Medicinal Chemistry - Volume 8, Issue 6, 2012

A new series of phenyl- and heteryl acetamidines were synthesized and evaluated as inhibitors of nitric oxide synthases (NOS). While the N-substitution of the acetamidine moiety with different heterocycles appears to completely destroy the activity, linking the phenyl core preserves it. Moreover, it was observed a strong dependence of the phenylacetamidines potency of action from the length of the alkyl chain that connects the aromatic ring to the acetamidine moiety.

Endoglin (CD105), a cell-surface co-receptor for transforming growth factor-beta (TGF-β) superfamily members, is over-expressed in tumor neovasculature and can be targeted with anti-endoglin antibodies, thus becoming an important tool for anti-tumoral therapy. Injury of the mouse tail induced the transient expression of endoglin, this peaking at three days after injury and disappearing six days later. An immunotoxin containing the anti-mouse endoglin rat monoclonal antibody MJ7/18 and the non-toxic ribosome-inactivating protein nigrin b (Ngb) was found to be very active in targeting mouse endoglin in the L929 fibroblast cell line (IC50 of 4 x 10-11 M). At that concentration, the immunotoxin lacked unspecific activity. Upon induction of endoglin after injury, the MJ7-Ngb immunotoxin strongly attacked and deranged the injured tail, inducing tissue damage. Such effects were dependent on the age of the animals and were evident in six-week-old mice, but not in eight-month-old mice. Our results indicate that endoglin is up-regulated in newly formed vessels upon injury and can be targeted by the MJ7-Ngb immunotoxin; thus, it could be a useful tool for tumor ablation research.

In the present work we described improvements in the 1-7 antiparasitic Morita-Baylis-Hillman Adducts synthesis and their antimitotic activity on sea urchin embryonic cells. The 2-[Hydroxy(2-nitrophenyl)methyl]acrylonitrile (1) and 2-[Hydroxy(4-bromophenyl) methyl]acrylonitrile (4) were the most effective compounds to block the progression to embryonic morula stage (EC50 = 75.8 µM and 72.6 µM, respectively). Compounds 1 and 4 were also effective in blocking the first cell division but to a lesser extent. The 2-[Hydroxy(pyridin-4-yl)methyl]acrylonitrile (7) exhibited a strong inhibition of cell divisions and progression to the first cleavage and morula stage. Fluorescent dye extrusion assay suggests that these adducts are not ABC protein substrates, which confers an additional interest in these new class of potential anticancer drugs.

In order to explore the detailed structure-activity relationship (SAR) around xanthone scaffold bearing hydroxyl and prenyl moieties, twenty-nine natural and non-natural hydroxylated and prenylated xanthones have been synthesized and evaluated for their in vitro anti-proliferative activities against five human cancer cell lines, including HepG2 (hepatocelluar carcinoma), HCT-116 (colon carcinoma), A549 (lung carcinoma), BGC823 (gastric carcinoma) and MDAMB- 231 (breast carcinoma). The SAR analysis revealed that the anti-proliferative activity of the xanthones is substantially influenced by the position and number of attached hydroxyl and prenyl groups, and the presence of hydroxyl group ortho to the carbonyl function of xanthone scaffold contributes significantly to their cytotoxicity. The new prenylated xanthone 20 with a relatively simple structure, namely 1,3,8-trihydroxy-2-prenylxanthone, was found to exhibit potent antitumor activities comparable to α-mangostin against all the five cancer cell lines. Further mechanistic studies suggested that compound 20 induces apoptosis and causes cell cycle arrest at S phase in HepG2 cells. These results have highlighted compound 20 as a new potential lead candidate for future development of novel potent broad-spectrum antitumor agents.

The use of ultrasound in therapeutic medicine is a developing field. The action of many anticancer agents can be improved with the use of ultrasonic exposure either in vitro or in vivo. Boron-based compounds have shown promising results as chemotherapeutic agents in specific forms of cancer. We synthesized a new boron compound of chloroacetohydroxamic acid, 2-hydroxyamino-oxoethylborate (HAOB). HAOB was used in combination with ultrasound (US) at a frequency of 25 KHz, and inhibitory effects on the growth of mouse ascites tumours were monitored by observing survival time, tumour growth, cell viability and DNA synthesis of treated Ehrlich ascites carcinoma (EAC) cells. 5-Fluorouracil (5- FU) was used as a positive control. The results indicated that HAOB alone produced significant antitumor action whereas combination of US with HAOB or 5-FU produced an extra antitumor action when compared to the actions of HAOB or 5- FU used alone.

Thromboxane A2 (TxA2) and the activation of its receptor have been shown to modulate vasoconstriction and platelet aggregation as well as dopaminergic and serotonergic signalling. Dopaminergic and serotonergic systems play a crucial role in the pathophysiology of schizophrenia and these systems are the main targets of antipsychotics (APs). As the first antipsychotic (AP) chlorpromazine (CPZ) has already been shown to reduce TxA2, we hypothesized that the AP clozapine and its metabolite N-desmethylclozapine (NDMC) might also influence TxA2 production. We measured levels of thromboxane B2 (TxB2), the metabolite of the very unstable molecule TxA2, in unstimulated and stimulated blood samples of 10 healthy female subjects in a whole blood assay using toxic shock syndrome toxin-1 (TSST-1) and monoclonal antibody against surface antigen CD3 combined with protein CD40 (OKT3/CD40) as stimulants. Blood was supplemented with the APs CPZ, clozapine or NDMC in one of four different concentrations. Additionally, thromboxane levels were measured in blood without the addition of APs under different stimulation conditions. Under TSST-1 as well as OKT3/CD40 stimulation, mean TxB2 concentrations were significantly (p<0.05) decreased by clozapine over all applied concentrations. NDMC led to a decrease in TxB2 levels under unstimulated conditions as well as under TSST-1 stimulation. CPZ reduced TxB2 production at low concentrations under unstimulated and TSST-1- stimulated conditions. Clozapine, NDMC and CPZ possibly act on neurotransmitter systems via modulation of TxA2 or TxB2 production. Additionally, known side effects of APs such as orthostatic hypotension may be a result of changes in the concentrations of TxA2 or TxB2.

Chagas disease continues to be one of the main parasitic diseases in Latin America. Despite the fact that it was discovered more than 100 years ago, no suitable pharmacologic treatment is available. We report the synthesis of new sulfonamidoquinoline and sulfonamides derivatives that were evaluated in vitro against two strains of Trypanosoma cruzi (NINOA and INC-5). Structure-activity relationship analysis indicated that small aromatic and large aromatic substituents on 4-aminoquinaldine increased trypanocidal activity on INC-5 and NINOA strains, respectively. Additionally, results show the importance of the sulfonamide group as a scaffold for the development of new anti-T. cruzi agents. Seven sulfonamide derivatives showed better lytic activity than nifurtimox and beznidazole against both strains of T. cruzi. N- (biphenyl-4-yl-sulfonyl)-nicotinamide (P-012) was established as the leader of the series for the development of more effective agents.

A quantitative structure–activity relationship analysis was employed to explore the relationship between the molecular structure of thiosemicarbazone analogues and the inhibition of the cysteine protease cruzain, a validated target for Chagas’ disease treatment. A data set containing 53 thiosemicarbazone derivatives was used to produce a quantitative model for activity prediction of unknown compounds. Several electronic descriptors were obtained through DFT calculations, along with a large amount of Dragon descriptors. The ordered predictor selection (OPS) algorithm was employed to select the most relevant descriptors to perform PLS regressions. With this procedure, significant correlation coefficients (r 2 = 0.85, q 2 = 0.78) were achieved. Furthermore, predicted values for an external test set are in good agreement with the experimental results, indicating the potential of the model for untested compounds. Additional validation tests were carried out, indicating that a robust and reliable model was obtained to be used in the design of new thiosemicarbazones with improved cruzain inhibition potential.

Synthesis of 1-(substituted aryl)-3-(thiazol-2-yl)urea derivatives was undertaken as our efforts to discover novel antiparkinsonian agents with improved pharmacological profile in haloperidol-induced catalepsy and oxidative stress in mice. Furfuryl, 2- and/or 3-methoxy substituted phenyl derivatives emerged as potent agents. With exception of 2-chloro,5-trifluoromethyl substituted analog, halogen substituted derivatives exhibited moderate antiparkinsonian activity. The results of biochemical investigations from brain homogenate of mice outline the importance of neuroprotective/ antioxidant therapy for Parkinson’s disease (PD), supporting the notion that the oxidative stress may play a significant role in the pathophysiological mechanisms underlying PD. Molecular docking studies of these compounds with adenosine A2A receptor exhibited very good binding interactions and warrants further studies to confirm their binding with human A2A receptor for the design and development of potent antagonists. Parameters for Lipinski’s rule of 5 were calculated computationally because pharmacokinetic and metabolic behaviors in the body often are linked to the physical properties of a compound. None of the synthesized compounds violated Lipinski’s rule, making them suitable drug candidate for the treatment of PD.

A series of novel N,N-diphenyl-2-[4-(substituted phenyl)piperazin-1-yl]acetamides was designed, synthesized and evaluated for anti-dopaminergic activity, anti-serotonergic activity and catalepsy induction studies in mice as an approach to novel potential antipsychotic agent. Antipsychotic activity of these compounds in terms of blocking of dopaminergic transmission was evaluated by their ability to inhibit apomorphine induced climbing behavior in mice and antiserotonergic activity of synthesized compounds was assessed by studying inhibition of 5-HTP induced head twitches. All the synthesized compounds were found to exhibit anti-dopaminergic and anti-serotonergic activity in behavioral models. The compound 3f showed better antipsychotic potential among the different synthesized compounds. The descriptor based similarities study for blood brain permeation established a good similarity between the synthesized compounds with standard atypical antipsychotics.

In this study, a novel series of 7-substituted-[1,2,4]triazolo[4,3-f]pyrimidine derivatives was synthesized as potential anticonvulsant agents. Their anticonvulsant activities were evaluated by the maximal electroshock (MES) test, and their neurotoxicities were evaluated by the rotarod neurotoxicity test. The pharmacological results showed that the compound 3i (7-(4-chlorophenoxy)-[1,2,4]triazolo[4,3-f]pyrimidine) was among the most active agent with median effective dose (ED50) value of 34.7 mg/kg, median toxicity dose (TD50) of 262.9 mg/kg, and providing a protective index (PI=TD50 /ED50) value of 7.6. The compound 3i also showed oral activity against MES-induced seizures and lower oral neurotoxicity. The compound 3i demonstrated antagonistic activity against seizures induced by PTZ, ISN, 3-MP and thiosemicarbazide.

On the basis of the high resolution crystal structures of bovine rhodopsin, human beta2-adrenergic receptor and human A2a adenosine receptor, three-dimensional structure of the human histamine H2 receptor (HHR2) was developed by homology modeling. Results of the evaluations suggest that a high quality homology model for HHR2 has been obtained. Three antagonists, cimetidine, ranitidine and nizatidine, were applied to binding site study with this model through molecular docking, molecular dynamics simulations and the molecular mechanics-Poisson-Boltzmann surface area calculations. One aspartic acid, Asp98 in transmembrane domain 7 (TM3), has been identified as major contributors to ligand binding by H-bond interactions. Asn159 in TM4 and Asp186 in TM5 are of great importance in stabilizing HHR2- antagonist complexes. Two hydrophobic sites especially two residues, Val99 in TM3 and Phe254 in TM6, were identified to be essential for their strong hydrophobic interactions with antagonists. The findings reported here are in agreement with available experimental mutagenesis data. This study should be very helpful for a better understanding of the action mode of the antagonist and for guiding further drug design and mutagenesis studies.

We describe the synthesis and positive inotropic evaluation of a series of 2-(4-substitutedbenzylpiperazin-1-yl)- N-(2-oxo-2,3-dihydrobenzooxazol-6-yl)acetamides by measuring left atrial stroke volume in preparations of isolated rabbit hearts. Several compounds were developed from and showed favorable activities compared with the standard drug milrinone. Compound 4l was the most potent with an increased stroke volume of 11.78 ± 0.18% (milrinone 6.36 ± 0.13%) at 1 × 10–4 M in our in-vitro study. The chronotropic effects of compounds having inotropic effects were also evaluated.

The Benzothiadiazine derivatives have been regarded as a novel class of HCV genotype 1 polymerase inhibitors. To explore the relationship between the structures of substituted Benzothiadiazine derivatives and their inhibitory activities against HCV, 3D-QSAR and molecular docking studies were performed on a dataset of ninty-eight compounds. The 3D-QSAR models resulted from seventy-eight molecules in the training set gave q 2 value of 0.81 and a test set of twenty compounds, gave predictive r 2 value of 0.94. 3D-QSAR model generated from kNN-MFA along with the docking binding structures provided enough information about the structural requirements for better activity. The results can serve as a useful guideline to design novel HCV genotype 1 inhibitors with better potencies.

QSAR study on a data set of 5-lipoxygenase inhibitors (1-phenyl [2H]-tetrahydro-triazine-3-one analogues) was carried out by using Support Vector Regression (SVR) and physicochemical parameters. Wrapper methods were used to select descriptors, while Leave-One-Out Cross Validation (LOOCV) method and independent set test were used to judge the predictive power of different models. We found out that the generalization ability of SVR model outperformed multiple linear regression (MLR) and Partial Least Squares (PLS) models in this work. An online web server for activity prediction is available at http://chemdata.shu.edu.cn/qsar5lip.

The receptor tyrosine kinase c-Met has multiple roles during cancer development and is currently considered as a promising target for cancer therapies. Pharmacophore models of c-Met kinase inhibitors have been developed based on 22 diverse compounds by using HypoGen algorithm implemented in Discovery studio program package. The best quantitative pharmacophore model, Hypo 1, which had the highest correlation coefficient (0.9623), consists of two hydrogen bond acceptors, one hydrophobic feature and two excluded volumes. Then best model was validated by test set prediction, Fischer randomization and decoy set. Besides, the features of Hypo1 were verified to correctly reflect the interactions between kinase active site and its ligands by comparison and superimposition of Hypo 1 in active site of c-Met kinase. The results shows that Hypo 1 has strong capability to identify c-Met kinase inhibitors and to predict the activities of structurally diverse molecules. Therefore, our pharmacophore models were considered as valuable tools for the discovery and development of specific c-Met kinase inhibitors.

Several N-hydroxyalkyl desloratadines and N-methoxyl ethyl desloratadine were prepared and evaluated for H1 antihistamine activity. The effects on isolated ileum smooth muscle tension in guinea pigs in vitro and asthma-relieving effects on the histamine-induced asthmatic reaction in guinea-pigs in vivo were examined. Most of them exhibited satisfactory H1 antihistamine activity and were obviously more potent than loratadine. Among these, Compound 3, N-(3- hydroxy)propyl desloratadine was the most active one. And it was chosen as a candidate for evaluation of acute toxicity (LD50= 0.876(0.784-0.980) g/kg), significantly superior to that of desloratadine (LD50=0.353 g/kg). Meanwhile, the experimental results demonstrated that the oxygen atom in the side carbon chain is crucial for enhancing the antihistamine activities.

Ecto-5'-Nucleotidase inhibitors have great potential as anti-tumor agents. We have investigated biochemical properties of human and rat ecto-5'-Nucleotidases and characterized 19 small molecule sulfonic acid derivatives as potential inhibitors of ecto-5'-Nucleotidases. We identified 11 potent inhibitors of human and rat ecto-5'-Nucleotidases and checked their selectivity. Compound 10 (Sodium 2,4-dinitrobenzenesulfonate) with Ki value of 0.66 µM and 19 (N-(4- sulfamoylphenylcarbamothioyl) pivalamide) with Ki value of 0.78 µM were identified as the most potent inhibitors for human and rat ecto-5'-Nucleotidase, respectively. The present compounds have low molecular weights, water solubility and equal potency as compared to the reported inhibitors.

The dramatic worldwide increase of dangerous infections by resistant and multi-resistant microbes makes the search of new molecules and new chemical entities an important topic in Medicinal Chemistry. As the ideal drug candidate has not been attained, an intensive search for new and innovative antimicrobials is still needed. A small series of 3- amino/nitrocoumarins without substitutions or substituted by methyl or methoxy groups at different positions were synthesized and evaluated for their antibacterial and antifungal activities against clinical isolates of Staphylococcus aureus, Escherichia coli and Candida albicans strains. Some of these structurally simple molecules exhibited antibacterial activity. The preliminary SAR study showed that the antibacterial activity against E. coli and S. aureus was dependent on the kind and position of the substitution pattern at the coumarin moiety.

The design and synthesis of hydroxyethylamine isosteres as inhibitors of cathepsin D based on SAR data have been accomplished. A library of 96 of these hydroxyethylamine isosteres are described and many have proven to be very potent inhibitors of human cathepsin D activity as measured using a fluorometric assay technique, via peptide substrate Ac-Glu-Glu(Edans)-Lys-Pro-Ile-Cys-Phe-Phe-Arg-Leu-Gly-Lys(Methyl Red)-Glu-NH2. Compounds showing strongest inhibition of cathepsin D activity were those that contain a hydroxyethyl-N’-2- or N’-(4-chlorophenyl)piperazine moiety (IC50 values range from 0.55 to 8.5 nM), with N’-(2-pyrimidyl)piperizine (IC50 values range from 0.5 to 21.6 nM), with NN’- L-piperazinocolinamide (IC50 values range from 0.001 – 0.25 nM), or N-N’-L-piperazinocolin-N-methylamide (IC50 values range from 0.015 – 7.3 nM) .

Forkhead box (Fox) proteins are a superfamily of evolutionarily conserved transcriptional regulators, which control a wide spectrum of biological processes. FoxG1 is a transcriptional repressor, whose function has been elucidated recently. FoxG1 overexpression was found to be associated with medulloblastoma and hepatoblastoma. It was suggested that the inhibition of FoxG1 could be a potential target for the development of molecular therapeutics in such type of cancers. Since, experimentally derived structure for FoxG1 is unavailable in any of the structural databases, modeling of the DNA binding domain of this protein was carried out. Potential binding sites on the protein surface were predicted. Pharmacophoric features were derived from the binding site that lies near the protein-DNA binding interface and this pharmacophore was employed for virtual screening of compounds. To the best of our knowledge, this is the first pharmacophore model proposed for screening inhibitors of FoxG1, which may interfere with its transcriptional repressor functionality. The interactions of the binding site residues with the top scoring ligand hits were analyzed. These ligands may be used for the development of potential inhibitors of FoxG1 protein.

The main use of glycopeptide antibiotics is treatment of infections which are resistant to the commonly used β- lactam antibiotics. Antitumor activity has also been reported for some glycopeptide antibiotics like bleomycin. In the present study we investigated the chemotherapeutic and diagnostic potential of two imaging agent derivatives of the glycopeptide antibiotic vancomycin. For the first conjugate, vancomycin was coupled to the fluorescent dye rhodamine, used in confocal laser scanning microscopy (CLSM) and fluorescence-activated cell sorting (FACS). The second conjugate consisted of vancomycin coupled to gadolinium-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (GdDOTA), a magnetic resonance imaging (MRI) contrast agent. The cellular uptake, specificity, and the accessibility by imaging methods of the two vancomycin conjugates was evaluated on 8 human cell lines (one benign, 7 malignant) by CLSM, FACS, and MRI experiments. Cytotoxicity of both vancomycin conjugates was determined in the FACS experiments with the annexin test indicating disrupted cell membranes. Some of the malignant cell lines showed clearly stronger uptake than the others and the benign cell line was among the cell lines with the lowest uptake. In the annexin test the cytotoxicity could be correlated to the conjugate uptake for all cell lines. The intracellular uptake of the vancomycin conjugates and the increased uptake into some of the malignant cell lines were interesting findings which should be further pursued.

256 pediatric patients with primary hyperlipidemia aged 14.2 ± 8.5 years (females: 155; males:101) seen in our lipid clinic were evaluated retrospectively to assess the effect of multiple lipid-lowering treatment (diet only, diet+glucomannan 1.000 mg/day (G), diet+ezetimibe (E) 10 mg/day and diet+atorvastatin (A) 10 mg/day). The patients were assigned to four groups according to their type of treatment: A-Diet (#82; age 12.7 ± 8 years; females 52, males:30); B-Diet+G (#78; age 13.3 ± 9 years; females 61, males 17); C-Diet+E 10 mg/day (#50; age 14.5 ± 7 years; females 31, males 19); D-Diet+A 10 mg/day (#46; age 16.4 ± 10 years; males 35, females 11). The follow-up visits were at 3, 6 and 9 months, respectively. The time period considered was of 9 months. The results obtained in the four groups after 9 months of treatment are given below: Group A: Total Cholesterol (TC) (-20%), LDL-Cholesterol (LDLC) (-26%), triglycerides (TG) (-25%), nonHDLCholesterol (nonHDLC) (-26%) levels, and TC/HDLC ratio (-21%) were statistically significant reduced (all: P<0001). HDLC was not significantly increased (+2%). The body weight (BW) mean change in the group was statistically significant (-22%; P≤0.001). Group B: TC (-24%), LDLC (-32%), TG (-29%), nonHDLC (-32%) levels and TC/HDLC (-26%) were significantly decreased (all: P≤0.001). HDLC showed a -2.3% not significant decrease. The BW mean change was not statistically significant (-18%). Group C: TC (-36%), LDLC (-51%), nonHDLC (-45%) levels and TC/HDLC (-38%) were significantly decreased (all: P≤0.001). HDLC (+4%) was only slightly increased, and TG (-16%) decreased, but the changes were not statistically significant. The BW mean change was not statistically significant (-15%). Group D: TC (-47%), LDLC (-63%), TG (-23%) and nonHDLC (-58%) levels and TC/HDLC (-50%) showed a statistically significant reduction (all: P≤0001). HDLC concentration in plasma showed only a slight not significant reduction (- 4%). The BW mean change was statistically significant (-20%; P≤0.001). Hyperlipidemia in children can be successfully treated without side effects. The most severe hyperlipidemia is, the most appropriate treatment (diet only,or diet+G, or diet+drugs) is to be given. The reduction of TC/HDLC ratio in childhood prevents future increase of cardiovascular risk in adulthood.

We proposed a method of synthesis to produce [11C]Choline using TRACERlab FXc module that utilized gas phase iodination. The product had radiochemical purity of 99.79 + 0.14 % and specific activity of 45.7 + 7.59 GBq/µmol. [11C]Choline did not have at the moment a specific monograph in European Pharmacopeia therefore we used, when possible, as quality controls reference the monograph of [18F]FDG and we proposed suitable methods to verify radiochemical purity and to quantify residual DMAE and choline amounts.

Two series of 2-adamantyl/adamantylmethyl-5-aryl-1,3,4-oxadiazoles (4a-l and 5a-l) were synthesized by cyclodehydration of adamantan-1-carboxylic acid/adamantylacetic acid with various aryl hydrazides (3a-l) in the presence of POCl3. The synthesis was supported by spectroanalytical techniques and verified further by crystal structure determination of compounds 4e and 5k. The synthesized compounds were screened for their inhibitory activity against HIV-1 and HIV-2 in MT-4 cells. Compound 5b exhibited a moderate activity in vitro for the replication of both virus types, suggesting for further structural modification as a new lead in the development of an antiviral agent.