Synthesis,characterization, molecular modeling,and potential antimicrobial and anticancer activities of novel 2-aminoisoindoline-1,3-dione derivatives

In an effort to establish new drug candidates with improved antimicrobial and anticancer activities, we report here synthesis, molecular modeling, and in vitro biological evaluation of novel substituted N-amino phthalamide derivatives (3a-b, 4a-b, 5a-j, and 6). Structures of the newly synthesized compounds were described by IR, ¹H & ¹³CNMR and LC-MS spectral data. The novel compounds were evaluated for their antibacterial activity against four types of Gm+ve and two for Gm−ve types, and antifungal activity against three fungi microorganisms by well diffusion method. Of these novel compounds, Schiff bases showed mostly promising antibacterial activity compared to reference drugs. A successful step was done for explanation of their mode of action through molecular docking of most active molecules at DNA gyrase B enzyme and further were biologically tested. Moreover, the antiproliferative activity was tested against two human carcinoma cell lines (Human colon carcinoma (HCT-116) and human breast adenocarcinoma (MCF-7)) showing promising anticancer activity compared to doxorubicin drug. The data from structure-activity relationship (SAR) analysis revealed that the lypophilic properties of these compounds might be essential parameter for their activity and suggest that 2-amino phthalamide scaffold derivatives 5g and 5h exhibited good antimicrobial and anticancer activities and might used as leads for further optimization.     

Additive effects on the improvement of insecticidal activity: Design,synthesis, and insecticidal activity of novel pymetrozine derivatives

A series of new pymetrozine analogues containing both methyl on the imine carbon and phenoxy group at the pyridine ring were designed and synthesized. Their insecticidal activities against bean aphid (Aphis craccivora), mosquito larvae (Culex pipiens pallens), cotton bollworm (Helicoverpa armigera), corn borer (Ostrinia nubilalis) and oriental armyworm (Mythimna separata) were evaluated. The results of bioassays indicated that most of the target compounds showed good insecticidal activity against bean aphid; especially, IIIf (80%) and IIIl (80%) exhibited higher aphicidal activity than pymetrozine (30%) at 5 mg/kg, and the two compounds still showed 20% and 30% mortality at 2.5 mg/kg, respectively, whereas pymetrozine displayed no activity at the same concentration. These compounds exhibited a completely different structure–activity relationship to that of known pymetrozine derivatives, in which it is thought introducing alkyl group on the imine carbon could be detrimental to the activities. Our new result suggested that the methyl on the imine carbon and phenoxy group at the pyridine ring of phenoxy group may play additive effects on the improvement of aphicidal activity. Besides this, compound IIIs, containing an allyl at the para position of phenoxy group, exhibited excellent insecticidal activity against mosquito larvae, lepidoptera pests cotton bollworm, corn borer and oriental armyworm.     

Design,synthesis and antibacterial activities of thiouracil derivatives containing acyl thiourea as SecA inhibitors

A series of novel thiouracil derivatives containing an acyl thiourea moiety (7a–7x) have been synthesized by structural modification of a lead SecA inhibitor, 2. All the compounds have been evaluated for their antibacterial activities against Bacillus amyloliquefaciens, Staphylococcus aureus, and Bacillus subtilis. Compounds 7c, 7m, 7u, 7v exhibited promising activities against above bacteria. Such four compounds were further tested for their inhibitory activity against SecA ATPase, and the results showed that compounds 7c and 7u had higher inhibitory activities than that of compound 2. Molecular docking work suggests that compound 7u might bind at a pocket close to the ATPase ATP-binding domain.     

Synthesis,antimicrobial and anti-biofilm activities of novel Schiff base analogues derived from methyl-12-aminooctadec-9-enoate

A novel library of Schiff base analogues (5a–q) were synthesized by the condensation of methyl-12-aminooctadec-9-enoate and different substituted aromatic aldehydes. The synthesized compounds were thoroughly characterized by spectroscopic techniques (FT-IR, ¹H NMR, ¹³C NMR, ESI-MS and HRMS). The Schiff base analogues with different substitutions were screened for in vitro antibacterial activity against 7 different bacterial strains. Among these, the compounds with electron withdrawing substituent, namely chlorine (5a) and electron donating substituents, namely hydroxy (5n) and methoxy (5o), were found to exhibit excellent to good antimicrobial activities (MIC value 9–18 μM) against Staphylococcus aureus MTCC 96, Staphylococcus aureus MLS-16 MTCC 2940 and Bacillus subtilis MTCC 121. The products were also screened for anti-biofilm and MBC (Minimum Bactericidal Concentration) activities which exhibited promising activities.     

Design,synthesis and antifungal activity of amide and imine derivatives containing a kakuol moiety

In continuation of our program to discover new potential antifungal agents, a series of amide and imine derivatives containing a kakuol moiety were synthesized and characterized by the spectroscopic analysis. By using the mycelium growth rate method, the target compounds were evaluated systematically for antifungal activities in vitro against four plant pathogenic fungi, and structure–activity relationships (SAR) were derived. Compounds 7d, 7e, 7h, 7i and 7r showed obvious inhibitory activity against the corresponding tested fungi at 50 μg/mL. Especially, compounds 7e and 7r displayed more potent antifungal activity against B. cinerea than that of thiabendazole (a positive control). Moreover, compound 7e also exhibited good activity against A. alternata with EC₅₀ values of 11.0 µg/mL, and the value was slightly superior to that of thiabendazole (EC₅₀ = 14.9 µg/mL). SAR analysis showed that the ether group was a highly sensitive structural moiety to the activity and the type as well as position of substituents on benzene ring could make some effects on the activity.     

Metal-based biologically active azoles and β-lactams derived from sulfa drugs

Metal complexes of Schiff bases derived from sulfamethoxazole (SMZ) and sulfathiazole (STZ), converted to their β-lactam derivatives have been synthesized and experimentally characterized by elemental analysis, spectral (IR, ¹H NMR, ¹³C NMR, and EI-mass), molar conductance measurements and thermal analysis techniques. The structural and electronic properties of the studied molecules were investigated theoretically by performing density functional theory (DFT) to access reliable results to the experimental values. The spectral and thermal analysis reveals that the Schiff bases act as bidentate ligands via the coordination of azomethine nitrogen to metal ions as well as the proton displacement from the phenolic group through the metal ions; therefore, Cu complexes can attain the square planner arrangement and Zn complexes have a distorted tetrahedral structure. The thermogravimetric (TG/DTG) analyses confirm high stability for all complexes followed by thermal decomposition in different steps. In addition, the antibacterial activities of synthesized compounds have been screened in vitro against various pathogenic bacterial species. Inspection of the results revealed that all newly synthesized complexes individually exhibit varying degrees of inhibitory effects on the growth of the tested bacterial species, therefore, they may be considered as drug candidates for bacterial pathogens. The free Schiff base ligands (1–2) exhibited a broad spectrum antibacterial activity against Gram negative Escherichia coli, Pseudomonas aeruginosa, and Proteus spp., and Gram positive Staphylococcus aureus bacterial strains. The results also indicated that the β-lactam derivatives (3–4) have high antibacterial activities on Gram positive bacteria as well as the metal complexes (5–8), particularly Zn complexes, have a significant activity against all Gram negative bacterial strains. It has been shown that the metal complexes have significantly higher activity than corresponding ligands due to chelation process which reduces the polarity of metal ion by coordinating with ligands.     

Design,synthesis and biological activities of sorafenib derivatives as antitumor agents

A series of novel sorafenib derivatives, 9a–w, was designed and synthesized in high yields using various substituted anilines, and their antiproliferative activities against HCT116, PC-3 and MDA-MB-231 cell lines were also evaluated and described. All compounds exhibited potent antiproliferative activity against HCT116 and PC-3 cells with IC₅₀ = 2.8–52.0 and 2.2–45.6 μM; compounds 9p and 9q demonstrated competitive antiproliferative activities to sorafenib against all three cancer cell lines, the cytotoxicity of compound 9r is more potent than that of sorafenib. Compounds (9g, 9p, 9q and 9r) were chosen for further evaluation of the anti-angiogenesis activity, and showed the inhibition of sprout formation from aortic ring ex vivo. The structures of all the newly synthesized compounds were determined by ¹H NMR, ¹³C NMR and HRMS.     

Synthesis and biological evaluation of rhodanine derivatives bearing a quinoline moiety as potent antimicrobial agents

Three series of rhodanine derivatives bearing a quinoline moiety (6a–h, 7a–g, and 8a–e) have been synthesized, characterized, and evaluated as antibacterial agents. The majority of these compounds showed potent antibacterial activities against several different strains of Gram-positive bacteria, including multidrug-resistant clinical isolates. Of the compounds tested, 6g and 8c were identified as the most effective with minimum inhibitory concentration (MIC) values of 1 μg/mL against multidrug-resistant Gram-positive organisms, including methicillin-resistant and quinolone-resistant Staphylococcus aureus (MRSA and QRSA, respectively). None of the compounds exhibited any activity against the Gram-negative bacteria Escherichia coli 1356 at 64 μg/mL. The cytotoxic activity assay showed that compounds 6g, 7g and 8e exhibited in vitro antibacterial activity at non-cytotoxic concentrations. Thus, these studies suggest that rhodanine derivatives bearing a quinoline moiety are interesting scaffolds for the development of novel Gram-positive antibacterial agents.     

Synthesis and biological evaluation of water-soluble derivatives of chiral gossypol as HIV fusion inhibitors targeting gp41

A series of novel or known water-soluble derivatives of chiral gossypol were synthesized and screened in vitro for their anti-HIV-1 activity. (?)-gossypol derivative was more active against HIV-1 than the corresponding (+)-gossypol derivative, respectively. Among these derivatives, d-glucosamine derivative of (?)-gossypol, oligopeptide derivative of (?)-gossypol and taurine derivative of (?)-gossypol, such as compounds 1a, 3a and 14a, showed significant inhibitory activities against HIV-1 replication, HIV-1 mediated cell-cell fusion and HIV gp41 6-helix bundle formation as some amino acid derivatives of (?)-gossypol.     

Synthesis,antitumor activity evaluation and mechanistic study of novel hederacolchiside A1 derivatives bearing an aryl triazole moiety

In an attempt to arrive at a more potent antitumor agent than the parent natural saponin hederacolchiside A₁, 23 hederacolchiside A₁ derivatives (4a-4w) were synthesized via Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition and screened in vitro for cytotoxicity against six human cancer cell lines. The structure-activity relationship of these compounds was elucidated, and the biological screening results showed that most of the compounds exhibited moderate to high levels of antitumor activities against the tested cell lines and some of them displayed more potent inhibitory activities compared with hederacolchiside A₁. Compound 4f showed a 2- to 7-fold more potent activity than hederacolchiside A₁. The mechanistic study of 4f revealed that this compound can induce cell apoptosis in HepG2 cells via mitochondrial-mediated intrinsic pathways.     

Design,synthesis and biological activity of novel tacrine-isatin Schiff base hybrid derivatives

A series of novel tacrine-isatin Schiff base hybrid derivatives (7a-p) were designed, synthesized and evaluated as multi-target candidates against Alzheimer’s disease (AD). The biological assays indicated that most of these compounds displayed potent inhibitory activity toward acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) and specific selectivity for AChE over BuChE. It was also found that they act as excellent metal chelators. The compounds 7k and 7m were found to be good inhibitors of AChE-induced amyloid-beta (Aβ) aggregation. Most of the compounds inhibited AChE with the IC₅₀ values, ranging from 0.42 nM to 79.66 nM. Amongst them, 7k, 7m and 7p, all with a 6 carbon linker between tacrine and isatin Schiff base exhibited the strongest inhibitory activity against AChE with IC₅₀ values of 0.42 nM, 0.62 nM and 0.95 nM, respectively. They were 92-, 62- and 41-fold more active than tacrine (IC₅₀ = 38.72 nM) toward AChE. Most of the compounds also showed a potent BuChE inhibition among which 7d with an IC₅₀ value of 0.11 nM for BuChE is the most potent one (56-fold more potent than that of tacrine (IC₅₀ = 6.21 nM)). In addition, most compounds exhibited the highest metal chelating property. Kinetic and molecular modeling studies revealed that 7k is a mixed-type inhibitor, capable of binding to catalytic and peripheral site of AChE. Our findings make this hybrid scaffold an excellent candidate to modify current drugs in treating Alzheimer’s disease (AD).     

Synthesis and biological evaluation of arylpiperazine derivatives as potential anti-prostate cancer agents

A novel scaffold of arylpiperazine derivatives was discovered as potent androgen receptor (AR) antagonist through rational drug designation based on our pre-work, leading to the discovery of a series of new antiproliferative compounds. Compounds 10, 16, 27, 29 and 31 exhibited relatively strong antagonistic potency against AR and exhibited potent AR binding affinities, while compounds 5, 6, 10, 14, 16, 19, 21, 27 and 31 exhibited strong cytotoxic activities against LNCaP cells (AR-rich) as well as also displayed the higher activities than finasteride toward PC-3 (AR-deficient) and DU145 (AR-deficient). Docking study suggested that the most potent antagonist 16 mainly bind to AR ligand binding pocket (LBP) site through hydrogen bonding interactions. The structure-activity relationship (SAR) of these designed arylpiperazine derivatives was rationally explored and discussed. These results indicated that the novel scaffold compounds demonstrated a step towards the development of novel and improved AR antagonists, and promising candidates for future development were identified.     

Design and synthesis of new 7-(N-substituted-methyl)-camptothecin derivatives as potent cytotoxic agents

A series of novel 7-(N-substituted-methyl)-camptothecin derivatives was designed, synthesized, and evaluated for in vitro cytotoxicity against four human tumor cell lines, A-549, MDA-MB-231, KB, and KBvin. All of the derivatives showed promising in vitro cytotoxic activity against the tested tumor cell lines, with IC₅₀ values ranging from 0.0023 to 1.11 μM, and were as or more potent than topotecan. Compounds 9d, 9e, and 9r exhibited the highest antiproliferative activity among all prepared derivatives. Furthermore, all of the compounds were more potent than paclitaxel against the multidrug-resistant (MDR) KBvin subline. With a concise efficient synthesis and potent cytotoxic profiles, especially significant activity towards KBvin, compounds 9d, 9e, and 9r merit further development as a new generation of camptothecin-derived anticancer clinical trial candidates.     

Synthesis and antifungal activity of imidazo[1,2-b]pyridazine derivatives against phytopathogenic fungi

A series of 3,6-disubstituted imidazo[1,2-b]pyridazine derivatives have been synthesized and characterized with spectroscopic analyses. The antifungal activities of these compounds against nine phytopathogenic fungi were evaluated by the mycelium growth rate method. The in vitro antifungal bioassays indicated that most of compounds displayed excellent and broad-spectrum antifungal activities. Especially, compounds 4a, 4c, 4d, 4l and 4r exhibited 1.9–25.5 fold more potent than the commercially available fungicide hymexazol against Corn Curvalaria Leaf Spot (CL), Alternaria alternate (AA), Pyricularia oryzae (PO) and Alternaria brassicae (AB) strains. Structure-activity relationship analysis showed that the enhanced antifungal activity is significantly affected by the substituents on the benzene ring and pyridazine ring.     

Design,synthesis and evaluation of novel quinazoline-2,4-dione derivatives as chitin synthase inhibitors and antifungal agents

A series of novel 1-methyl-3-substituted quinazoline-2,4-dione derivatives were designed, synthesized, and characterized by ¹H NMR, ¹³C NMR and MS spectral data. Their inhibition against chitin synthase (CHS) and antifungal activities were evaluated in vitro. Results showed compounds 5b, 5c, 5e, 5f, 5j, 5k, 5l, and 5o had strong inhibitory potency against CHS. Compound 5c, which has the highest potency among these compounds, had a half-inhibition concentration (IC₅₀) of 0.08 mmol/L, while polyoxin B as positive drug had IC₅₀ of 0.18 mmol/L. These IC₅₀ values of compounds 5i, 5m, 5n, and 5s were greater than 0.75 mmol/L, which revealed that those compounds had weak inhibition activity against CHS. Moreover, most of these compounds exhibited moderate to excellent antifungal activities. In detail, to Candida albicans, the activities of compound 5g and 5k were 8-fold stronger than that of fluconazole and 4-fold stronger than that of polyoxin B; to Aspergillus flavus, the activities of 5g, 5l and 5o were16-fold stronger than that of fluconazole and 8-fold stronger than that of polyoxin B; to Cryptococcus neoformans, the minimum-inhibition-concentration (MIC) values of compounds 5c, 5d, 5e and 5l were comparable to those of fluconazole and polyoxin B. The antifungal activities of these compounds were positively correlated to their IC₅₀ values against CHS. Furthermore, these compounds had negligible actions to bacteria. Therefore, these compounds were promising selective antifungal agents.     

Design,synthesis, and biological evaluation of novel aminopyrimidinylisoindolines as AXL kinase inhibitors

A novel series of aminopyrimidinylisoindoline derivatives 1a-w having an aminopyrimidine scaffold as a hinge region binding motif were designed and synthesized. Among them, six compounds showed potent inhibitory activities against AXL kinase with IC₅₀ values of submicromolar range. Especially, compound 1u possessing (4-acetylpiperazin-1-yl)phenyl moiety exhibited extremely excellent efficacy (IC₅₀?=?<0.00050?μM). Their in vitro antiproliferative activities were tested over five cancer cell lines. Most compounds showed good antiproliferative activities against HeLa cell line. The kinase panel profiling of 50 different kinases and the selected inhibitory activities for the representative compound 1u were carried out. The compound 1u exhibited excellent inhibitory activities (IC₅₀?=?<0.00050, 0.025, and 0.050?μM for AXL, MER, and TYRO3, respectively) against TAM family, together with potent antiproliferative activity against MV4-11 cell line (GI₅₀?=?0.10?μM) related to acute myeloid leukemia (AML).     

Design,synthesis, and biological evaluation of 4-phenoxyquinoline derivatives as potent c-Met kinase inhibitor

A series of novel 4-phenoxyquinoline derivatives containing 3-oxo-3,4-dihydro-quinoxaline moiety were synthesized and evaluated for their antiproliferative activity against five human cancer cell lines (A549, H460, HT-29, MKN-45 and U87MG) in vitro. Most of the tested compounds exhibited more potent inhibitory activities than the positive control foretinib. Compound 1b, 1s and 1t were further examined for their inhibitory activity against c-Met kinase. The most promising compound 1s (with c-Met IC₅₀ value of 1.42 nM) showed remarkable cytotoxicity against A549, H460, HT-29, MKN45 and U87MG cell lines with IC₅₀ values of 0.39 μM, 0.18 μM, 0.38 μM, 0.81 μM, respectively. Their preliminary structure-activity relationships (SARs) study indicated that the replacement of the aromatic ring with the cyclohexane improved their antiproliferative activity.     

Pyrazolo[3,4-d]pyrimidine derivatives containing a Schiff base moiety as potential antiviral agents

A series of pyrazolo[3,4-d]pyrimidine derivatives containing a Schiff base moiety were synthesized, characterised, and evaluated for their activity against tobacco mosaic virus (TMV). Biological assays indicated that several of the derivatives exhibited significant activity against TMV. In particularly, compounds 5y and 5aa displayed excellent inactivating activity against TMV, with half maximal effective concentration (EC₅₀) values of 70.3 and 53.65?μg/mL, respectively, which were much better than that of ribavirin (150.45?μg/mL), and 5aa was superior to ningnanmycin (EC₅₀?=?55.35?μg/mL). Interactions of compounds 5y and 5aa with TMV coat protein (TMV-CP) were investigated using microscale thermophoresis and molecular docking. Compounds 5y and 5aa displayed strong binding capability to TMV-CP with dissociation constant (K_d) values of 22.6 and 9.8?μM, respectively. These findings indicate that pyrazolo[3,4-d]pyrimidine derivatives containing a Schiff base may be potential antiviral agents.     

Design,synthesis, and biological evaluation of novel 4-oxobenzo[d]1,2,3-triazin-benzylpyridinum derivatives as potent anti-Alzheimer agents

Novel 4-oxobenzo[d]1,2,3-triazin derivatives bearing pyridinium moiety 6a–q were synthesized and screened against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Most of the synthesized compounds showed good inhibitory activity against AChE. Among the synthesized compounds, the compound 6j exhibited the highest AChE inhibitory activity. It should be noted that these compounds displayed low anti-BuChE activity with the exception of the compound 6i, as it exhibited BuChE inhibitory activity more than donepezil. The kinetic study of the compound 6j revealed that this compound inhibited AChE in a mixed-type inhibition mode. This finding was also confirmed by the docking study. The latter study demonstrated that the compound 6j interacted with both the catalytic site and peripheral anionic site of the AChE active site. The compound 6j was also observed to have significant neuroprotective activity against H₂O₂-induced PC12 oxidative stress, but low activity against β-secretase.     

Structure-Plant Phytotoxic Activity Relationship of 7,7′-epoxylignanes, (+)- and (−)-verrucosin: Simplification on the aromatic ring substituents

The synthesized 7-aryl derivatives of (7R,7′S,8S,8′S)-(+)-verrucosin were applied to growth inhibitory activity test against ryegrass at 1 mM. 7-(3-Ethoxy-4-hydroxyphenyl) derivative 12 and 7-(2-hydroxyphenyl) derivative 4 showed comparable activity to those of (+)-verrucosin against the root (−95%) and the shoot (−60%), respectively. The growth inhibitory activity test against lettuce using synthesized 7-aryl derivatives of (7S,7′R,8R,8′R)-(−)-verrucosin at 1 mM showed that the activities of 7-(3-hydroxyphenyl) derivative 20 and 7-(3-ethoxy-4-hydroxyphenyl) derivative 28 are similar to that of (−)-verrucosin against the root (−95%). Against the shoot, 7-(3-hydroxyphenyl) derivative 20 showed higher activity (−80%) than that of (−)-verrucosin (−60%). As the next step, (7S,7′R,8R,8′R)-7-(3-hydroxyphenyl)-7′-aryl-(−)-verrucosin derivatives, in which the most effective 3-hydroxyphenyl group is employed as 7-aromatic ring, were synthesized for the assay against lettuce. In this experiment, 7′-(2-hydroxyphenyl) derivative 37 and 7′-(3-hydroxyphenyl) derivative 38 showed similar activity to that of derivative 20. The effect of 7- and 7′-aryl structures of 7,7′-epoxylignanes on the plant growth inhibitory activity was clarified. The 7- and 7′-aryl structures were simplified to show comparable activity to or higher activity than that of (−)-verrucosin. The plant growth inhibitory activity of a nutmeg component, (+)-fragransin C_3b, was estimated as −80% inhibition at 1 mM against ryegrass roots.