Oxidative stress is bane in chronic liver diseases: Clinical and experimental perspective

Oxidative stress plays an important role in the pathogenesis of various chronic liver diseases (CLD) and increasing evidence have confirmed the contributory role of oxidative stress in the pathogenesis of drugs and chemical-induced CLD. Chronic liver injury is manifested as necrosis, cholestasis, fibrosis, and cirrhosis. Chronic administration of anti-tubercular, anti-retroviral, immunosuppressive drugs is reported to induce free radical generation during their biotransformation in the liver. Further, these reactive intermediates are said to induce profibrogenic cytokines, several inflammatory markers, collagen synthesis during the progression of hepatic fibrosis. Oxidative stress and free radicals are reported to induce activation and proliferation of hepatic stellate cells in the injured liver leading to the progression of CLD. Hence, to counteract or to scavenge these reactive intermediates, several plant-derived antioxidant principles have been effectively employed against oxidative stress and came out with promising results in human and experimental models of CLD. This review summarizes the relationships between oxidative stress and different liver pathogenesis induced by drugs and xenobiotics, focusing upon different chronic liver injury induced by alcohol, antitubercular drugs and hyperactivity of antiretroviral drugs in HIV patients, viral hepatitis infection induced oxidative stress.     

Age-related changes of forkhead transcription factor FOXO1 in the liver of senescence-accelerated mouse SAMP8

SAMP8 exhibits accelerated aging and a short lifespan. Insulin-like growth factor-1 receptor (IGF-1R)/FOXO pathway is associated with aging. Phosphorylation of IGF-1R, Akt, and FOXO1 was found to be increased during aging in the liver of SAMR1 normal aging mice. However, significant decreases in the phosphorylation of IGF-1R and Akt were observed in the liver of SAMP8 during aging compared with that in SAMR1, whereas phosphorylation of FOXO1 was markedly increased with age in SAMP8. In addition, the protein level of FOXO1 was decreased with age in SAMP8. Protein phosphatase 2A (PP2A) directly dephosphorylates FOXO1. Significant reduction of PP2A activity was observed in the liver nucleus of SAMP8. These results suggest the possibility that the increased FOXO1 phosphorylation might occur by the decreased activity of PP2A, resulting in the decrease in the protein level of FOXO1 in SAMP8. Furthermore, FOXO1 regulates longevity and the expression of antioxidant enzymes such as Mn-SOD and catalase. The expression of Mn-SOD and catalase was significantly decreased in the liver of SAMP8. Therefore, it is possible that the elevation of phosphorylated FOXO1 level with age causes a short lifespan in SAMP8.     

Bioprospecting medicinal plants for antioxidant components

ObjectiveTo evaluate antioxidant activities of seven medicinal plant species and their fractions, and to identify their phenolic compounds.MethodsTwo extractions were processed and further fractionated by column chromatography to evaluate the concentration that inhibit 50% of 2,2′-azinobis (3-ethylbenzothiazoline-6-suslfonic acid, 1,1-diphenyl-2-picryl-hydrazyl radicals, and their ferric reducing antioxidant power. The identification of the fractions of phenolic compounds was done by ultra performance liquid chromatography.ResultsThe aqueous-acetone extracts of Feretia apodanthera and Ozoroa insignis exhibited the highest antioxidant potentials comparable to those of the standard quercetin. Their subsequently silica gel column fractionation showed three most active fractions from which the major constituents quercetin, myricetin, kampferol, rutin and isoquercetin were identified.ConclusionsThese plant species have potent antioxidant profiles and polyphenol compounds that may help to manage with radical related disease and aging.     

The effectiveness of antioxidant therapy in aspirin resistance,diabetes population for prevention of thrombosis

Thrombosis as the main complication of coronary heart disease (CHD) represents the primary cause of morbidity and mortality in patients with diabetes mellitus (DM). In the course of diabetes mellitus some coagulation abnormalities occur, that may result in a thrombogenic propensity.Aspirin (ASA) as a platelet-inhibiting agent through inactivation of Cyclooxygenase-1 (COX-1) is mostly used for the prevention and treatment of atherothrombotic disorders. ASA inhibits the COX-1 enzyme and therefore blocks platelet thromboxane A2 (TXA2) synthesis. However, some of the serious vascular events in high-risk vascular patients are attributable to a failure of ASA to suppress platelet aggregation. The consumption of antioxidant or antioxidant rich foods such as vitamin C, E, and polyphenols might impart anti-thrombotic and cardiovascular protective effects via their inhibition of platelet hyper-activation or aggregation similar to the action of aspirin.This review will discuss the risk of thrombosis in diabetes, what aspirin resistance means, and the effectiveness of antioxidant therapy in the prevention and possible treatment of atherothrombotic disorders.     

Polyphenolic Antioxidants Enhance IgE Production

Epidemiological data showed that total IgE and IL‐4 levels in cigarette smokers were elevated, comparable to those in the asthmatics. The etiological agent(s) elevating IgE production are not clear. We evaluate whether tobacco polyphenols potentiate IgE production in a rodent model. Mice were fed with rutin or CGA in drinking water during antigen sensitization, followed by antigenic challenge i.p. in alum. CGA and rutin were also delivered in a bolus intraperitoneally or intranasally along with antigens during immunization. Antigen‐specific IgE and IgG responses were measured. Enhancement of total IgE responses via i.p. and drinking routes can be achieved at concentrations as low as 0.1% CGA. Furthermore, IgG1 responses but not IgG2a and IgG2b were augmented, indicating a Th2 type of response by CGA. Moreover, both antigen‐specific and serum IgE production can be achieved when CGA and antigenic challenges were delivered intranasally in the absence of alum. In contrast, nicotine does not enhance antigen‐specific IgE production, and only marginally affects serum IgE levels. The more polarized Th2 development in CGA‐treated mice may account for enhancement of both antigen‐specific and total IgE responses. High levels of IL‐4 but not IFN‐γ or IL‐12, were observed in antigen‐challenged mesenteric lymph nodes (MLN) cultures from CGA‐treated mice. In contrast, significant levels of IL‐4, IL‐12, and IFN‐γ were observed in antigen‐challenged cultures from nicotine‐treated mice. This study shows that tobacco polyphenols, CGA and rutin potentiated IgE production in vivo. Polyphenolic antioxidants enhance Th2 development. We propose that IgE production and T cell dichotomy may be critically influenced by the redox microenvironment. Enhanced Th2 development and IgE production henceforth may counteract more severe Th1‐mediated tissue damage triggered by environmental oxidative stress.     

Histological alterations and oxidative stress in adult zebrafish muscle after aluminium exposure

Aluminium (Al) is among the most abundant metals in nature, and its presence in the environment is further increasing by anthropogenic activities. In water bodies, the Al concentrations ranged between 0.001 and 50 mg/L, raising concerns about the health of aquatic organisms. For this reason, zebrafish was chosen as the model, since it is well suited for ecotoxicological studies. Adult specimens were exposed to 11 mg/L of Al for 10, 15 and 20 days to assess both the morphology and the oxidative state of muscle tissue. Considering the involvement of ROS, the activity of the main antioxidant enzymes, metallothioneins contents, but also oxidative damage and enzymes involved in energy consumption and neuromuscular transmission were assessed. Collected data showed an increase in the thickness of the endomysium and resorbed myofibrils in the organisms exposed to Al for 10 days, and an increase of myotomes' size in the organisms exposed to Al for 15 days. Moreover, the organisms exposed for less time to Al, it was evident an activation of anaerobic metabolism and the increased activity of antioxidant enzymes such as superoxide dismutase, glutathione peroxidase and glutathione S-transferases. However, these effects stabilized with increasing exposure time. In addition, only after 20 days of treatment did the oxidative damage to the proteins and the activity of acetylcholinesterase increase while the levels of metallothioneins and the lipid peroxidation were lower for all treated animals when compared to the control group. Overall, the biochemical and histological changes induced by aluminium exposure in the muscular tissue represent a relevant contribution to understanding the environmental risk due to the diffusion of this metal within the aquatic compartment.     

Mechanistic insights into the effects of Astaxanthin on lipid profile and glucose homeostasis parameters: A systematic review of animal and clinical trial studies

Background and aimsThe antioxidant Astaxanthin (ASTX) may have potential to improve cardiometabolic risk factors. This study aimed to systematically review the impact of ASTX supplementation on lipid profile and glycemic indices in animal and clinical trial studies.MethodElectronic databases, including PubMed, Scopus, Web of Science, and Google Scholar were searched from inception up to June 2021. All clinical trials and animal studies published in English that investigated the effects of ASTX on lipid profile and glycemic parameters were considered in the study.ResultsA total of 3258 studies were retrieved from the search strategy from which 20 animal and five human studies were included in this systematic review. Twenty animal studies evaluated the effect of ASTX on lipid profile, of which 17 studies reported significant beneficial impact on one or more lipids. In addition, of 20 animal studies assessing the effect of ASTX on glucose homeostasis parameters, only 11 detected significant improvements. Five clinical trials evaluated the effect of ASTX on lipid profile; from these, three reported significant beneficial effect on at least one lipid. Moreover, of five human studies in which glucose homeostasis parameters were measured, only two observed significant improvement.ConclusionEvidence supports positive effects of ASTX on lipid profile. Nevertheless, the results on glycemic parameters are controversial and more studies are needed to draw a definite conclusion. ASTX could have great potential for reducing the risk of CVD and prevent T2DM and obesity-associated metabolic disturbances.     

Protective Effect of ECQ on Rat Reflux Esophagitis Model

This study was designed to determine the protective effect of Rumex Aquaticus Herba extracts containing quercetin-3-β-D-glucuronopyranoside (ECQ) on experimental reflux esophagitis. Reflux esophagitis was induced by surgical procedure. The rats were divided into seven groups, namely normal group, control group, ECQ (1, 3, 10, 30 mg/kg) group and omeprazole (30 mg/kg) group. ECQ and omeprazole groups received intraduodenal administration. The Rats were starved for 24 hours before the experiments, but were freely allowed to drink water. ECQ group attenuated the gross esophagitis significantly compared to that treated with omeprazole in a dose-dependent manner. ECQ decreased the volume of gastric juice and increased the gastric pH, which are similar to those of omeprazole group. In addition, ECQ inhibited the acid output effectively in reflux esophagitis. Significantly increased amounts of malondialdehyde (MDA), myeloperoxidase (MPO) activity and the mucosal depletion of reduced glutathione (GSH) were observed in the reflux esophagitis. ECQ administration attenuated the decrement of the GSH levels and affected the MDA levels and MPO activity. These results suggest that the ECQ has a protective effect which may be attributed to its multiple effects including anti-secretory, anti-oxidative and anti-inflammatory actions on reflux esophagitis in rats.