Influence of 10-(6-plastoquinonyl) decyltriphenylphosphonium on free-radical homeostasis in the heart and blood serum of rats with streptozotocin-induced hyperglycemia

BACKGROUND It is known that under conditions of tissue tolerance to insulin,observed during type 2 diabetes mellitus(DM2),there is an increased production of reactive oxygen species.Moreover,the free radicals can initiate lipid peroxidation(LPO)in lipoprotein particles.The concentration of LPO products can influence the state of insulin receptors,repressing their hormone connection activity,which is expressed as a reduction of the glucose consumption by cells.It is possible that reduction in glucose concentration during administration of 10-(6-plastoquinonyl)decyltriphenylphosphonium(SkQ1)to rats with DM2 may be related to the antioxidant properties of this substance.AIM To establish the influence of SkQ1 on free-radical homeostasis in the heart and blood serum of rats with streptozotocin-induced hyperglycemia.METHODS To induce hyperglycemia,rats were fed a high-fat diet for 1 mo and then administered two intra-abdominal injections of streptozotocin with a 7-d interval at a 30 mg/kg of animal weight dose with citrate buffer equal to pH 4.4.SkQ1 solution was administered intraperitoneally at a 1250 nmol/kg dose per day.Tissue samples were taken from control animals,animals with experimental hyperglycemia,rats with streptozotocin-induced glycemia that were administered SkQ1 solution,animals housed under standard vivarium conditions that were administered SkQ1,rats that were administered intraperitoneally citrate buffer equal to pH 4.4 once a week during 2 wk after 1-mo high-fat diet,and animals that were administered intraperitoneally with appropriate amount of solution without SkQ1(98%ethanol diluted eight times with normal saline solution).To determine the intensity of free radical oxidation and total antioxidant activity,we used the biochemiluminescence method.Aconitate hydratase(AH),superoxide dismutase,and catalase activities were estimated using the Hitachi U-1900 spectrophotometer supplied with software.The amount of citrate was determined by means of the Natelson method.Real-time polymerase chain reaction was carried out using an amplifier ANK-32.RESULTS It was found that the mitochondrial-directed antioxidant elicits decrease of biochemiluminescence parameter values that increase by pathology as well as the levels of primary products of LPO,such as diene conjugates and carbonyl compounds,which indicate intensity of free radical oxidation.At the same time,the activity of AH,considered a crucial target of free radicals,which decreased during experimental hyperglycemia,increased.Apparently,increasing activity of AH influenced the speed of citrate utilization,whose concentration decreased after administering SkQ1 by pathology.Moreover,the previously applied antioxidant during hyperglycemia influenced the rate of antioxidant system mobilization.Thus,superoxide dismutase and catalase activity,as well as the level of gene transcript under influence of SkQ1 at pathology,were changing to the direction of control groups values.CONCLUSION According to the results of performed research,SkQ1 can be considered a promising addition to be included in antioxidant therapy of DM2.

Age-related peculiarities of change in content of free radical oxidation products in muscle during stress

The age-dependent peculiarities of stimulation of free radical processes in subcellular fractions of skeletal muscle of rats subjected to long-term immobilization stress were studied in order to improve knowledge about changes of muscular tissue during ontogenesis. It is found that adult animals do not show accumulation of proteins carbonyls, TBA-reactive substances, and Schiff bases in subcellular fractions of the thigh muscle when immobUized. Long-term immobilization causes apparent manifestation of oxidative stress only in mitochondrial fraction in pubertal rats. Mitochondrial oxidative stress defense systems are sufficiently effective, however, direction of pathways of free radical oxidation carbonyl products catabolism alters in the cytoplasm of myocytes in old rats under long-term immobilization conditions.

Insight into the Reaction Mechanism of Graphene Oxide with Oxidative Free Radical

Graphene oxide（GO）, as an important derivative of graphene, could be considered as a super aromatic molecule decorated with a range of reactive oxygen-containing groups on its surface, which endows graphene high reactivity with other molecules. In our previous work, we demonstrated that GO sheets were cut into small pieces（graphene quantum dots, GQDs） by oxidative free radicals（hydroxyl radical HO＂ or oxygen radical [0]） under UV irradiation. It is notable that reactions involving free radicals are influenced by reaction conditions pronouncedly. However, researches on details about reactions of GO with free radicals have not been reported thus far. In this work, the effects of different factors on the photo-Fenton reaction of GO were studied. It is demonstrated that the reaction rate is closely related to the concentration of free radicals. It is speculated that through the optimization of reaction conditions, the reaction of graphene with free radicals could carry out efficiently for further applications.

Estrogen inhibits lipid peroxidation after hypoxic-ischemic brain damage in neonatal rats

Sprague-Dawley neonatal rats within 7 days after birth were used in this study. The left common carotid artery was occluded and rats were housed in an 8% O2 environment for 2 hours to establish a hypoxic-ischemic brain damage model. 17β-estradiol （1 × 10-5 M） was injected into the rat abdominal cavity after the model was successfully established. The left hemisphere was obtained at 12, 24, 48, 72 hours after operation. Results showed that malondialdehyde content in the left brain of neonatal rats gradually increased as modeling time prolonged, while malondialdehyde content of 17β-estrodial-treated rats significantly declined by 24 hours, reached lowest levels at 48 hours, and then peaked at 72 hours after injury. Nicotinamide-adenine dinucleotide phosphate histochemical staining showed the nitric oxide synthase-positive cells and fibers dyed blue/violet and were mainly distributed in the cortex, hippocampus and medial septal nuclei. The number of nitric oxide synthase-positive cells peaked at 48 hours and significantly decreased after 17β-estrodial treatment. Our experimental findings indicate that estrogen plays a protective role following hypoxic-ischemic brain damage by alleviating lipid peroxidation through reducing the expression of nitric oxide synthase and the content of malondialdehyde.

Physiological significance of oxidative stress and its role in adaptation of the human body to deleterious factors

BACKGROUND： Oxidative stress is an extremely widespread condition manifested in an increased rate of free-radical processes and accumulation of reactive oxygen species （ROS） in the tissues. It appears in different physiologic states and pathological processes accompanied by stimulation of the sympathetic adrenal system or tissue hypoxia or under stress. However, until now, there is still no clarity on the issue of the significance of oxidative stress in the development of adaptation processes in the organism. OBJECTIVE： In the present work we will review the most recent finding about physiologic role of oxidative stress and its participation in adaptation of an organism to effect of different adverse factors. METHODS： A systematic literature search was performed using the Pubmed search engine. Studies published over past 18 years, i.e. between 1998 and 2015 were considered for review. Followed keywords were used： ＂oxidative stress,＂ ＂free radical oxidation,＂ ＂ROS,＂ ＂endogenous aldehydes,＂ ＂adaptation.＂ RESULTS： The article cites arguments supporting the notion that oxidative stress serves as a nonspecific link in the adaptation of the human body to the effects of injurious factors. Oxidative stress exerts regulatory effects by changing the redox state of the cell. Oxidative stress affects on various intracellular proteins containing cysteine residues, e.g., enzymes, chaperones, and transcription factors, etc. For this reason, the use of antioxidants for the treatment and prophylaxis of a wide range of diseases is not recommended. CONCLUSION： Further investigation is needed in this field. The most attention should be paid to careful experimental verification aimed at quantitative assessment of the ROS level in tissues under oxidative stress, as well as at the study of possibility of enhancing the catabolism of free radical oxidation carbonyl products in order to prevent tissue damage under oxidative stress.

Reaction mechanism of dicofol removal by cellulase

It remains unclear whether dicofol should be defined as a persistent organic pollutant. Its environmental persistence has gained attention. This study focused on its degradation by cellulase. Cellulase was separated using a gel chromatogram, and its degradation activity towards dicofol involved its endoglucanase activity. By analyzing the kinetic parameters of cellulase reacting with mixed substrates, it was shown that cellulase reacted on dicofol and carboxyl methyl cellulose through two different active centers. Thus, the degradation of dicofol was shown to be an oxidative process by cellulase. Next, by comparing the impacts of tert-butyl alcohol（a typical OH free-radical inhibitor） on the removal efficiencies of dicofol under both cellulase and Fenton reagent systems, it was shown that the removal of dicofol was initiated by OH free radicals produced by cellulase. Finally, 4,4′-dichlorodibenzophenone and chloride were detected using gas chromatography mass spectrometry and ion chromatography analysis, which supported our hypothesis. The reaction mechanism was analyzed and involved an attack by OH free radicals at the orthocarbon of dicofol, resulting in the degradation product 4,4′-dichloro-dibenzophenone.

Evaluation of In Vitro Enzymatic and Non-Enzymatic Antioxidant Properites of Leaf Extract from Alpinia Purpurata(Vieill.) K. Schum.

Objective： To evaluate the enzymatic and non-enzymatic antioxidants of leaf extract from Alpinia purpurata. Methods： One gram of fresh leaf of Alpinia purpurata was grinded in 2 mL of 50% ethanol and centrifuged at 10,000×g at 4 ℃ for 10 min. The supernatant obtained was used within 4 h for various enzymatic antioxidants assays like superoxide dismutase（SOD）, catalase（CAT）, glutathione peroxidase（GPx）, glutathione S-transferase（GST）, ascorbate oxidase, peroxidase, polyphenol oxidase（PPO） and non-enzymatic antioxidants such as vitamin C, total reduced glutathione（TRG） and lipid peroxidation（LPO）. Results： The leaf extract of Alpinia purpurata possess antioxidants like vitamin C 472.92±6.80 μg/mg protein, GST 372.11±5.70 μmol of 1-chloro 2,4 dinitrobenzene（CDNB）-reduced glutathione（GSH） conjugate formed/min/mg protein, GPx 281.69±6.43 μg of glutathione oxidized/min/mg protein, peroxidases 173.12±9.40 μmol/g tissue, TRG 75.27±3.55 μg/mg protein, SOD 58.03±2.11 U/mg protein, CAT 46.70±2.35 μmol of H_2O_2 consumed/min/mg protein in high amount whereas ascorbate oxidase 17.41±2.46 U/g tissue, LPO 2.71±0.14 nmol/L of malondialdehyde formed/min/mg protein and PPO 1.14±0.11 μmol/g tissue in moderate amount. Conclusion： Alpinia purpurata has the potential to scavenge the free radicals and protect against oxidative stress causing diseases. In future, Alpinia purpurata may serve as a good pharmacotherapeutic agent.