MM165 - A Small Hybrid Molecule Modulates the Kynurenine Pathway and Attenuates Lipopolysaccharide-Induced Memory Deficits and Inflammation.

Cognitive dysfunctions are now recognized as core symptoms of various psychiatric disorders e.g., major depressive disorder. Sustained immune activation may leads to cognitive dysfunctions. Proinflammatory cytokines shunt the metabolism of tryptophan towards kynurenine and quinolinic acid may accumulate at toxic concentrations. This acid triggers an increase in neuronal nitric oxide synthase function and promotes oxidative stress. The searching for small molecules that can regulate tryptophan metabolites produced in the kynurenic pathway has become an important goal in developing treatments for various central nervous system diseases with an inflammatory component. Previously we have identified a small hybrid molecule - MM165 which significantly reduces depressive-like symptoms caused by inflammation induced by lipopolysaccharide administration. In the present study, we investigated whether this compound would mitigate cognitive deficits induced by lipopolysaccharide administration and whether treatment with it would affect the plasma or brain levels of quinolinic acid and kynurenic acid. Neuroinflammation was induced in rats by administering lipopolysaccharide at a dose of 0.5 mg/kg body weight for 10 days. We conducted two tests: novel object recognition and object location, to assess the effect on memory impairment in animals previously treated with lipopolysaccharide. In plasma collected from rats, the concentrations of C-reactive protein and tumor necrosis factor alfa were determined. The concentrations of kynurenic acid and quinolinic acid were determined in plasma and homogenates obtained from the cerebral cortex of rats. Interleukin 6 in the cerebral cortex of rats was determined. Additionally, the body and spleen mass and spontaneous activity were measured in rats. Our study shows that MM165 may mitigate cognitive deficits induced by inflammation after administration of lipopolysaccharide and alter the concentrations of tryptophan metabolites in the brain. Compounds exhibiting a mechanism of action analogous to that of MM165 may serve as foundational structures for the development of a new class of antidepressants.

The Subtype Selectivity in Search of Potent Hypotensive Agents among 5,5-Dimethylhydantoin Derived α1-Adrenoceptors Antagonists.

In order to find new hypotensive drugs possessing higher activity and better selectivity, a new series of fifteen 5,5-dimethylhydantoin derivatives (1-15) was designed. Three-step syntheses, consisting of N-alkylations using standard procedures as well as microwaves, were carried out. Crystal structures were determined for compounds 7-9. All of the synthesized 5,5-dimethylhydantoins were tested for their affinity to α1-adrenergic receptors (α1-AR) using both in vitro and in silico methods. Most of them displayed higher affinity (Ki < 127.9 nM) to α1-adrenoceptor than urapidil in radioligand binding assay. Docking to two subtypes of adrenergic receptors, α1A and α1B, was conducted. Selected compounds were tested for their activity towards two α1-AR subtypes. All of them showed intrinsic antagonistic activity. Moreover, for two compounds (1 and 5), which possess o-methoxyphenylpiperazine fragments, strong activity (IC50 < 100 nM) was observed. Some representatives (3 and 5), which contain alkyl linker, proved selectivity towards α1A-AR, while two compounds with 2-hydroxypropyl linker (11 and 13) to α1B-AR. Finally, hypotensive activity was examined in rats. The most active compound (5) proved not only a lower effective dose than urapidil but also a stronger effect than prazosin.

Manifestations of Liver Impairment and the Effects of MH-76, a Non-Quinazoline α1-Adrenoceptor Antagonist, and Prazosin on Liver Tissue in Fructose-Induced Metabolic Syndrome.

Excessive fructose consumption may lead to metabolic syndrome, metabolic dysfunction-associated fatty liver disease (MAFLD) and hypertension. α1-adrenoceptors antagonists are antihypertensive agents that exert mild beneficial effects on the metabolic profile in hypertensive patients. However, they are no longer used as a first-line therapy for hypertension based on Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) outcomes. Later studies have shown that quinazoline-based α1-adrenolytics (prazosin, doxazosin) induce apoptosis; however, this effect was independent of α1-adrenoceptor blockade and was associated with the presence of quinazoline moiety. Recent studies showed that α1-adrenoceptors antagonists may reduce mortality in COVID-19 patients due to anti-inflammatory properties. MH-76 (1-[3-(2,6-dimethylphenoxy)propyl]-4-(2-methoxyphenyl)piperazine hydrochloride)) is a non-quinazoline α1-adrenoceptor antagonist which, in fructose-fed rats, exerted anti-inflammatory, antihypertensive properties and reduced insulin resistance and visceral adiposity. In this study, we aimed to evaluate the effect of fructose consumption and treatment with α1-adrenoceptor antagonists of different classes (MH-76 and prazosin) on liver tissue of fructose-fed rats. Livers were collected from four groups (Control, Fructose, Fructose + MH-76 and Fructose + Prazosin) and subjected to biochemical and histopathological studies. Both α1-adrenolytics reduced macrovesicular steatosis and triglycerides content of liver tissue and improved its antioxidant capacity. Treatment with MH-76, contrary to prazosin, reduced leucocytes infiltration as well as decreased elevated IL-6 and leptin concentrations. Moreover, the MH-76 hepatotoxicity in hepatoma HepG2 cells was less than that of prazosin. The use of α1-adrenolytics with anti-inflammatory properties may be an interesting option for treatment of hypertension with metabolic complications.

Antiplatelet Effects of Selected Xanthine-Based Adenosine A2A and A2B Receptor Antagonists Determined in Rat Blood.

The platelet aggregation inhibitory activity of selected xanthine-based adenosine A2A and A2B receptor antagonists was investigated, and attempts were made to explain the observed effects. The selective A2B receptor antagonist PSB-603 and the A2A receptor antagonist TB-42 inhibited platelet aggregation induced by collagen or ADP. In addition to adenosine receptor blockade, the compounds were found to act as moderately potent non-selective inhibitors of phosphodiesterases (PDEs). TB-42 showed the highest inhibitory activity against PDE3A along with moderate activity against PDE2A and PDE5A. The antiplatelet activity of PSB-603 and TB-42 may be due to inhibition of PDEs, which induces an increase in cAMP and/or cGMP concentrations in platelets. The xanthine-based adenosine receptor antagonists were found to be non-cytotoxic for platelets. Some of the compounds showed anti-oxidative properties reducing lipid peroxidation. These results may provide a basis for the future development of multi-target xanthine derivatives for the treatment of inflammation and atherosclerosis and the prevention of heart infarction and stroke.

Metabolic and cardiovascular benefits and risks of 4-hydroxy guanabenz hydrochloride: α2-adrenoceptor and trace amine-associated receptor 1 ligand.

BACKGROUND: α2-adrenoceptor ligands have been investigated as potential therapeutic agents for the treatment of obesity. Our previous studies have shown that guanabenz reduces the body weight of obese rats, presumably through its anorectic action. This demonstrates an additional beneficial effect on selected metabolic parameters, including glucose levels. The purpose of this present research was to determine the activity of guanabenz's metabolite-4-hydroxy guanabenz hydrochloride (4-OH-Guanabenz). METHODS: We performed in silico analyses, involving molecular docking to targets of specific interest as well as other potential biological targets. In vitro investigations were conducted to assess the selectivity profile of 4-OH-Guanabenz binding to α-adrenoceptors, along with intrinsic activity studies involving α2-adrenoceptors and trace amine-associated receptor 1 (TAAR1). Additionally, the effects of 4-OH-Guanabenz on the body weight of rats and selected metabolic parameters were evaluated using the diet-induced obesity model. Basic safety and pharmacokinetic parameters were also examined. RESULTS: 4-OH-guanabenz is a partial agonist of α2A-adrenoceptor. The calculated EC50 value for it is 316.3 nM. It shows weak agonistic activity at TAAR1 too. The EC50 value for 4-OH-Guanabenz calculated after computer simulation is 330.6 µM. Its primary mode of action is peripheral. The penetration of 4-OH-Guanabenz into the brain is fast (tmax = 15 min), however, with a low maximum concentration of 64.5 ng/g. 4-OH-Guanabenz administered ip at a dose of 5 mg/kg b.w. to rats fed a high-fat diet causes a significant decrease in body weight (approximately 14.8% compared to the baseline weight before treatment), reduces the number of calories consumed by rats, and decreases plasma glucose and triglyceride levels. CONCLUSIONS: The precise sequence of molecular events within the organism, linking the impact of 4-OH-Guanabenz on α2A-adrenoceptor and TAAR1 with weight reduction and the amelioration of metabolic disturbances, remains an unresolved matter necessitating further investigation. Undoubtedly, the fact that 4-OH-Guanabenz is a metabolite of a well-known drug has considerable importance, which is beneficial from an economic point of view and towards its further development as a drug candidate.

Evaluation of Some Safety Parameters of Dual Histamine H3 and Sigma-2 Receptor Ligands with Anti-Obesity Potential.

Many studies have shown the high efficacy of histamine H3 receptor ligands in preventing weight gain. In addition to evaluating the efficacy of future drug candidates, it is very important to assess their safety profile, which is established through numerous tests and preclinical studies. The purpose of the present study was to evaluate the safety of histamine H3/sigma-2 receptor ligands by assessing their effects on locomotor activity and motor coordination, as well as on the cardiac function, blood pressure, and plasma activity of certain cellular enzymes. The ligands tested at a dose of 10 mg/kg b.w. did not cause changes in locomotor activity (except for KSK-74) and did not affect motor coordination. Significant reductions in blood pressure were observed after the administration of compounds KSK-63, KSK-73, and KSK-74, which seems logically related to the increased effect of histamine. Although the results of in vitro studies suggest that the tested ligands can block the human ether-a-go-go-related gene (hERG) potassium channels, they did not affect cardiac parameters in vivo. It should be noted that repeated administration of the tested compounds prevented an increase in the activity of alanine aminotransferase (AlaT) and gamma-glutamyl transpeptidases (gGT) observed in the control animals fed a palatable diet. The obtained results show that the ligands selected for this research are not only effective in preventing weight gain but also demonstrate safety in relation to the evaluated parameters, allowing the compounds to proceed to the next stages of research.

The Influence of Caramel Carbon Quantum Dots and Caramel on Platelet Aggregation, Protein Glycation and Lipid Peroxidation.

Caramel, defined as a coloring agent and as an antioxidant, is used in several kinds of food products and is consumed by many people in different amounts. In our research we showed that the caramelization of sucrose under special conditions leads to the formation of carbon quantum dots (CQDs). So, it makes sense that humans also consume this type of CQDs, and it is theoretically possible for these particles to affect the body. Despite an increasing number of studies describing different types of CQDs, their biosafety is still not clearly understood. In our in vitro research, we examined the effects on platelet aggregation, protein glycation and lipid peroxidation of CQDs and caramel formed from a 20% sucrose solution. In vitro aggregation tests were conducted using freshly collected whole rat blood in a multiplate platelet function analyzer and measurer of electric impedance. The cytotoxic effect of the tested solutions on blood platelets was evaluated based on the release of lactate dehydrogenase. The formation of glycated bovine serum albumin was measured as fluorescence intensity and fructosamine level. The reducing power of the solutions was determined in adipose tissue, and their effect on lipid peroxidation in adipose tissue in vitro was also assessed. By measuring the intensity of hemolysis after incubation in solutions with red blood cell, we assessed their influence on the integration of the red blood cell membrane. All tests were performed in comparison with glucose and fructose and other frequently used sweeteners, such as erythritol and xylitol. Our study showed that caramel and CQDs formed from caramel may influence the glycation process and integrity of the red blood cell membrane, but unlike glucose and fructose, they decrease lipid peroxidation and may reduce Fe (III). Additionally, it is unlikely that they affect platelet aggregation. Compared to glucose and fructose, they may be safer for patients with metabolic disorders; however, further research is needed on the safety and biological activity of caramel and CQD.

Milk-Derived Carbon Quantum Dots: Study of Biological and Chemical Properties Provides Evidence of Toxicity.

Carbon dots (CDs) are carbon-based zero-dimensional nanomaterials that can be prepared from a number of organic precursors. In this research, they are prepared using fat-free UHT cow milk through the hydrothermal method. FTIR analysis shows C=O and C-H bond presence, as well as nitrogen-based bond like C-N, C=N and -NH2 presence in CDs, while the absorption spectra show the absorption band at 280 ± 3 nm. Next, the Biuret test was performed, with the results showing no presence of unreacted proteins in CDs. It can be said that all proteins are converted in CDs. Photo luminance spectra shows the emission of CDs is 420 nm and a toxicity study of CDs was performed. The Presto Blue method was used to test the toxicity of CDs for murine hippocampal cells. CDs at a concentration of 4 mg/mL were hazardous independent of synthesis time, while the toxicity was higher for lower synthesis times of 1 and 2 h. When the concentration is reduced in 1 and 2 h synthesized CDs, the cytotoxic effect also decreases significantly, ensuring a survival rate of 60-80%. However, when the synthesis time of CDs is increased, the cytotoxic effect decreases to a lesser extent. The CDs with the highest synthesis time of 8 h do not show a cytotoxic effect above 60%. The cytotoxicity study shows that CDs may have a concentration and time-dependent cytotoxic effect, reducing the number of viable cells by 40%.

Preliminary Evidence of the Potent and Selective Adenosine A2B Receptor Antagonist PSB-603 in Reducing Obesity and Some of Its Associated Metabolic Disorders in Mice.

The adenosine A2A and A2B receptors are promising therapeutic targets in the treatment of obesity and diabetes since the agonists and antagonists of these receptors have the potential to positively affect metabolic disorders. The present study investigated the link between body weight reduction, glucose homeostasis, and anti-inflammatory activity induced by a highly potent and specific adenosine A2B receptor antagonist, compound PSB-603. Mice were fed a high-fat diet for 14 weeks, and after 12 weeks, they were treated for 14 days intraperitoneally with the test compound. The A1/A2A/A2B receptor antagonist theophylline was used as a reference. Following two weeks of treatment, different biochemical parameters were determined, including total cholesterol, triglycerides, glucose, TNF-α, and IL-6 blood levels, as well as glucose and insulin tolerance. To avoid false positive results, mouse locomotor and spontaneous activities were assessed. Both theophylline and PSB-603 significantly reduced body weight in obese mice. Both compounds had no effects on glucose levels in the obese state; however, PSB-603, contrary to theophylline, significantly reduced triglycerides and total cholesterol blood levels. Thus, our observations showed that selective A2B adenosine receptor blockade has a more favourable effect on the lipid profile than nonselective inhibition.

Hydroalcoholic Leaf Extract of Isatis tinctoria L. via Antioxidative and Anti-Inflammatory Effects Reduces Stress-Induced Behavioral and Cellular Disorders in Mice.

Stress that can occur at different levels of a person's life can cause and exacerbate various diseases. Oxidative stress and inflammation underlie this process at the cellular level. There is an urgent need to identify new and more effective therapeutic targets for the treatment of stress-induced behavioral disorders and specific drugs that affect these targets. Isatis tinctoria L. is a herbaceous species in the Brassicaceae family. Due to its potential antioxidant, nitric oxide- (NO-) inhibiting, anti-inflammatory, and neuroprotective properties, I. tinctoria could be used to treat depression, anxiety, and stress resistance. Hence, the present study is aimed at delineating whether administration of I. tinctoria leaf extract may improve stress-induced disorders in mice. A set of four behavioral tests was selected that together are suitable for phenotyping acute restraint stress-associated behaviors in mice, namely locomotor activity, social integration, dark/light box, and splash tests. The plasma and brains were collected. A brain-derived neurotrophic factor, tumor necrosis factor-alpha, C-reactive protein, corticosterone, NO, reactive oxygen species levels, superoxide dismutase and catalase activity, and ferric-reducing antioxidant power were measured. In mice stressed by immobilization, decreased locomotor activity, anxiety-like behavior, and contact with other individuals were observed, as well as increased oxidative stress and increased levels of nitric oxide in the brain and plasma C-reactive protein. A single administration of I. tinctoria leaf extract was able to reverse the behavioral response to restraint by a mechanism partially dependent on the modulation of oxidative stress, neuroinflammation, and NO reduction. In conclusion, Isatis tinctoria hydroalcoholic leaf extract can reduce stress-induced behavioral disturbances by regulating neurooxidative, neuronitrosative, and neuroimmune pathways. Therefore, it could be recommended for further research on clinical efficacy in depression and anxiety disorder treatment.

KSK-74: Dual Histamine H3 and Sigma-2 Receptor Ligand with Anti-Obesity Potential.

Many studies involving compounds that enhance histamine release, such as histamine H3 receptor (H3R) antagonists, have shown efficacy in inhibiting weight gain, but none have passed clinical trials. As part of the search for H3 receptor ligands that have additional properties, the aim of this study is to evaluate the activity in the reduction in weight gain in a rat model of excessive eating, as well as the impact on selected metabolic parameters, and the number and size of adipocytes of two new H3R antagonists, KSK-60 and KSK-74, which also exert a significant affinity at the sigma-2 receptor. Compounds KSK-60 and KSK-74 are homologues and the elongation of the distal part of the molecule resulted in an approximate two-fold reduction in affinity at H3R, but simultaneously an almost two-fold increase in affinity at the sigma-2 receptor. Animals fed palatable feed and receiving KSK-60 or KSK-74 both at 10 mg/kg b.w. gained significantly less weight than animals in the control obese group. Moreover, KSK-74 significantly compensated for metabolic disturbances that accompany obesity, such as an increase in plasma triglyceride, resistin, and leptin levels; improved glucose tolerance; and protected experimental animals against adipocyte hypertrophy. Furthermore, KSK-74 inhibited the development of inflammation in obesity-exposed adipose tissue. The in vivo pharmacological activity of the tested ligands appears to correlate with the affinity at the sigma-2 receptors; however, the explanation of this phenomenon requires further and extended research.

Histamine H3 Receptor Ligands-KSK-59 and KSK-73-Reduce Body Weight Gain in a Rat Model of Excessive Eating.

Noting the worldwide rapid increase in the prevalence of overweight and obesity new effective drugs are now being sought to combat these diseases. Histamine H3 receptor antagonists may represent an effective therapy as they have been shown to modulate histamine synthesis and release and affect a number of other neurotransmitters (norepinephrine, acetylcholine, γ-aminobutyric acid, serotonin, substance P) thus influencing the food intake. Based on the preliminary studies determining affinity, intrinsic activity, and selected pharmacokinetic parameters, two histamine H3 receptor ligands were selected. Female rats were fed palatable food for 28 days and simultaneously administered the tested compounds intraperitoneally (i.p.) at a dose of 10 or 1 mg/kg b.w./day. Weight was evaluated daily and calorie intake was evaluated once per week. The plasma levels of cholesterol, triglycerides, leptin, adiponectin, ghrelin, corticosterone, CRP and IL-6 were determined at the end of experiment. The glucose tolerance test was also performed. To exclude false positives, the effect of tested compounds on spontaneous activity was monitored during the treatment, as well as the amount of consumed kaolin clay was studied as a reflection of possible gastrointestinal disturbances comparable to nausea. The histamine H3 receptor antagonists KSK-59 and KSK-73 administered i.p. at a dose of 10 mg/kg b.w. prevented weight gain in a rat model of excessive eating. They reduced adipose tissue deposits and improved glucose tolerance. Both compounds showed satisfying ability to penetrate through biological membranes determined in in vitro studies. Compound KSK-73 also reduced the caloric intake of the experimental animals what indicates its anorectic effect. These results show the pharmacological properties of histamine H3 receptor antagonists, (4-pyridyl)piperazine derivatives, as the compounds causing not only slower weight gain but also ameliorating some metabolic disorders in rats having the opportunity to overeat.

The Structural Determinants for α1-Adrenergic/Serotonin Receptors Activity among Phenylpiperazine-Hydantoin Derivatives.

Several studies confirmed the reciprocal interactions between adrenergic and serotoninergic systems and the influence of these phenomena on the pathogenesis of anxiety. Hence, searching for chemical agents with a multifunctional pharmacodynamic profile may bring highly effective therapy for CNS disorders. This study presents a deep structural insight into the hydantoin-arylpiperazine group and their serotonin/α-adrenergic activity. The newly synthesized compounds were tested in the radioligand binding assay and the intrinsic activity was evaluated for the selected derivatives. The computer-aided SAR analysis enabled us to answer questions about the influence of particular structural fragments on selective vs. multifunctional activity. As a result of the performed investigations, there were two leading structures: (a) compound 12 with multifunctional adrenergic-serotonin activity, which is a promising candidate to be an effective anxiolytic agent; (b) compound 14 with high α1A/α1D affinity and selectivity towards α1B, which is recommended due to the elimination of probable cardiotoxic effect. The structural conclusions of this work provide significant support for future lead optimization in order to achieve the desired pharmacodynamic profile in searching for new CNS-modulating agents.

The GPR18 Agonist PSB-KD-107 Exerts Endothelium-Dependent Vasorelaxant Effects.

GPR18 is an orphan GPCR that is activated by the cannabinoid tetrahydrocannabinol (THC). Emerging evidence indicates its involvement in the control of cardiovascular functions, including heart rate, contractility, vascular tone, as well as blood pressure. Therefore, we investigated the effects of selective GPR18 receptor ligands, namely PSB-KD-107 (agonist) and PSB-CB-92 (antagonist), on blood pressure, electrocardiogram (ECG), and vascular dilatation in vitro and in vivo, as well as their anti-oxidative potential in in vitro ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picryl-hydrazyl-hydrate free radical (DPPH) assays. Our results clearly show that PSB-KD-107 dilates blood vessels. This effect is related to its activation of GPR18 as it can be blocked by the GPR18 antagonist PSB-CB-92. Moreover, our finding confirms the presence of GPR18 in blood vessels. The mechanism of the vasorelaxant activity of PSB-KD-107 is mainly related to endothelial nitric oxide generation; however, we cannot exclude additional nitric oxide-independent mechanisms or a direct influence on K+ channels. PSB-KD-107 may affect blood pressure and heart function after a single administration; however, this effect was no longer observed after repeated administrations once daily for eight days. PSB-KD-107 does not affect platelet aggregation-an important feature considering the safety of its administration. PSB-KD-107 also shows a significant anti-oxidant effect and further studies of its antioxidant activity in vivo are justified.

Design, Sustainable Synthesis and Biological Evaluation of a Novel Dual α2A/5-HT7 Receptor Antagonist with Antidepressant-Like Properties.

The complex pathophysiology of depression, together with the limits of currently available antidepressants, has resulted in the continuous quest for alternative therapeutic strategies. Numerous findings suggest that pharmacological blockade of α2-adrenoceptor might be beneficial for the treatment of depressive symptoms by increasing both norepinephrine and serotonin levels in certain brain areas. Moreover, the antidepressant properties of 5-HT7 receptor antagonists have been widely demonstrated in a large set of animal models. Considering the potential therapeutic advantages in targeting both α2-adrenoceptors and 5-HT7 receptors, we designed a small series of arylsulfonamide derivatives of (dihydrobenzofuranoxy)ethyl piperidines as dually active ligands. Following green chemistry principles, the designed compounds were synthesized entirely using a sustainable mechanochemical approach. The identified compound 8 behaved as a potent α2A/5-HT7 receptor antagonist and displayed moderate-to-high selectivity over α1-adrenoceptor subtypes and selected serotonin and dopaminergic receptors. Finally, compound 8 improved performance of mice in the forced swim test, displaying similar potency to the reference drug mirtazapine.

Metabolic benefits of novel histamine H3 receptor ligands in the model of excessive eating: The importance of intrinsic activity and pharmacokinetic properties.

AIMS: One of the therapeutic approaches in the treatment of obesity is the use of histamine H3 receptor ligands. Histamine plays a significant role in eating behavior because it causes a loss of appetite and is considered to be a satiety signal released during food intake. MATERIAL AND METHODS: Histamine ligands were selected based on the preliminary studies which included determination of intrinsic activity and selected pharmacokinetic parameters. Female Wistar rats were fed palatable feed for 28 days and simultaneously the tested compounds were administered intraperitoneally at a dose of 10 mg/kg b.w./day. Rats' weight was evaluated daily and calories intake was evaluated once per week. At the end of experiment insulin and glucose tolerance tests was performed. Plasma levels of cholesterol, triglycerides, leptin, insulin, glucose, C-peptide and CRP were also determined. In order to rule out false-positive results the influence of tested compounds on spontaneous activity of rats was monitored. RESULTS: Animals fed palatable feed and treated with KSK-61 or KSK-63 compounds showed the slowest weight gain which was comparable to the one observed in control animals. Both compounds with the highest pharmacological activity have also similar pharmacokinetic properties with quite long half-life and high volume of distribution indicating that they can freely cross most biological barriers. Some compounds, especially KSK-63, compensated for metabolic disorders. CONCLUSION: The presented study proves that search among the active histamine H3 receptor ligands for the new therapeutic agents to treat obesity is justified. Compounds KSK-61 and KSK-63 can be considered as the leading structures.

MH-76, a Novel Non-Quinazoline α1-Adrenoceptor Antagonist, but Not Prazosin Reduces Inflammation and Improves Insulin Signaling in Adipose Tissue of Fructose-Fed Rats.

BACKGROUND: Quinazoline α1-adrenoceptors antagonists have been shown to exert moderately favorable effects on the metabolic profile in hypertensive patients. However, based on AntiHypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) results, they are no longer recommended as a first line therapy of hypertension. Recent studies have shown that quinazoline-based α1-adrenoceptors antagonists (prazosin, doxazosin) induce the apoptosis and necrosis, which may be responsible for ALLHAT outcomes; however, these effects were proven to be independent of α1-adrenoceptor blockade and were associated with the presence of quinazoline moiety. MH-76 (1-[3-(2,6-dimethylphenoxy)propyl]-4-(2-methoxyphenyl)piperazine hydrochloride)) is a non-quinazoline α1-adrenoceptor antagonist which, in fructose-fed rats, exerted antihypertensive effect, and, contrary to prazosin, reduced insulin resistance and abdominal adiposity. In this study we aimed to further investigate and compare the effects of MH-76 and prazosin on inflammation in adipose tissue of fructose-fed rats. METHODS: Abdominal adipose tissue was collected from four groups of fructose-fed rats (Control, Fructose, Fructose + MH-76 and Fructose + Prazosin) and subjected to biochemical, histopathological and immunohistochemical studies. Moreover, selected tissue distribution studies were performed. RESULTS: Treatment with MH-76 but not with prazosin improved endothelial integrity, reduced adipose tissue inflammation and infiltration by immune cells, resulting in lowering leptin, MCP-1, IL-6, TNF-α and PAI-1 levels. In adipose tissue from Fructose + MH-76 animals, a higher amount of eosinophils accompanied with higher IL-4 concentration was observed. Treatment with MH-76 but not with prazosin markedly reduced phosphorylation of IRS-1 at Ser307. CONCLUSION: MH-76 may improve insulin signaling in adipose tissue by reducing the pro-inflammatory cytokine production and inhibiting the inflammatory cells recruitment. In contrast, in adipose tissue from animals treated with prazosin, the inflammatory effect was clearly enhanced.

PSB 603 - a known selective adenosine A2B receptor antagonist - has anti-inflammatory activity in mice.

A2B adenosine receptors are present in a wide spectrum of tissues, especially on cells of the immune system. Since these particular receptors have the lowest, of all adenosine receptor subtypes, affinity for adenosine they are believed to play a special role in immunological processes associated with elevated adenosine levels such as inflammation. The aim of this preliminary study was to determine the potential anti-inflammatory properties of compound PSB-603, a potent and selective adenosine A2B receptor antagonist, in two different experimental models of local and systemic inflammation. In a model of inflammation induced by local carrageenan administration paw edema was measured using a pletysmometer. Additionally, levels of C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α) and reactive oxygen species (ROS) were determined in the inflamed paw. Using the mouse model of peripheral inflammation induced by intraperitoneal (ip) administration of zymosan A, the influence of the A2B antagonist on the infiltration of neutrophils into the peritoneum and its effect on the plasma levels of CRP, TNF-α, and IL-6 were investigated. The results showed that PSB-603 administered at a dose of 5 mg/kg b.w. ip significantly reduced inflammation in both tested models. Particularly, it significantly decreased levels of the inflammatory cytokines IL-6, TNF-α and of ROS in the inflamed paw and reduced inflammation of the peritoneum by significantly decreasing the infiltration of leukocytes. Additionally, in the latter model, no statistically significant difference was observed in the CRP level between the control group without inflammation and the group which has been treated with the PSB-603 compound. Thus, the results may indicate the anti-inflammatory activity of adenosine A2B receptor antagonists in two different models of inflammation.

Structural modifications in the distal, regulatory region of histamine H3 receptor antagonists leading to the identification of a potent anti-obesity agent.

A series of 4-pyridylpiperazine derivatives with varying regulatory region substituents proved to be potent histamine H3 receptor (H3R) ligands in the nanomolar concentration range. The most influential modification that affected the affinity toward the H3R appeared by introducing electron-withdrawing moieties into the distal aromatic ring. In order to finally discuss the influence of the characteristic 4-pyridylpiperazine moiety on H3R affinity, two Ciproxifan analogues 2 and 3 with a slight modification in their basic part were obtained. The replacement of piperazine in 3 with piperidine in compound 2, led to slightly reduced affinity towards the H3R (Ki = 3.17 and 7.70 nM, respectively). In fact, 3 showed the highest antagonistic properties among all compounds in this series, hence affirming our previous assumptions, that the 4-pyridylpiperazine moiety is the key element for suitable interaction with the human histamine H3 receptor. While its structural replacement to piperidine is also tolerated for H3R binding, the heteroaromatic 4-pyridyl moiety seems to be essential for proper ligand-receptor interaction. The putative protein-ligand interactions responsible for their high affinity were demonstrated using molecular modeling techniques. Furthermore, selectivity, intrinsic activity at the H3R, as well as drug-like properties of ligands were evaluated using in vitro methods. Moreover, pharmacological in vivo test results of compound 9 (structural analogue of Abbott's A-331440) clearly indicate that it may affect the amount of calories consumed, thus act as an anorectic compound.

The antidepressant-like activity of chiral xanthone derivatives may be mediated by 5-HT1A receptor and ß-arrestin signalling.

BACKGROUND: Our previous studies showed that xanthone derivatives with N-(2-methoxyphenyl)piperazine fragment have an affinity to the 5-HT1A receptor and show antidepressant-like properties in rodents. In this study, we tested three xanthone derivatives, HBK-1 (R, S) and its enantiomers, in which we increased the distance between the piperazine and xanthone fragments by using a hydroxypropoxy linker. We hypothesized that this would increase the binding to the 5-HT1A receptor and consequently, pharmacological activity. AIMS: We aimed to assess the in vitro and in vivo pharmacological activity of the xanthone derivatives. METHODS: We evaluated the in vitro affinity for serotonin 5-HT1A and 5-HT2A receptors and serotonin transporter. We also determined the intrinsic activity at the 5-HT1A receptor. We investigated the antidepressant-like properties and safety after acute administration (dose range: 1.25-20 mg/kg) using the forced swim, tail suspension, locomotor activity, rotarod and chimney tests in mice. We also evaluated the basic pharmacokinetic parameters. RESULTS: Our results indicated that the compounds showed a high affinity for the 5-HT1A receptor but very weak antagonistic properties in the Ca2+ mobilization assay; however, they showed significant agonistic properties in the ß-arrestin recruitment assay. In both behavioural tests the studied xanthone derivatives showed antidepressant-like activity. Pre-treatment with p-chlorophenylalanine or WAY-100635 abolished their antidepressant-like activity. None of the compounds caused motor impairments at antidepressant-like doses. The racemate penetrated the blood-brain barrier and had a relatively high bioavailability after intraperitoneal administration. CONCLUSIONS: Xanthone derivatives with N-(2-methoxyphenyl)piperazine fragment and hydroxypropoxy linker show increased binding to the 5-HT1A receptor and may represent an attractive putative treatment candidate for depression.