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Synthesis and biological evaluation of New Chloro / Acetoxy Substituted Isoindole Analogues as new tyrosine kinase inhibitors
... In this study, the ether cleavage reaction mechanism of norcantharimide derivatives using Ac2O and AcCl was examined in detail. The compounds used were synthesized and characterized by the NMR technique previously (Köse et al. 2017 and2020). Here, detailed NMR spectroscopy studies depending on the specified reaction time intervals, conversions between of trans-1,4-diacetates and trans-1,2-chloroacetates, and detailed and descriptive synthesis mechanisms of the products were discussed and explained, unlike in the previous work (Köse et al. 2020). ...
... The compounds used were synthesized and characterized by the NMR technique previously (Köse et al. 2017 and2020). Here, detailed NMR spectroscopy studies depending on the specified reaction time intervals, conversions between of trans-1,4-diacetates and trans-1,2-chloroacetates, and detailed and descriptive synthesis mechanisms of the products were discussed and explained, unlike in the previous work (Köse et al. 2020). Moreover, the products that formed at specified time intervals were identified and the data from these conversions were graphed. ...
... In contrast to our previous work, in this study, soft density functional theory (DFT) studies and computational calculations were performed. Computed energies of the products in the reactions were calculated using theoretical data (Köse et al. 2020). Physical and theoretical formation energy calculations were performed to better explain the mechanisms of the products obtained. ...
The aim in this study was first to explain, in detail the conversion of diacetates over time into chlorinated monoacetates following ether cleavage with AcCl of norcantharimide derivatives with the help of the NMR technique and second, to verify this conversion theoretically and computationally. Ether cleavage reactions of N-methyl, N-benzyl, and N-acetoxyethyl-substituted norcantharimide derivatives were performed with Ac2O or AcCl in the presence of H2SO4, and the mechanisms of these reactions were elucidated in detail. According to the 1H NMR analyses of aliquots from the reactions with AcCl, trans-1,4-diacetates formed firstly. Upon the continuation of the reaction, trans-1,4-diacetates transformed into trans-1,2-chloroacetates via an SN2' mechanism. Additionally, this explanation was further supported by the soft theoretical and physical calculations.
... More recently, in particular, we reported the synthesis of diacetoxy and chloroacetoxy substituted isoindole derivatives and their inhibitory effects on the viability of HeLa cells. 9 The best cytotoxic activity was determined in N-benzyl isoindole derivatives 3 and 4 ( Figure 2). ...
... The structure and individuality of the obtained substances were proved by nuclear magnetic resonance (NMR) analysis and elemental analysis. 9 2.1. Cell Cultures. ...
... Benzyl derivatives of isoindole-1,3-dione 3 and 4 were synthesized according to the method used in our previous work. 9 First, the cytotoxic effects of both compounds against A549-Luc cells were examined. IC 50 values of those drugs were calculated using the MTT activity assay. ...
The anticancer activity of N-benzylisoindole-1,3-dione derivatives was evaluated against adenocarcinoma (A549-Luc). First, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide activity assay studies of two isoindole-1,3-dione derivatives were performed against A549 cell lines. Both compounds showed inhibitory effects on the viability of A549 cells. Then, we explored the potential of these compounds as active ingredients by in vivo studies. Nude mice were given A549-luc lung cancer cells, and tumor growth was induced with a xenograft model. Then, nude mice were divided into three groups: the control group, compound 3 group, and compound 4 group. After application of each compound to the mice, tumor sizes, their survival, and weight were determined for 60 days. Furthermore, toxicological studies were performed to examine the effects of the drugs in mice. In addition to toxicological studies, histopathological analyses of organs taken from mice were performed, and the results were evaluated. The obtained results showed that both N-benzylisoindole derivatives are potential anticancer agents.
... Isoindoles are compounds revealing their own activity. It was reported that the IC 50 values of some isoindole derivatives against HeLa cells are placed between 140.60 and 383.82 µM [61]. Therefore, developed Pcs should present an optimal photostability. ...
Newly developed tetra- and octasubstituted methimazole-phthalocyanine conjugates as potential photosensitizers have been obtained. Synthesized intermediates and final products were characterized by the MALD-TOF technique and various NMR techniques, including 2D methods. Single-crystal X-ray diffraction was used to determine the crystal structures of dinitriles. The studied phthalocyanines revealed two typical absorption bands—the Soret band and the Q band. The most intense fluorescence was observed for octasubstituted magnesium(II) phthalocyanine in DMF (ΦFL = 0.022). The best singlet oxygen generators were octasubstituted magnesium(II) and zinc(II) phthalocyanines (Φ∆ 0.56 and 0.81, respectively). The studied compounds presented quantum yields of photodegradation at the level between 10−5 and 10−6. Due to their low solubility in a water environment, the liposomal formulations were prepared. Within the studied group, octasubstituted zinc(II) phthalocyanine at the concentration of 100 µM activated with red light showed the highest antibacterial activity against S. aureus equal to a 5.68 log reduction of bacterial growth.
3aR,4S,7R,7aS)‐2‐Alkyl/aryl‐3a,4,7,7a‐tetrahydro‐1H‐4,7‐epoxyisoindole‐1,3(2H)‐diones, which are norcantharimide derivatives, were synthesized and their effects on carbonic anhydrase I (hCA I) and II (hCA II), acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) inhibitory activity were investigated. For enzyme activity studies, hCA I and II isoenzymes purified from human erythrocytes and the commercially available enzymes AChE and BChE, which are both markers and significantly affect the known symptoms of Alzheimer's disease, were used. The two derivatives exerted efficient inhibition with IC50=4.530 nM (Ki=4.483) and 4.426 nM (Ki=4.696) against hCA I and with IC50=3.825 nM (Ki=3.854) and 3.457 nM (Ki=3.292) against hCA II, respectively. The another two derivatives exerted considerable inhibition with IC50=0.526 nM (Ki=0.224) and 0.575 nM (Ki=0.292) against AChE and with IC50=0.135 nM (Ki=0.057) and IC50=0.180 nM (Ki=0.070) against BChE, respectively. The compounds showed activity at the nanomolar level. These remarkable inhibition results were compared with those of standard inhibitors (acetazolamide for hCA I and II and tacrine for AChE and BChE) of each enzyme, reported, and graphed. In addition, molecular docking studies were carried out by in silico methods and the structure–activity relationship was discussed. The poses of compound 4 c are presented along with the ligand–receptor interaction against all metabolic enzymes.
In this study, synthesis of novel isoindole‐1,3‐dione analogues bearig halo, hydroxy, and acetoxy groups at the position 4,5,6 of the bicyclic imide ring was performed to examine their potential anticancer effects against some cell lines. A multistep chemical pathway was used to synthesize the derivatives. The cytotoxic effect of trisubstituted isoindole derivatives were evaluated by determining cellular viability using the MTT assay against A549, PC‐3, HeLa, Caco‐2, and MCF‐7 cell lines. The C‐2 selective ring‐opening products were obtained from the ring‐opening reaction of 5‐alkyl/aryl‐2‐hydroxyhexahydro‐4 H ‐oxireno[2,3‐e]isoindole‐4,6(5 H )‐diones with nucleophiles such as chloride (Cl ⁻ ) and bromide (Br ⁻ ) ions. In addition, the ring‐opening products halodiols were converted to their related acetates. The anticancer activity of synthesized isoindole‐1,3‐dione derivatives was investigated against HeLa, A549, MCF‐7, PC3, and Caco‐2 cells in vitro and resulted in varies cytotoxic effect depend on the group attached to the isoindole molecule. Furthermore, the evaluation of the antimicrobial action of trisubstituted isoindole derivatives against Gram‐positive ( Staphylococcus aureus ) and Gram‐negative ( Escherichia coli ) bacteria was assessed and found out selective inhibition of the both bacterial growth via different trisubstituted isoindole derivatives. The results of this work encourage further research on the potential utilization of trisubstituted isoindole derivatives as cytotoxic and antimicrobial agents.
Aziridine‐containing compounds have many biological activities, and particularly antitumor and antibacterial activities, due to the presence of an aziridine ring. The aim of this study was to synthesize four hybrid isoindol‐1,3‐dione analogues containing aziridine units (8a‐d) and evaluate their cytotoxic potential against the A549, MCF7, and PC3 cell lines. A549, MCF7, and PC3 cells exposed to each obtained compound at doses of 5 μM, 25 μM, and 100 μM were incubated for 24 h and 8c was found to exhibit obvious anticancer activity against all three cancer cell lines. Further apoptosis assays and in vitro wound healing tests were performed and the results were evaluated. This article is protected by copyright. All rights reserved.
A palladium-catalyzed strategy for isoindole N-oxide ring construction by C-H functionalization of aldonitrones is described. Our protocol is of general character, providing isoindole N-oxides with a variety of functional groups, including very sterically congested products. Further transformations into spirocyclic isoindolines, isoindoles, or a polycyclic isoquinolinium salt have been demonstrated as well. A mechanistic study suggests that the catalytic process proceeds via a Heck-type addition to the double C═N bond.
The ring-opening reactions of (1aS,2S,6bR)-5-ethyl-2-hydroxyhexahydro-4H-oxireno[2,3-e]isoindole-4,6(5H)-dione were investigated under very mild and nonchelated conditions. C-2 selective ring-opening products were obtained with nucleophilic additions such as Cl⁻, Br⁻ and N3⁻. The exact configuration of (3aS,4R,5R,6S,7aS)-5-chloro-2-ethyl-4,6-dihydroxyhexahydro-1H-isoindole-1,3(2H)-dione was determined by X-ray diffraction analysis which was obtained from the reaction of epoxy alcohol with HCl . On the other hand, theoretical computations were carried out to explain the regioselectivity in the ring opening reaction of epoxy alcohols. The results showed that the ring-opening reaction of both epoxy alcohols proceeds in a kinetically controlled manner and regioselectivity occurs depending on the transition state.
In this study, the reaction of 2-(benzyl/ethyl/phenyl/methyl)-3a,4,7,7a-tetrahydro-1Hisoindole-1,3-(2H)-dione compounds with m-CPBA (m-chloroperbenzoic acid) has been examined. Syn-epoxides were obtained as the main product from the epoxidation reactions. Then, ring opening reactions of syn-epoxides with HBr and HCl were carried out. Eight different isoindole derivatives containing halohydrin units were synthesized from epoxide ring opening reactions in stereocontrol. The structures of the synthesized compounds were elucidated using spectroscopic methods. Thus, starting or precursor compounds were obtained for the synthesis of polyfunctional derivatives containing isoindole-1,3-dione main skeletal structure using easy and applicable methods.
In this work, seven new norcantharimide derivatives were synthesized by an acidolysis method. The compounds were prepared by acidolyzing trans‐1,4‐diacetate and trans‐1,2‐chloroacetate structures, which were obtained by stereospecific cleavage of the internal etheric bond of the tricyclic imides. The HCl(gas) was produced from the reaction of H2SO4 with NaCl. The resulting gas was bubbled into the reaction mixture. Trans‐1,4‐diacetate and trans‐1,2‐chloroacetate were thus acidolyzed, and the corresponding diol and halohydrin products were obtained respectively in moderate overall yields from low cost starting materials, using simple and easily scalable chemistry. The products were characterized by means of spectroscopic techniques. The synthesized compounds have high potential as anticancer agents and can be valuable for studies in this area.
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Several D-(+)-camphoric acid imides, not previously described in the literature, were synthesized with good yields. The synthesis of
previously known imides was improved. The cytotoxicity and antiviral activity of all synthesized imides were studied.
A series of novel Norcantharimide derivatives were synthesized and their structures were characterized by FTIR, ¹H and ¹³C NMR spectroscopy as well as elemental analyses. The absorption, distribution, metabolism and excretion (ADME) properties of the synthesized molecules were investigated. The results obtained in silico demonstrated that these molecules can be considered as orally active drug candidates due to their physicochemical properties. Also, docking studies demonstrated that all derivatives exhibit a good theoretical affinity with MolDock Score in between 124–138 against the main protease of Coronavirus Disease 2019 (COVID‐19 Mpr°) that caused worldwide epidemics. We believe that newly synthesized norcantharimide derivatives can guide many future studies in organic synthesis, medicine and pharmaceutical applications.
We have developed a versatile synthetic approach for the synthesis of new isoindole derivatives via the cleavage of ethers from tricyclic imide skeleton compounds. An exo-cycloadduct prepared from the Diels–Alder reaction of furan and maleic anhydride furnished imide derivatives. The epoxide ring was opened with Ac2O in the presence of a catalytic amount of H2SO4 in order to yield new isoindole derivatives (8a and 8b). The anticancer activity of these compounds was evaluated against MCF-7 (breast adenocarcinoma) and A549 (adenocarcinomic human alveolar basal epithelial) cell lines. The synthesized compounds showed concentration- and time-dependent inhibitory effects on the viability of both cell lines. Compound 8a was more toxic compared to 8b in both cancer cell lines, having higher cytotoxicity against A549 cells. Testing the toxicity properties of these compounds on the BEAS 2B (human bronchial epithelial) cell line indicated that while both compounds decreased the cell viability of cancer cells, they were less toxic on healthy lung cells. Microscopy images of A549 cells after treatment with the new isoindole derivatives displayed characteristic apoptotic morphology compared to BEAS 2B cells. The results demonstrated here suggest that these new compounds might be considered as possible potential anticancer agents for the treatment of lung and breast cancer.
The natural agent, 1-(2-hydroxy-5-methylphenyl)-3-phenyl-1,3-propanedione (HMDB), has been reported to have growth inhibitory effects on several human cancer cells. However, the role of HMDB in cervical cancer remains unclear. Herein, we found that HMDB dose- and time-dependently inhibited growth of HeLa cervical cancer cells, accompanied with G1 cell cycle arrest. HMDB decreased protein expression of cyclins D1/D3/E and cyclin-dependent kinases (CDKs) 2/4/6 and reciprocally increased mRNA and protein levels of CDK inhibitors (p15, p16, p21, and p27), thereby leading to the accumulation of hypophosphorylated retinoblastoma (Rb) protein. HMDB also triggered the accumulation of acidic vesicles and formation of microtubule-associated protein-light chain 3 (LC3), followed by increased expression of LC3 and Beclin-1 and decreased expression of p62, suggesting that HMDB triggered autophagy in HeLa cells. Meanwhile, suppression of the expression of survivin and Bcl-2 implied that HMDB-induced autophagy is tightly linked to apoptosis. Exploring the action mechanism, HMDB induced autophagy via the modulation of AMP-activated protein kinase (AMPK) and mTOR signaling pathway rather than the class III phosphatidylinositol 3-kinase pathway. These results suggest that HMDB inhibits HeLa cell growth by eliciting a G1 arrest through modulation of G1 cell cycle regulators and by concomitantly inducing autophagy through the mediation of AMPK-mTOR and Akt-mTOR pathways, and may be a promising antitumor agent against cervical cancer.
Marine bacterium, strain MB30 isolated from the deep sea sediment of Bay of Bengal, India, exhibited antimicrobial activity against human pathogenic bacteria. Based on the 16S rRNA sequence homology and subsequent phylogenetic tree analysis, the strain MB30 was identified as Staphylococcus sp. The bioactive metabolite produced by the strain MB30 was purified through silica gel column chromatography and preparative HPLC. Purified metabolite was further characterized by FT-IR, LC-MS and NMR analyses. On the basis of spectroscopic data, the metabolite was identified as pyrrole (1, 2, a) pyrazine 1, 4, dione, hexahydro 3-(2-methyl propyl) (PPDHMP). The PPDHMP exhibited in vitro anticancer potential against lung (A549) and cervical (HeLa) cancer cells in a dose-dependent manner with the IC50 concentration of 19.94 ± 1.23 and 16.73 ± 1.78 μg ml(-1) respectively. The acridine orange (AO)/ethidium bromide (EB) and 4,6-diamidino-2-phenylindole dihydrochloride (DAPI) staining of the IC50 concentration of PPDHMP-treated cancer cells exhibited an array of morphological changes such as nuclear condensation, cell shrinkage and formation of apoptotic bodies. The PPDHMP-treated cancer cells induced the progressive accumulation of fragmented DNA in a time-dependent manner. Based on the flow cytometric analysis, it has become evident that the compound was also effective in arresting the cell cycle at G1 phase. Further, the Western blotting analysis confirmed the down-regulation of cyclin-D1, cyclin dependent kinase (CDK-2), anti-apoptotic Bcl-2 family proteins (Bcl-2 and Bcl-xL), activation of caspase-9 and 3 with the cleavage of PARP. The PPDHMP-treated cancer cells also showed the inhibition of migration and invasive capacity of cancer cells. In the present investigation, for the first time, we have reported the extraction, purification and characterization of an anticancer metabolite, PPDHMP from a new marine bacterium, Staphylococcus sp. strain MB30.
The X-ray diffraction and spectroscopic properties of 1-amino-4-hydroxy-9,10-anthraquinone (1-AHAQ), a simple analogue of anthracycline chemotherapeutic drugs were studied by adopting experimental and computational methods. The optimized geometrical parameters obtained from computational methods were compared with the results of X-ray diffraction analysis and the two were found to be in reasonably good agreement. X-ray diffraction study, DFT and NBO analysis indicated two types of hydrogen bonds in the molecule. The IR spectra of 1-AHAQ were studied by Vibrational Energy Distribution Analysis (VEDA) using potential energy distribution (PED) analysis. The electronic spectra were studied by TDDFT computation and compared with the experimental results. Experimental and theoretical results corroborated each other to a fair extent. To understand the biological efficacy of 1-AHAQ, it was allowed to interact with calf thymus DNA and human breast adino-carcinoma cell MDA-MB-231. It was found that the molecule induces apoptosis in this adinocarcinoma cell, with little, if any, cytotoxic effect in HBL-100 normal breast epithelial cell.
Sixteen new phthalimide derivatives were synthesized and evaluated for their in vitro anti-microbial, anti-oxidant and anti-inflammatory activities. The cytotoxicity for all synthesized compounds was also determined in cancer cell lines and in normal human cells. None of the target derivatives had any cytotoxic activity. (ZE)-2-[4-(1-Hydrazono-ethyl) phenyl]isoindoline-1,3-dione (12) showed remarkable anti-microbial activity. Its activity against Bacillus subtilis was 133%, 106% and 88.8% when compared with the standard antibiotics ampicillin, cefotaxime and gentamicin, respectively. Compound 12 also showed its highest activities in Gram negative bacteria against Pseudomonas aeruginosa where the percentage activities were 75% and 57.6% when compared sequentially with the standard antibiotics cefotaxime and gentamicin. It was also found that the compounds 2-[4-(4-ethyl-3-methyl-5-thioxo-1,2,4-triazolidin-3-yl)phenyl]isoindoline-1,3-dione (13b) and 2-[4-(3-methyl-5-thioxo-4-phenyl-1,2,4-triazolidin-3-yl)phenyl]isoindoline-1,3-dione (13c) had anti-oxidant activity. 4-(N'-{1-[4-(1,3-Dioxo-1,3-dihydro-isoindol-2-yl)-phenyl]-ethylidene}-hydrazino)-benzenesulfonamide (17c) showed the highest in vitro anti-inflammatory activity of the tested compounds (a decrease of 32%). To determine the mechanism of the anti-inflammatory activity of 17c, a docking study was carried out on the COX-2 enzyme. The results confirmed that 17c had a higher binding energy score (-17.89 kcal/mol) than that of the ligand celecoxib (-17.27 kcal/mol).
New types of norcantharimide analogues were prepared by three methods: epoxidation, photooxidation, and bromination. Epoxidation of deoxynorcantharimide with m-chloroperoxybenzoic acid gave an isomeric mixture. The selective formation of the synisomers was attributed to dipole-dipole interactions between the peracid and imide moiety. Photooxidation of deoxynorcanthamide gave syn- and anti- hydroperoxide analogues through ene addition of singlet oxygen; the anti-hydroperoxide was the major product in this case, as a result of the steric effect of the imide ring. Bromination of deoxynorcantharimide and subsequent transformations gave a pyrrolidine and the phthalimide core structure.
Three new polysubstituted isoindole-1,3-diones were prepared from 2-ethyl-5-hydroxy-3a,4,5,7a-tetrahydroisoindole-1,3-dione. The reaction of 2-ethyl-5-hydroxy-3a,4,5,7a-tetrahydro-isoindole-1,3-dione with m-CPBA gave the corresponding epoxide. The triacetate derivative was obtained via cis-hydroxylation using OsO4, followed by acetylation. An aromatic derivative, a secondary reaction product, was also formed during the acetylation. Finally, a tricyclic derivative from 2-ethyl-5-hydroxy-3a,4,5,7a- tetrahydro-isoindole-1,3-dione was synthesized via dichloroketene addition under microwave irradiation. The exact structures of epoxide and tricyclic derivatives were determined by X-ray diffraction analysis.
This research attempted to study the effect of lipophilicity on the anticancer activity of N-substituted norcantharimide derivatives. Twenty-three compounds were synthesized and their cytotoxicities against five human cancer cell lines studied. The lipophilicity of each derivative was altered by its substituent, an alkyl, alkyloxy, terpenyl or terpenyloxy group at the N-position of norcantharimide. Further, among all synthesized derivatives studied, the compounds N-farnesyloxy-7-oxabicyclo[2.2.1]heptane-2,3-dicarboximide (9), and N-farnesyl-7-oxabicyclo[2.2.1]heptane-2,3-dicarboximide (18), have shown the highest cytotoxicity, anti-proliferative and apoptotic effect against human liver carcinoma HepG2 cell lines, yet displayed no significant cytotoxic effect on normal murine embryonic liver BNL CL.2 cells. Their overall performance led us to believe that these two compounds might be potential candidates for anticancer drugs development.
The activity of the ribosome protein subunit 6 kinase 1 (S6K1) is stimulated by phosphorylation of Thr389 in the hydrophobic motif by mTORC1 and phosphorylation of Thr229 in the activation loop by PDK1; however, the order of the two events is still ambiguous. Here we report six crystal structures of the S6K1 kinase domain alone or plus the hydrophobic motif in various forms, in complexes with a highly specific inhibitor. The structural data together with the biochemical data reveal in vivo phosphorylation of Thr389 in the absence of Thr229 phosphorylation and demonstrate the importance of two conserved residues, Gln140 and Arg121, in the establishment of a hydrogen-bonding network between the N-lobe and the hydrophobic motif. Phosphorylation of Thr389 or introduction of a corresponding negatively charged group leads to reinforcement of the network and stabilization of helix αC. Furthermore, comparisons of S6K1 with other AGC family kinases suggest that the structural and sequence differences in the hydrophobic motif and helix αC account for their divergence in PDK1 dependency. Together, these results indicate that phosphorylation of the hydrophobic motif in S6K1 is independent of and probably, precedes and promotes phosphorylation of the activation loop.
A new method, called Protonate3D, is presented for the automated prediction of hydrogen coordinates given the 3D coordinates of the heavy atoms of a macromolecular structure. Protonate3D considers side-chain "flip," rotamer, tautomer, and ionization states of all chemical groups, ligands, and solvent, provided suitable templates are available in a parameter file. The energy model includes van der Waals, Coulomb, solvation, rotamer, tautomer, and titration effects. The results of computational validation experiments suggest that Protonate3D can accurately predict the location of hydrogen atoms in macromolecular structures.
The Protein Data Bank (PDB; http://www.rcsb.org/pdb/ ) is the single worldwide archive of structural data of biological macromolecules. This paper describes the goals of the PDB, the systems in place for data deposition and access, how to obtain further information, and near-term plans for the future development of the resource.
We made an effort to prepare effective cantharidinimides by heating the reactants 1 and 2a-j to 200 degreesC with toluene and triethylamine to provide 10 N-thiazolyl-and N-thiadiazolylcantharidinimides 3a-j in high yields of;48-91%. All of the synthetic compounds were tested for their capability to suppress growth of the human hepatocellular carcinoma cell lines, SK-Hep-1 and Hep 3B. The results showed that compound 3f was the most potent, and it was more cytotoxic than cantharidin. (C) 2000 Academic Press.
New series of isoindoline-1,3-diones 2-9, pyrazolo[5,1-a]isoindoles 10-14, and pyridines 16-18 were synthesized. Twenty of the synthesized compounds were screened for their antibacterial activity against S. aureus, B. cereus, and E. coli. Compound 5 was proved to be the most active member in this study, showing the highest antibacterial activity against the three selected microorganisms. The antifungal activity of these compounds was also tested against C. albicans and A. flavus 3375. Compounds 4, 5, 8, and 17a exhibited the best antifungal activity against A. flavus 3375. The same compounds were examined for their antiquorum-sensing activity against Ch. violacium ATCC 12472, whereas compound 5 displayed strong antiquorum-sensing activity. The in vitro cytotoxicity testing of compounds 4-9 and 17a against human normal lung fibroblast (W138) cell line revealed that compounds 4, 5, and 8 are the least cytotoxic analogs in this study. In vivo acute toxicity testing of compounds 4, 5, and 8 was performed. The DNA-binding affinity of compounds 4-9 and 17a was also tested and the obtained results showed that all tested compounds have moderate DNA-binding affinity.
© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
The Protein Data Bank (PDB; http://www.rcsb.org/pdb/ ) is the single worldwide archive of structural data of biological macromolecules. This paper describes the goals of the PDB, the systems in place for data deposition and access, how to obtain further information, and near-term plans for the future development of the resource.
A new and convenient synthesis for amino-phthalimide (1H-isoindole-1,3(2H)-dione) derivatives
has been developed starting from an a,b-unsaturated ketone. The ketones were reacted with amines to
give aromatic amine products. This is the first time that substituted amine groups have been incorporated
in aromatic rings. The mechanism of the product formation is rationalized by the 1,2-addition of amines
to ketones. All aromatic compounds exhibited high fluorescence properties at the blue-green region.
The effects of structural modification of cantharidin on the inhibition of protein Ser/Thr phosphatases are described. Removal of the methyl substituents at C2 and C3 in cantharidin improved the inhibition of PP2B. In contrast, introduction of a substituent to C1/C4-position drastically decreased inhibition of PP1 and PP2A1. PP2B was found to be quite tolerant to modifications at the C5 position.
Chemical and pharmacological information on cantharidin-based SMs was analyzed. The review summarizes new facts about blister beetles metabolites for the period 2006-2012. General synthetic approaches to cantharidin-based small molecules as well as its chemical transformations and the biological activities related with cantharidin, norcantharidin, cantharidimide and norcantharimide analogues, specially their inhibitory activity of phosphoprotein phosphatases in cancer treatment, were discussed in this mini review that could help to design new small molecules modulators for other biological models. This article is protected by copyright. All rights reserved.
The hydroperoxy endoperoxide 3, obtained by photooxygenation of isotetralin (= 1,4,5,8-tetrahydronaphthalene; 1), was reduced with thiourea, and the resulting intermediate 4 was converted, after acetylation with acetyl chloride, to the interesting, double-chlorinated acetate 5 in an unprecedented tandem reaction (Scheme 1). The structures and relative configurations of 3 and 5 were determined by NMR spectroscopy and by single-crystal X-ray-diffraction analyses (Figs. 1 and 2, resp.). A mechanistic rationalization for the conversion of 4 to 5 is proposed (Scheme 2).
The mammalian target of rapamycin (mTOR), a phosphoinositide 3-kinase-related protein kinase, controls cell growth in response to nutrients and growth factors and is frequently deregulated in cancer. Here we report co-crystal structures of a complex of truncated mTOR and mammalian lethal with SEC13 protein 8 (mLST8) with an ATP transition state mimic and with ATP-site inhibitors. The structures reveal an intrinsically active kinase conformation, with catalytic residues and a catalytic mechanism remarkably similar to canonical protein kinases. The active site is highly recessed owing to the FKBP12-rapamycin-binding (FRB) domain and an inhibitory helix protruding from the catalytic cleft. mTOR-activating mutations map to the structural framework that holds these elements in place, indicating that the kinase is controlled by restricted access. In vitro biochemistry shows that the FRB domain acts as a gatekeeper, with its rapamycin-binding site interacting with substrates to grant them access to the restricted active site. Rapamycin-FKBP12 inhibits the kinase by directly blocking substrate recruitment and by further restricting active-site access. The structures also reveal active-site residues and conformational changes that underlie inhibitor potency and specificity.
We made an effort to prepare effective cantharidinimides by heating the reactants 1 and 2a-j to 200 degrees C with toluene and triethylamine to provide 10 N-thiazolyl- and N-thiadiazolylcantharidinimides 3a-j in high yields of 48-91%. All of the synthetic compounds were tested for their capability to suppress growth of the human hepatocellular carcinoma cell lines, SK-Hep-1 and Hep 3B. The results showed that compound 3f was the most potent, and it was more cytotoxic than cantharidin. Copyright 2000 Academic Press.
A tetrazolium salt has been used to develop a quantitative colorimetric assay for mammalian cell survival and proliferation. The assay detects living, but not dead cells and the signal generated is dependent on the degree of activation of the cells. This method can therefore be used to measure cytotoxicity, proliferation or activation. The results can be read on a multiwell scanning spectrophotometer (ELISA reader) and show a high degree of precision. No washing steps are used in the assay. The main advantages of the colorimetric assay are its rapidity and precision, and the lack of any radioisotope. We have used the assay to measure proliferative lymphokines, mitogen stimulations and complement-mediated lysis.
The open-ring series (IC50,PP1=2.0−4.8 μM, PP2A=0.2−0.5 μM)maintained the PP2A selectivity ofcantharidin (IC50, PP1=1.8 μM,PP2A=0.2 μM), although some were lesspotent. The closed-ring series (IC50,PP1 = 12.5->1000 μM,PP2A=5->1000 μM) were considerablyless potent inhibitors, confirming the needof ring opening for inhibition. Thecytotoxicity (IC50, 72 h, MTT assay) ofcantharidin ranged from 6−15 μM, whilethe new analogues ranged from 14 to>1000 μM. Cytotoxicity of the agentsdid not consistently parallel the invitro potency of protein phosphataseinhibition. A number of analogues showedcolon cancer selectivity, particularlyNovo-6, where the cytotoxicity ranged from14−88 μM in the colon cancer cells and275−680 μM in all other cell linesincluding normal colon cells. The reasonfor this selectivity was not apparent andmay involve additional intracellulartargets. Cell cycle analysis showedcantharidin to enhance cell cycleprogression as evident from an increasedS-phase population and enhanced DNAsynthesis, culminating in G2/M arrestand apoptosis. With Novo-1 and Novo-6, thecell cycle changes paralleled thecytotoxicity responses, with thepredominant effect of G2/M cell cyclearrest followed by cell death. Inconclusion, we have synthesised newanticancer agents that show selectivecytotoxicity in colon cancer cells whileremaining inactive in normal colon cells,and which mediate their effects viathe G2/M phase of the cell cycle.
Previous SAR studies (Part 1: Mai, A.; et al. J. Med. Chem. 2003, 46, 512-524) performed on some portions (pyrrole-C4, pyrrole-N1, and hydroxamate group) of 3-(4-benzoyl-1-methyl-1H-pyrrol-2-yl)-N-hydroxy-2-propenamide (1a) highlighted its 4-phenylacetyl (1b) and 4-cynnamoyl (1c) analogues as more potent compounds in inhibiting maize HD2 activity in vitro. In the present paper, we investigated the effect on anti-HD2 activity of chemical substitutions performed on the pyrrole-C2 ethene chains of 1a-c, which were replaced with methylene, ethylene, substituted ethene, and 1,3-butadiene chains (compounds 2). Biological results clearly indicated the unsubstituted ethene chain as the best structural motif to get the highest HDAC inhibitory activity, the sole exception to this rule being the introduction of the 1,3-butadienyl moiety into the 1a chemical structure (IC50(2f) = 0.77 microM; IC50(1a) = 3.8 microM). IC50 values of compounds 3, prepared as 1b homologues, revealed that between benzene and carbonyl groups at the pyrrole-C(4) position a hydrocarbon spacer length ranging from two to five methylenes is well accepted by the APHA template, being that 3a (two methylenes) and 3d (five methylenes) are more potent (2.3- and 1.4-fold, respectively) than 1b, while the introduction of a higher number of methylene units (see 3e,f) decreased the inhibitory activities of the derivatives. Particularly, 3a (IC50 = 0.043 microM) showed the same potency as SAHA in inhibiting HD2 in vitro, and it was 3000- and 2.6-fold more potent than sodium valproate and HC-toxin and was 4.3- and 6-fold less potent than trapoxin and TSA, respectively. Finally, conformationally constrained forms of 1b,c (compounds 4), prepared with the aim to obtain some information potentially useful for a future 3D-QSAR study, showed the same (4a,b) or higher (4c,d) HD2 inhibiting activities in comparison with those of the reference drugs. Molecular modeling and docking calculations on the designed compounds performed in parallel with the chemistry work fully supported the synthetic effort and gave insights into the binding mode of the more flexible APHA derivatives (i.e., 3a). Despite the difference of potency between 1b and 3a in the enzyme assay, the two APHA derivatives showed similar antiproliferative and cytodifferentiating activities in vivo on Friends MEL cells, being that 3a is more potent than 1b in the differentiation assay only at the highest tested dose (48 microM).
A remarkable control of the potency of cantharimide is described based on the electronic properties of functional group and it exhibits a relatively less toxic effect to the non-malignant hematological disorder bone marrow cells.
Norcantharidin (3) is a potent PP1 (IC(50)=9.0+/-1.4 microM) and PP2A (IC(50)=3.0+/-0.4 microM) inhibitor with 3-fold PP2A selectivity and induces growth inhibition (GI(50) approximately 45 microM) across a range of human cancer cell lines including those of colorectal (HT29, SW480), breast (MCF-7), ovarian (A2780), lung (H460), skin (A431), prostate (DU145), neuroblastoma (BE2-C), and glioblastoma (SJ-G2) origin. Until now limited modifications to the parent compound have been tolerated. Surprisingly, simple heterocyclic half-acid norcantharidin analogues are more active than the original lead compound, with the morphilino-substituted (9) being a more potent (IC(50)=2.8+/-0.10 microM) and selective (4.6-fold) PP2A inhibitor with greater in vitro cytotoxicity (GI(50) approximately 9.6 microM) relative to norcantharidin. The analogous thiomorpholine-substituted (10) displays increased PP1 inhibition (IC(50)=3.2+/-0 microM) and reduced PP2A inhibition (IC(50)=5.1+/-0.41 microM), to norcantharidin. Synthesis of the analogous cantharidin analogue (19) with incorporation of the amine nitrogen into the heterocycle further increases PP1 (IC(50)=5.9+/-2.2 microM) and PP2A (IC(50)=0.79+/-0.1 microM) inhibition and cell cytotoxicity (GI(50) approximately 3.3 microM). These analogues represent the most potent cantharidin analogues thus reported.
A range of amines was reacted with norcantharidin (2) to provide the corresponding norcantharimides (9-43). Treatment of norcantharidin with allylamine afforded the corresponding allyl-norcantharimide (20) which was amenable to epoxidation (mCPBA, 22) and subsequent ring opening (MeOH/H(+); 23) or alternatively, osmylation (OsO(4)/NMO; 24). These simple synthetic modifications of 2 facilitated the development of a novel series of norcantharimides displaying modest to good broad spectrum cytotoxicity against HT29 and SW480 (colorectal carcinoma); MCF-7 (breast adenocarcinoma); A2780 (ovarian carcinoma); H460 (lung carcinoma); A431 (epidermoid carcinoma); DU145 (prostate carcinoma); BE2-C (neuroblastoma); and SJ-G2 (glioblastoma). Analogues possessing a C(10), C(12) or C(14) alkyl chain or a C(12) linked bis-norcantharimide displayed the highest levels of cytotoxicity.
The early stages of the retro-Diels-Alder reaction are clearly apparent in the structures of the cycloadducts formed between furan or 5-trimethylsilylcyclopentadiene with maleic anhydride and N-methylmaleimide. The degree of lengthening of the C-C bonds that break in this reaction is clearly related to the known reactivity of these cycloadducts toward this reaction. In the structures of the cycloadducts 21 and 22 derived from 2-methoxyfuran, the early stages of an alternative fragmentation reaction are apparent, consistent with the reactivity of these compounds in solution.
A new generalized Born model for estimating the free energy of hydration is presented. The new generalized Born/volume integral (GB/VI) estimates the free energy of hydration as a classical electrostatic energy plus a cavitation energy that is not based upon atomic surface area (SA) used in GB/SA hydration models but on a VI London dispersion energy estimated from quantities already calculated in the classical electrostatic energy. The (relatively few) GB/VI model parameters are fitted to experimental data, and parameterizations for two different atomic partial charge models are presented. Comparison of the calculated and experimental free energies of hydration for 560 small molecules (both neutral and charged) shows good agreement (r(2) = 0.94).
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