Lipoic Acid Prevents High-Fat Diet-Induced Hepatic Steatosis in Goto Kakizaki Rats by Reducing Oxidative Stress Through Nrf2 Activation

Baicalin attenuated metabolic dysfunction-associated fatty liver disease by suppressing oxidative stress and inflammation via the p62-Keap1-Nrf2 signalling pathway in db/db mice

Metabolic dysfunction-associated fatty liver disease (MAFLD) is the main cause of chronic liver disease. Baicalin (Bai), a bioactive molecule found in Scutellaria baicalensis Georgi, possesses antioxidant and antiinflammatory properties. These activities suggest Bai could be a promising therapeutic agent against NAFLD; however, its specific effects and underlying mechanism are still not clear. This study aims to explore the effect of Bai to attenuate MAFLD and associated molecular mechanisms. Bai (50, 100 or 200 mg/kg) was orally administered to db/db mice with MAFLD for 4 weeks or db/m mice as the normal control. Bai markedly attenuated lipid accumulation, cirrhosis and hepatocytes apoptosis in the liver tissues of MAFLD mice, suggesting strong ability to attenuate MAFLD. Bai significantly reduced proinflammatory biomarkers and enhanced antioxidant enzymes, which appeared to be modulated by the upregulated p62-Keap1-Nrf2 signalling cascade; furthermore, cotreatment of Bai and all-trans-retinoic acid (Nrf2 inhibitor) demonstrated markedly weakened liver protective effects by Bai and its induced antioxidant and antiinflammatory responses. The present study supported the use of Bai in attenuating MAFLD as a promising therapeutic agent, and its strong mechanism of action in association with the upregulating the p62-keap1-Nrf2 pathway.

Influence of Maternal Alpha-Lipoic Acid Supplementation on Postpartum Body Weight and Metabolic Health in Rats with Obesity

We examined the influence of dietary α-lipoic acid (LA; R enantiomer) supplementation in obese-complicated pregnancies on maternal postpartum body weight and metabolic health. Forty-eight female Sprague-Dawley rats were randomized into three dietary groups throughout pre-pregnancy, gestation, and lactation: (i) a low-calorie control diet (CON); (ii) a high calorie obesity-inducing diet (HC); or (iii) the HC diet with 0.25% LA (HC+LA). Following offspring weaning, all mothers were switched to the CON diet for a postpartum period of 140 days to assess maternal body weight and markers of metabolic health. HC-fed mothers showed excessive (p < 0.05) gestational weight gain (GWG), higher (p < 0.05) postpartum body weight, reduced (p < 0.05) glycemic control (lower glucose:insulin ratio) and higher (p = 0.06) hepatic cholesterol concentration versus CON mothers. In contrast, HC+LA mothers demonstrated lower (p < 0.05) body weight throughout the experimental period compared with HC mothers, primarily due to a marked reduction in GWG. Although LA did not protect (p > 0.05) against reduced glycemic control, it did alter several aspects of lipid metabolism including reduced serum HDL-C and a lower concentration of hepatic cholesterol which was mediated partly through a reduction in low-density lipoprotein receptor expression. We conclude that maternal obesity during pregnancy leads to a longer-term detrimental impact on weight gain and glycemic control, even after switching to a low-calorie postpartum diet. Maternal LA supplementation may be able to partially offset these effects, likely by protecting against excessive GWG during pregnancy. However, further work is required to determine the consequences of reduced serum HDL-C in LA-supplemented mothers.

Alpha-lipoic Acid: An Antioxidant with Anti-aging Properties for Disease Therapy

The anti-aging effects of alpha-lipoic acid (αLA), a natural antioxidant synthesized in human tissues, have attracted a growing interest in recent years. αLA is a short- -chain sulfur-containing fatty acid occurring in the mitochondria of all kinds of eukaryotic cells. Both the oxidized disulfide of αLA and its reduced form (dihydrolipoic acid, DHLA) exhibit prominent antioxidant function. The amount of αLA inside the human body gradually decreases with age resulting in various health disorders. Its lack can be compensated by supplying from external sources such as dietary supplements or medicinal dosage forms. The primary objectives of this study were the analysis of updated information on the latest two-decade research regarding the use of αLA from an anti-aging perspective. The information was collected from PubMed, Wiley Online Library, Scopus, ScienceDirect, SpringerLink, Google Scholar, and clinicaltrials.gov. Numerous in silico, in vitro, in vivo, and clinical studies revealed that αLA shows a protective role in biological systems by direct or indirect reactive oxygen/nitrogen species quenching. αLA demonstrated beneficial properties in the prevention and treatment of many age-related disorders such as neurodegeneration, metabolic disorders, different cancers, nephropathy, infertility, and skin senescence. Its preventive effects in case of Alzheimer's and Parkinson's diseases are of particular interest. Further mechanistic and clinical studies are highly recommended to evaluate the wide spectrum of αLA therapeutic potential that could optimize its dietary intake for prevention and alleviation disorders related to aging.

Pathophysiological Features of Rat Models of Nonalcoholic Fatty Liver Disease/Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH) is caused by various factors, including genetic and/or environmental factors, and has complicated pathophysiological features during the development of the disease. NAFLD/NASH is recognized as an unmet medical need, and NAFLD/NASH animal models are essential tools for developing new therapies, including potential drugs and biomarkers. In this review, we describe the pathological features of the NAFLD/NASH rat models, focusing on the histopathology of hepatic fibrosis. NAFLD/NASH rat models are divided into three categories: diet-induced, genetic, and combined models based on diet, chemicals, and genetics. Rat models of NASH with hepatic fibrosis are especially expected to contribute to the development of new therapies, such as drugs and biomarkers.

Potential Hepatoprotective Effect of Matricaria Pubescens on High-Fat Diet-Induced Non-Alcoholic Fatty Liver Disease in Rats

This study aimed to identify the phytochemical compounds of Matricaria pubescens by LC-MS/MS and evaluate the potential protective effect of its supplementation in high-fat diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) in adult rats through modulation of oxidative stress and histopathological changes. Twenty-four male rats were randomly divided into four groups. The first group served as control and received the standard diet. The second group (HFD) received a high-fat diet only (30 % of sheep fat). The third group's (control+MP) animals received a standard diet supplemented with 5 % M. pubescens (w/w). The fourth group (HFD+MP) received a high-fat diet supplemented with 5 % M. pubescens for 16 weeks. LC-MS/MS analysis showed that M. pubescens contains many phytochemical compounds. It was observed that the ethanolic extract of M. pubescens has a higher phenolic content than the aqueous extract. The supplementation of M. pubescens (5 % w/w) to HFD rats decreased significantly (p<0.01) body weight, liver and epididymal adipose tissue relative weights, glycemia, triglycerides (TG), insulin resistance, liver markers, TNF-α, malondialdehyde (MDA), protein carbonyl (PCO), advanced oxidation protein products (AOPP) level, and increased reduced glutathione (GSH) level, glutathione peroxidase (GPx), glutathione-S-transferase (GST), superoxide dismutase (SOD), and catalase activities as well as ameliorated histological alterations through the reduction hepatic lipid deposition and adipocytes hypertrophy compared to the HFD group. We conclude that M. pubescens powder may be effective for correcting hyperglycemia, hypertriglyceridemia, insulin resistance, and liver markers while decreasing inflammation and oxidative stress in the liver of high-fat diet-fed rats.

Nrf2 prevents diabetic cardiomyopathy via antioxidant effect and normalization of glucose and lipid metabolism in the heart

Metabolic disorders and oxidative stress are the main causes of diabetic cardiomyopathy. Activation of nuclear factor erythroid 2-related factor 2 (Nrf2) exerts a powerful antioxidant effect and prevents the progression of diabetic cardiomyopathy. However, the mechanism of its cardiac protection and direct action on cardiomyocytes are not well understood. Here, we investigated in a cardiomyocyte-restricted Nrf2 transgenic mice (Nrf2-TG) the direct effect of Nrf2 on cardiomyocytes in DCM and its mechanism. In this study, cardiomyocyte-restricted Nrf2 transgenic mice (Nrf2-TG) were used to directly observe whether cardiomyocyte-specific overexpression of Nrf2 can prevent diabetic cardiomyopathy and correct glucose and lipid metabolism disorders in the heart. Compared to wild-type mice, Nrf2-TG mice showed resistance to diabetic cardiomyopathy in a streptozotocin-induced type 1 diabetes mouse model. This was primarily manifested as improved echocardiography results as well as reduced myocardial fibrosis, cardiac inflammation, and oxidative stress. These results showed that Nrf2 can directly act on cardiomyocytes to exert a cardioprotective role. Mechanistically, the cardioprotective effects of Nrf2 depend on its antioxidation activity, partially through improving glucose and lipid metabolism by directly targeting lipid metabolic pathway of AMPK/Sirt1/PGC-1α activation via upstream genes of sestrin2 and LKB1, and indirectly enabling AKT/GSK-3β/HK-Ⅱ activity via AMPK mediated p70S6K inhibition.

Lias overexpression alleviates pulmonary injury induced by fine particulate matter in mice

Oxidative stress and inflammation are mechanisms underlying toxicity induced by fine particulate matter (PM2.5). The antioxidant baseline of the human body modulates the intensity of oxidative stress in vivo. This present study aimed to evaluate the role of endogenous antioxidants in alleviating PM2.5-induced pulmonary injury using a novel mouse model (LiasH/H) with an endogenous antioxidant capacity of approximately 150% of its wild-type counterpart (Lias+/+). LiasH/H and wild-type (Lias+/+) mice were randomly divided into control and PM2.5 exposure groups (n = 10), respectively. Mice in the PM2.5 group and the control group were intratracheally instilled with PM2.5 suspension and saline, respectively, once a day for 7 consecutive days. The metal content, major pathological changes in the lung, and levels of oxidative stress and inflammation biomarkers were examined. The results showed that PM2.5 exposure induced oxidative stress in mice. Overexpression of the Lias gene significantly increased the antioxidant levels and decreased inflammatory responses induced by PM2.5. Further study found that LiasH/H mice exerted their antioxidant function by activating the ROS-p38MAPK-Nrf2 pathway. Therefore, the novel mouse model is useful for the elucidation of the mechanisms of pulmonary injury induced by PM2.5.

A review of edible plant-derived natural compounds for the therapy of liver fibrosis

Liver fibrosis has a high incidence worldwide and is the common pathological basis of many chronic liver diseases. Liver fibrosis is caused by the excessive deposition of extracellular matrix and concomitant collagen accumulation in livers and can lead to the development of liver cirrhosis and even liver cancer. A large number of studies have provided evidence that liver fibrosis can be blocked or even reversed by appropriate medical interventions. However, the antifibrosis drugs with ideal clinical efficacy are still insufficient. The edible plant-derived natural compounds have been reported to exert effective antifibrotic effects with few side-effects, representing a kind of promising source for the treatment of liver fibrosis. In this article, we reviewed the current progress of the natural compounds derived from dietary plants in the treatment of liver fibrosis, including phenolic compounds (capsaicin, chlorogenic acid, curcumin, ellagic acid, epigallocatechin-3-gallate, resveratrol, sinapic acid, syringic acid, vanillic acid and vitamin E), flavonoid compounds (genistein, hesperidin, hesperetin, naringenin, naringin and quercetin), sulfur-containing compounds (S-allylcysteine, ergothioneine, lipoic acid and sulforaphane) and other compounds (betaine, caffeine, cucurbitacin B, lycopene, α-mangostin, γ-mangostin, ursolic acid, vitamin C and yangonin). The pharmacological effects and related mechanisms of these compounds in in-vivo and in-vitro models of liver fibrosis are focused.

Anti-diabetic Activity of Brucine in Streptozotocin-Induced Rats: In Silico, In Vitro, and In Vivo Studies

Diabetes mellitus (DM) is a complex and multiple group of disorders, and understanding the molecular mechanisms is a key role in identifying various markers involved in the diagnosis of the disease. Brucine is derived from the seeds of Strychnos nux-vomica L. (Loganiaceae), which has been used in traditional medicine to cure a variety of ailments, such as chronic rheumatism, nervous system diseases, dyspepsia, gonorrhea, anemia, and bronchitis, and has analgesic, anti-inflammatory, anti-oxidant, anti-snake venom, and anti-diabetic properties. The anti-diabetic potential of brucine was studied utilizing in vitro, in silico, in vivo, and molecular methods, including streptozotocin-induced diabetic rat models, α-glucosidase and α-amylase inhibitory assays, and via Auto-DocVina software. Brucine exhibits binding affinities of -5.0 to -10.1 Kcal/mol against chosen protein targets, according to an in silico investigation. In vitro studies revealed that brucine inhibited the enzymes α-amylase and α-glucosidase, and brucine (20 mg/kg) reduced blood glucose levels, oral glucose tolerance overload, body weight, glycosylated hemoglobin levels, total cholesterol, triglycerides, low-density lipoprotein, alanine transaminase, aspartate aminotransferase, total bilirubin, and alkaline phosphatase and elevated high-density lipoprotein levels in in vivo studies. The brucine binding energy against certain protein targets ranges from -5.0 to -10.1 Kcal/mol. It has anti-diabetic, anti-hyperlipidemic, hepatoprotective, anti-oxidant, and anti-inflammatory properties, which are mediated via inhibition of α-glucosidase and α-amylase.

The Protective Effect of α-Lipoic Acid against Gold Nanoparticles (AuNPs)-Mediated Liver Damage Is Associated with Upregulating Nrf2 and Suppressing NF-κB

This study examined if regulating the keap-1? Nrf2 antioxidant pathway mediated gold nanoparticles (AuNPs) induced liver damage, and examined the protective effect of co-supplement of α-lipoic acid (α-LA). Rats were separated into 4 groups (n = 8/each) as control, α-LA (200 mg/kg), AuNPs (5 µg/2.85 × 10¹¹), and AuNPs (5 µg/2.85 × 10¹¹) + α-LA (200 mg/kg). After 7 days, AuNPs induced severe degeneration in the livers of rats with the appearance of some fatty changes. In addition, it increased serum levels of alanine aminotransferase (ALT) and gamma-glutamyl transferase (ɣ-GTT), and aspartate aminotransferase (AST), as well as liver levels of malondialdehyde (MDA). Concomitantly, AuNPs significantly depleted hepatic levels of total glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) but increased hepatic levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). It also reduced mRNA levels of B-cell lymphoma 2 (Bcl2) and heme oxygenase-1 (HO-1) but significantly increased those of Bax and cleaved caspase-3, as well as the ratio of Bax/Bcl2. In addition, AuNPs enhanced the total and nuclear levels of NF-κB p65 but reduced the mRNA and total and nuclear protein levels of Nrf2. Of note, AuNPs did not affect the mRNA levels of keap-1. All these events were reversed by α-LA in the AuNPs-treated rats. In conclusion, α-LA attenuated AuNPs-mediated liver damage in rats by suppressing oxidative stress and inflammation, effects that are associated with upregulation/activation of Nrf2.

Dietary phenolic-type Nrf2-activators: implications in the control of toxin-induced hepatic disorders

Numerous studies have exemplified the importance of nuclear factor erythroid 2-related factor 2 (Nrf2) activation in the alleviation of toxin-induced hepatic disorders primarily through eliminating oxidative stress. Whereafter, increasingly more efforts have been contributed to finding Nrf2-activators, especially from dietary polyphenols. The present review summarized the phenolic-type Nrf2-activators published in the past few decades, analyzed their effectiveness based on their structural characteristics and outlined their related mechanisms. It turns out that flavonoids are the largest group of phenolic-type Nrf2-activators, followed by nonflavonoids and phenolic acids. When counting on subgroups, the top three types are flavonols, flavones, and hydroxycinnamic acids, with curcuminoids having the highest effective doses. Moreover, most polyphenols work through the phosphorylation of Nrf2. Besides, mitogen-activated protein kinases (MAPKs) and protein kinase B (Akt) are the frequent targets of these Nrf2-activators, which indirectly mediate the behavior of Nrf2. However, current data are not sufficient to conclude any structure-activity relationship.

Effect of Metaswitch® dietary supplement on anthropometric parameters, serum lipids, glucose level, oxidative stress and in vivo antioxidant properties in high fat diet-induced overweight Sprague Dawley rats

PURPOSE

Obesity and overweight are metabolic disorders associated with oxidative stress, and risk factors for many chronic diseases. We sought to investigate the effects of Metaswitch dietary supplement on weight gain and associated acute metabolic alterations in a high-fat diet-induced overweight rat model.

METHODS

Female Sprague Dawley (SD) rats were put into 6 groups. Control groups were fed normal (NCD) or high-fat diet (HFD). Treatment groups on HFD receieved 3 different daily doses of Metaswitch for 3 weeks. Another group on HFD received Slimrite® (phenylpropanolamine), a standard drug. Rats on HFD also received cyproheptadine to stimulate appetite. Food consumption and anthropometric parameters were determined weekly. Serum lipids, glucose level, hepatic lipid peroxidation, and antioxidant activity were used to assess overweight in rats.

RESULTS

Food intake remained relatively constant among groups. Rats on HFD had significantly increased body weight compared to rats fed NCD. Metaswitch significantly prevented weight gain; this effect was greater or similar to rats administered Slimrite, but was not dose-dependant. No significant changes occurred in the levels of serum lipids and glucose among the groups. However, serum triglyceride (TG) was significantly increased. The TG/HDL-C ratio revealed significant metabolic alterations which was prevented by Metaswitch. Catalase activity was significantly decreased in the HFD untreated group but was restored in Metaswitch-treated groups.

CONCLUSIONS

A 3-week HFD regimen with cyproheptadine supplementation in female SD rats resulted in a significant increase in body weight and acute metabolic alterations. The aforementioned changes were found to have been prevented with the administration of Metaswitch.

Long-Term Alpha-Lipoic Acid (ALA) Antioxidant Therapy Reduces Damage in the Cardiovascular System of Streptozotocin-Induced Diabetic Rats

Cellular damage, lipid oxidation and the action of inflammatory cytokines are implicated in the evolution of vascular complications associated with diabetes mellitus (DM) hyperglycemia. In contrast, alpha-lipoic acid (ALA) is a supplement with antioxidant and anti-inflammatory effects. This study aims to evaluate the overall effects of ALA supplementation by assessing its long-term systemic action on the vascular morphology of rats with induced diabetes. A total of 28 male rats were divided into 4 groups with seven animals each. For diabetes induction, two groups received streptozotocin. The animals in the lipoic and diabetic lipoic groups received ALA supplement. After 8 weeks the animals were anesthetized and blood collected was for hematological, biochemical and serological analyses. The thoracic aorta was removed, processed for paraffin and histological sections were stained for morphometric analysis. In diabetic groups, an improvement in hematological profile was observed, with platelet reduction in the diabetic lipoic group. ALA addition to the diet attenuated the negative effects in lipid profile; moreover, renal, hepatic and inflammatory parameters reduced or displayed values close to the values of the normal control. The anti-inflammatory effect of ALA was observed in diabetic animals, with a reduction of inflammatory citokines, accompanied by the improvement of morphological parameters in the aorta. In conclusion, long-term supplementation with ALA promoted systemic improvement, thus reducing the risk of vascular diseases. The changes in the renal and hepatic parameters without any negative impact in the hematological profile also show that ALA can be indicated as a low-risk prophylaxis or complementary therapy.

Decrypting the potential role of α-lipoic acid in Alzheimer's disease

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases with motor disturbances, cognitive decline, and behavioral impairment. It is characterized by the extracellular aggregation of amyloid-β plaques and the intracellular accumulation of tau protein. AD patients show a cognitive decline, which has been associated with oxidative stress, as well as mitochondrial dysfunction. Alpha-lipoic acid (α-LA), a natural antioxidant present in food and used as a dietary supplement, has been considered a promising agent for the prevention or treatment of neurodegenerative disorders. Despite multiple preclinical studies indicating beneficial effects of α-LA in memory functioning, and pointing to its neuroprotective effects, to date only a few studies have examined its effects in humans. Studies performed in animal models of memory loss associated with aging and AD have shown that α-LA improves memory in a variety of behavioral paradigms. Furthermore, molecular mechanisms underlying α-LA effects have also been investigated. Accordingly, α-LA shows antioxidant, antiapoptotic, anti-inflammatory, glioprotective, metal chelating properties in both in vivo and in vitro studies. In addition, it has been shown that α-LA reverses age-associated loss of neurotransmitters and their receptors. The review article aimed at summarizing and discussing the main studies investigating the neuroprotective effects of α-LA on cognition as well as its molecular effects, to improve the understanding of the therapeutic potential of α-LA in patients suffering from neurodegenerative disorders, supporting the development of clinical trials with α-LA.

Fustin Ameliorates Elevated Levels of Leptin, Adiponectin, Serum TNF-α, and Intracellular Oxidative Free Radicals in High-Fat Diet and Streptozotocin-Induced Diabetic Rats

Fustin is a prominent ingredient of Rhus verniciflua Stokes (Anacardiaceae) and has a wide range of pharmacological and clinical effects. The present study attempted to evaluate the antidiabetic potential of fustin in streptozotocin- and high-fat diet-induced diabetes in rats. The efficacy of fustin 50 mg/kg and 100 mg/kg/day p.o. was studied in 60% of total calories from fat as a high-fat diet along with single-dose administration streptozotocin (50 mg/kg, i.p.) experimentally induced diabetes in rats for 42 days. The mean body weight; blood glucose; and biochemical parameters such as lipid profile, total protein (TP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), insulin, leptin levels, adiponectin levels, glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) activity in serum were measured. The rats' weight was maintained in the fustin groups compared to the diabetic control group. Diabetes caused a significant increase in serum levels in blood glucose, lipid profile, MDA, TNF-α, ALT, and AST parameters and a decrease in serum insulin, adiponectin, leptin, GSH, SOD, and CAT compared to healthy rats. The treatment regimen with fustin (50 and 100 mg/kg) significantly restored all serum parameters in test groups. The present study found clinical evidence for the first time regarding the significant antidiabetic property of fustin, which could be a worthwhile candidate for the treatment of diabetes.

Pharmacological evaluation of continentalic acid for antidiabetic potential

BACKGROUND

Diabetes is a complex endocrine and metabolic disorder. Continentalic acid is a natural drug product found in roots of Aralia continentalis (family Araliaceae), which used in traditional medicine for treatment of rheumatic arthritis, lumbag, lameness, inflammation, gastritis, nephritis and diabetes mellitus.

PURPOSE

This study is aim to investigate the continentalic acid anti-diabetic potential.

METHODS

In-silico, in-vitro, in-vivo and molecular techniques were used to investigate various effects of continentalic acid by Auto Doc Vina, α-amylase and α-glucosidase inhibitory assay and alloxan-induced diabetes rats model.

RESULTS

In-silico results revealed that continentalic acid exhibits binding energy values of - 5 to - 9.3Kcal/mol against selected targets. In-vitro assay showed that continentalic acid caused α-amylase and α-glucosidase enzymes inhibition. In-vivo finding exhibits that continentalic acid (50 mg/kg) decreased blood glucose level, body weight, oral glucose tolerance overload, glycosylated hemoglobin, triglycerides, total cholesterol, low density lipoprotein, aspartate transaminase, aspartate aminotransferase, alkaline phosphate, total bilirubin and increased high density lipoprotein (P < 0.05, P < 0.01, P < 0.001 vs. diabetic control group). In animals pancreas and liver tissues, continentalic acid enhanced glutathione-s-transferase, reduced glutathione, catalase and decreased lipid hydroperoxide level, improved cellular architecture in histopathological examination and decrease expression of inflammatory markers: cyclooxygenase 2, tumor necrosis factor alpha, phosphorylated-nuclear factor kappa B, prostaglandins E2, interleukin-18 and increased heme oxygenase-1, as evidenced in immunohistochemistry and enzyme-linked immunosorbent assay molecular investigations.

CONCLUSIONS

This study shows that continentalic acid exhibited binding affinities against the different targets and anti-diabetic action, mediated possibly through α-amylase and α-glucosidase inhibition, anti-hyperlipidemic, hepatoprotection, antioxidant and anti-inflammatory pathways.

Overexpression of lipoic acid synthase gene alleviates diabetic nephropathy of Leprdb/db mice

INTRODUCTION

Diabetic nephropathy (DN) develops in about 40% of patients with type 2 diabetes and remains the leading cause of end-stage renal disease. The mechanisms of DN remain to be elucidated. Oxidative stress is thought to be involved in the development of DN but antioxidant therapy has produced conflicting results. Therefore, we sought to define the role of antioxidant in retarding the development of DN in this study.

RESEARCH DESIGN AND METHODS

We generated a new antioxidant/diabetes mouse model, Lias^H/HLepr^db/db mice, by crossing db/db mice with Lias^H/H mice, which have overexpressed Lias gene (~160%) compared with wild type, and also correspondingly increased endogenous antioxidant capacity. The new model was used to investigate whether predisposed increased endogenous antioxidant capacity was able to retard the development of DN. We systemically and dynamically examined main pathological alterations of DN and antioxidant biomarkers in blood and kidney mitochondria.

RESULTS

Lias^H/HLepr^db/db mice alleviated major pathological alterations in the early stage of DN, accompanied with significantly enhanced antioxidant defense. The model targets the main pathogenic factors by exerting multiple effects such as hypoglycemic, anti-inflammation, and antioxidant, especially protection of mitochondria.

CONCLUSION

The antioxidant animal model is not only very useful for elucidating the underlying mechanisms of DN but also brings insight into a new therapeutic strategy for clinical applications.

An updated systematic review and dose-response meta-analysis of the randomized controlled trials on the effects of Alpha-Lipoic acid supplementation on inflammatory biomarkers

Data about the effects of alpha-lipoic acid (ALA) supplementation on inflammatory markers are inconsistent. This systematic review and dose-response meta-analysis of randomized controlled trials was performed to summarize the effects of ALA supplementation on inflammatory markers such as C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in adults. A comprehensive literature search was conducted in the electronic databases of PubMed, Web of Science, ProQuest, Embase, and SCOPUS from inception to February 2020. Among all of the eligible studies, 20 articles were selected. The weighted mean differences (WMD) and 95% confidence intervals (CI) were calculated to evaluate the pooled effect size. Between-study heterogeneity was evaluated using Cochran's Q test and I². Subgroup analysis was done to evaluate the potential sources of heterogeneity. The dose-response relationship was evaluated using fractional polynomial modeling. Twenty eligible studies with a total sample size of 947 participants were included in the current meta-analysis. The findings of the meta-analysis showed that ALA supplementation significantly reduced CRP (WMD: -0.69 mg/L, 95% CI: -1.13, -0.26, P=0.002), IL-6 (WMD: -1.83 pg/ml, 95% CI: -2.90, -0.76, P=0.001), and TNF-α concentrations (WMD: -0.45 pg/ml, 95% CI: -0.85, -0.04, P=0.032). No evidence of departure from linearity was observed between dose and duration of the ALA supplementation on serum CRP, IL-6 and TNF-α concentration. In subgroup analysis, ALA dosage, baseline concentrations of the parameter, sample size, and gender were considered as possible sources of heterogeneity. In summary, ALA supplementation improves inflammatory markers without any evidence of non-linear association to dose or duration of the trial.

Alpha-lipoic acid supplementation increases the efficacy of exercise- and diet-induced obesity treatment and induces immunometabolic changes in female mice and women

The decrease in the regulatory T cells (Tregs) population is highly involved in adipose tissue inflammation and insulin resistance in obesity. Tregs depend on fatty acids via β-oxidation for immunosuppressive function adapting their antioxidant systems to allow survival to oxidative stress. In this study, we have hypothesized that a dietary supplementation with alpha-lipoic acid (ALA), a powerful antioxidant, would improve immunometabolism when added to the classical strategy of obesity treatment. First, we showed by in vitro experiments that ALA favors the polarization of mice CD4 + T cells toward Tregs. Next, we have carried out a translational study where female obese mice and women were supplemented with ALA or vehicle/placebo (mice: 2.5 gALA /kgfood ; 6 weeks; women: 600 mgALA /day, 8 weeks) while following a protocol including regular exercise and a change in diet. Fatty acid oxidation potential and activity of nuclear erythroid-related factor 2 (NRF2) of mouse secondary lymphoid tissues were improved by ALA supplementation. ALA reduced visceral adipose tissue (VAT) mass and preserved Tregs in VAT in mice. In women, ALA supplementation induced significant metabolic changes of circulating CD4 + T cells including increased oxidative capacity and fatty acid oxidation, ameliorated their redox status, and improved the reduction of visceral fat mass. While appropriate biological markers are still required to be used in clinics to judge the effectiveness of long-term obesity treatment, further studies in female mice and women are needed to determine whether these immunometabolic changes would reduce VAT mass-associated risk for secondary health issues arising from obesity.

Alpha lipoic acid attenuates ER stress and improves glucose uptake through DNAJB3 cochaperone

Persistent ER stress, mitochondrial dysfunction and failure of the heat shock response (HSR) are fundamental hallmarks of insulin resistance (IR); one of the early core metabolic aberrations that leads to type 2 diabetes (T2D). The antioxidant α-lipoic acid (ALA) has been shown to attenuate metabolic stress and improve insulin sensitivity in part through activation of the heat shock response (HSR). However, these studies have been focused on a subset of heat shock proteins (HSPs). In the current investigation, we assessed whether ALA has an effect on modulating the expression of DNAJB3/HSP40 cochaperone; a potential therapeutic target with a novel role in mitigating metabolic stress and promoting insulin signaling. Treatment of C2C12 cells with 0.3 mM of ALA triggers a significant increase in the expression of DNAJB3 mRNA and protein. A similar increase in DNAJB3 mRNA was also observed in HepG2 cells. We next investigated the significance of such activation on endoplasmic reticulum (ER) stress and glucose uptake. ALA pre-treatment significantly reduced the expression of ER stress markers namely, GRP78, XBP1, sXBP1 and ATF4 in response to tunicamycin. In functional assays, ALA treatment abrogated significantly the tunicamycin-mediated transcriptional activation of ATF6 while it enhanced the insulin-stimulated glucose uptake and Glut4 translocation. Silencing the expression of DNAJB3 but not HSP72 abolished the protective effect of ALA on tunicamycin-induced ER stress, suggesting thus that DNAJB3 is a key mediator of ALA-alleviated tunicamycin-induced ER stress. Furthermore, the effect of ALA on insulin-stimulated glucose uptake is significantly reduced in C2C12 and HepG2 cells transfected with DNAJB3 siRNA. In summary, our results are supportive of an essential role of DNAJB3 as a molecular target through which ALA alleviates ER stress and improves glucose uptake.

Ganoderma Lucidum Polysaccharides Ameliorates Hepatic Steatosis and Oxidative Stress in db/db Mice via Targeting Nuclear Factor E2 (Erythroid-Derived 2)-Related Factor-2/Heme Oxygenase-1 (HO-1) Pathway

Background

Type 2 diabetes mellitus (T2DM) and its comorbidities, including obesity, hypertension, and hyperlipidemia, are commonly associated with non-alcoholic fatty liver disease (NAFLD). Ganoderma lucidum polysaccharide (GDLP) is one of the central bioactive components in Ganoderma lucidum with anti-inflammatory, antioxidant, and hepatoprotective properties. However, the effect and mechanisms of GDLP in hepatic steatosis remain largely unknown. In the present study, we aimed to investigate the function of GDLP in hepatic steatosis and the underlying mechanism.

Material/Methods

In this study, male db/db mice were received with a high-fat diet (HFD) to investigate the effect of GDLP in T2DM-induced hepatic steatosis. The biological characteristics of the hepatic steatosis were evaluated through the detection of clinical indicators, including biochemical parameters, histopathology, and related cytokine levels. Additionally, the protein expression levels of Nrf2 (nuclear factor E2 (erythroid-derived 2)-related factor-2) signaling pathway were investigated by using western blotting and immunohistochemical staining.

Results

The levels of food/water intake, body weight, fasting blood glucose, plasma lipids, urinary biomarkers, hepatic lipid accumulation, and tumor necrosis factor (TNF)-α were observably decreased in GDLP-treated db/db mice. Additionally, administration of GDLP increased the expression of various antioxidases, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), whereas it reduced the level of malonaldehyde (MDA). Furthermore, GDLP was significantly promoted protein expression level of Nrf2 and its downstream target gene HO-1 (heme oxygenase-1) while decreased TNF-α expression.

Conclusions

These results indicate that GDLP against T2DM-induced hepatic steatosis, oxidative stress, and inflammation by improving the Nrf2/HO-1 signaling pathway in db/db mice, suggesting the GDLP may serve as an effective strategy for in fatty liver treatment.

Resveratrol ameliorates inflammatory and oxidative stress in type 2 diabetic Goto-Kakizaki rats

Type 2 diabetes is associated with inflammatory and oxidative stress. Resveratrol, a naturally occurring diphenolic compound, was shown to improve glycemic control and alleviate metabolic disturbances in Goto-Kakizaki (GK) rats, a non-obese model of type 2 diabetes. However, in GK rats effects of resveratrol addressing inflammatory and oxidative stress were not explored. The present study aimed to determine anti-inflammatory and anti-oxidative properties of resveratrol in these rats. GK and Sprague-Dawley (SD) rats were divided into 4 groups: GK control, GK treated with resveratrol, SD control and SD treated with resveratrol. Resveratrol (20 mg/kg b.w.) was given once a day for 10 weeks. It was shown that contents of inflammatory markers, interleukin 6 (IL-6), interleukin 1 β (IL-1β), tumor necrosis factor α (TNF-α) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), were increased in the skeletal muscle of diabetic rats, but these effects were prevented by resveratrol therapy. Similarly, amounts of IL-1β and TNF-α were elevated in livers of GK rats; however, this rise was alleviated in resveratrol-treated animals. Moreover, the contents of inflammation-related factors (IL-6, IL-1β, TNF-α and NF-κB) were augmented in adipose tissue of GK rats; nevertheless, in this tissue resveratrol was ineffective. Resveratrol reduced also lipid peroxidation in the skeletal muscle, reduced activities of glutathione peroxidase in blood serum and catalase in the livers of GK rats. Our new findings show that resveratrol therapy results in relieving inflammatory and oxidative stress in GK rats, which may be largely associated with the alleviation of metabolic disturbances in this model of diabetes. Nevertheless, it was demonstrated that the efficacy of resveratrol action is tissue-specific.

Natural Sulfur-Containing Compounds: An Alternative Therapeutic Strategy against Liver Fibrosis

Liver fibrosis is a pathophysiologic process involving the accumulation of extracellular matrix proteins as collagen deposition. Advanced liver fibrosis can evolve in cirrhosis, portal hypertension and often requires liver transplantation. At the cellular level, hepatic fibrosis involves the activation of hepatic stellate cells and their transdifferentiation into myofibroblasts. Numerous pro-fibrogenic mediators including the transforming growth factor-β1, the platelet-derived growth factor, endothelin-1, toll-like receptor 4, and reactive oxygen species are key players in this process. Knowledge of the cellular and molecular mechanisms underlying hepatic fibrosis development need to be extended to find novel therapeutic strategies. Antifibrotic therapies aim to inhibit the accumulation of fibrogenic cells and/or prevent the deposition of extracellular matrix proteins. Natural products from terrestrial and marine sources, including sulfur-containing compounds, exhibit promising activities for the treatment of fibrotic pathology. Although many therapeutic interventions are effective in experimental models of liver fibrosis, their efficacy and safety in humans are largely unknown. This review aims to provide a reference collection on experimentally tested natural anti-fibrotic compounds, with particular attention on sulfur-containing molecules. Their chemical structure, sources, mode of action, molecular targets, and pharmacological activity in the treatment of liver disease will be discussed.

α-Lipoic Acid Inhibits IL-8 Expression by Activating Nrf2 Signaling in Helicobacter pylori-infected Gastric Epithelial Cells

Helicobacter pylori (H. pylori) causes gastritis and gastric cancers. Oxidative stress is involved in the pathological mechanism of H. pylori-induced gastritis and gastric cancer induction. Therefore, reducing oxidative stress may be beneficial for preventing the development of H. pylori-associated gastric diseases. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a crucial regulator for the expression of antioxidant enzyme heme oxygenase-1 (HO-1), which protects cells from oxidative injury. α-Lipoic acid (α-LA), a naturally occurring dithiol, shows antioxidant and anti-inflammatory effects in various cells. In the present study, we examined the mechanism by which α-LA activates the Nrf2/HO-1 pathway, suppresses the production of pro-inflammatory cytokine interleukine-8 (IL-8), and reduces reactive oxygen species (ROS) in H. pylori-infected AGS cells. α-LA increased the level of phosphorylated and nuclear-translocated Nrf2 by decreasing the amount of Nrf2 sequestered in the cytoplasm by complex formation with Kelch-like ECH1-associated protein 1 (KEAP 1). By using exogenous inhibitors targeting Nrf2 and HO-1, we showed that up-regulation of activated Nrf2 and of HO-1 results in the α-LA-induced suppression of interleukin 8 (IL-8) and ROS. Consumption of α-LA-rich foods may prevent the development of H. pylori-associated gastric diseases by decreasing ROS-mediated IL-8 expression in gastric epithelial cells.

Characteristics of Selected Antioxidative and Bioactive Compounds in Meat and Animal Origin Products

Meat and meat products have a high nutritional value. Besides major components, meat is rich in bioactive components, primarily taurine, l-carnitine, choline, alpha-lipoic acid, conjugated linoleic acid, glutathione, creatine, coenzyme Q10 and bioactive peptides. Many studies have reported their antioxidant and health-promoting properties connected with their lipid-lowering, antihypertensive, anti-inflammatory, immunomodulatory activity and protecting the organism against oxidative stress. The antioxidant activity of meat components results, among others, from the capability of scavenging reactive oxygen and nitrogen species, forming complexes with metal ions and protecting cells against damage. This review is focused to gather accurate information about meat components with antioxidant and biological activity.

Protective effect of alpha-lipoic acid against apical periodontitis-induced cardiac injury in rats

This study was designed to assess the possible protective effect of alpha-lipoic acid (ALA) on apical periodontitis (AP)-induced cardiac injury. Wistar albino rats were randomized into four groups: control; ALA; AP; and ALA + AP. Rats of the control and ALA groups were not endodontically treated, but saline and ALA (100 mg kg^-1 ) were administered. In rats of the AP and ALA + AP groups, the pulp chambers of mandibular first molar teeth were exposed and left open for 30 d to induce AP. Saline and ALA (100 mg kg^-1 ) were administered intraperitoneally every 24 h during the experiment. At the end of the experiment, the rats were killed. Establishment of AP was verified by radiographic and histopathological evaluation. Serum alkaline phosphatase (ALP), lactate dehydrogenase (LDH), creatine kinase (CK), and superoxide dismutase (SOD) activities were determined using an automated biochemical analyzer, and the structural cardiac injury was assessed pathologically. Serum ALP, LDH, and CK activities were elevated, and SOD activities were decreased, in the AP group. The changed enzyme activities were significantly normalized by treatment with ALA. We conclude that ALA administration alleviated the AP-induced heart injury and improved cardiac structure and function, and therefore this agent may be of potential therapeutic value in protecting cardiac tissue from systemic injury caused by AP.

Impact of dietary lipoic acid supplementation on liver mitochondrial bioenergetics and oxidative status on normally fed Wistar rats

The aim of this study was to examine the effects of α-lipoic acid (α-LA) on liver mitochondrial bioenergetics and oxidative status for 8 weeks in normal-healthy animals. A pair-fed group was included to differentiate between α-LA direct effects and those changes due to reduced food intake. α-LA decreased body weight gain, liver weight and insulin levels with no differences compared to its pair-fed group. α-LA significantly reduced energy efficiency, the activity of the electron transport chain complexes and induced a lower efficiency of oxidative phosphorylation with reduced ATP production. α-LA supplementation directly decreased plasma triglycerides (TGs), free fatty acids and ketone bodies levels. A significant reduction in hepatic TG content was also observed. A significant up-regulation of Cpt1a, Acadl and Sirt3, all β-oxidation genes, along with a significant deacetylation of the forkhead transcription factor 3a (FOXO3A) was found in α-LA-treated animals. Thus, α-LA along with a standard chow diet has direct actions on lipid metabolism and liver by modulating mitochondrial function in normal-weight rats. These results should be taken into account when α-LA is administered or recommended to a healthy population.