BRAF^V600E, which were comparable with the positive control Erlotinib.     

Toward discovery of mutant EGFR inhibitors; Design,synthesis and in vitro biological evaluation of potent 4-arylamino-6-ureido and thioureido-quinazoline derivatives

A new series of 4-anilinoquinazolines with C-6 ureido and thioureido side chains and various substituents at the C-4 anilino moiety was designed, synthesized and evaluated as wild type (WT) and mutant EGFR inhibitors. Most of the compounds inhibited EGFR kinase wild type (EGFR WT) with IC₅₀ values in the low nanomolar range (<0.495–9.05 nM) and displayed more potent cytotoxic effect in BaF/3 expressing EGFR WT than reference compound gefitinib. The anti-proliferative effect of all synthesized compounds against gefitinib insensitive double mutant cell lines Ba/F3 expressing Del19/T790M and Ba/F3 expressing L858R/T790M were assayed. Compounds 4d, 6f, 7e showed significant inhibition (IC₅₀ = 1.76–2.38 μM) in these mutant lines and significant Her2 enzyme inhibition (IC₅₀ = 19.2–40.6 nM) compared to lapatinib (60.1 nM). The Binding mode of compounds 6d, 6f, 7a, 7b and 8b were demonstrated. Furthermore, growth inhibition against gefitinib insensitive cell lines PC9-GR4 (Del19/T790M) were tested, compounds 6f and 7e showed about eight and three folds respectively greater potency than gefitinib. Our structure–activity relationships (SAR) studies suggested that presence of ethyl piperidino urea/thiourea at 6-position and bulky group of (3-chloro-4-(3-fluorobenzyloxy)phenyl)amino at 4-position of quinazoline may serve as promising scaffold for developing inhibitors against wild type and mutant EGFR.