β-Sitosterol increases mitochondrial electron transport by fluidizing mitochondrial membranes and enhances mitochondrial responsiveness to increasing energy demand by the induction of uncoupling in C2C12 myotubes

Phytosterol organic acid esters: Characterization, anti-inflammatory properties and a delivery strategy to improve mitochondrial function

Phytosterol organic acid esters are important food resources and the components of biomembrane structure. Due to the lack of extraction and synthesis techniques, more research has been focused on phytosterols, and the research on phytosterol acid esters have encountered a bottleneck, but phytosterol acid esters confer substantial benefits to human health. In this study, stigmasteryl vanillate (VAN), stigmasteryl protocatechuate (PRO) and stigmasteryl sinapate (SIN) were prepared through the Steglich reaction. The processes are promotable and the products reach up to 95% purity. In addition, their stability was evaluated by differential scanning calorimetry and thermogravimetric analysis. HPLC analysis revealed an enhancement in water solubility after esterification with phenolic acid. In an in vitro digestion model, the bioaccessibility of stigmasteryl phenolates was significantly higher than that of stigmasterols (STIs). Regarding the anti-inflammatory properties, VAN, PRO, and SIN exhibit superior effects against TNF-α induced pro-inflammatory responses compared to STI. All stigmasteryl phenolates supplementation increased the ATP production, the basal, and maximal oxygen consumption rate in mitochondrial stress test. Overall, we present a synthesis method for stigmasteryl phenolates. It will contribute to the development and research of phytosterol acid ester analysis, functions and utilization in food. Moreover, the nutrient-stigmasterol hybrids tactic we have constructed is practical and can become a targeted mitochondrial delivery strategy with enhanced anti-inflammatory effects.

Avocado oil alleviates non-alcoholic fatty liver disease by improving mitochondrial function, oxidative stress and inflammation in rats fed a high fat-High fructose diet

Non-alcoholic fatty liver disease (NAFLD) is characterized by lipid accumulation in hepatocytes, and in advanced stages, by inflammation and fibrosis. Excessive ROS production due to mitochondrial dysfunction contributes to NAFLD development, making the decrease in mitochondrial ROS production an emerging target to alleviate NAFLD. Previously, we have shown that avocado oil, a source of several bioactive compounds with antioxidant effects, decreases oxidative stress by improving the function of the mitochondrial electron transport chain (ETC) and decreasing ROS levels in mitochondria of diabetic and hypertensive rats. Therefore, we tested in this work whether avocado oil alleviates NAFLD by attenuating mitochondrial dysfunction, oxidative stress and inflammation. NAFLD was induced in rats by a high fat-high fructose (HF) diet administered for six (HF6) or twelve (HF12) weeks. Hepatic steatosis, hypertrophy and inflammation were detected in both the HF6 and HF12 groups. Hyperglycemia was observed only in the HF12 group. The HF6 and HF12 groups displayed dyslipidemia, impairments in mitochondrial respiration, complex III activity, and electron transfer in cytochromes in the complex III. This led to an increase in the levels of ROS and lipid peroxidation. The substitution of the HF6 diet by standard chow and avocado oil for 6 weeks (HF6+AVO + D), or supplementation of the HF12 diet with avocado oil (HF12 + AVO), ameliorated NAFLD, hyperglycemia, dyslipidemia, and counteracted mitochondrial dysfunctions and oxidative stress. The substitution of the HF6 diet by standard chow without avocado oil did not correct many of these abnormalities, confirming that the removal of the HF diet is not enough to counteract NAFLD and mitochondrial dysfunction. In summary, avocado oil decreases NAFLD by improving mitochondrial function, oxidative stress, and inflammation.

Bioactive Components in Whole Grains for the Regulation of Skeletal Muscle Function

Skeletal muscle plays a primary role in metabolic health and physical performance. Conversely, skeletal muscle dysfunctions such as muscular dystrophy, atrophy and aging-related sarcopenia could lead to frailty, decreased independence and increased risk of hospitalization. Dietary intervention has become an effective approach to improving muscle health and function. Evidence shows that whole grains possess multiple health benefits compared with refined grains. Importantly, there is growing evidence demonstrating that bioactive substances derived from whole grains such as polyphenols, γ-oryzanol, β-sitosterol, betaine, octacosanol, alkylresorcinols and β-glucan could contribute to enhancing myogenesis, muscle mass and metabolic function. In this review, we discuss the potential role of whole-grain-derived bioactive components in the regulation of muscle function, emphasizing the underlying mechanisms by which these compounds regulate muscle biology. This work will contribute toward increasing awareness of nutraceutical supplementation of whole grain functional ingredients for the prevention and treatment of muscle dysfunctions.

β-Sitosterol Attenuates Dexamethasone-Induced Muscle Atrophy via Regulating FoxO1-Dependent Signaling in C2C12 Cell and Mice Model

Sarcopenia refers to a decline in muscle mass and strength with age, causing significant impairment in the ability to carry out normal daily functions and increased risk of falls and fractures, eventually leading to loss of independence. Maintaining protein homeostasis is an important factor in preventing muscle loss, and the decrease in muscle mass is caused by an imbalance between anabolism and catabolism of muscle proteins. Although β-sitosterol has various effects such as anti-inflammatory, protective effect against nonalcoholic fatty liver disease (NAFLD), antioxidant, and antidiabetic activity, the mechanism of β-sitosterol effect on the catabolic pathway was not well known. β-sitosterol was assessed in vitro and in vivo using a dexamethasone-induced muscle atrophy mice model and C2C12 myoblasts. β-sitosterol protected mice from dexamethasone-induced muscle mass loss. The thickness of gastrocnemius muscle myofibers was increased in dexamethasone with the β-sitosterol treatment group (DS). Grip strength and creatine kinase (CK) activity were also recovered when β-sitosterol was treated. The muscle loss inhibitory efficacy of β-sitosterol in dexamethasone-induced muscle atrophy in C2C12 myotube was also verified in C2C12 myoblast. β-sitosterol also recovered the width of myotubes. The protein expression of muscle atrophy F-box (MAFbx) was increased in dexamethasone-treated animal models and C2C12 myoblast, but it was reduced when β-sitosterol was treated. MuRF1 also showed similar results to MAFbx in the mRNA level of C2C12 myotubes. In addition, in the gastrocnemius and tibialis anterior muscles of mouse models, Forkhead Box O1 (FoxO1) protein was increased in the dexamethasone-treated group (Dexa) compared with the control group and reduced in the DS group. Therefore, β-sitosterol would be a potential treatment agent for aging sarcopenia.

Potential Health Benefits of Whole Grains: Modulation of Mitochondrial Biogenesis and Energy Metabolism

Mitochondria play an essential role in maintaining cellular metabolic homeostasis. However, its dysfunction will cause different pathophysiological consequences. A specific mechanism of action has been developed by cells to adapt to changes in physiological conditions or in response to different stimuli, by meditating mitochondrial number, structure, and energy metabolism. Whole grains are considered healthier than refined grains for their higher amounts of bioactive components, with proven multiple health benefits. The modulation of an appropriate mitochondrial function contributes to the bioactive-component-based health improvements. Thus, this review aims to represent current studies that identify the impact of natural bioactive components in whole grains against metabolic disorders by modulating mitochondrial biogenesis and energy metabolism. It seems most attractive to aim nutritional intervention at the prevention or treatment of metabolic abnormalities and hence to target dietary management at improvement of mitochondrial function.

Antioxidant Properties and Cytoprotective Effect of Pistacia lentiscus L. Seed Oil against 7β-Hydroxycholesterol-Induced Toxicity in C2C12 Myoblasts: Reduction in Oxidative Stress, Mitochondrial and Peroxisomal Dysfunctions and Attenuation of Cell Death

Aging is characterized by a progressive increase in oxidative stress, which favors lipid peroxidation and the formation of cholesterol oxide derivatives, including 7β-hydroxycholesterol (7β-OHC). This oxysterol, which is known to trigger oxidative stress, inflammation, and cell death, could contribute to the aging process and age-related diseases, such as sarcopenia. Identifying molecules or mixtures of molecules preventing the toxicity of 7β-OHC is therefore an important issue. This study consists of determining the chemical composition of Tunisian Pistacia lentiscus L. seed oil (PLSO) used in the Tunisian diet and evaluating its ability to counteract the cytotoxic effects induced by 7β-OHC in murine C2C12 myoblasts. The effects of 7β-OHC (50 µM; 24 h), associated or not with PLSO, were studied on cell viability, oxidative stress, and on mitochondrial and peroxisomal damages induction. α-Tocopherol (400 µM) was used as the positive control for cytoprotection. Our data show that PLSO is rich in bioactive compounds; it contains polyunsaturated fatty acids, and several nutrients with antioxidant properties: phytosterols, α-tocopherol, carotenoids, flavonoids, and phenolic compounds. When associated with PLSO (100 µg/mL), the 7β-OHC-induced cytotoxic effects were strongly attenuated. The cytoprotection was in the range of those observed with α-tocopherol. This cytoprotective effect was characterized by prevention of cell death and organelle dysfunction (restoration of cell adhesion, cell viability, and plasma membrane integrity; prevention of mitochondrial and peroxisomal damage) and attenuation of oxidative stress (reduction in reactive oxygen species overproduction in whole cells and at the mitochondrial level; decrease in lipid and protein oxidation products formation; and normalization of antioxidant enzyme activities: glutathione peroxidase (GPx) and superoxide dismutase (SOD)). These results provide evidence that PLSO has similar antioxidant properties than α-tocopherol used at high concentration and contains a mixture of molecules capable to attenuate 7β-OHC-induced cytotoxic effects in C2C12 myoblasts. These data reinforce the interest in edible oils associated with the Mediterranean diet, such as PLSO, in the prevention of age-related diseases, such as sarcopenia.

The targets of β-sitosterol as a novel therapeutic against cardio-renal complications in acute renal ischemia/reperfusion damage

This research is the first to use β-sitosterol on myocardial and renal tissues in renal ischemia/reperfusion (IR) damage. Female Wistar rats were randomly divided into three groups: control (sham), renal IR (50 min ischemia - 3 h reperfusion), and renal IR + 150 mg/kg/p.o. β-sitosterol (the rats were treated with β-sitosterol orally once 1 h before the IR procedure). β-Sitosterol pretreatment caused an increase in superoxide dismutase and glutathione activities and a decrease in malondialdehyde levels in the kidney and heart. Moreover, it alleviated histopathological changes and downregulated the levels of tumor necrosis factor-alpha and interleukin-6 and upregulated the levels of endothelial nitric oxide synthase. As conclusion, the potential of β-sitosterol for renal and cardiac necrosis and apoptosis appears to act by limiting inflammatory response and oxidative stress. Thus, the potential of this compound is noteworthy and may serve as a potential therapeutic in the treatment of acute organ damages due to renal IR.

Linking phytosterols and oxyphytosterols from food to brain health: origins, effects, and underlying mechanisms

Phytosterols and their oxidation products, namely oxyphytosterols, are natural compounds present in plant foods. With increased intake of phytosterol-enriched functional food products, the exposure of both phytosterols and oxyphytosterols is rising. Over the past ten years, researches have been focused on their absorption and metabolism in human body, as well as their biological effects. More importantly, recent studies showed that phytosterols and oxyphytosterols can traverse the blood-brain barrier and accumulate in the brain. As brain health problems resulting from ageing being more serious, attenuating central nervous system (CNS) disorders with active compounds in food are becoming a hot topic. Phytosterols and oxyphytosterols have been shown to implicated in cognition altering and the pathologies of several CNS disorders, including Alzheimer's disease and multiple sclerosis. We will overview these findings with a focus on the contents of phytosterols and oxyphytosterols in food and their dietary intake, as well as their origins in the brain, and illustrate molecular pathways through which they affect brain health, in terms of inflammation, cholesterol homeostasis, oxidative stress, and mitochondria function. The existing scientific gaps of phytosterols and oxyphytosterols to brain health in knowledge are also discussed, highlighting research directions in the future.

Interplay between NADH oxidation by complex I, glutathione redox state and sirtuin-3, and its role in the development of insulin resistance

Metabolic diseases are characterized by high NADH/NAD⁺ ratios due to excessive electron supply, causing defective mitochondrial function and impaired sirtuin-3 (SIRT-3) activity, the latter driving to oxidative stress and altered fatty acid β-oxidation. NADH is oxidized by the complex I in the electron transport chain, thereby factors inhibiting complex I like acetylation, cardiolipin peroxidation, and glutathionylation by low GSH/GSSG ratios affects SIRT3 function by increasing the NADH/NAD⁺ ratio. In this review, we summarized the evidence supporting a role of the above events in the development of insulin resistance, which is relevant in the pathogenesis of obesity and diabetes. We propose that maintenance of proper NADH/NAD⁺ and GSH/GSSG ratios are central to ameliorate insulin resistance, as alterations in these redox couples lead to complex I dysfunction, disruption of SIRT-3 activity, ROS production and impaired β-oxidation, the latter two being key effectors of insulin resistance.

Dietary β-Sitosterol Improves Growth Performance, Meat Quality, Antioxidant Status, and Mitochondrial Biogenesis of Breast Muscle in Broilers

Simple Summary

Fast growth of modern broilers induces their muscle abnormality and myopathy, and therefore could compromise meat quality attributes. Antibiotic growth promoters have been banned by European Union and restricted by other countries in livestock production due to the public concern about food safety and antibiotic resistance. The search for efficacious, environmentally friendly, safe, and consumer favorable feed additives have become a necessity to poultry meat production. β-sitosterol—the most abundant phytosterol similar to cholesterol in chemical structure—is found in several plant products. It was incorporated at four levels into broiler diets (40, 60, 80, and 100 mg/kg). Dietary β-sitosterol supplementation improved growth performance and breast muscle meat quality of broilers, and the improved meat quality may be related with the simultaneously enhanced oxidative status and mitochondrial biogenesis in the breast muscle. The β-sitosterol dietary supplementation at the level of 80 mg/kg is recommended in broilers

Abstract

The present study evaluated effects of β-sitosterol on growth performance, meat quality, oxidative status, and mitochondrial biogenesis of breast muscle in broilers. One-day-old chicks were allocated to five treatments of six replicates. Broilers were fed a basal diet supplemented either with 0 (control), 40, 60, 80, or 100 mg/kg β-sitosterol for 42 days. β-sitosterol linearly and quadratically reduced feed/gain ratio, lightness_24h and cooking loss_24h in breast muscle, whereas 2, 2-diphenyl-1-picrylhydrazyl scavenging activity of breast muscle followed an opposite trend. β-sitosterol linearly decreased drip loss_24h and malondialdehyde content, whereas linearly increased pH_24h, superoxide dismutase activity, and mRNA abundances of peroxisome proliferator-activated receptor γ coactivator 1α (PCG-1α) and mitochondrial transcription factor A (TFAM) in breast muscle. Compared with control, levels of β-sitosterol higher than 40 mg/kg reduced feed/gain ratio, muscular lightness_24h, cooking loss_24h, and malondialdehyde level, whereas increased muscular 2, 2-diphenyl-1-picrylhydrazyl scavenging activity, and mRNA abundances (except 60 mg/kg) of PCG-1α and TFAM. Eighty milligram/kilogram β-sitosterol increased muscular pH_24h and superoxide dismutase activity, but decreased its drip loss_24h. Therefore, β-sitosterol could improve growth performance and meat quality, oxidative status, and mitochondrial biogenesis of breast muscle in broilers. Furthermore, supplementation level of 80 mg/kg β-sitosterol is recommended for broiler diets.

Ursolic acid induces mitochondrial biogenesis through the activation of AMPK and PGC-1 in C2C12 myotubes: a possible mechanism underlying its beneficial effect on exercise endurance

Mitochondrial biogenesis, which involves an increase in mitochondrial number and the overall capacity of oxidative phosphorylation, is a critical determinant of skeletal muscle function. Recent findings have shown that some natural products can enhance mitochondrial adaptation to aerobic exercise, which in turn improves exercise performance, presumably by delaying muscle fatigue. Ursolic acid (UA), a natural triterpene, is commonly found in various vegetables and fruits. In the current study, UA was shown to increase mitochondrial mass and ATP generation capacity, with a concomitant production of a low level of mitochondrial reactive oxygen species (ROS) in C2C12 myotubes. Mitochondrial ROS, in turn, activated the redox sensitive adenosine monophosphate-dependent protein kinase (AMPK)/peroxisome proliferator-activated receptor γ coactivator-1(PGC-1) pathway. The activation of AMPK/PGC-1 further increased the expression of cytochrome c oxidase (COX) and uncoupling protein 3. Animal studies showed that UA can also dose-dependently increase the endurance exercise capacity in mice, as assessed by a weight-loaded swimming test and a hanging wire test. Our findings suggest that UA may induce mitochondrial biogenesis through the activation of AMPK and PGC-1 pathways in skeletal muscle, thereby offering a promising prospect for its use to enhance exercise endurance and alleviating fatigue in humans.