Antioxidant enzymes and Nrf2/Keap1 in human skeletal muscle: Influence of age, sex, adiposity and aerobic fitness

Optimization of ultrasonic-assisted extraction of total flavonoids from Oxalis corniculata by a hybrid response surface methodology-artificial neural network-genetic algorithm (RSM-ANN-GA) approach, coupled with an assessment of antioxidant activities

The objective of this research endeavor is to refine the ultrasonic-assisted extraction technique for total flavonoids from Oxalis corniculata (TFO), utilizing a synergistic approach combining response surface methodology (RSM) and artificial neural network integrated with genetic algorithm (RSM-ANN-GA). The optimized extraction parameters determined through RSM yielded a TFO concentration of 13.538 mg g-1 under the following conditions: an ethanol concentration of 61.95%, a liquid-solid ratio of 41.06 mL g-1, an ultrasonic power setting of 351.57 W, and an ultrasonic exposure duration of 58.95 minutes. Conversely, the RSM-ANN-GA approach identified an even more refined set of conditions, achieving a TFO concentration of 13.7844 mg g-1, with an ethanol concentration of 58.93%, a liquid-solid ratio of 41.16 mL g-1, an ultrasonic power of 350.22 W, and an ultrasonic exposure time of 58.18 minutes. These findings underscore the superior predictive accuracy and enhanced extraction efficiency offered by the RSM-ANN-GA model over the conventional RSM method. Furthermore, the study demonstrated that TFO possesses a potent antioxidant effect, as evidenced by its ability to scavenge DPPH, hydroxyl, and superoxide anion free radicals in vitro, highlighting its potential as a valuable source of natural antioxidants.

Unlocking peak performance: The role of Nrf2 in enhancing exercise outcomes and training adaptation in humans

Since the discovery of the nuclear factor erythroid-derived 2-like 2 (Nrf2) transcription factor thirty years ago, it has been shown that it regulates more than 250 genes involved in a multitude of biological processes, including redox balance, mitochondrial biogenesis, metabolism, detoxification, cytoprotection, inflammation, immunity, autophagy, cell differentiation, and xenobiotic metabolism. In skeletal muscle, Nrf2 signalling is primarily activated in response to perturbation of redox balance by reactive oxygen species or electrophiles. Initial investigations into human skeletal muscle Nrf2 responses to exercise, dating back roughly a decade, have consistently indicated that exercise-induced ROS production stimulates Nrf2 signalling. Notably, recent studies employing Nrf2 knockout mice have revealed impaired skeletal muscle contractile function characterised by reduced force output and increased fatigue susceptibility compared to wild-type counterparts. These deficiencies partially stem from diminished basal mitochondrial respiratory capacity and an impaired capacity to upregulate specific mitochondrial proteins in response to training, findings corroborated by inducible muscle-specific Nrf2 knockout models. In humans, baseline Nrf2 expression in skeletal muscle correlates with maximal oxygen uptake and high-intensity exercise performance. This manuscript delves into the mechanisms underpinning Nrf2 signalling in response to acute exercise in human skeletal muscle, highlighting the involvement of ROS, antioxidants and Keap1/Nrf2 signalling in exercise performance. Furthermore, it explores Nrf2's role in mediating adaptations to chronic exercise and its impact on overall exercise performance. Additionally, the influence of diet and certain supplements on basal Nrf2 expression and its role in modulating acute and chronic exercise responses are briefly addressed.

Rubus urticifolius Compounds with Antioxidant Activity, and Inhibition Potential against Tyrosinase, Melanin, Hyaluronidase, Elastase, and Collagenase

In our study, using chromatographic techniques, we isolated three bioactive compounds, which were structurally elucidated as (E)-2-(3-(3,4-dimethoxyphenyl)acrylamido)-N-methylbenzamide (1), 4-Hydroxyquinoline-2-carboxylic acid (2), and (E)-2-Cyano-3-(4-hydroxyphenyl)acrylic acid (3), using spectroscopic methods. The anti-melanogenic, anti-inflammatory, antioxidant, and anti-aging properties were evaluated in vitro by measuring the activity of pharmacological targets including tyrosinase, melanin, NF-κB, hyaluronidase, elastase, collagenase, and Nrf2. Our results show that compound 1 is the most active with IC50 values of 14.19 μM (tyrosinase inhibition), 22.24 μM (melanin inhibition), 9.82-12.72 μM (NF-κB inhibition), 79.71 μM (hyaluronidase inhibition), 80.13 μM (elastase inhibition), 76.59 μM (collagenase inhibition), and 116-385 nM (Nrf2 activation) in the THP-1, HEK001, WS1, and HMCB cells. These findings underscore the promising profiles of the aqueous extract of R. urticifolius at safe cytotoxic concentrations. Additionally, we report, for the first time, the isolation and characterisation of these nitrogenous compounds in the R. urticifolius species. Finally, compound 1, isolated from R. urticifolius, is a promising candidate for the development of more effective and safer compounds for diseases related to skin pigmentation, protection against inflammation, and oxidative stress.

Oyster (Ostrea Plicatula Gmelin) Peptides Improve Exercise Endurance Capacity via Activating AMPK and HO-1

OBJECTIVE

Previous studies have shown that oyster peptides (OPs) have antioxidant and anti-fatigue activities. This study aimed to investigate the effects of OPs on swimming endurance in mice and the underlying mechanisms.

METHODS

The mice were subjected to gavage with OPs and subjected to exercise training. After 14 days, various biochemical indicators in the blood and gastrocnemius muscle of mice were assessed, and real-time PCR was utilized to detect the level of signal pathway regulation by OPs in the gastrocnemius muscle. Molecular docking technology was employed to observe the potential active components in OPs that regulate signal pathways.

RESULTS

In this study, OPs supplementation combined with and without exercise significantly extended swimming time compared to the sedentary group. OPs supplementation with exercise also increased glycogen levels and decreased blood urea nitrogen, lactate dehydrogenase, and lactic acid levels. Additionally, mice in the exercise with OPs group exhibited higher activities of antioxidant enzymes. OPs can upregulate metabolic regulatory factors such as AMP-activated protein kinase, peroxisome proliferator-activated receptor gamma coactivator-1 alpha, peroxisome proliferator-activated receptor delta, and glucose transporter 4, thereby increasing energy supply during exercise. Additionally, OPs enhances the expression of heme oxygenase 1 and superoxide dismutase 2, thereby reducing oxidative stress during physical activity. Molecular docking analyses revealed that peptides found in OPs formed hydrogen bonds with AMPK and HO-1, indicating that they can exert bioactivity by activating target proteins such as AMPK and HO-1.

CONCLUSIONS

OPs supplementation improved energy reserves, modulated energy metabolism pathways, and coordinated antioxidative stress responses, ultimately enhancing swimming endurance. These findings suggest that OPs have the potential to improve exercise levels by promoting metabolism and improving energy utilization efficiency.

Ginsenoside Rg3 attenuates myocardial ischemia/reperfusion-induced ferroptosis via the keap1/Nrf2/GPX4 signaling pathway

BACKGROUND

Ginsenoside Rg3 is a component of ginseng that protects against myocardial ischemia/reperfusion (MI/R) injury. Ferroptosis is a new form of cell death characterized by oxidative damage to phospholipids. The purpose of this study was to examine the role and of ginsenoside Rg3 in MI/R and the mechanism.

METHODS

A mouse model of left anterior descending (LAD) ligation-induced myocardial ischemia/reperfusion (MI/R) injury and oxygen-glucose deprivation/reperfusion (OGD/R) were used as in vitro and in vivo models, respectively. Echocardiographic analysis, 2,3,5-triphenyltetrazolium chloride (TTC) staining and hematoxylin-eosin (H&E) staining were used to assess the cardioprotective effects of ginsenoside Rg3. Western blotting, biochemical analysis, small interfering RNA analysis and molecular docking were performed to examine the underlying mechanism.

RESULTS

Ginsenoside Rg3 improved cardiac function and infarct size in mice with MI/R injury. Moreover, ginsenoside Rg3 increased the expression of the ferroptosis-related protein GPX4 and inhibited iron deposition in mice with MI/R injury. Ginsenoside Rg3 also activated the Nrf2 signaling pathway. Ginsenoside Rg3 attenuated myocardial ischemia/reperfusion-induced ferroptosis via the Nrf2 signaling pathway. Notably, ginsenoside Rg3 regulated the keap1/Nrf2 signaling pathway to attenuate OGD/R-induced ferroptosis in H9C2 cells. Taken together, ginsenoside Rg3 attenuated myocardial ischemia/reperfusion-induced ferroptosis via the keap1/Nrf2/GPX4 signaling pathway.

CONCLUSIONS

Our findings demonstrated that ginsenoside Rg3 ameliorate MI/R-induced ferroptosis via the keap1/Nrf2/GPX4 signaling pathway.

Physiological and molecular predictors of cycling sprint performance

The study aimed to identify novel muscle phenotypic factors that could determine sprint performance using linear regression models including the lean mass of the lower extremities (LLM), myosin heavy chain composition (MHC), and proteins and enzymes implicated in glycolytic and aerobic energy generation (citrate synthase, OXPHOS proteins), oxygen transport and diffusion (myoglobin), ROS sensing (Nrf2/Keap1), antioxidant enzymes, and proteins implicated in calcium handling. For this purpose, body composition (dual-energy X-ray absorptiometry) and sprint performance (isokinetic 30-s Wingate test: peak and mean power output, Wpeak and Wmean ) were measured in young physically active adults (51 males and 10 females), from which a resting muscle biopsy was obtained from the musculus vastus lateralis. Although females had a higher percentage of MHC I, SERCA2, pSer16 /Thr17 -phospholamban, and Calsequestrin 2 protein expressions (all p < 0.05), and 18.4% lower phosphofructokinase 1 protein expression than males (p < 0.05), both sexes had similar sprint performance when it was normalized to body weight or LLM. Multiple regression analysis showed that Wpeak could be predicted from LLM, SDHB, Keap1, and MHC II % (R 2  = 0.62, p < 0.001), each variable contributing to explain 46.4%, 6.3%, 4.4%, and 4.3% of the variance in Wpeak , respectively. LLM and MHC II % explained 67.5% and 2.1% of the variance in Wmean , respectively (R 2  = 0.70, p < 0.001). The present investigation shows that SDHB and Keap1, in addition to MHC II %, are relevant determinants of peak power output during sprinting.