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Novel acid mono azo dye, 2-[(E)-(8-hydroxyquinolin-5yl)-diazenyl]-4,5-dimethoxybenzoic acid (HQD), was synthesized by coupling diazonium salt solution of 2-amino-4,5-dimethoxybenzoic acid (DMA) with 8-hydroxyquinoline (HQ). This dye was characterized by UV-vis, IR & Raman, (1)H and (13)C NMR spectroscopic techniques and elemental analysis. The normal coordinate analysis of HQD was also performed to assign each band in vibrational spectra. DFT (B3LYP and B3PW91) calculations were employed to optimize the geometry, to interpret NMR spectra, to calculate and to determine the stable tautomeric structure of the compound. Natural Bond Orbital (NBO) analysis was performed to investigate intramolecular interactions. The vibrational spectral data obtained from solid phase IR & Raman spectra were assigned based on the results of the theoretical calculations. UV-vis spectroscopic technique was employed to obtain the optical band gap of HQD. The analysis of the optical absorption data revealed the existence of direct and indirect transitions in the optical band gaps. The optical band gaps of HQD have been found 1.95 and 1.90eV for direct and indirect transitions, respectively., (Published by Elsevier B.V.)

The first total synthesis of prasinic acid is being reported along with its biological evaluation. The ten step synthesis involved readily available and cheap starting materials and can easily be transposed to large scale manufacturing. The crucial steps of the synthesis included the formation of two different aromatic units (7 and 9) and their coupling reaction. The synthetic prasinic acid exhibited moderate antitumor activity (IC(50) 4.3-9.1 μM) in different lines of cancer cells., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

A new series of phenylcarbamoylbenzoic acid analogs were designed, synthesized, and evaluated for their in vitro antioxidant activity, aiming to find a lead for the treatment of oxidative stress. The target compounds were prepared by substituting the core phenylcarbamoylbenzoic acid moiety with certain functionalities via simple and efficient synthetic strategies. A molecular modeling study was performed to evaluate the recognition of target compounds at the 3MNG binding pocket. The docking data revealed that compounds 8c and 9a selectively bind to the crucial amino acid residues in the active site of 3MNG. The in vitro antioxidant activity was determined by ABTS antioxidant assay. Compounds 8c, 9a, and 9b showed high antioxidant activity and are thus promising as potent antioxidant leads., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Glucagon-like peptide 2 (GLP-2) is an intestinotropic peptide that binds to GLP-2 receptor (GLP-2R), a class-B G protein-coupled receptor (GPCR). Few synthetic agonists have been reported so far for class-B GPCRs. Here, we report the first scaffold compounds of ago-allosteric modulators for human GLP-2R, derived from methyl 2-{[(2Z)-2-(2,5-dichlorothiophen-3-yl)-2-(hydroxyimino)ethyl]sulfanyl}benzoate (compound 1)., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Silicon chemistry offers the potential to tune the effects of biologically active organic molecules. Subtle changes in the molecular backbone caused by the exchange of a carbon atom for a silicon atom (sila-substitution) can significantly alter the biological properties. In this study, the biological effects of a two-fold sila-substitution in the synthetic retinoids EC23 (4-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalen-2-ylethynyl)benzoic acid (4a)) and TTNN (6-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalen-2-yl)-2-naphthoic acid (7a)) as well as their corresponding analogues with an indane instead of a 1,2,3,4-tetrahydronaphthalene skeleton (compounds 5a and 8a) were investigated. Two-fold C/Si exchange in 4a, 5a, 7a and 8a leads to the silicon-analogues disila-EC23 (4b), 5b, disila-TTNN (7b) and 8b, which contain a 1,2,3,4-tetrahydro-1,4-disilanaphthalene (4b, 7b) or 1,3-disilaindane skeleton (5b, 8b). Exchange of the SiCH(2)Si moiety of 5b for an SiOSi fragment leads to the disiloxane 6 (2-oxa-1,3-disilaindane skeleton). The EC23 derivative 5a, the TTNN derivative 8a and the silicon-containing analogues 4b, 5b, 6, 7b and 8b were synthesised, and the biological properties of the C/Si pairs 4a/4b, 5a/5b, 7a/7b and 8a/8b and compound 6 were evaluated in vivo using RAR isotype-selective reporter cells. EC23 (4a) and its derivatives disila-EC23 (4b), 5a, 5b and 6 are very potent RAR agonists, which are even more potent than the powerful reference compound TTNPB. Disila-substitution of EC23 (4a) and 5a leads to a moderate decrease in RARα activation, whereas the RARβ,γ activation is almost not affected. In contrast, two-fold C/Si exchange in the weak retinoid agonist TTNN (7a) and 8a resulted in considerably different effects: a significant increase (7a→7b) and almost no change (8a→8b) in transcription activation potential for all three RAR isotypes. Disila-TTNN (7b) can be regarded as a powerful RARβ,γ-selective retinoid.

RGD peptides, radiolabeled with (18)F, have been used in the clinic for PET imaging of tumor angiogenesis in cancer patients. RGD peptides are typically labeled using a prosthetic group such as N-succinimidyl 4-[(18)F]-fluorobenzoate ([(18)F]SFB) or 4-nitrophenyl 2-[(18)F]-fluoropropionate ([(18)F]NPFP). However, the complex radiosynthetic procedures have impeded their broad application in clinical studies. We previously radiolabeled proteins and peptides with the prosthetic group, N-succinimidyl 4-[(18)F]-fluoromethylbenzoate ([(18)F]SFMB), which was prepared in a simple one-step procedure. In this study, we labeled a PEGylated cyclic RGD peptide dimer, PEG(3)-E[c(RGDyK)](2) (PRGD2), using [(18)F]SFMB and evaluated for imaging tumor αvβ3 integrin expression with positron emission tomography (PET). [(18)F]SFMB was prepared in one step using [(18)F]fluoride displacement of a nitrobenzenesulfonate leaving group under mild reaction conditions followed by HPLC purification. The (18)F-labeled peptide, [(18)F]FMBPRGD2 was prepared by coupling PRGD2 with [(18)F]SFMB in pH 8.6 borate buffer and purified with HPLC. The direct labeling on BMBPRGD2 was also attempted. A Siemens Inveon PET was used to image the uptake of the [(18)F]FMBPRGD2 into a U87MG xenograft mouse model. [(18)F]FMBPRGD2, was prepared with a 15% overall radiochemical yield (uncorrected) in a total synthesis time of 90 min, which was considerably shorter than the preparation of [(18)F]SFB- and [(18)F]NPFP-labeled RGD peptides. The direct labeling, however, was not successful. High quality microPET images using [(18)F]FMBPRGD2 clearly visualized tumors by 15 min with good target to background ratio. Early tracer accumulation in the bladder suggests fast renal clearance. No obvious bone uptake can be detected even at 4-h time point indicating that fluorine attachment is stable in mice. In conclusion, N-succinimidyl 4-[(18)F]-fluoromethylbenzoate ([(18)F]SFMB) prosthetic group can be a good alternative for labeling RGD peptides to image αvβ3 integrin expression and for labeling other peptides.

Metronidazole thiosalicylate conjugates were synthesized and crystallised in order to discover new molecules having better efficacy than therapeutically administered drug metronidazole, used against Entamoeba histolytica. The three compounds (4-6) showed lower IC(50) values than metronidazole on HM1:IMSS strain of E. histolytica and displayed low cytotoxicity on MCF-7 cell line. In order to get an insight into the mechanisms of action of these compounds, a homology model of E. histolytica thioredoxin reductase (EhTHRase) was constructed and molecular docking was performed into the binding pocket to identify the nature of interactions. The docking studies suggest that the improved inhibitory activity of the newly synthesised metronidazole analogues could be due to involvement of the additional hydrophobic interactions in the binding mode. The result of the present study indicates the molecular fragments that play an essential role in improving the antiamoebic activity., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Searching for novel antimicrobial agents still represents a current topic in medicinal chemistry. In this study, the synthesis and analytical data of eighteen salicylanilide esters with 4-(trifluoromethyl)benzoic acid are presented. They were assayed in vitro as potential antimycotic agents against eight fungal strains, along with their parent salicylanilides. The antifungal activity of the presented derivatives was not uniform and moulds showed a higher susceptibility with minimum inhibitory concentrations (MIC) ≥ 0.49 µmol/L than yeasts (MIC ≥ 1.95 µmol/L). However, it was not possible to evaluate a range of 4-(trifluoromethyl)benzoates due to their low solubility. In general, the most active salicylanilide was N-(4-bromophenyl)-4-chloro-2-hydroxybenzamide and among esters, the corresponding 2-(4-bromophenylcarbamoyl)-5-chlorophenyl 4-(trifluoromethyl) benzoate exhibited the lowest MIC of 0.49 µmol/L. However, the esterification of salicylanilides by 4-(trifluoromethyl)benzoic acid did not result unequivocally in a higher antifungal potency.

The urokinase receptor (uPAR) serves as a docking site to the serine protease urokinase-type plasminogen activator (uPA) to promote extracellular matrix (ECM) degradation and tumor invasion and metastasis. Previously, we had reported a small molecule inhibitor of the uPAR·uPA interaction that emerged from structure-based virtual screening. Here, we measure the affinity of a large number of derivatives from commercial sources. Synthesis of additional compounds was carried out to probe the role of various groups on the parent compound. Extensive structure-based computational studies suggested a binding mode for these compounds that led to a structure-activity relationship study. Cellular studies in non-small cell lung cancer (NSCLC) cell lines that include A549, H460 and H1299 showed that compounds blocked invasion, migration and adhesion. The effects on invasion of active compounds were consistent with their inhibition of uPA and MMP proteolytic activity. These compounds showed weak cytotoxicity consistent with the confined role of uPAR to metastasis., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

D-Glucose, lactose, maltose, and melibiose were benzoylated with Bz(2)O-Et(3)N reagent to give fully benzoylated β products. Under the same conditions, D-mannose produced a mixture where the β-benzoate predominated. Treatment of the foregoing compounds with EtSH at slightly elevated temperature (50-60°C) in the presence of BF(3)·Et(2)O as a promoter gave the corresponding ethyl 1-thio glycosides in high yields. The α-products predominated in all cases in the anomeric mixtures formed. Individual products of all reactions were isolated by chromatography, they were obtained in analytically pure state, and were fully characterized by (1)H and (13)C NMR data and physical constants., (Published by Elsevier Ltd.)

A series of thiol-based glutamate carboxypeptidase II (GCPII) inhibitors have been synthesized with either a 3-(mercaptomethyl)benzoic acid or 2-(2-mercaptoethyl)benzoic acid scaffold. Potent inhibitors were identified from each of the two scaffolds with IC(50) values in the single-digit nanomolar range, including 2-(3-carboxybenzyloxy)-5-(mercaptomethyl)benzoic acid 27c and 3-(2-mercaptoethyl)biphenyl-2,3'-dicarboxylic acid 35c. Compound 35c was found to be metabolically stable and selective over a number of targets related to glutamate-mediated neurotransmission. Furthermore, compound 35c was found to be orally available in rats and exhibited efficacy in an animal model of neuropathic pain following oral administration.

In this study, the synthesis and anticonvulsant properties of sixteen 2/3-benzoylaminopropionanilide derivatives were described. Molecular design of the compounds has been based on the modification of lacosamide which is a functionalized amino acid with a novel anticonvulsant activity. The structural confirmation of the title compounds was achieved by spectral and analytical data. The anticonvulsant activity profile of synthesized compounds was determined by maximal electroshock (MES) and subcutaneous metrazole (scMet) seizure tests, whereas their neurotoxicity was examined using rotarod test. All these tests were performed in accordance with the procedures of the Antiepileptic Drug Development (ADD) program. The majority of the compounds were effective in the MES or scMet screening tests. None of the compounds showed neurotoxicity according to the rotarod test at studied doses. Most active compounds in the series were 3, 12 and 13, which bearing 2-methyl, 2-ethyl and 2-isopropyl substituent on the N-phenyl ring, respectively., (© Georg Thieme Verlag KG Stuttgart · New York.)

AMP-activated protein kinase (AMPK) is a critical monitor of cellular energy status and also controls processes related to tumor development, including cell cycle progression, protein synthesis, cell growth and survival. Therefore AMPK as an anti-cancer target has received intensive attention recently. It has been reported that the anti-diabetic drug metformin and some natural compounds, such as quercetin, genistein, capsaicin and green tea polyphenol epigallocatechin gallate (EGCG), can activate AMPK and inhibit cancer cell growth. Indeed, natural products have been the most productive source of leads for the development of anti-cancer drugs but perceived disadvantages, such as low bioavailability and week potency, have limited their development and use in the clinic. In this study we demonstrated that synthetic EGCG analogs 4 and 6 were more potent AMPK activators than metformin and EGCG. Activation of AMPK by these EGCG analogs resulted in inhibition of cell proliferation, up-regulation of the cyclin-dependent kinase inhibitor p21, down-regulation of mTOR pathway, and suppression of stem cell population in human breast cancer cells. Our findings suggest that novel potent and specific AMPK activators can be discovered from natural and synthetic sources that have potential to be used for anti-cancer therapy in the clinic., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

We report here for the first time the in vitro effects of (1S,2R,4S)-1,7,7-trimethyl-bicyclo[2·2·1]heptan-2-yl-3',4',5'-trimethoxy benzoate (1) and (1S,2R,4S)-1,7,7-trimethyl-bicyclo[2·2·1]heptan-2-yl benzoate (2) on the growth and ultrastructure of Trypanosoma cruzi. These two synthetic compounds exerted an antiproliferative effect on the epimastigote forms of the parasite. The ICs(50/72h) of two synthetic L-bornyl benzoates, 1 and 2, was 10·1 and 12·8 μg/ml, respectively. Both compounds were more selective against epimastigotes than HEp-2 cells. Ultrastructural analysis revealed intense cytoplasmic vacuolization and the appearance of cytoplasmic materials surrounded by membranes. The treatment of peritoneal macrophages with compounds 1 and 2 caused a significant decrease in the number of T. cruzi-infected cells. L-Bornyl benzoate derivatives may serve as a potential source for the development of more effective and safer chemotherapeutic agents against T. cruzi infections.

Herein we describe a general three-step synthesis of 4-substituted chlorophthalazines in good overall yields. In the key step, N,N-dimethylaminophthalimide (8a) directs the selective monoaddition of alkyl, aryl, and heteroaryl organometallic reagents to afford 3-substituted 3-hydroxyisoindolinones 9b, 9i-9am. Many of these hydroxyisoindolinones are converted to chlorophthalazines 1b-1v via reaction with hydrazine, followed by chlorination with POCl(3). We have also discovered two novel transformations of 3-vinyl- and 3-alkynyl-3-hydroxyisoindolinones. Addition of vinyl organometallic reagents to N,N-dimethylaminophthalimide (8a) provided dihydrobenzoazepinediones 15a-15c via the proposed ring expansion of 3-vinyl-3-hydroxyisoindolinone intermediates. 3-Alkynyl-3-hydroxyisoindolinones react with hydrazine and substituted hydrazines to afford 2-pyrazolyl benzoic acids 16a-16d and 2-pyrazolyl benzohydrazides 17a-17g rather than the expected alkynyl phthalazinones., (© 2012 American Chemical Society)

2-[2-Benzoylamino)benzoylamino]benzoic acid (1) was previously identified as a potent and nontoxic antiadenoviral compound (Antimicrob. Agents Chemother. 2010, 54, 3871). Here, the potency of 1 was improved over three generations of compounds. We found that the ortho, ortho substituent pattern and the presence of the carboxylic acid of 1 are favorable for this class of compounds and that the direction of the amide bonds (as in 1) is obligatory. Some variability in the N-terminal moiety was tolerated, but benzamides appear to be preferred. The substituents on the middle and C-terminal rings were varied, resulting in two potent inhibitors, 35g and 35j, with EC(50) = 0.6 μM and low cell toxicity., (© 2012 American Chemical Society)

To develop RAF/VEGFR2 inhibitors that bind to the inactive DFG-out conformation, we conducted structure-based drug design using the X-ray cocrystal structures of BRAF, starting from an imidazo[1,2-b]pyridazine derivative. We designed various [5,6]-fused bicyclic scaffolds (ring A, 1-6) possessing an anilide group that forms two hydrogen bond interactions with Cys532. Stabilizing the planarity of this anilide and the nitrogen atom on the six-membered ring of the scaffold was critical for enhancing BRAF inhibition. The selected [1,3]thiazolo[5,4-b]pyridine derivative 6d showed potent inhibitory activity in both BRAF and VEGFR2. Solid dispersion formulation of 6d (6d-SD) maximized its oral absorption in rats and showed significant suppression of ERK1/2 phosphorylation in an A375 melanoma xenograft model in rats by single administration. Tumor regression (T/C = -7.0%) in twice-daily repetitive studies at a dose of 50 mg/kg in rats confirmed that 6d is a promising RAF/VEGFR2 inhibitor showing potent anticancer activity., (© 2012 American Chemical Society)

A series of raltegravir derivatives 20-42 were prepared and systematically evaluated for their anti-HIV activity. The bioassay results showed that most of the compounds possess good to excellent anti-HIV activity. Especially, compounds 25 and 35 with subpicomole IC(50) values seemed to be the most potent anti-HIV agents among all of the reported synthesized compounds. These compounds may therefore be considered as new potent anti-HIV agents. The 5-hydroxyl modification of raltegravir derivatives significantly increased the anti-HIV activity, which indicates that the hydroxyl may not be indispensable for raltegravir. The introducing of acyl at 5-position of raltegravir derivatives is favorable for antiviral activity. In addition, a high-throughput cell-based assay method with pseudotyped virus stocks was developed and used to identify HIV inhibitors., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

In pursuing our research targeting the identification of potent inhibitors of PTP1B and LMW-PTP, we have identified new 4-[(5-arylidene-2-arylimino-4-oxo-3-thiazolidinyl)methyl]benzoic acids endowed with interesting in vitro inhibitory profiles. Most compounds proved to be inhibitors of PTP1B and LMW-PTP isoform IF1. The tested inhibitors also showed selectivity towards PTP1B over the closely related TC-PTP. These compounds were found to activate the insulin-mediated signalling on mouse C2C12 skeletal muscle cells by increasing the phosphorylation levels of the insulin receptor and promoting cellular 2-deoxyglucose uptake. Interestingly, 4-{[5-(4-benzyloxybenzylidene)-2-(4-trifluoromethylphenylimino)-4-oxo-3-thiazolidinyl]methyl}benzoic acid (7d), the best in vitro inhibitor of PTP1B and the isoform IF1 of LMW-PTP, provided the highest activation level of the insulin receptor and was found to be endowed with an excellent insulinomimetic effect on the selected cells. This compound therefore represents an interesting lead compound for developing novel PTP1B and LMW-PTP inhibitors which could be achieved by improving both its pharmacological profile and its potentiating effects on insulin signalling., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

Introduction: β-Amyloid (Aβ) plaques and neurofibrillary tangles are the main characteristics of Alzheimer's disease (AD). Positron emission tomography (PET), a high-resolution, sensitive, and noninvasive imaging technique, has been widely utilized in visualizing the localization of plaques and tangles and thereby distinguishing between AD and healthy controls. A small 12-mer D-enantiomeric peptide (amino acid sequence=QSHYRHISPAQV), denoted as D1, has high binding affinity to Aβ in vitro in the sub-micromolar range, and consequently, its radiolabeled analogues have a potential as radioligands for visualizing amyloid plaques in vivo by PET., Aim: The aims of the present work were to develop three different potent D1 derivative peptides labeled with fluorine-18 and to examine them in the AD and control postmortem human brain by autoradiography (ARG)., Methods: Three different D1 derivative peptides were radiolabeled with fluorine-18 ([(18)F]ACI-87, [(18)F]ACI-88, [(18)F]ACI-89) using the prosthetic group N-succinimidyl-4-[(18)F]fluorobenzoate ([(18)F]SFB) and purified by high performance liquid chromatography (HPLC). Preliminary ARG measurements were performed in AD and control brains., Results: The three fluorine-18-labeled d-peptides were obtained in a total synthesis time of 140 min with radiochemical purity higher than 98%. The specific radioactivities of the three different D1 derivative peptides were between 9 and 113 GBq/μmol. ARG demonstrated a higher radioligand uptake in the cortical gray matter and the hippocampus in the AD brain as compared to age-matched control brain., Conclusions: Fluorine-18 labeling of the three novel D1 derivative peptides using [(18)F]SFB was successfully accomplished. Higher contrast between AD and control brain slices demonstrates their potential applicability for further use in vivo by PET., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Total synthesis of the published structure of amathamide D is described. Methyl 2,3,4-tribromo-5-hydroxybenzoate was selected as starting compound because it is readily accessible via acid-mediated Grob fragmentation-aromatization reaction of 1,4,5,6-tetrabromo-7,7-dimethoxybicyclo[2.2.1]hept-5-en-2-one. The aforementioned ester was transformed into the reported structure of amathamide D through methylation of a hydroxyl group and conversion of the ester moiety to a β-aminoethyl side chain. The NMR data of the synthetic compound did not conform to the reported natural product structure possessing contiguously positioned β-aminoethyl side chain, a set of three adjacent bromines, and a methyl ether linkage on the phenyl ring. This prompted us to redefine the natural product structure by synthesizing a product whose spectral data exactly matched with the reported data of amathamide D. The convolutamine H, with completely substituted phenyl ring adorned with an extra methyl ether functional group, has also been synthesized by application of Grob fragmentation-aromatization strategy to 3-(benzyloxy)-1,4,5,6-tetrabromo-7,7-dimethoxybicyclo[2.2.1]hept-5-en-2-one. This approach furnished directly methyl 2,3,4-tribromo-5,6-dimethoxybenzoate, which was converted straightforwardly into convolutamine H. Further, synthesis of convolutamine F and lutamide A and C is also described.

Four new triphenyltin(IV) complexes of composition Ph(3)SnLH (where LH=2-/4-[(E)-2-(aryl)-1-diazenyl]benzoate) (1-4) were synthesized and characterized by spectroscopic (((1))H, ((13))C and ((119))Sn NMR, IR, ((119))Sn Mössbauer) techniques in combination with elemental analysis. The ((119))Sn NMR spectroscopic data indicate a tetrahedral coordination geometry in non-coordinating solvents. The crystal structures of three complexes, Ph(3)SnL((1))H (1), Ph(3)SnL((3))H (3), Ph(3)SnL((4))H (4), were determined. All display an essentially tetrahedral geometry with angles ranging from 93.50(8) to 124.5(2)°; ((119))Sn Mössbauer spectral data support this assignment. The cytotoxicity studies were performed with complexes 1-4, along with a previously reported complex (5) in vitro across a panel of human tumor cell lines viz., A498, EVSA-T, H226, IGROV, M19 MEL, MCF-7 and WIDR. The screening results were compared with the results from other related triphenyltin(IV) complexes (6-7) and tributyltin(IV) complexes (8-11) having 2-/4-[(E)-2-(aryl)-1-diazenyl]benzoates framework. In general, the complexes exhibit stronger cytotoxic activity. The results obtained for 1-3 are also comparable to those of its o-analogs i.e. 4-7, except 5, but the advantage is the former set of complexes demonstrated two folds more cytotoxic activity for the cell line MCF-7 with ID(50) values in the range 41-53 ng/ml. Undoubtedly, the cytotoxic results of complexes 1-3 are far superior to CDDP, 5-FU and ETO, and related tributyltin(IV) complexes 8-11. The quantitative structure-activity relationship (QSAR) studies for the cytotoxicity of triphenyltin(IV) complexes 1-7 and tributyltin(IV) complexes 8-11 is also discussed against a panel of human tumor cell lines., (Copyright © 2011 Elsevier Inc. All rights reserved.)

A series of analogs of the natural antifungal compound crassinervic acid, a constituent of Piper crassinervium, were synthesized to gain insight into the most relevant structural features affecting the activity of the parent molecule. Most compounds were prepared by aldol reaction of methyl 3-acetyl-4-hydroxybenzoate with a series of ketones, followed by reduction, hydrolysis, and oxidation. The antifungal activities of crassinervic acid and its analogs was assessed against Cladosporium cladosporioides by using the method of bioautography. The bioassay results allowed us to depict structureactivity relationships for this class of compounds., (Copyright © 2012 Verlag Helvetica Chimica Acta AG, Zürich.)

Multifunctional trans-cinnamaldehyde (CA) and its analogs display anti-cancer properties, with 2-benzoyloxycinnamaldehyde (BCA) and 5-fluoro-2-hydroxycinnamaldehyde (FHCA) being identified as the ortho-substituted analogs that possess potent anti-tumor activities. In this study, BCA, FHCA and a novel analog 5-fluoro-2-benzoyloxycinnamaldehyde (FBCA), were demonstrated to decrease growth and colony formation of human colon-derived HCT 116 and mammary-derived MCF-7 carcinoma cells under non-adhesive conditions. The 2-benzoyloxy and 5-fluoro substituents rendered FBCA more potent than BCA and equipotent to FHCA. The cellular events by which these cinnamaldehydes caused G(2)/M phase arrest and halted proliferation of HCT 116 cells were thereby investigated. Lack of significant accumulation of mitosis marker phospho-histone H3 in cinnamaldehyde-treated cells indicated that the analogs arrested cells in G(2) phase. G(2) arrest was brought about partly by cinnamaldehyde-mediated depletion of cell cycle proteins involved in regulating G(2) to M transition and spindle assembly, namely cdk1, cdc25C, mad2, cdc20 and survivin. Cyclin B1 levels were found to be increased, which in the absence of active cdk1, would fail to drive cells into M phase. Concentrations of cinnamaldehydes that brought about dysregulation of levels of cell cycle proteins also caused tubulin aggregation, as evident from immunodetection of dose-dependent tubulin accumulation in the insoluble cell lysate fractions. In a cell-free system, reduced biotin-conjugated iodoacetamide (BIAM) labeling of tubulin protein pretreated with cinnamaldehydes was indicative of drug interaction with the sulfhydryl groups in tubulin. In conclusion, cinnamaldehydes treatment at proapoptotic concentrations caused tubulin aggregation and dysegulation of cell cycle regulatory proteins cdk1 and cdc25C that contributed at least in part to arresting cells at G(2) phase, resulting in apoptotic cell death characterized by emergence of cleaved forms of caspase 3 and poly (ADP-ribose) polymerase (PARP). Results presented in this study have thus provided further insights into the intricate network of cellular events by which cinnamaldehydes induce tumor cell death.

Esters are of widespread use for protecting carboxylic acids in organic synthesis. However, methods to cleave esters often employ harsh conditions. Herein, we report a new and mild method for the reductive cleavage of 2,2,2-trichloroethylesters (TCE esters). Our radical method employs Cp(2)TiCl as an electron transfer catalyst and Zn dust as stoichiometric reducing agent. It avoids the use of strong Brønstedt-acids as well as aqueous conditions and can be carried out at room temperature.

The present study was designed to synthesize and evaluate pyrrolo-isoxazole benzoic acid derivatives as potential acetylcholinesterase (AChE) inhibitors for the management of Alzheimer's disease. The synthesis of pyrrolo-isoxazole benzoic acid derivatives involved ring opening cyclization of p-aminobenzoic acid with maleic anhydride to yield maleanilic acid, which in turn afforded N-arylmaleimide via ring closed cyclization. Azomethine-N-oxides were obtained by condensation of N-arylhydroxylamine with differently substituted benzaldehydes followed by refluxing of N-arylmaleimide with differently substituted azomethine-N-oxides to pyrrolo-isoxazole benzoic acid derivatives as cis- and trans-stereoisomers. The synthesized compounds were evaluated in vitro for AChE inhibitory activity in rat brain homogenate with donepezil as standard AChE inhibitor. Thereafter, the most potent test compound was evaluated for in vitro butyrylcholinesterase inhibitory activity and in vivo memory evaluation in scopolamine (0.4mg/kg)-induced amnesia in mice by employing Morris water maze test. All pyrrolo-isoxazole benzoic acid derivatives demonstrated potent AChE inhibitory activity. Most of compounds exhibited similar activity to donepezil and four of them (7h, 7i, 8i, and 8h, IC(50)=19.1±1.9-17.5±1.5nM) displayed higher inhibitory activity as compared to donepezil (21.5±3.2nM) with compound 8ia (IC(50)=17.5±1.5nM) being the most active one. The test compound 8ia also ameliorated scopolamine-induced amnesia in mice in terms of restoration of time spent in target quadrant (TSTQ) and escape latency time (ELT). It may be concluded that pyrrolo-isoxazole benzoic acid derivatives may be employed as potential AChE inhibitors., (Copyright © 2011. Published by Elsevier Ltd.)

Edema factor (EF) toxin of Bacillus anthracis (NIAID category A), and several other toxins from NIAID category B Biodefense target bacteria are adenylyl cyclases or adenylyl cyclase agonists that catalyze the conversion of ATP to 3',5'-cyclic adenosine monophosphate (cAMP). We previously identified compound 1 (3-[(9-oxo-9H-fluorene-1-carbonyl)-amino]-benzoic acid), that inhibits EF activity in cultured mammalian cells, and reduces diarrhea caused by enterotoxigenic Escherichia coli (ETEC) at an oral dosage of 15μg/mouse. Here, molecular docking was used to predict improvements in potency and solubility of new derivatives of compound 1 in inhibiting edema toxin (ET)-catalyzed stimulation of cyclic AMP production in murine monocyte-macrophage cells (RAW 264.7). Structure-activity relationship (SAR) analysis of the bioassay results for 22 compounds indicated positions important for activity. Several derivatives demonstrated superior pharmacological properties compared to our initial lead compound, and are promising candidates to treat anthrax infections and diarrheal diseases induced by toxin-producing bacteria., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

A chiral monolithic capillary column for rapid enantioseparation was prepared by covalently bonding of cellulose tris(4-methylbenzoate) (CTMB) on N-acryloxysuccinimide-based monolith. The preparation and derivatization conditions of the monolithic column were optimized. The successful grafting of CTMB was confirmed on the characterizations of the infrared spectrum and the cathodic electroosmotic flow (EOF). The effects of acetic acid concentration and methanol content on the enantioseparation were studied. The solvent resistance, reproducibility and stability of the monolithic column have also been investigated. The rapid enantioseparation of the five solutes (phenylalanine, tyrosine, tryptophan, propranolol and phenylethanol) with resolution (R(s)) values up to 1.31 was achieved within 1.2 min on the prepared chiral capillary monolithic column by capillary electrochromatography.

Purpose: The aim of this work was to automate the radiosynthesis of [(18)F]SFB, a widely used reagent for the labeling of biomolecules with (18)F on a new generation commercial synthesis module (FASTLab™, GE Healthcare)., Procedures: Two synthesis approaches were implemented on this module: the classical "two-pot radiosynthesis" and the more recently described "one-pot" method., Results: The "two-pot" approach affords [(18)F]SFB with a 42% decay-corrected yield in 57 min (n = 24) with a chemical purity sufficient to avoid an intermediate HPLC purification. The recently established "one-pot" method, afforded a product with a lower chemical purity, in the conditions used in this report. The lower d.c. yield obtained (32% (n = 15)) was related to the low (18)F labeling yields obtained in MeCN compared with DMSO. The subsequent conjugation step with a RGD (PRGD2) peptide was also successfully automated., Conclusions: The formulated [(18)F]FPRGD2 was obtained without any operator manipulation with a d.c. yield of 13% ± 3% (n = 13) in 130 min, a radiochemical purity >98% and a specific activity of 140 ± 40 TBq/mmol.

Retinoids are a class of compounds with structural similarity to vitamin A. These compounds inhibit the proliferation of many cancer cell lines but have had limited medical application as they are often toxic at therapeutic levels. Efforts to synthesize retinoids with a greater therapeutic index have met with limited success. 4-[(1E)-2-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-2-naphthalenyl)-1-propen-1-yl]benzoic acid (TTNPB) is one of the most biologically active all-trans-retinoic acid (atRA) analogues and is highly teratogenic. In this study, we show that modification of the TTNPB carboxyl group with an N-(4-hydroxyphenyl)amido (4HPTTNPB) or a 4-hydroxybenzyl (4HBTTNPB) group changes the activity of the compound in cell culture and in vivo. Unlike TTNPB, both compounds induce apoptosis in cancer cells and bind poorly to the retinoic acid receptors (RARs). Like the similarly modified all-trans-retinoic acid (atRA) analogues N-(4-hydroxyphenyl)retinamide (4-HPR/fenretinide) and 4-hydroxybenzylretinone (4-HBR), 4HBTTNPB is a potent activator of components of the ER stress pathway. The amide-linked analogue, 4HPTTNPB, is less toxic to developing embryos than the parent TTNPB, and most significantly, the 4-hydroxybenzyl-modified compound (4HBTTNPB) that cannot be hydrolyzed in vivo to the parent TTNPB compound is nearly devoid of teratogenic liability.

2-(Cyclohexylamino)-2-oxo-1-(pyridin-2-yl)ethyl benzoate has been synthesized and characterized by elemental analysis, FT-IR, (1)H NMR and (13)C NMR. Geometrical structures, vibrational frequencies, (1)H and (13)C chemical shift values, molecular electrostatic potential maps and several thermodynamic parameters of title compound in the ground state have been calculated by using the density functional method with 6-31G(d) basis set. The IR spectrum of title compound was interpreted in terms of potential energy distribution (PED) analysis and NMR chemical shifts were also simulated using the GaussView program. Comparison of the theoretical vibrational spectra, (1)H and (13)C NMR chemical shifts of title compound showed a good agreement with the experimental data., (Copyright © 2011 Elsevier B.V. All rights reserved.)

New methodology for the stereoselective synthesis of trisubstituted olefins is presented. The use of ortho-diphenylphosphanyl benzoate (o-DPPB) as a directing leaving group for copper-mediated allylic substitution with Grignard reagents allowed for the stereoselective construction of a wide range of E olefins, without the need for an adjacent electron-withdrawing group. Our modular three-step approach toward trisubstituted alkenes commenced with geminal α-methylene aldehydes. Addition of an organometallic reagent and introduction of the o-DPPB group by esterification was followed by the o-DPPB-directed copper-mediated allylic substitution with a Grignard reagent to furnish stereodefined trisubstituted olefins. Additionally, incorporation of a stereocenter from the chiral pool allowed the preparation of an enantiomerically pure olefin that bore three alkyl substituents in high E/Z selectivity., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An efficient synthesis of chloroisosulochrin was accomplished using a novel ortho-selective chlorination of a phenol with sulfuryl chloride and 2,2,6,6-tetramethylpiperidine as the key step. Further elaboration by a biomimetic route converted chloroisosulochrin to dihydromaldoxin, maldoxone (lactone formed by dehydration of dihydromaldoxin), and maldoxin and isosulochrin to dechlorodihydromaldoxin and dechloromaldoxin., (© 2011 American Chemical Society)

New ferrocene and N-alkylcarbazole retinoids were designed and synthesized stereoselectively in good yields. A number of these synthesized ligands, in particular 2, 3, and 11, were found to exhibit a high RARα activation potential and to effectively induce post-differentiation apoptosis in NB4 acute promyelocytic leukemia (APL) cells. Increasing the length of the side chain attached to the heterocycle of the carbazole arotinoids creates new opportunities for altered compound catabolism and for fine-tuning of the apoptosis-inducing potential of the ligand. In the carbazole series of new retinoids, maximal activity was established for N-butylcarbazole analogue 11 in all assays (i.e., RARα activation, differentiation induction, and apoptosis induction). Study of the mechanism of apoptosis revealed an activation of initiator caspases-8 and -9, followed by efficient cleavage of effector caspase-3 on day 6 of treatment. Subsequent induction of a caspase cascade in NB4 cells triggered ultimate leukemic cell death. The selected ligands 2, 3, and 11 may provide alternate options for the treatment of APL in cases of life-threatening ATRA syndrome, resistance, and high toxicity to conventionally used retinoids., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Most ischemic stroke results from brain blood vessel blockage by platelet-mediated thrombus, and anti-platelet therapy has been demonstrated clinical benefits in the treatment of this disease. In the present work, novel nitric oxide (NO)-releasing derivatives of an anti-ischemic stroke drug 3-n-butylphthalide (NBP) were synthesized. Compounds 7a and 7c exhibited more potent anti-platelet activity than NBP and aspirin, and released a moderate amount of NO, which is beneficial in improving cardiovascular and cerebral circulation. These findings provide an alternative approach to the development of drugs more potent than NBP for the intervention of ischemic stroke., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

This discovered and optimized several novel HIV-1 fusion inhibitors and further evaluated the inhibitory activities of these compounds in vitro. Here, we have reported the computer-aided design, synthesis, and biological evaluation of a series of small molecule fusion inhibitors targeting HIV-1 gp41. Based on the structure of inhibitor (NB2), we carried out de novo design and screened out a series of novel structure molecules by using Leapfrog and Autodock programs. Our structure-based modification obtained a potent fusion inhibitor (IC₅₀ = 41.1 µg/mL). Several novel compounds were discovered as fusion inhibitors, which suggested that our design methodology is reliable, paving the way for de novo design of novel small-molecule HIV inhibitors targeting gp41.

We have designed cancer antiproliferative compounds, starting from aniline or phenol derivative, which comprise one or two nitrooxymethylphenyl groups as do the hybrid drugs NCX4040 and NCX530. Compound 2a with p-nitrooxymethylbenzoyl-oxy and -amino groups as well as 8a with a p-nitrooxymethylbenzoylamino group showed more promising effects than NCX4040 against human colon and breast cancer cells. Since 2a and 8a, but not NCX4040, arrested human colon carcinoma HCT116 cells in the M phase, the former two compounds may inhibit cell growth differently from NCX4040. Merged images of immunofluorescence-stained α-tubulin and Hoechst-stained nuclei in human fibrosarcoma HT1080 cells showed that 2a and 8a disrupted microtubule formation just as did vincristine, the tubulin polymerization inhibitor. In experiments in vivo, the intraperitoneal administration of 8a at 80 mg/kg/day reduced the growth of HCT116 xenografts in nude mice to T/C 55%., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Based on the original spirodiketopiperazine design framework, further optimization of an orally available CCR5 antagonist was undertaken. Structural hybridization of the hydroxylated analog 4 derived from one of the oxidative metabolites and the new orally available non-hydroxylated benzoic acid analog 5 resulted in another potent orally available CCR5 antagonist 6a as a clinical candidate. Full details of a structure-activity relationship (SAR) study and ADME properties are presented., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Biomolecules, including peptides¹⁻⁹, proteins¹⁰⁻¹¹, and antibodies and their engineered fragments¹²⁻¹⁴, are gaining importance as both potential therapeutics and molecular imaging agents. Notably, when labeled with positron-emitting radioisotopes (e.g., Cu-64, Ga-68, or F-18), they can be used as probes for targeted imaging of many physiological and pathological processes.¹⁵⁻¹⁸ Therefore, significant effort has devoted to the synthesis and exploration of ¹⁸F-labeled biomolecules. Although there are elegant examples of the direct ¹⁸F-labeling of peptides,¹⁹⁻²² the harsh reaction conditions (i.e., organic solvent, extreme pH, high temperature) associated with direct radiofluorination are usually incompatible with fragile protein samples. To date, therefore, the incorporation of radiolabeled prosthetic groups into biomolecules remains the method of choice.²³(,)²⁴ N-Succinimidyl-4-[¹⁸F]fluorobenzoate ([¹⁸F]SFB),²⁵⁻³⁷ a Bolton-Hunter type reagent that reacts with the primary amino groups of biomolecules, is a very versatile prosthetic group for the ¹⁸F-labeling of a wide spectrum of biological entities, in terms of its evident in vivo stability and high radiolabeling yield. After labeling with [¹⁸F]SFB, the resulting [F]fluorobenzoylated biomolecules could be explored as potential PET tracers for in vivo imaging studies.¹ Most [¹⁸F]SFB radiosyntheses described in the current literatures require two or even three reactors and multiple purifications by using either solid phase extraction (SPE) or high-performance liquid chromatography (HPLC). Such lengthy processes hamper its routine production and widespread applications in the radiolabeling of biomolecules. Although several module-assisted [¹⁸F]SFB syntheses have been reported²⁹⁻³²,⁴¹⁻⁴² they are mainly based on complicated and lengthy procedures using costly commercially-available radiochemistry boxes (Table 1). Therefore, further simplification of the radiosynthesis of [¹⁸F]SFB using a low-cost setup would be very beneficial for its adaption to an automated process. Herein, we report a concise preparation of [¹⁸F]SFB, based on a simplified one-pot microwave-assisted synthesis (Figure 1). Our approach does not require purification between steps or any aqueous reagents. In addition, microwave irradiation, which has been used in the syntheses of several PET tracers,³⁸⁻⁴¹ can gives higher RCYs and better selectivity than the corresponding thermal reactions or they provide similar yields in shorter reaction times.³⁸Most importantly, when labeling biomolecules, the time saved could be diverted to subsequent bioconjugation or PET imaging step. ²⁸(,)⁴³The novelty of our improved [¹⁸F]SFB synthesis is two-fold: (1) the anhydrous deprotection strategy requires no purification of intermediate(s) between each step and (2) the microwave-assisted radiochemical transformations enable the rapid, reliable production of [¹⁸F]SFB.

The use of a novel electrophoric derivatisation reagent, o-(pentafluorobenzyloxycarbonyl)-benzoyl chloride, for the quantitative determination of methylphenidate in plasma is described. The drug can be quantitatively measured down to 72 pg/mL plasma using only 250 μL of sample due to the extraordinary sensitivity of the derivatives under negative ion chemical ionisation mass spectrometry. Plasma samples were made alkaline with carbonate buffer and treated with extraction solvent n-hexane and reagent solution for 30 min, which, after concentration, was measured by GC-NICI-MS. The method is rapid as extraction and derivatisation occur in one single step. A stable isotope-labelled internal standard was used and its synthesis described. Full validation data are given to demonstrate the usefulness of the assay, including specificity, linearity, accuracy and precision, long-term stability, short-term stability, freeze-thaw stability, stock solution stability, autosampler stability, aliquot analysis, robustness, matrix effect, and prospective analytical batch size accuracy. The method has been successfully applied to pharmacokinetic profiling of the drug after oral application.

Objective: Telmisartan, a nonpeptide angiotensin II AT1 receptor antagonist, is an antihypertensive drug. Positron emission tomography (PET) imaging with [(11)C]Telmisartan is expected to provide information about the whole body pharmacokinetics of telmisartan as well as the transport function of hepatic OATP1B3. We developed a first automatic preparation system of [(11)C]Telmisartan to applicable clinical research using a new (11)C and (18)F multipurpose synthesizer., Methods: Two milligrams of precursor (1) in 5 μl of 1 M KOH in 0.5 ml of dimethyl sulfoxide was reacted with [(11)C]CH(3)I for 5 min at 120°C. The resultant solution was hydrolyzed with 1 M NaOH at 100°C for 3 min. The neutralization was carried out with acetic acid, followed by purification with high-performance liquid chromatography. The desired radioactive fraction was collected and solvent was replaced by 10 ml saline containing 0.3 ml of EtOH and 0.5 ml of PEG400, and then passed through a sterile 0.22 μm filter (Millex-GV, Millipore) to a pyrogen-free vial as the final product., Results: The yield of [(11)C]Telmisartan for clinical research use was 16.8 ± 2.9% EOB as decay corrected (n = 8, mean ± SD) in 32-36 min. The radiochemical purity of [(11)C]Telmisartan was >97%, and specific activity was higher than 86.3 MBq/nmol., Conclusions: We succeeded in the first synthesis of [(11)C]Telmisartan for clinical research use by appropriate quality tests.

The title compound, which was reported to be a constituent of the fruiting body of the fungus Antrodia camphorata, has been synthesized. The reactivity and spectroscopic properties of the synthetic material do not match those of the natural product. There is currently insufficient information for a definitive structural reassignment.

A new catalytic procedure of ortho-olefination of benzoates and benzaldehydes has been developed. Ester and carboxaldehyde units were revealed to be effective chelating groups in focusing the activation of aryl C-H bonds ortho to the directing moieties under the Rh-catalyzed oxidative conditions. The reaction is highly regioselective with a range of benzoates and benzaldehydes enabling the efficient olefination with acrylates, acrylic acid, and styrenes.

Cyclooxygenase-1/2 (COX-1/2) and 5-lipoxygenase (5-LOX) are enzymes in two different pathways in the inflammatory process. In the present study, a variety of new nimesulide derivatives were synthesized through incorporation of a 5-LOX pharmacophore into nimesulide followed with some structural modifications, which were then characterized for dual enzyme inhibitors for these two types of enzymes. Their structure-activity relationships (SARs) were studied, and compound 20f was found to be an excellent dual enzyme inhibitor. Its binding conformation and interaction mode were studied with molecular docking experiments. Compound 20f could become a lead compound for further development for potential anti-inflammatory drugs., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

HIV-1 reverse transcriptase is a bifunctional enzyme, having both DNA polymerase (RNA- and DNA-dependent) and ribonuclease H activities. HIV-1 reverse transcriptase has been an exceptionally important target for antiretroviral therapeutic development, and nearly half of the current clinically used antiretrovirals target reverse transcriptase DNA polymerase. However, no inhibitors of reverse transcriptase ribonuclease H are on the market or in preclinical development. Several drug-like small molecule inhibitors of reverse transcriptase ribonuclease H have been described, but little structural information is available about the interactions between reverse transcriptase ribonuclease H and inhibitors that exhibit antiviral activity. In this report, we describe NMR studies of the interaction of a new ribonuclease H inhibitor, BHMP07, with a catalytically active HIV-1 reverse transcriptase ribonuclease H domain fragment. We carried out solution NMR experiments to identify the interaction interface of BHMP07 with the ribonuclease H domain fragment. Chemical shift changes of backbone amide signals at different BHMP07 concentrations clearly demonstrate that BHMP07 mainly recognizes the substrate handle region in the ribonuclease H fragment. Using ribonuclease H inhibition assays and reverse transcriptase mutants, the binding specificity of BHMP07 was compared with another inhibitor, dihydroxy benzoyl naphthyl hydrazone. Our results provide a structural characterization of the ribonuclease H inhibitor interaction and are likely to be useful for further improvements of the inhibitors., (© 2010 John Wiley & Sons A/S.)

Ischemic stroke is one of the most severe brain pathologies that is extremely difficult to treat. Recently it has been found that acidosis accompanying cerebral ischemia induces activation of acid-sensing ion channel ASIC1a which results in its turn in the neuronal death. Here we present novel derivatives of 3-carboxamidinocoumarines that effectively inhibit ASIC1a and ASIC3 channels in concentration-dependent manner. The most active compound inhibits ASIC1a and ASIC3 channels with corresponding IC50 of 7.3 and 13.2 microM. Our data suggest that 3-carboxamidinocoumarines can be used as a scaffold for novel type of highly efficient anti-ischemic drugs.

Various inflammatory stimuli that activate the nuclear factor kappa B (NF-κB) signaling pathway converge on a serine/threonine kinase that displays a key role in the activation of NF-κB: the I kappa B kinase β (IKK-β). Therefore, IKK-β is considered an interesting target for combating inflammation and cancer. In our study, we developed a ligand-based pharmacophore model for IKK-β inhibitors. This model was employed to virtually screen commercial databases, giving a focused hit list of candidates. Subsequently, we scored by molecular shape to rank and further prioritized virtual hits by three-dimensional shape-based alignment. One out of ten acquired and biologically tested compounds showed inhibitory activity in the low micromolar range on IKK-β enzymatic activity in vitro and on NF-κB transactivation in intact cells. Compound 8 (2-(1-adamantyl)ethyl 4-[(2,5-dihydroxyphenyl)methylamino]benzoate) represents a novel chemical class of IKK-β inhibitors and shows that the presented model is a valid approach for identification and development of new IKK-β ligands., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Novel quinazolines 4-11, 15 and triazoloquinazolines 12-14 bearing biologically active sulfonamide moieties were synthesized. All the newly synthesized compounds were evaluated for their in vitro anticancer activity against liver cancer cell line (HEPG2). Some of the screened compounds exhibited interesting cytotoxic activity compared to doxorubicin as a reference drug. The most active compounds 13 and 15 were selected and evaluated for their ability to enhance the cell killing effect of gamma-radiation, compound 15 was superior to doxorubicin in radiation combination therapy.

Integrin αvβ3 plays a critical role in tumor-induced angiogenesis and metastasis. Previously, a 64Cu-AmBaSar- RGD monomer with high in vivo stability compared with 64Cu-DOTA-RGD was developed for integrin αvβ3 PET imaging. It has been established that dimeric RGD peptides have higher receptor-binding affinity and superior in vivo kinetics compared with monomeric RGD peptides due to the polyvalency effect. In this context, we synthesized and evaluated 64Cu-labeled AmBaSar dimeric RGD conjugates (64Cu-AmBaSar-RGD2) for PET imaging of integrin αvβ3 expression. The dimeric RGD peptide was conjugated with a cage-like chelator AmBaSar and labeled with 64Cu. Cell binding, microPET imaging, receptor blocking, and biodistribution studies of 64Cu-AmBaSar-RGD2 were conducted in the U87MG human glioblastoma xenograft model. AmBaSar-RGD2 conjugate was obtained in reasonable yield (45.0 ± 2.5%, n= 4) and the identity was confirmed by HPLC and MS (found 1779.8, calculated m/z for [M+H]+ M: C81H125N27O19 1779.9). 64Cu-AmBaSar-RGD2 was obtained with high radiochemical yield (92.0 ± 1.3%) and purity (≥ 98.0%) under mild conditions (pH 5.0~5.5, 23~37 °C) in 30 min. The specific activity of 64Cu-AmBaSar-RGD2 was estimated to be 15-22 GBq/µmol at the end of synthesis. Based on microPET imaging and biodistribution studies, 64Cu-AmBaSar-RGD2 has demonstrated higher tumor uptake at selected time points than 64Cu-AmBaSar-RGD. At 20 h p.i., the tumor uptake reached 0.65 ± 0.05 %ID/g for 64Cu-AmBaSar-RGD and 1.76 ± 0.38 %ID/g for 64Cu-AmBaSar-RGD2, respectively. The integrin αvβ3 targeting specificity was confirmed by blocking experiments. Therefore, the new tracer 64Cu-AmBaSar- RGD2 exhibited better tumor-targeting efficacy and more favorable in vivo pharmacokinetics than the 64Cu labeled RGD monomer due to the polyvalency effect.