Melatonin Enhanced the Tolerance of Arabidopsis thaliana to High Light Through Improving Anti-oxidative System and Photosynthesis

Land plants live in a crisis-filled environment and the fluctuation of sunlight intensity often causes damage to photosynthetic apparatus. Phyto-melatonin is an effective bioactive molecule that helps plants to resist various biotic and abiotic stresses. In order to explore the role of melatonin under high light stress, we investigated the effects of melatonin on anti-oxidative system and photosynthesis of Arabidopsis thaliana under high light. Results showed that exogenous melatonin increased photosynthetic rate and protected photosynthetic proteins under high light. This was mainly owing to the fact that exogenous melatonin effectively decreased the accumulation of reactive oxygen species and protected integrity of membrane and photosynthetic pigments, and reduced cell death. Taken together, our study promoted more comprehensive understanding in the protective effects of exogenous melatonin under high light.

Biochemical responses of Digitaria commutata and Cenchrus ciliaris to water stress: antioxidative reactions, proline and soluble sugars accumulation

The impact of water stress on antioxidant enzyme activities, proline, soluble sugars, and carotenoids contents found in Digitaria commutata and Cenchrus ciliaris plants was investigated. Two different watering regimes were used on plants over a period of three months. Water stress decreased total chlorophyll content in plants, but increased carotenoids content. Interestingly, no change was observed in the quantum yield of PSII photochemistry (Fv/Fm). Malondialdehyde (MDA) content increased to a higher extent in both species. Enhanced activities of all the enzymes (peroxidase, catalase, and superoxide dismutase) studied, except for catalase in the roots were observed. Proline and soluble sugars contents increased significantly following water stress exposure. No clear differences were found between both species. The results link drought tolerance of Digitaria commutata and Cenchrus ciliaris plants with better capabilities of anti-oxidative system. Additionally, it is linked to the accretion of osmoprotectants proline and soluble sugars when exposed to drought.

The role of oxidants and antioxidative parameters in patients with hepatic encephalopathy

<p class="abstract"><strong>Background:</strong> Hepatic encephalopathy is a serious neuropsychiatric complication of cirrhosis. Changes in the oxidative and anti-oxidative system and nitric oxide levels in brain tissue contribute to the development of symptoms related to HE and HE. Purpose of the study to reveal the alterations in oxidative, anti-oxidative system and nitric oxide levels in cirrhotic patients during and after hepatic encephalopathy periods.</p><p class="abstract"><strong>Methods:</strong> This was a randomized controlled double-blind study conducted in Erciyes University Hospital between 3 July 2010 and 30 March 2011. We investigated the oxidative and anti-oxidative stress parameters by quantification of total antioxidant capacity (TAC), total oxidant capacity (TOC), nitric oxide (NO), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), total thiol and xanthine oxidase (XO) levels in serum. We compared the group of patients with hepatic encephalopathy, post-hepatic encephalopathy (clinically recovered) and control groups (healthy control). </p><p class="abstract"><strong>Results:</strong> Thirty hepatic encephalopathy patients were studied. Serum levels of nitric oxide and xanthine oxidase were statistically significantly high in the hepatic encephalopathy group according to control group (p&lt;0.031, and p&lt;0.001, respectively). Serum thiol levels were significantly low in hepatic encephalopathy patients than the controls (p&lt;0.001). Total oxidant capacity, total antioxidant capacity, glutathione peroxidase and superoxide dismutase levels were not significantly different in hepatic encephalopathy group than the controls. Serum thiol levels were low and serum NO levels were high in recovered clinically from hepatic encephalopathy group according to control group currently (p&lt;0.001, p&lt;0.001, respectively). Total antioxidant capacity, total oxidant capacity, glutathione peroxidase, superoxide dismutase and xanthine oxidase levels were similar in both groups (p&gt;0.05). Total antioxidant capacity and especially xanthine oxidase levels were significantly decreased in recovered clinically from hepatic encephalopathy group compared to hepatic encephalopathy group (p&lt;0.05, p&lt;0.001, respectively).</p><p class="abstract"><strong>Conclusions:</strong> Oxidative system, in systemic circulation, is activated during hepatic encephalopathy and changes in XO level during and after hepatic encephalopathy is very different. This parameter may be a potential marker in differential diagnosis of hepatic encephalopathy from other coma causes. Further investigation is needed.</p>

Effects of Pyruvate Supplementation on High-intensity Interval Exercise Induced Metabolic Acidosis and Repeated Sprint Exercise Performance of College Soccer Athletes

Background: The effects of pyruvate on metabolic acidosis and oxidative metabolism had been studied. The ability to attenuate acidosis and improve oxidative system contribution are critical to the performance of team sport athletes during perform multiple high-intensity exercise over a limited period of time. This study aimed to investigate the impact of pyruvate supplementation on energy metabolism and metabolic acidosis during high-intensity interval exercise (HIIE), as well as to evaluate its role on repeated sprint exercise (RSE) performance.Methods: 14 well-trained male college soccer athletes (age: 20 ± 2 years, body fat: 13.11 ± 3.50 %) were studied in a randomized, double-blind, cross-over study. The participants ingested either 0.1g/kg/d of pyruvate or a placebo for 1-week. Metabolic acidosis was induced by HIIE after the supplement period, and RSE ability in the acidosis state was assessed. Venous blood pH, bicarbonate (HCO3-) and base excess (BE) were measured at baseline, pre-HIIE, post-HIIE, pre-RSE and post-RSE. Finger-stick blood lactate were collected at baseline, immediately after each bout of HIIE and 3, 5, 7, 10 min after HIIE. The energy systems contribution during HIIE were estimated. Results: Blood pH, HCO3- and BE were significantly lower than baseline after HIIE (p < 0.01) in both pyruvate group (PYR) and placebo group (PLA). Compared to PLA, the blood pH, HCO3- and BE were significantly improved in PYR at pre-HIIE (p < 0.01), post-HIIE (p < 0.01) and pre-RSE (p < 0.01). Furthermore, blood BE remained higher in PYR than PLA till end of RSE (p < 0.05). The contribution of oxidative system in the fourth bout of HIIE was higher in PYR than PLA (p < 0.05). In PLA, the ratio of total anaerobic energy contribution during HIIE was higher than that of aerobic (oxidative) (p < 0.01), but not in PYR (p > 0.05). Relative peak power (RPP) of first, fifth sprint, relative average power (RAP) of fifth sprint, the average of RPP and RAP during RSE were significantly improved in PYR compared with PLA (p < 0.05). While no significant changes in the PD% of each bout (p > 0.05) or average PD% (p > 0.05) were observed between the two groups. Conclusion: Pyruvate supplementation for 1-week enhances oxidative system energy contribution and buffers metabolic acidosis during HIIE, and improves RSE performance in acidosis.