Flavonoids exhibit a wide range of biological activities, including antioxidant, anti-inflammatory, antidiabetic, antitumor, antiproliferative, and hemorheological effects. This review discusses the hemorheological activity of flavonoids and the underlying mechanisms. The hemorheological activity of flavonoids and flavonoid complexes has been studied in both in vitro and in vivo models of myocardial infarction, arterial hypertension, atherosclerosis, cerebrovascular insufficiency, pancreatitis, hepatitis, and rheumatoid arthritis, as well as in aging animals. Flavonoids are known to decrease whole blood viscosity, reduce red blood cell (RBC) aggregation, improve RBC deformability, and even, in some cases, decrease fibrinogen levels and plasma viscosity. The key mechanisms underlying the hemorheological effects of flavonoids are the following: (1) antioxidant protection from oxidative stress and (2) stabilization of membrane fluidity. The antioxidant effect is mediated through neutralization of reactive oxygen species outside RBCs, within the RBC membrane, and in the cytoplasm, thereby protecting RBC membranes (both lipid and protein constituents) from oxidative damage. Flavonoids also contribute to the maintenance and enhancement of endogenous antioxidant defense systems in RBCs. Clinical trials of flavonoid-based agents have demonstrated both hemorheological activity and therapeutic efficacy in patients with diabetes mellitus, coronary heart disease, venous insufficiency, dyscirculatory encephalopathy, arterial hypertension, and other conditions. The introduction of effective and low-toxicity flavonoid preparations with hemorheological activity into treatment regimens for conditions associated with hyperviscosity syndrome may enable the development of new therapeutic strategies for many diseases and improve patient outcomes.

We investigated the effect of a decrease in blood viscosity on the mean BP during isovolumic hemodilution and vasodilating activity of the endothelium in normotensive Wistar rats and spontaneously hypertensive rats (SHR). Blood viscosity was reduced by isovolumic hemodilution (replacement of 10% of circulating blood with an equal volume of plasma). Hemodilution caused the same reduction in blood viscosity by 16% in both groups of rats. In Wistar rats, a decrease in blood viscosity did not significantly change in the mean BP; no significant correlations between blood viscosity and mean BP were observed before and after hemodilution. In SHR, a decrease in blood viscosity led to a significant decrease in the mean BP by 18%. Correlations were found between the mean BP and blood viscosity in SHR before (r=0.63; p=0.028) and after (r=0.71; p=0.009) isovolumic hemodilution. In SHR, a decrease in the index of vasodilating activity of the endothelium due to a decrease in the vasodilatory response to intravenous administration of the endothelium-dependent vasodilator acetylcholine was revealed. In SHR, BP passively follows the change, in this case, the decrease in blood viscosity, which attests to impaired BP regulation in response to changes in shear stress on the vascular endothelium caused by the development of endothelial dysfunction in hypertensive animals.

In experiments on Wistar rats, the effect of a new selective JNK inhibitor tryptanthrin oxime (TR-Ox) on parameters of systemic hemodynamics, cardiohemodynamics, and post-infarction fibrosis was studied 4 months after acute myocardial ischemia (1 h) followed by reperfusion. TR-Ox was administered intraperitoneally at a dose of 12 mg/kg 20 min before reperfusion, and then once a day for the next 4 days. Administration of TR-Ox to animals in the acute phase of myocardial infarction contributed to more complete preservation of myocardial viability in the delayed period: a relative increase of muscle elements proportion in the scar, a decrease in the formation of connective tissue areas with complete and >50% replacement of the myocardium, and deceleration of fibrotic scarring in myocardium areas distant from the focus of injury, resulting in improved systolic and diastolic myocardial function. Four months after myocardial infarction, significant improvement in systemic hemodynamics and cardiohemodynamics parameters was observed in the group treated with TR-Ox: stroke volume, cardiac output, left ventricular systolic pressure, maximum rates of left ventricle pressure rise and fall significantly increased and the left ventricle end-diastolic pressure decreased in comparison with the corresponding parameters in the control group.

The effect of a new JNK inhibitor IQ-1 (11 H -indeno[1,2- b ]quinoxalin-11-one oxime) was studied in male Wistar rats in a model of acute myocardial ischemia/reperfusion. Area at risk and myocardial infarct zones were studied in two series of experiments: 16 h after a single dose of IQ-1 (25 mg/kg intraperitoneally during cardiac ischemia) and on day 5 after its course administration (25 mg/kg intraperitoneally during cardiac ischemia and daily over 4 days). On day 5 after ischemia/reperfusion, cardiodynamic indicators were also studied: systolic, end-diastolic, and minimum pressure in the left ventricle, stress—time index, as well as the maximum rates of pressure rise and fall in the left ventricle (+dP/dt max and -dP/dt max ). In 16 h after ischemia/reperfusion, the infarct area in the control was 24±2% of the total area of the sections, while after administration of IQ-1 this parameter was 14±1% ( p <0.05). On day 5, the infarct area in the control group was 25±1% of the total area of myocardial sections. A course of IQ-1 administration led to a significant reduction in the infarct area to 10±2% of the total area of myocardial slices. Course administration of IQ-1 led to improvement in contractile function and weakening of the diastolic dysfunction of the left ventricle: systolic pressure in the left ventricle increased by 20%, +dP/dt max by 23%, voltage—time index by 12%, -dP/dt max by 43%, and the minimum pressure in the left ventricle decreased by 3.4 times.

We studied the radical-binding and antioxidant activities of the alkaloid tryptanthrin (TR) and its new synthetic derivative tryptanthrin oxime (TR-Ox), as well as the cytoprotective activity of TR-Ox under conditions of oxidative stress. The antiradical activity of TR-Ox was revealed in the test of binding with stable chromogen radical 2,2-diphenyl-1-picrylhydrazyl and in the superoxide radical generation test (riboflavin photoreduction reaction with detection by NBT reduction). TR-Ox was inferior to ionol and dihydroquercetin by the antiradical activity. In these tests, TR did not exhibit antiradical activity. TR-Ox did not show iron-chelating activity (in the test with the formation of the o-phenanthroline-Fe2+ complex and its destruction in the presence of chelating agents). In brain homogenate, TR-Ox significantly reduced the increase in spontaneous chemiluminescence. Under conditions of oxidative stress induced by 15 mM H2O2 in the SH-SY5Y neuroblastoma cell culture, TR-Ox exhibited cytoprotective activity and increased the number of viable cells.

We studied the action of a new indolinone derivative GRS, acetylsalicylic acid (ASA), and their combination on platelet aggregation, vasodilatory endothelial function, neurological status, and cerebral infarction area in experimental focal cerebral ischemia/reperfusion in rats. GRS compound (10 mg/kg), ASA (10 mg/kg), and their combination in the same doses were administered orally once a day as a suspension in 1% starch solution over 5 days after pathology modeling. Sham-operated and control animals were administered 1% starch solution. On day 5 after pathology modeling, platelet aggregation and brain damage area were studied in a half of rats in each group, and the vasodilatory function of the endothelium was studied in the other half. Neurological deficit was assessed 4 h and 1, 3, and 5 days after pathology modeling. GRS compound and ASA equally effectively prevent platelet aggregation and the development of neurological deficit in rats. GRS compound restores the vasodilatory effects of the endothelium, but only ASA contributes to reduction of the cerebral infarction area. In case of combined administration, GRS and ASA do not exhibit synergy in their antiaggregant effect.

Activation of c-Jun N-terminal kinases (JNKs) is involved in myocardial injury, left ventricular remodeling (LV), and heart failure (HF) after myocardial infarction (MI). The aim of this research was to evaluate the effects of a selective JNK inhibitor, 11H-indeno [1,2-b]quinoxalin-11-one oxime (IQ-1), on myocardial injury and acute myocardial ischemia/reperfusion (I/R) in adult male Wistar rats. Intraperitoneal administration of IQ-1 (25 mg/kg daily for 5 days) resulted in a significant decrease in myocardial infarct size on day 5 after MI. On day 60 after MI, a significant (2.6-fold) decrease in LV scar size, a 2.2-fold decrease in the size of the LV cavity, a 2.9-fold decrease in the area of mature connective tissue, and a 1.7-fold decrease in connective tissue in the interventricular septum were observed compared with the control group. The improved contractile function of the heart resulted in a significant (33%) increase in stroke size, a 40% increase in cardiac output, a 12% increase in LV systolic pressure, a 28% increase in the LV maximum rate of pressure rise, a 45% increase in the LV maximum rate of pressure drop, a 29% increase in the contractility index, a 14% increase in aortic pressure, a 2.7-fold decrease in LV end-diastolic pressure, and a 4.2-fold decrease in LV minimum pressure. We conclude that IQ-1 has cardioprotective activity and reduces the severity of HF after MI.

Aim. To assess the effect of an indolinone derivative (2-[2-[(5RS)-5-(hydroxymethyl)-3-methyl-1,3-oxazolidine-2yliden]-2-cyanoethylidene]-1H-indole-3(2H)-one (codename – GRS) on right ventricular contractility, endothelial vasodilator function, and histologic changes in the lungs and heart in a rat model of monocrotaline-induced pulmonary hypertension. Materials and methods. Pulmonary arterial hypertension (PAH) was induced in Wistar rats by a single subcutaneous administration of monocrotaline at a dose of 60 mg / kg. Starting from day 15 after PAH induction, the rats received either GRS at a dose of 10 mg / kg or riociguat at a dose of 1 mg / kg orally once a day. Blood pressure in the right ventricle, right ventricular weight, endothelial vasodilator function, and the histologic structure of the lungs and heart were studied after the last administration of test substances. Results. Twenty-eight days after monocrotaline administration, the rats developed PAH, as shown by the increase in the maximal blood pressure in the right ventricle and the right ventricular weight / total heart weight ratio. GRS after multiple administration reduced the maximal blood pressure in the right ventricle, had no significant effect on its contractility, improved endothelial vasodilator function, and normalized blood pressure. Riociguat had a hypotensive effect and did not alleviate endothelial dysfunction in experimental PAH. Conclusion. The indolinone derivative GRS and riociguat, both soluble guanylate cyclase stimulators, lowered blood pressure in the right ventricle. GRS also alleviated endothelial dysfunction in animals with experimental PAH.

The activation of c-Jun N-terminal kinase (JNK) plays an important role in stroke outcomes. Tryptanthrin-6-oxime (TRYP-Ox) is reported to have high affinity for JNK and anti-inflammatory activity and may be of interest as a promising neuroprotective agent. The aim of this study was to investigate the neuroprotective effects of TRYP-Ox in a rat model of transient focal cerebral ischemia (FCI), which involved intraluminal occlusion of the left middle cerebral artery (MCA) for 1 h. Animals in the experimental group were administered intraperitoneal injections of TRYP-Ox 30 min before reperfusion and 23 and 47 h after FCI. Neurological status was assessed 4, 24, and 48 h following FCI onset. Treatment with 5 and 10 mg/kg of TRYP-Ox decreased mean scores of neurological deficits by 35–49 and 46–67% at 24 and 48 h, respectively. At these doses, TRYP-Ox decreased the infarction size by 28–31% at 48 h after FCI. TRYP-Ox (10 mg/kg) reduced the content of interleukin (IL) 1β and tumor necrosis factor (TNF) in the ischemic core area of the MCA region by 33% and 38%, respectively, and attenuated cerebral edema by 11% in the left hemisphere, which was affected by infarction, and by 6% in the right, contralateral hemisphere 24 h after FCI. TRYP-Ox reduced c-Jun phosphorylation in the MCA pool at 1 h after reperfusion. TRYP-Ox was predicted to have high blood–brain barrier permeability using various calculated descriptors and binary classification trees. Indeed, reactive oxidant production was significantly lower in the brain homogenates from rats treated with TRYP-Ox versus that in control animals. Our data suggest that the neuroprotective activity of TRYP-Ox may be due to the ability of this compound to inhibit JNK and exhibit anti-inflammatory and antioxidant activity. Thus, TRYP-Ox may be considered a promising neuroprotective agent that potentially could be used for the development of new treatment strategies in cerebral ischemia.

Background. Correction of endothelial dysfunction during arterial hypertension (AH) is an important measure in preventing cerebrovascular stroke. Drugs activating soluble guanylate cyclase (sGC) and 3’,5’-guanosine monophosphate (cGMP) production independently of nitric oxide (NO) were shown to be therapeutically useful in reducing the risk of stroke. The present work aims to study the antiaggregant and endothelium-protective activity of a new sGC stimulator, an indolinone derivative (2-[2-[(5RS)-5-(hydroxymethyl)-3-methyl-1,3-oxazolidine-2- yliden]-2-cyanoethylidene]-1H-indole-3(2H)-one (codename — GRS) in a model of ischemic stroke with AH. Prior studies have shown that GRS compound inhibits platelet aggregation, lowers blood pressure (BP) in spontaneouslyhypertensive SHR rats, prevents vascular occlusion in models of arterial and venous thrombosis. Antiplatelet drug clopidogrel, a P2Y 12 receptor inhibitor, included in the standard of care for secondary prevention of ischemic stroke, was used as the reference drug. Objective. To assess the antiaggregant and endothelium-protective activity of a new indolinone derivative GRS, an sGC stimulator, compared to clopidogrel in a model of ischemic stroke concomitant with high arterial BP in spontaneously-hypertensive SHR rats. Design and methods. Focal brain ischemia/reperfusion was modelled in spontaneously-hypertensive SHR rats (n = 78). GRS in 10 mg/kg dose and clopidogrel in 10 mg/kg dose were administered orally once daily 3 days before modelling ischemia/reperfusion and for 5 days afterwards. Platelet aggregation and functioning of vascular endothelium were monitored. Results. Focal brain ischemia/reperfusion in SHR rats resulted in increased platelet aggregation and the development of endothelial dysfunction and disruption of vasodilatory function of endothelium. GRS compound and clopidogrel in repeated administration have prevented an increase in platelet aggregation (p < 0,05), GRS compound also alleviated endothelial dysfunction (p < 0,05). Conclusions. The indolinone derivative GRS, an sGC stimulator, inhibits increased platelet aggregation and prevents endothelial dysfunction in rats after focal brain ischemia/ reperfusion; the endothelium-protective effects of GRS aren’t related to its antiaggregant activity.

New antithrombotic drug GRS, a soluble guanylate cyclase stimulator, after repeated administration in a dose of 10 mg/kg alleviates the symptoms of endothelial dysfunction in rats with myocardial infarction; it restores antiplatelet activity of the blood vessel wall and vasodilatory function of the endothelium without producing significant effect on endothelium-independent vasodilation. GRS also has direct antiaggregant and antihypertensive effects in therapeutic doses. The obtained data suggest that GRS can be therapeutically useful in patients with cardiovascular diseases accompanied by endothelial dysfunction.

The c-Jun N-terminal kinases (JNKs) regulate many physiological processes, including inflammatory responses, morphogenesis, cell proliferation, differentiation, survival, and cell death. Therefore, JNKs represent attractive targets for therapeutic intervention. In an effort to develop improved JNK inhibitors, we synthesized the lithium salt of 11H-indeno[1,2-b]quinoxaline-11-one oxime (IQ-1L) and evaluated its affinity for JNK and biological activity in vitro and in vivo. According to density functional theory (DFT) modeling, the Li+ ion stabilizes the six-membered ring with the 11H-indeno[1,2-b]quinoxaline-11-one (IQ-1) oximate better than Na+. Molecular docking showed that the Z isomer of the IQ-1 oximate should bind JNK1 and JNK3 better than (E)-IQ-1. Indeed, experimental analysis showed that IQ-1L exhibited higher JNK1-3 binding affinity in comparison with IQ-1S. IQ-1L also was a more effective inhibitor of lipopolysaccharide (LPS)-induced nuclear factor-κB/activating protein 1 (NF-κB/AP-1) transcriptional activity in THP-1Blue monocytes and was a potent inhibitor of proinflammatory cytokine production by MonoMac-6 monocytic cells. In addition, IQ-1L inhibited LPS-induced c-Jun phosphorylation in MonoMac-6 cells, directly confirming JNK inhibition. In a rat model of focal cerebral ischemia (FCI), intraperitoneal injections of 12 mg/kg IQ-1L led to significant neuroprotective effects, decreasing total neurological deficit scores by 28, 29, and 32% at 4, 24, and 48 h after FCI, respectively, and reducing infarct size by 52% at 48 h after FCI. The therapeutic efficacy of 12 mg/kg IQ-1L was comparable to that observed with 25 mg/kg of IQ-1S, indicating that complexation with Li+ improved efficacy of this compound. We conclude that IQ-1L is more effective than IQ-1S in treating cerebral ischemia injury and thus represents a promising anti-inflammatory compound.

We developed a model of blood hyperviscosity avoiding extreme impact on the blood. The model shows reproducibility in rat blood under common storage conditions (4±1°C; stabilization with citrate-phosphate-glucose additive solution). Storage of rat blood under these condition leads to impairment of its rheological properties, which manifested in an increase in blood viscosity in a wide range of shear rates (3-300 sec —1 ). An increase in blood viscosity appeared the first day of storage and reached a maximum on the third day. During further 11-day storage, the blood viscosity did not change significantly. A hybrid macromolecular compound O-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoyl)-(1→6)-α-D-glucan improved the hemorheological properties during storage. The most pronounced effect was observed on the third day of storage and manifested in a decrease in blood viscosity in the range of shear rates of 50-300 sec —1 . Thus, storage of rat blood with citrate-phosphate-glucose additive solution for 3 days at 4±1°C reproduces the phenomenon of blood hyperviscosity; this model can be used to screen agents with hemorheological activity.

A single administration of phenylhydrazine at a dose of 50 mg/kg led to a decrease in hematocrit, impaired aggregation and deformability of erythrocytes, which manifested itself in a decrease in the efficiency of oxygen delivery to tissues. Hybrid macromolecular compounds (10 mg/kg intravenously daily for 4 days) attenuated hemorheological parameters disturbances and increased the efficiency of oxygen delivery to tissues.

Introduction . Hyperviscosity syndrome plays an important role in the pathogenesis of arterial hypertension and its complications associated with impaired microcirculation in target organs. Therefore, along with the use of antihypertensive drugs, it is important to pay attention to the correction of the hyperviscosity syndrome with means of hemorheological agents. The aim is to study the effect of metoprolol and its combined use with dihydroquercetin (DHQ) on the rheological parameters of blood in rats with spontaneous arterial hypertension. Materials and methods . The experiments were carried out on normotensive male Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). SHRs of the experimental groups received metoprolol (50 mg/kg) or metoprolol and DHQ (50 mg/kg each) daily intragastrically for 6 weeks in 1 % starch mucus; SHRs of the control group and normotensive rats received 1 % starch mucus according to the same scheme. Systemic blood pressure was registered in awake animals. Blood was sampled from the catheterized right common carotid artery. Blood viscosity, plasma viscosity, hematocrit, erythrocyte aggregation and deformability were studied. Results . Compared with the parameters in normotensive rats, SHRs showed significant increase of blood viscosity, hematocrit, erythrocyte aggregation, and decrease of erythrocyte deformability. The course administration of metoprolol induced to a further increase in blood viscosity at low shear rates (15–45 s– 1 ); plasma viscosity, hematocrit and micro-rheological parameters in rats of this group did not significantly differ from those in the control. With the combined administration of metoprolol and DHQ, blood viscosity at shear rates of 300 and 450 s– 1 and erythrocyte aggregation were significantly lower than in the control SHRs. Conclusions . The course administration of metoprolol increases the severity of the hyperviscosity syndrome in SHRs. The use of DHQ together with metoprolol partially eliminates adverse effects of the beta blocker on blood rheology parameters.

A novel specific inhibitor of c-Jun N-terminal kinase, 11H-indeno[1,2-b]quinoxalin-11-one oxime sodium salt (IQ-1S), has a high affinity to JNK3 compared to JNK1/JNK2. The aim of this work was to study the mechanisms of neuroprotective activity of IQ-1S in the models of reversible focal cerebral ischemia (FCI) in Wistar rats. The animals were administered with an intraperitoneal injection of IQ-1S (5 and 25 mg/kg) or citicoline (500 mg/kg). Administration of IQ-1S exerted a pronounced dose-dependent neuroprotective effect, not inferior to the effects of citicoline. Administration of IQ-1S at doses of 5 and 25 mg/kg reduced the infarct size by 20% and 50%, respectively, 48 h after FCI, whereas administration of citicoline reduced the infarct size by 34%. The administration of IQ-1S was associated with a faster amelioration of neurological status. Control rats showed a 2.0-fold increase in phospho-c-Jun levels in the hippocampus compared to the corresponding values in sham-operated rats 4 h after FCI. Administration of IQ-1S at a dose of 25 mg/kg reduced JNK-dependent phosphorylation of c-Jun by 20%. Our findings suggest that IQ-1S inhibits JNK enzymatic activity in the hippocampus and protects against stroke injury when administered in the therapeutic and prophylactic regimen in the rat model of FCI.

Introduction. The potential of a new compound in the ongoing drugs discovery process is initially explored using virtual instruments, where its activity is predicted based on its molecular structure.Aim. This study aimed to evaluate the pharmacokinetic parameters and possible toxicity of isobornyl compounds based on virtual tools.Material and Methods. Several free Internet resources were used to assess the absorption, distribution, metabolism, excretion (ADME), and toxicity (T) of 2,6-diisobornyl-4-methylphenol (1, Dibornol), 2-hydroxy-3-isobornyl-5-methylbenzaldehyde (2), and 2-((di-n-butylamino) methyl)-6-isobornyl-4-methylphenol (3). Pharmacokinetic properties were calculated on ADMETlab platform. Toxicity and physical properties were evaluated using TEST software based on the structure-property quantification models of organic substances according to structure–property principle. Web server ProTox_II was used for acute toxicity assessment.Results. Plasma protein binding degrees were 76,9% for (1), 85,9% for (2), and 91,8% for (3). All three compounds were capable of penetrating the blood-brain barrier. Dibornol was identified neither as a substrate nor as an inhibitor of P-glycoprotein unlike (2) and (3). The half-life of all compounds was short (about 2 hours); the clearance was slow (about 2 mL/min*kg). The study showed that (2) and (3) potentially exert the toxic effects during the developmental stage of the organism, while ADMETlab showed potential cardio- and hepatotoxicity for (2) and (3), respectively. All compounds had extremely low solubility in water, which affected the assessments of other indicators by TEST software. The ProTox_II server showed the extremely low toxicity LD50 for all compounds (toxicity class 5).

c-Jun N-terminal kinases (JNKs) are involved in the myocardial and aortic remodeling, increased arterial tone, and arterial blood pressure elevation associated with hypertension. The aim of the present study was to investigate the antihypertensive effect of a new JNK inhibitor, 1H-indeno[1,2-b]quinoxalin-11-one oxime sodium salt (IQ-1S), on spontaneously hypertensive rats (SHRs). Experiments were performed using normotensive Wistar-Kyoto (WKY) rats and SHRs. Experimental groups of SHRs received IQ-1S intragastrically for 6 weeks in daily doses of 5 and 50 mg/kg; experimental groups of WKY rats received 50 mg/kg IQ-1S according to the same regimen. The IQ-1S administration regimen induced decreases in systolic blood pressure, mean arterial blood pressure, total peripheral resistance, blood viscosity, hematocrit, myocardial cell cross-sectional area, and aortic wall thickness in SHRs vs untreated SHRs. There were no significant differences in systolic blood pressure values between the control and experimental groups of WKY rats during the treatment period. A concentration-dependent decrease in the tone of carotid arterial rings isolated from SHRs was observed after JNK inhibitor application in vitro. Application of the JNK inhibitor diminished endothelin-1 secretion by human umbilical vein endothelial cells in vitro. The main mechanisms of the antihypertensive effect of IQ-1S included the attenuation of blood viscosity due to decreased hematocrit, a vasodilatory effect on arterial smooth muscle cells, and a decrease in endothelin-1 production by endothelial cells.