Correction of Experimental Retinal Ischemia by l-Isomer of Ethylmethylhydroxypyridine Malate

Ethoxidol as a Broad-spectrum Adaptogen

BACKGROUND

Stress factors lead to a shift in the antioxidant-prooxidant relationship, allowing an increase in the generation of reactive oxygen species (ROS) by mitochondria, which results in the development of oxidative stress. Consequently, it is possible to put forward an assumption that drugs which reduce the excessive generation of ROS by these organelles should increase the body's resistance to stress factors. Antioxidants can be used as such drugs. In this regard, the aim of this work was to study the bioenergetics characteristic of mitochondria under stress conditions and under the action of 2-ethyl-6-methyl-3-hydroxypyridinium hydroxybutanedioate (ethoxidol).

METHODS

The antiradical activity of the drug was evaluated by the chemiluminescent method (CL). The functional state of the mitochondria was studied with reference to the level of lipid peroxidation by the spectrofluorimetry and in terms of fatty acid composition of mitochondrial membranes using the chromatography technique. The study of mitochondrial morphology was performed employing the method of atomic force microscopy.

RESULTS

The injection in mice of ethoxidol at a dose of 10^-5 mol/kg for 7 days led to the prevention of the stress-induced increase in the intensity of LPO in the membranes of the mitochondria, and swelling of these organelles; it also prevented a decrease in the content of unsaturated fatty acids, containing 18 and 20 carbon atoms. At the same time, ethoxidol increased the life expectancy of mice by 3.0-4.2 times in conditions of various types of hypoxia.

CONCLUSION

The adaptogenic properties of ethoxidol can be attributed to its antiradical and antioxidant properties.

Novel Hydroxypyridine Compound Protects Brain Cells against Ischemic Damage In Vitro and In Vivo

A non-surgical pharmacological approach to control cellular vitality and functionality during ischemic and/or reperfusion-induced phases of strokes remains extremely important. The synthesis of 2-ethyl-6-methyl-3-hydroxypyridinium gammalactone-2,3-dehydro-L-gulonate (3-EA) was performed using a topochemical reaction. The cell-protective effects of 3-EA were studied on a model of glutamate excitotoxicity (GluTox) and glucose-oxygen deprivation (OGD) in a culture of NMRI mice cortical cells. Ca2+ dynamics was studied using fluorescent bioimaging and a Fura-2 probe, cell viability was assessed using cytochemical staining with propidium iodide, and gene expression was assessed by a real-time polymerase chain reaction. The compound anti-ischemic efficacy in vivo was evaluated on a model of irreversible middle cerebral artery (MCA) occlusion in Sprague-Dawley male rats. Brain morphological changes and antioxidant capacity were assessed one week after the pathology onset. The severity of neurological disorder was evaluated dynamically. 3-EA suppressed cortical cell death in a dose-dependent manner under the excitotoxic effect of glutamate and ischemia/reoxygenation. Pre-incubation of cerebral cortex cells with 10-100 µM 3-EA led to significant stagnation in Ca2+ concentration in a cytosol ([Ca2+]i) of neurons and astrocytes suffering GluTox and OGD. Decreasing intracellular Ca2+ and establishing a lower [Ca2+]i baseline inhibited necrotic cell death in an acute experiment. The mechanism of 3-EA cytoprotective action involved changes in the baseline and ischemia/reoxygenation-induced expression of genes encoding anti-apoptotic proteins and proteins of the oxidative status; this led to inhibition of the late irreversible stages of apoptosis. Incubation of brain cortex cells with 3-EA induced an overexpression of the anti-apoptotic genes BCL-2, STAT3, and SOCS3, whereas the expression of genes regulating necrosis and inflammation (TRAIL, MLKL, Cas-1, Cas-3, IL-1β and TNFa) were suppressed. 3-EA 18.0 mg/kg intravenous daily administration for 7 days following MCA occlusion preserved rats' cortex neuron population, decreased the severity of neurological deficit, and spared antioxidant capacity of damaged tissues. 3-EA demonstrated proven short-term anti-ischemic activity in vivo and in vitro, which can be associated with antioxidant activity and the ability to target necrotic and apoptotic death. The compound may be considered a potential neuroprotective molecule for further pre-clinical investigation.

Magnesium acetyltaurate prevents retinal damage and visual impairment in rats through suppression of NMDA-induced upregulation of NF-κB, p53 and AP-1 (c-Jun/c-Fos)

Magnesium acetyltaurate (MgAT) has been shown to have a protective effect against N-methyl-D-aspartate (NMDA)-induced retinal cell apoptosis. The current study investigated the involvement of nuclear factor kappa-B (NF-κB), p53 and AP-1 family members (c-Jun/c-Fos) in neuroprotection by MgAT against NMDA-induced retinal damage. In this study, Sprague-Dawley rats were randomized to undergo intravitreal injection of vehicle, NMDA or MgAT as pre-treatment to NMDA. Seven days after injections, retinal ganglion cells survival was detected using retrograde labelling with fluorogold and BRN3A immunostaining. Functional outcome of retinal damage was assessed using electroretinography, and the mechanisms underlying antiapoptotic effect of MgAT were investigated through assessment of retinal gene expression of NF-κB, p53 and AP-1 family members (c-Jun/c-Fos) using reverse transcription-polymerase chain reaction. Retinal phospho-NF-κB, phospho-p53 and AP-1 levels were evaluated using western blot assay. Rat visual functions were evaluated using visual object recognition tests. Both retrograde labelling and BRN3A immunostaining revealed a significant increase in the number of retinal ganglion cells in rats receiving intravitreal injection of MgAT compared with the rats receiving intravitreal injection of NMDA. Electroretinography indicated that pre-treatment with MgAT partially preserved the functional activity of NMDA-exposed retinas. MgAT abolished NMDA-induced increase of retinal phospho-NF-κB, phospho-p53 and AP-1 expression and suppressed NMDA-induced transcriptional activity of NF-κB, p53 and AP-1 family members (c-Jun/c-Fos). Visual object recognition tests showed that MgAT reduced difficulties in recognizing the visual cues (i.e. objects with different shapes) after NMDA exposure, suggesting that visual functions of rats were relatively preserved by pre-treatment with MgAT. In conclusion, pre-treatment with MgAT prevents NMDA induced retinal injury by inhibiting NMDA-induced neuronal apoptosis via downregulation of transcriptional activity of NF-κB, p53 and AP-1-mediated c-Jun/c-Fos. The experiments were approved by the Animal Ethics Committee of Universiti Teknologi MARA (UiTM), Malaysia, UiTM CARE No 118/2015 on December 4, 2015 and UiTM CARE No 220/7/2017 on December 8, 2017 and Ethics Committee of Belgorod State National Research University, Russia, No 02/20 on January 10, 2020.

Evaluation of the Neuroprotective Effect of Magnesium-Bis-(2-Aminoethanesulfonic)-Butanedioate in Simulated Ischemic Stroke in Rats

Sudden loss of blood flow to an area of the brain causes ischemic stroke, which leads to the loss of nerve function in the brain. The brain tissue leads to the death of brain cells in less than a few minutes due to the lack of oxygen and nutrients. This study aimed to evaluate the effectiveness of pharmacological correction of the consequences of ischemic stroke with a new derivative of taurine magnesium-bis-(2-aminoethanesulfonic)-butanedioate under laboratory code LKHT 3-17 in rats. The ischemic stroke was simulated by electrocoagulation of the right middle cerebral artery. The assessment of lethality, neurological status, locomotor, exploratory behavior, and morphological pattern of the brain damage was carried out on the 1^st, 3^rd, and 7^th day after the pathology simulation. Neurological deficit was determined by the McGrow stroke index scale. The locomotor and exploratory behavior was evaluated using the Acti-track software and hardware complex. When assessing the morphological changes in the brain, attention was paid to two criteria, including the average thickness of the brain cortex and the number of neurons without degenerative changes. The substances were administered 60 minutes before the start of surgery. The animals were divided into an intact group (n=20); ischemic stroke simulation group without pharmacological correction (n=50); a group with correction of the ischemic stroke with taurine at the dose of 50 mg/kg (n=50); and a group with correction of ischemic stroke with magnesium-bis-(2-aminoethanesulfonic)-butadioate (LKHT 3-17) at the dose of 150 mg/kg (n=50).LHT 3-17 (150 mg/kg) and taurine (50 mg/kg) reduced lethality by 1.55 and 1.47 times, respectively, on the 7^th day after stroke, compared to the control group (P<0.05). In parallel, an effective correction of neurological deficit was found for LKHT 3-17 and taurine to 4.0±0.8 and 7.6±0.9, respectively, on the 3^rd day in contrast to the control of 8.1±0.8 points. The locomotor and exploratory behavior was most significantly different on the 1^st and 7^th days and was accompanied by a significant increase in the speed of movement under the influence of LKHT3-17 to 20 and 20 conventional units, compared to the control of 7 and 5 cu. On the 1^st day, the thickness of the cortex was 1877.3±43.3 µm in the control group, and 1531.8±39.1 µm in the LKHT 3-17 group. The number of neurons without neurodegenerative changes prevailed in the group administered with LHT 3-17 (19.3±4.3), and the lowest number was observed in the group without pharmacological correction of the pathology (14.3±3.7).LKHT 3-17 at a dose of 150 mg/kg is more effective than taurine 50 mg/kg in protecting nerve activity in experimental ischemic stroke and reducing lethality, minimizing nerve defects, reducing volume, accelerating the process of tissue repair, helping stroke, and activating the regenerative processes.

The effect of methylethylpiridinol addition to the therapy on the level of pigment epithelium-derived factor and oxidative status in patients with diabetic nephropathy: randomized controlled open-label clinical study

Purpose

The diabetic nephropathy is associated with oxidative stress and increases in pigment epithelium-derived factor (PEDF) level in the patient's blood. For the first time, authors investigated the effect of methylethylpiridinol addition to the therapy on oxidative status and pigment epithelium-derived factor concentrations, and examined the relationship between these indicators and clinical markers of pathology development.

Methods

Study design: open label randomized controlled trial study. Authors assessed the effect of methylethylpiridinol addition to the therapy vs basic treatment on antioxidant and NADPH-generating enzymes activity, glutathione's concentration and free radical-induced oxidation's intensity using a spectrophotometric method and iron-induced biochemiluminescence. The pigment epithelium-derived factor concentration in the serum was measured by enzyme-linked immunosorbent assay.

Results

Patients receiving combination therapy with methylethylpiridinol showed a more substantial increase in activity of glutathione peroxidase (Δ = 0.04 ± 0.11, p = 0.002), glutathione transferase (Δ = 0.12 ± 0.08, p < 0.001) and the concentration of reduced glutathione (Δ = 0.30 ± 0.17, p = 0.039). In addition, there was a significant decrease in PEDF level (Δ = -6.4 ± 5.4, p = 0.004). Correlation analysis showed a negative link between Δ postprandial glucose and Δ NADP-isocitrate dehydrogenase (-0.39, p = 0.033), Δ reduced glutathione and Δ postprandial glucose (-0.372, p = 0.043), Δ glutathione transferase and Δ PEDF (-0.37, p = 0.044).

Conclusions

The methylethylpiridinol addition to the therapy had a more potent stimulating effect on the patients' oxidative status in comparison with standard treatment, and reliably decreased pigment epithelium-derived factor level in patients' serum. The observed differences seem to be associated with the antioxidant activity of methylethylpiridinol which contributing to the mitigation of oxidative stress reducing at diabetes mellitus.

ADDITIVE NEUROPROTECTIVE EFFECT OF 3-HYDROXYPYRIDINE DERIVATIVES AND HUMAN ERYTHROPOETIN ANALOGUE ON A HEMORRHAGIC STROKE MODEL IN RATS

The correction of free radical oxidation processes is one of the most promising strategies of neuroprotection in acute cerebrovascular disorders.

The aim of the study is an experimental study of the neuroprotective effects of 3-hydroxypyridine and erythropoietin derivatives, as well as their combined use.

Materials and methods. The study was performed on 109 male Wistar rats. The neuroprotective effect of the substances was studied on a hemorrhagic stroke model. The study drugs were administered to the animals intraperitoneally. Carbamylated darbepoetin was administered three times in advance at the dose of 100 µg/kg within intervals of 3 days, the last injection took place 1 hour before the operation (the total dose was 300 mg/kg). Etoxidol was administered once 1 hour before the surgery at the dose of 50 mg/kg. The survival rate, behavioral features and the state of the animals on the 1st, 3rd, 7th and 14th days were recorded, and the morphological assessment of the brain was carried out.

Results. The investigated substances had a positive effect on both the survival rate of the animals during the first day and on the 14th day. The best survival rates on the 14th day were recorded in the group of a combined use of ethoxydol and carbamylated darbepoetin (75%). Thus, in this group of rats, a faster recovery of neurological disorders was already distinguished from the first day on. By the 7th day, more than 50% of the rats receiving the combination of the studied drugs, had had a slight neurological deficit (up to 3 points on the McGrow scale); by the 14th day there had been only minor changes in the neurological status in the rats of this group. A pronounced neuroprotective effect of the combination of 3-hydroxypyridine and erythropoietin derivatives has been confirmed by a histological examination of brain slices – a more rapid decrease in the size of perifocal edema and microcirculation disorders, less damage to neurons and glial elements, and faster processes of resorption and organization of hemorrhage. A macroscopic examination of the brain sections stained with triphenyltetrazolium chloride of the dying rats, showed that perifocal necrosis had been the main cause of high mortality in the control group after the 3rd day.

Conclusion. As a result of the experiment, the nephroprotective effect of the studied derivatives of 3-hydroxypyridine and erythropoietin has been proved. Moreover, the combination of these drugs has shown a greater neuroprotective activity than their isolated use. The additive effect of these drugs was due to their action mechanism resulting from the synergism of various structures and components of the cells.

Erythropoietin Mimetic Peptide (pHBSP) Corrects Endothelial Dysfunction in a Rat Model of Preeclampsia

Preeclampsia is a severe disease of late pregnancy. Etiological factors and a pathogenetic pattern of events still require significant clarification, but it is now recognized that a large role is played by placentation disorders and emerging endothelial dysfunction. The administration of short-chain peptides mimicking the spatial structure of the B erythropoietin chain may become one of the directions of searching for new drugs for preeclampsia prevention and therapy. Simulation of ADMA-like preeclampsia in Wistar rats was performed by the administration of a non-selective NOS blocker L-NAME from the 14th to 20th day of pregnancy. The administration of the pHBSP at the doses of 10 µg/kg and 250 µg/kg corrected the established morphofunctional disorders. The greatest effect was observed at a dose of 250 µg/kg. There was a decrease in systolic and diastolic blood pressure by 31.2 and 32.8%, respectively (p < 0.0001), a decrease in the coefficient of endothelial dysfunction by 48.6% (p = 0.0006), placental microcirculation increased by 82.8% (p < 0.0001), the NOx concentration was increased by 42,6% (p = 0.0003), the greater omentum edema decreased by 11.7% (p = 0.0005) and proteinuria decreased by 76.1% (p < 0.0002). In addition, there was an improvement in the morphological pattern of the fetoplacental complex and the ratio of BAX to Bcl-2 expression which characterizes the apoptotic orientation of the cells.

Retinoprotective Effect of 2-Ethyl-3-hydroxy-6-methylpyridine Nicotinate

An important task of pharmacology is to find effective agents to improve retinal microcirculation and resistance to ischemia. The purpose of the study is to pharmacologically evaluate the retinoprotective effect of 2-ethyl-3-hydroxy-6-methylpyridine nicotinate in a rat model of retinal ischemia–reperfusion. A retinal ischemia–reperfusion model was used, in which an increase in intraocular pressure (IOP) to 110 mmHg was carried out within 30 min. The retinoprotective effect of 2-ethyl-3-hydroxy-6-methylpyridine nicotinate at a dose of 3.8 mg/kg, in comparison with nicotinic acid at a dose of 2 mg/kg and emoxipine at a dose of 2 mg/kg, was estimated by the changes in the eye fundus during ophthalmoscopy, the retinal microcirculation level with laser Doppler flowmetry (LDF), and electroretinography (ERG) after 72 h of reperfusion. The use of 2-ethyl-3-hydroxy-6-methylpyridine nicotinate prevented the development of ischemic injuries in the fundus and led to an increase in the retinal microcirculation level to 747 (median) (lower and upper quartiles: 693;760) perfusion units (p = 0.0002) in comparison with the group that underwent no treatment. In the group with the studied substance, the b-wave amplitude increased significantly (p = 0.0022), and the b/a coefficient increased reliably (p = 0.0002) in comparison with the group with no treatment. Thus, 2-ethyl-3-hydroxy-6-methylpyridine nicotinate has established itself as a potential retinoprotector.

Studies to Elucidate the Effects of Furostanol Glycosides from Dioscorea deltoidea Cell Culture in a Rat Model of Endothelial Dysfunction

Currently, there is no doubt surrounding a theory that the cardiotropic effects of sex hormones can be due to their direct effect on the cardiovascular system. In recent years, interest in the study of steroid glycosides has increased. We studied the effects of furostanol glycosides (protodioscin and deltozid) from the cell culture of the Dioscorea deltoidea (laboratory code DM-05) on the physiological and biochemical parameters of vascular endothelial function in hypoestrogen-induced endothelial dysfunction after bilateral ovariectomy. It was shown that the use of DM-05 at a dose of 1 mg/kg makes it possible to prevent the development of arterial hypertension (the level of systolic blood pressure (SBP) decreases by 9.7% (p < 0.05) and diastolic blood pressure (DBP) by 8.2%), to achieve a decrease in the coefficient of endothelial dysfunction by 1.75 times against the background of a hypoestrogenic state. With DM-05, an increase in the concentration of stable nitric oxide metabolites (NOx) by 45.6% (p < 0.05) and an increase in mRNA endothelial nitric oxide synthase (eNOS) expression by 34.8% (p < 0.05) was established, which indicates a positive effect of furostanol glycosides on the metabolism of nitric oxide after ovariectomy. Positive dynamics in the histological structure of the heart and the abdominal aorta indicate the pronounced endothelio- and atheroprotective effects of DM-05.