2-(Methyl(phenyl)amino)-N-(phenyloxyphenyl)acetamide structural motif representing a framework for selective SIRT2 inhibition.

The mammalian cytoplasmic protein SIRT2, a class III histone deacetylase family member, possesses NAD+-dependent lysine deacetylase/deacylase activity. Dysregulation of SIRT2 has been implicated in the pathogenesis of several diseases, including neurological and metabolic disorders and cancer; thus, SIRT2 emerges as a potential therapeutic target. Herein, we identified a series of diaryl acetamides (ST61-ST90) by the structural optimization of our hit STH2, followed by enhanced SIRT2 inhibitory potency and selectivity. Among them, ST72, ST85, and ST88 selectively inhibited SIRT2 with IC50 values of 9.97, 5.74, and 8.92 µM, respectively. Finally, the entire study was accompanied by in silico prediction of binding modes of docked compounds and the stability of SIRT2-ligand complexes. We hope our findings will provide substantial information for designing selective inhibitors of SIRT2.

In silico approach reveals N-(5-phenoxythiophen-2-yl)-2-(arylthio)acetamides as promising selective SIRT2 inhibitors: the case of structural optimization of virtual screening-derived hits.

Epigenetic modifications play an essential role in tumor suppression and promotion. Among the diverse range of epigenetic regulators, SIRT2, a member of NAD+-dependent protein deacetylates, has emerged as a crucial regulator of cellular processes, including cell cycle progression, DNA repair, and metabolism, impacting tumor growth and survival. In the present work, a series of N-(5-phenoxythiophen-2-yl)-2-(arylthio)acetamide derivatives were identified following a structural optimization of previously reported virtual screening hits, accompanied by enhanced SIRT2 inhibitory potency. Among the compounds, ST44 and ST45 selectively inhibited SIRT2 with IC50 values of 6.50 and 7.24 µM, respectively. The predicted binding modes of the two compounds revealed the success of the optimization run. Moreover, ST44 displayed antiproliferative effects on the MCF-7 human breast cancer cell line. Further, the contribution of SIRT2 inhibition in this effect of ST44 was supported by western blotting, affording an increased α-tubulin acetylation. Furthermore, molecular dynamics (MD) simulations and binding free energy calculations using molecular mechanics/generalized born surface area (MM-GBSA) method evaluated the accuracy of predicted binding poses and ligand affinities. The results revealed that ST44 exhibited a remarkable level of stability, with minimal deviations from its initial docking conformation. These findings represented a significant improvement over the virtual screening hits and may contribute substantially to our knowledge for further selective SIRT2 drug discovery.Communicated by Ramaswamy H. Sarma.

Indoleamine-2,3-dioxygenase-related anti-inflammatory effects of 3-aminobenzamide and infliximab in experimental colitis.

OBJECTIVE: This study aimed to investigate the presence of indoleamine-2,3-dioxygenase and bacterial translocation after the administration of 3-aminobenzamide and infliximab in the TNBS model of rat colitis. METHODS: The study group was divided into five categories as follows: group 1: (control), group 2: colitis+saline, group 3: colitis+3-aminobenzamide, group 4: colitis+infliximab, and group 5: colitis+3-aminobenzamide+infliximab. Intestinal mesenteric cultures were incubated on specific agar media plates under aerobic and anaerobic conditions, bacterial translocation was evaluated and assessed as colony-forming units per gram of tissue. Colonic tissue samples were evaluated by Western blotting method to detect the presence of indoleamine-2,3-dioxygenase. RESULTS: The results obtained were as follows: group 1: normal gut flora; group 2: eight of nine samples had bacterial translocation, of which six of them had positive indoleamine-2,3-dioxygenase protein; group 3: five of nine samples had bacterial translocation, of which seven of them had positive indoleamine-2,3-dioxygenase; group 4: three of nine samples had bacterial translocation, of which seven of them had positive indoleamine-2,3-dioxygenase; and group 5: only one sample had exact indoleamine-2,3-dioxygenase protein. CONCLUSION: Altered expression of indoleamine-2,3-dioxygenase results in a lower bacterial translocation via infliximab compared with 3-aminobenzamide treatment. Combined treatments emphasized different approaches for the new molecules related to indoleamine-2,3-dioxygenase.

Hit evaluation results in 5-benzyl-1,3,4-thiadiazole-2-carboxamide based SIRT2-selective inhibitor with improved affinity and selectivity.

Sirtuin 2 (SIRT2), member of sirtuin family, belongs to class III histone deacetylases (HDACs) and is majorly cytosolic with occasional nuclear translocation. The enzymatic activity of SIRT2 is dependent on nicotinamide adenine dinucleotide (NAD+) and SIRT2 regulates post-translational modifications that are responsible for deacetylation of lysine residues in histone and non-histone substrates. SIRT2, thus affects most likely multiple cellular processes, such as signaling, gene expression, aging, autophagy, and has been identified as potential drug target in relation to inflammation, neurodegenerative diseases and cancer. Therefore, probing potential selective inhibitors is essential for the accurate understanding of enzyme functions. Here, we report a series of heteroaryl-2-carboxamide hybrids bearing substituted benzyl or substituted phenoxy group at the 5-position of the central heterocyclic ring. The synthesized compounds were screened against SIRT1-3 and MCF-7 human breast cancer cell line to evaluate their biological activity. The best SIRT2 inhibition profiles were displayed by ST29 (SIRT2 IC50 = 38.69 µM) and ST30 (SIRT2 IC50 = 43.29 µM) with excellent selectivity against SIRT2 over SIRT1 and SIRT3. Molecular docking study of the synthesized compounds into SIRT2 active site was performed to rationalize the remarkable SIRT2 inhibitory activity. Furthermore, we performed all-atom, explicit-solvent molecular dynamics (MD) simulations and end-point binding free energy calculations using molecular mechanics/generalized Born surface area (MM/GBSA) method to evaluate whether this design strategy was successfully deployed. The results implied that the binding poses and ligand affinities were predicted without significant loss of accuracy. Conclusively, the developed chemotypes were advocated as promising leads for SIRT2 inhibition and required further investigation for SIRT2-targeted drug discovery and development.

Indoleamine-2,3-dioxygenase-related anti-inflammatory effects of 3-aminobenzamide and infliximab in experimental colitis

SUMMARY OBJECTIVE: This study aimed to investigate the presence of indoleamine-2,3-dioxygenase and bacterial translocation after the administration of 3-aminobenzamide and infliximab in the TNBS model of rat colitis. METHODS: The study group was divided into five categories as follows: group 1: (control), group 2: colitis+saline, group 3: colitis+3-aminobenzamide, group 4: colitis+infliximab, and group 5: colitis+3-aminobenzamide+infliximab. Intestinal mesenteric cultures were incubated on specific agar media plates under aerobic and anaerobic conditions, bacterial translocation was evaluated and assessed as colony-forming units per gram of tissue. Colonic tissue samples were evaluated by Western blotting method to detect the presence of indoleamine-2,3-dioxygenase. RESULTS: The results obtained were as follows: group 1: normal gut flora; group 2: eight of nine samples had bacterial translocation, of which six of them had positive indoleamine-2,3-dioxygenase protein; group 3: five of nine samples had bacterial translocation, of which seven of them had positive indoleamine-2,3-dioxygenase; group 4: three of nine samples had bacterial translocation, of which seven of them had positive indoleamine-2,3-dioxygenase; and group 5: only one sample had exact indoleamine-2,3-dioxygenase protein. CONCLUSION: Altered expression of indoleamine-2,3-dioxygenase results in a lower bacterial translocation via infliximab compared with 3-aminobenzamide treatment. Combined treatments emphasized different approaches for the new molecules related to indoleamine-2,3-dioxygenase.

Identification of novel antiplatelet agents by targeting Glycoprotein VI: A combined virtual screening study.

Cardiovascular diseases are the primary reason for deaths in the world. However, antiplatelet drugs in the market have limitations in use because of the risk of increased bleeding and other side effects that impair primary homeostasis. Therefore, safe and effective antithrombotic drugs are needed for the treatment of plaque formation in blood vessels. Glycoprotein VI (GPVI) is a platelet major collagen receptor and a target for potent and safe antithrombotic therapy. We designed this study based on the molecular interaction pattern of previously published GPVI receptor antagonists within the reported binding site. We selected sixteen hit compounds from a large chemical database that contains>6 million in-stock compounds by following a combined virtual screening. Then, we evaluated their inhibitory effects on platelet aggregation induced by GPVI receptor agonists (collagen, collagen related peptide (CRP), convulxin) and the most potent platelet agonist, thrombin, in vitro by using washed human platelets. IC50 values of compounds 1 and 2 are, respectively, 0.35 µM and 1.01 µM for collagen, 0.80 µM and 1.92 µM for CRP, 195.2 and 7.24 µM for convulxin and 81.38 and 51.74 µM for thrombin. We identified compounds 1 and 2 as the most promising antiplatelet agents out of sixteen compounds. Additionally, compounds 1 and 2 may serve as promising starting points and shed light on the design of new, potent and selective GPVI receptor antagonists.

Hit-to-lead optimization on aryloxybenzamide derivative virtual screening hit against SIRT.

Sirtuins (SIRTs) are a class of nicotinamide adenine dinucleotide (NAD+)-dependent protein histone deacetylases (HDACs) that are evolutionarily conserved from bacteria to mammals. This group of enzymes catalyses the reversible deacetylation of lysine residues in the histones or non-histone substrates using NAD+ as a cosubstrate. Numerous studies have demonstrated that the aberrant enzymatic activity of SIRTs has been linked to various diseases like diabetes, cancer, and neurodegenerative disorders. Previously, we performed a pharmacophore-based virtual screening campaign and an aryloxybenzamide derivative (1) displaying SIRT1/2 inhibitory effect was identified as a hit compound. In the current study, the hit-to-lead optimization on the hit compound was explored in order to improve the SIRT binding and inhibition. Fourteen compounds, ten of which were new, have been synthesized and subjected to in vitro biological evaluation for their inhibitory activity against SIRT1-3. By the structural modifications performed, a significant improvement was observed in selective SIRT1 inhibition for ST01, ST02, and ST11 compared to that of the hit compound. The highest SIRT2 inhibitory activity was observed for ST14, which was designed according to compatibility with pharmacophore model developed for SIRT2 inhibitors and thus, providing the interactions required with key residues in SIRT2 active site. Furthermore, ST01, ST02, ST11, and ST14 were subjected to in vitro cytotoxicity assay against MCF-7 human breast cancer cell line to determine the influence of the improvement in SIRT1/2 inhibition along with the structural modifications on the cytotoxic properties of the compounds. The cytotoxicity of the compounds was found to be correlated with their SIRT inhibitory profiles indicating the effects of SIRT1/2 inhibition on cancer cell viability. Overall, this study provides structural insights for further inhibitor improvement.

Determination of Tryptophan and Kynurenine by LC-MS/MS by Using Amlodipine as an Internal Standard.

Tryptophan is an essential amino acid that plays an important role in cell metabolism, and kynurenine is its main metabolic pathway. By using ultra-high-performance liquid chromatography coupled to electrospray ionization triple-quadrupole mass spectrometry, tryptophan and kynurenine were determined using amlodipine as an internal standard. The analysis was carried out on an ACE-C18 (4.6 mm × 50 mm, 5 µm) reversed-phase analytical column using the gradient elution mode. For quantitative determination, amlodipine was used as an internal standard. Detection was performed using multiple reaction monitoring in electrospray ionization mode at m/z 205.1 → 117.7 and 187.9 for tryptophan, m/z 209.1 → 146 and 93.9 for kynurenine, and m/z 409.2 → 294.1 for the internal standard. Good linearity of the analyte to internal standard peak area ratios was seen in the concentration range 1.25-4000 ng/mL for tryptophan and 0.5-1600 ng/mL for kynurenine. The method showed excellent linearity with regression coefficients of 0.99 for kynurenine and 0.996 for tryptophan. The limits of quantification were 0.55 ng/mL for tryptophan and 0.47 ng/mL for kynurenine. The % RSD for all analytes ranged from 0.3 to 3.4% for intraday and 0.4 to 8.9% for interday experiments. A simple LC-MS/MS method has been developed and validated for measuring Kyn and Trp by using an affordable and more easily available internal standard, which is amlodipine.

Identification of small-molecule urea derivatives as novel NAMPT inhibitors via pharmacophore-based virtual screening.

Nicotinamide phosphoribosyltransferase (NAMPT) catalyzes the condensation of nicotinamide (NAM) with 5-phosphoribosyl-1-prophosphate (PRPP) to yield nicotinamide mononucleotide (NMN), a rate limiting enzyme in a mammalian salvage pathway of nicotinamide adenine dinucleotide (NAD+) synthesis. Recently, intracellular NAD+ has received substantial attention due to the recent discovery that several enzymes including poly(ADP-ribose) polymerases (PARPs), mono(ADP-ribose) transferases (ARTs), and sirtuins (SIRTs), use NAD+ as a substrate, suggesting that intracellular NAD+ level may regulate cytokine production, metabolism, and aging through these enzymes. NAMPT is found to be upregulated in various types of cancer, and given its importance in the NAD+ salvage pathway, NAMPT is considered as an attractive target for the development of new cancer therapies. In this study, the reported NAMPT inhibitors bearing amide, cyanoguanidine, and urea scaffolds were used to generate pharmacophore models and pharmacophore-based virtual screening studies were performed against ZINC database. Following the filtering steps, ten hits were identified and evaluated for their in vitro NAMPT inhibitory effects. Compounds GF4 (NAMPT IC50 = 2.15 ± 0.22 µM) and GF8 (NAMPT IC50 = 7.31 ± 1.59 µM) were identified as new urea-typed inhibitors of NAMPT which also displayed cytotoxic activities against human HepG2 hepatocellular carcinoma cell line with IC50 values of 15.20 ± 1.28 and 24.28 ± 6.74 µM, respectively.

Microwave-assisted synthesis and pharmacological screening of some triazolothiadiazole derivatives

In this study, twenty-two new [1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles (5a-n, 6a-h) were synthesized under microwave irradiation (MWI). The chemical structures of the compounds were elucidated by their IR, 1H-NMR, LC-MS, and elemental analysis. The compounds were tested for antinociceptive activity by using the tail clip, tail flick, hot plate, and writhing methods in mice. The varying levels of antinociceptive activity of the compounds were compared with those of aspirin. Among these compounds, compound 5g and 5j were found to be significantly more active than the other compounds and the standard in the tests. Also, inhibitory effects of the test compounds on COX-1 and COX-2 activities were investigated. DuP-697 for COX-2 and SC-560 for COX-1 were used as reference standards.

Pharmacophore modeling and virtual screening studies to identify novel selective SIRT2 inhibitors.

Sirtuins (SIRTs) are a class of NAD+-dependent protein histone deacetylases (HDACs) that catalyse the reversible deacetylation of lysine residues in the histones or non-histone substrates. Mammalian sirtuins consist of seven isoforms (SIRT1-7), which show different subcellular localizations and enzymatic functions. Among the seven human sirtuins, SIRT2 predominantly located in the cytoplasm but is enriched in the nucleus during mitosis. Its activity has been found to be modulate the pathophysiology of various diseases such as cancer, metabolic and neurodegenerative disorders. Therefore, selective SIRT2 inhibitors are of growing interest as potentially candidate therapeutic agents to treat SIRT2-driven pathologies as well as valuable tools to investigate and define the biological roles of SIRT2. Herein, in order to identify potent leads against SIRT2, a multi-step pharmacophore based-virtual screening campaign was performed and 31 predicted compounds were subjected to in vitro biological evaluation. Finally, compound 2 and 3 showing better SIRT2 inhibition potency were selected for further in vitro cytotoxic assays against a panel of three human cancer cell lines. This study will hopefully provide a basis for developing potent and selective SIRT2 inhibitors.

Design, synthesis and biological evaluation of novel 1,3-diarylpyrazoles as cyclooxygenase inhibitors, antiplatelet and anticancer agents.

With the aim of achieving new compounds possessing both anti-inflammatory and antiplatelet activities, we synthesized (E)-3-[3-(pyridin-3/4-yl)-1-(phenyl/sulfonylmethylphenyl)-1H-pyrazol-4-yl]acrylamides, and evaluated their COX-1 and COX-2 inhibitory and antiplatelet activities. Since COX-2 inhibitory and antiplatelet compounds have anticancer potential, we also screened their antiproliferative effects against three human cancer cell lines. Compounds 5n, 5p, 5s, 10d, 10g and 10i were determined as dual COX-2 inhibitor/antiplatelet compounds. Compound 10h appeared to be a compound that exhibited antiplatelet activity without inhibiting the COX enzyme. Compounds 5h, 10a and 10i were the most effective derivatives which displayed antiproliferative activity against Huh7, MCF7 and HCT116 cells. Particularly, compound 10i, as the compound exhibiting the highest cytotoxic, antiplatelet and COX-2 inhibitory activity, was remarkable.

Evaluation of Tryptophan/Kynurenine Pathway Relevance With Immune System Biomarkers of Low Energy Trauma Hip Fractures in Osteoporotic Patients.

OBJECTIVES: This study aims to evaluate tryptophan degradation and clarify whether altered levels of kynurenine and tryptophan (Kyn/Trp) ratio could be correlated to osteoporotic hip fractures via immune system. PATIENTS AND METHODS: The study included 60 patients with osteoporotic hip fracture (20 males, 40 females, mean age 76.6±6.9 years; range 59 to 95 years). Patients were divided into two as patients with collum femoris fractures (group 1; n=23) and intertrochanteric fractures (group 2; n=37). Fifteen healthy subjects without any fracture were selected as control group (group 3; 3 males, 12 females; mean age 69.7±8.4; range 60 to 86 years). All fractures were simple falls due to low energy trauma. Bone mineral density measurements were performed with Lunar dual energy X-ray absorptiometry. Kyn/Trp levels were measured by high performance liquid chromatography. Interleukin (IL)-6 and IL-1 beta levels were measured with solid-phase sandwich enzyme-linked immunosorbent assay. RESULTS: All bone mineral density values were in agreement for osteoporosis and there was no significant difference between the two groups. Higher Kyn/Trp ratios were observed in groups 1 and 2 compared to group 3. This difference was more significant in group 1 (p=0.0001) than that in group 2 (p=0.048). Also, group 1 had significantly higher Kyn/Trp ratio than group 2 (p=0.011). There were significantly higher IL-6 and lower IL-1 beta levels both in groups 1 and 2 compared to group 3 (p=0.0001). There was no significant difference between group 1 and group 2 in terms of IL-6 and IL-1 beta levels. There was positive correlation with Kyn/Trp ratio (r=0.581, p=0.004) in group 2. Also, significant correlation was detected between IL-6 and IL-1 beta levels in the same group (r=0.665, p=0.036). CONCLUSION: Both increased degradation of tryptophan and ratio of Kyn/Trp indicate the relationship of immune activation with bone healing.

Synthesis and biological evaluation of some dibenzofuran-piperazine derivatives.

In the present paper, a novel series of dibenzofuran-piperazine derivatives were synthesized via the treatment of N-(2-methoxy-3-dibenzofuranyl)-2-chloroacetamide with substituted piperazine derivatives. The chemical structures of the compounds were elucidated by (1)H NMR, (13)C NMR, mass spectral data; elemental analysis and HPLC analysis. Each derivative was evaluated for antiplatelet activity and anticholinesterase activity. Compound 2 m with 2-furoyl moiety exhibited high percentage inhibition as much as standard drug aspirin on arachidonic acid (AA)-induced platelet aggregation. None of the compounds presented significant inhibitor effect on collagen-induced platelet aggregation. Furthermore, the anticholinesterase activity of the compounds was determined and they did not show promising inhibitor activity compared with standard drug donepezil.

Determination of TiO2 and AgTiO2 Nanoparticles in Artemia salina: Toxicity, Morphological Changes, Uptake and Depuration.

In this study, aquatic stability and toxic effects of TiO2 and AgTiO2 nanoparticles (NPs) were investigated on Artemia salina nauplii. AgTiO2 was found to be more toxic to nauplii compared to TiO2. The mortality rate in nauplii increased significantly with increasing concentrations and duration of exposure. TiO2 eliminations ranged between 27.8% and 96.5% at 50 and 1 mg/L TiO2 exposed to nauplii, respectively. Accumulation and elimination of Ag in AgTiO2 exposed nauplii were similar except at 1 mg/L AgTiO2. When NPs were mixed with water, the hydrodynamic dimensions of NPs significantly increased because of aggregation in saltwater but NP size decreased over time. NPs-exposed nauplii showed changes in eye formation, enlargement of the intestine, malformations in the outer shell and antennae loss were also observed. Since accumulation and toxicity of AgTiO2 NPs was higher than TiO2 alone, inevitably release of AgTiO2 into aqueous environments can cause ecological risks.

Association of obstructive sleep apnea with homocystein, nitric oxide and total antioxidant capacity levels in patients with or without coronary artery disease.

INTRODUCTION: Obstructive sleep apnea (OSA) is associated with cardiovascular morbidity and mortality. Deficiency of nitric oxide (NO) and plasma levels of homocystein have been implicated in the pathogenesis of cardiovascular disease. OSA results in oxygen desaturation and arousal from sleep. Free oxygen radicals can be produced by hypoxia-reoxygenation. To test for the hypothesis that OSA is associated with cardiovascular morbidity, we investigated levels of homocystein, NO and total antioxidant capacity in OSA patients with and without coronary artery disease (CAD) in comparison with normal subjects and patients with CAD without OSA. MATERIALS AND METHODS: Polysomnography was performed in 27 patients who had a myocardial infarction and in 25 patients without evidence of CAD. Patients were grouped according their polysomnography results as OSA with CAD (group 1), OSA without CAD (group 2), CAD (group 3), and normal (group 4) . Levels of homocystein, NO and total antioxidant capacity were determined after an overnight fasting. Data were analysed with parametric and non parametric statistical tests. RESULTS: According to apnea-hypopnea index (AHI) 44.4% of CAD patients were OSA. After polysomnographic evaluation, the patients were re-distributed as follows: OSA with CAD (n= 12), OSA without CAD (n= 14), CAD (n= 15), and normal (n= 11). Homocystein levels were higher in 3 groups compared to controls. AHI, MDI and desaturation time was higher in three -vessel disease compared to one and two- vessel diseases (p< 0.05). NO levels were correlated with the period of oxygen desaturation (r: -0.45, p= 0.031). The antioxidant capacity did not differ between OSA and healthy groups. CONCLUSION: OSA is frequent in CAD. AHI, MDI and desaturation time are higher in patients with severe CAD. It is important to evaluate OSA patients for CAD.

Relation of kynurenine/tryptophan with immune and inflammatory markers in coronary artery disease.

BACKGROUND: Inflammation and immune activation have a crucial role in the pathogenesis of cardiovascular diseases. Indolamine 2,3-dioxygenase, a tryptophan catabolising enzyme, is up-regulated with various inflammatory stimuli. The aim of this study was to evaluate the relationship of tryptophan degradation with immune and inflammatory markers in coronary artery disease. METHODS: 57 subjects undergoing coronary angiography were recruited. 18 subjects with normal coronary arteries according to Gensini scoring were selected as a control group and the rest of subjects were included in patient group. Serum tryptophan and kynurenine levels were determined with HPLC-UV method, and kynurenine/tryptophan ratio was evaluated as IDO activity. Serum neopterin and myeloperoxidase activity were measured by ELISA method. RESULTS: While the kynurenine/tryptophan ratio and neopterin levels were similar in both groups, the patient group had higher myeloperoxidase and hs-CRP levels than controls (p = 0.02, p = 0.002, respectively). The kynurenine/tryptophan ratio was correlated with neopterin in both groups (r = 0.389, p = 0.025; r = 0.683, p = 0.002, respectively) and with hs-CRP in patients (r = 0.637, p = 0.001). Also, neopterin levels were correlated with hs-CRP in patients (r = 0.755, p = 0.0001). CONCLUSIONS: Our results are in line with a role of inflammation in coronary artery disease. The study provides evidence that IDO activity is related with immune and inflammatory states. Also, the study was performed in a limited hospital-based population. Further studies are warranted in the larger groups.

Serum homocysteine levels and sildenafil 50 mg response in young-adult male patients without vascular risk factors.

The aim of the present study was to investigate serum homocysteine levels in patients with erectile dysfunction and to evaluate the relationship between serum homocysteine levels and response to the standard 50 mg phosphodiesterase 5 inhibitor treatment. Twenty-eight erectile dysfunction patients having normal vascular parameter according to Penile Doppler Ultrasonography and twenty healthy subjects were enrolled in the study. All subjects filled The International Index of Erectile Function (IIEF) questionnaire. A total of 4-6 doses of phosphodiesterase 5 inhibitor (sildenafil 50 mg) were given to patients. Later, they were divided into two groups as sildenafil responder and non-responder. Serum homocysteine levels were compared in groups based on sildenafil response. Compared with healthy subject, higher homocysteine levels were observed in patients with erectile dysfunction (p = 0.005), especially in sildenafil non-responder group (p = 0.005). There was significant negative correlation between homocysteine and IIEF scores in group responder to sildenafil treatment (r = -0.698, p = 0.008). Mean IIEF scores of patients with non-responder to sildenafil 50 mg were lower than those of controls (p = 0.0001), but mean IIEF scores of patients with responders approached values observed in control subjects (p = 0.002). The results indicated that measurement of serum homocysteine levels could be used as a marker for the evaluation of efficacy of phosphodiesterase 5 inhibitor and the selection of efficacious alternative therapies.

Pyrazole derivatives as inhibitors of arachidonic acid-induced platelet aggregation.

Antiplatelet drugs are promising therapeutics to intervene with platelet aggregation in arterial thrombosis, most prominently in myocardial infarction and ischemic stroke. Here, we describe the synthesis and structure-activity relationships of potent inhibitors of platelet aggregation based on the 1,5-diarylpyrazol-3-carboxamide scaffold. Analogs from this series demonstrated potent anti-aggregatory activities against arachidonic acid-induced platelet aggregation, as measured by turbidimetric method of Born. 1,5-Diarylpyrazole-3-carboxamides obtained with small-basic amines (7, 8, 50, 51, 61, 62) displayed the strongest activity with IC50 values in low nanomolar range (5.7-83 nM). On the basis of their high potency in cellular environment, these straightforward pyrazole derivatives may possess potential in the design of more potent compounds for intervention with cardiovascular diseases.

Tryptophan degradation and neopterin levels in treated rheumatoid arthritis patients.

Increased kynurenine/tryptophan-reflects trytophan degradation-and neopterin levels have been regarded as a biochemical marker of cell-mediated immune response and inflammation. This study was designed to evaluate the usefulness of tryptophan degradation and neopterin levels in active rheumatoid arthritis patients under therapy. In this case-control study, kynurenine and tryptophan levels were determined by HPLC; neopterin and tumor necrosis factor-α levels were measured with ELISA in 32 active rheumatoid arthritis patients and 20 healthy controls. Although mean values of tryptophan, kynurenine, ratio of kynurenine to tryptophan, neopterin, and tumor necrosis factor-α levels did not show statistically significant differences between patient and control groups, neopterin levels correlated positively with kynurenine (r = 0.582, p < 0.02), kynurenine/tryptophan (r = 0.486, p < 0.05), erythrocyte sedimentation rate (r = 0.472, p < 0.05) and RF (r = 0.478, p < 0.05) in the rheumatoid arthritis group. CRP levels of the patient group correlated with kynurenine levels (r = 0.524, p < 0.03). Determination of tryptophan degradation and neopterin levels in chronic inflammatory disease may provide a better understanding of progression of the disease.