Trilobatin, a Naturally Occurring Food Additive, Ameliorates Exhaustive Exercise-Induced Fatigue in Mice: Involvement of Nrf2/ARE/Ferroptosis Signaling Pathway

Trilobatin, a Novel Naturally Occurring Food Additive, Ameliorates Alcoholic Liver Disease in Mice: Involvement of Microbiota-Gut-Liver Axis and Yap/Nrf2 Signaling Pathway

Trilobatin, a novel natural food additive, exerts a protective effect on acute liver injury. However, whether Trilobatin can protect against alcoholic liver disease (ALD) has not been elucidated. This research is intended to ascertain the impact of Trilobatin on ALD in mice and decipher the potential underlying mechanisms. Lieber-DeCarli liquid alcohol diet was used to induce ALD in mice, followed by administration of Trilobatin (10, 20, 40 mg·kg-1·d-1) for 15 days. The results suggested that Trilobatin significantly alleviated ethanol-induced hepatic injury in mice. Furthermore, RNA-Seq analysis revealed that yes-associated protein (YAP) downregulation occurred in the liver after Trilobatin treatment. Mechanistically, Trilobatin directly bound to YAP and hindered its nuclear translocation, which activated the Nrf2 pathway to reduce pro-inflammatory cytokines and oxidative stress. Intriguingly, 16S rDNA analysis results revealed that Trilobatin reshaped the gut microbiota, reducing harmful bacteria and increasing beneficial bacteria. It also enhanced tight junction proteins, defending against damage to the intestinal barrier. These findings not only highlight the microbiota-gut-liver axis and YAP/Nrf2 pathway as crucial potential targets to treat ALD but also reveal that Trilobatin effectively protects against ALD, at least partly, through modulating the microbiota-gut-liver axis and YAP/Nrf2 pathway.

Protective function of albiflorin against ferroptosis in exhaustive exerciseinduced myocardial injury via the AKT/Nrf2/HO-1 signaling

PURPOSE

It has been reported that exhaustive exercise (EE) causes myocyte injury, and eventually damages the function of the myocardia. Albiflorin (AF) has anti-inflammatory, antioxidant, and anti-apoptosis effects. In this study, we determined whether AF could mitigate the EE-induced myocardial injury and research the potential mechanisms.

METHODS

The rat model of EE was built by forced treadmill running method. Rats were intraperitoneally injected with AF before EE once daily for one week. The relative factors levels were examined by commercial kits. The apoptosis was appraised using a TdT-mediated dUTP nick end labeling assay kit. The ACSL4, GPX4, Nrf2, pAKT/AKT, and HO-1 contents were assessed by western blot.

RESULTS

AF lessened EE-induced cardiac myocytes ischemic/hypoxic injury and reduced the contents of myocardial injury biomarkers in the serum. AF lessened EE-induced cardiac myocyte apoptosis, inflammatory response, oxidative stress, and ferroptosis in myocardial tissues. However, the influences of AF were overturned by the co-treatment of AF and LY294002. AF activated the AKT/Nrf2/HO-1 signaling pathway in myocardial tissues in vivo.

CONCLUSIONS

AF could curb cardiac myocytes ferroptosis, thus diminishing the EE-induced myocardial injury through activating the AKT/Nrf2/HO-1 cascade.

Study on Anti-fatigue Effects and Mechanisms of Polysaccharide from Paris polyphylla

The objectives of this study were to investigate the anti-fatigue effects of Paris polyphylla polysaccharide component 1 (PPPm-1) and explore its mechanisms. A mouse model of exercise-induced fatigue was established by weight-bearing swimming to observe the effects of different concentrations of PPPm-1 on weight-bearing swimming time. The anti-fatigue effect of PPPm-1 was determined by the effects of contraction amplitude, contraction rate, and diastolic rate of the frog gastrocnemius muscle in vivo before and after infiltration with 5 mg/mL PPPm-1. The effects of PPPm-1 on the contents of blood lactate, serum urea nitrogen, hepatic glycogen, muscle glycogen in the exercise fatigue model of mice, and acetylcholine (ACh) content and acetylcholinesterase (AChE) activity at the junction of the frog sciatic nerve-gastrocnemius under normal physiological, and Na+-K+-ATPase and Ca2+-Mg2+-ATPase activities of the frog gastrocnemius were determined by enzyme-linked immunosorbent assay (ELISA), to investigate the anti-fatigue mechanisms of PPPm-1. The results showed that PPPm-1 could significantly prolong the weight-bearing swimming time in mice (P < 0.01), decrease the contents of blood lactate and serum urea nitrogen, increase the contents of the hepatic glycogen and muscle glycogen of mice after exercise fatigue compared with those of the control group, and there was extremely significant difference in most indicators (P < 0.01). The 5 mg/mL of PPPm-1 could significantly promote the contraction amplitude, contraction rate, and relaxation rate of the gastrocnemius muscle in the frogs, and the content of ACh at the junction of the frog sciatic nerve-gastrocnemius (P < 0.01), but it had obvious inhibitory effetc on the activity of AChE at the junction of the frog sciatic nerve-gastrocnemius (P < 0.01). PPPm-1 could increase the Na+-K+-ATPase and Ca2+-Mg2+-ATPase activities of gastrocnemius in the frogs (for Ca2+-Mg2+-ATPase, P < 0.01). The above results suggested that the PPPm-1 had a good anti-fatigue effect, and its main mechanisms were related to improving endurance and glycogen reserve, reducing glycogen consumption, lactate and serum urea nitrogen accumulation, and promoting Ca2+ influx.

Trilobatin attenuates cerebral ischaemia/reperfusion-induced blood-brain barrier dysfunction by targeting matrix metalloproteinase 9: The legend of a food additive

BACKGROUND AND PURPOSE

Blood-brain barrier (BBB) breakdown is one of the crucial pathological changes of cerebral ischaemia-reperfusion (I/R) injury. Trilobatin (TLB), a naturally occurring food additive, exerts neuroprotective effects against cerebral I/R injury as demonstrated in our previous study. This study was designed to investigate the effect of TLB on BBB disruption after cerebral I/R injury.

EXPERIMENTAL APPROACH

Rats with focal cerebral ischaemia caused by transient middle cerebral artery occlusion were studied along with brain microvascular endothelial cells and human astrocytes to mimic BBB injury caused by oxygen and glucose deprivation/reoxygenation (OGD/R).

KEY RESULTS

The results showed that TLB effectively maintained BBB integrity and inhibited neuronal loss following cerebral I/R challenge. Furthermore, TLB increased tight junction proteins including ZO-1, Occludin and Claudin 5, and decreased the levels of apolipoprotein E (APOE) 4, cyclophilin A (CypA) and phosphorylated nuclear factor kappa B (NF-κB), thereby reducing proinflammatory cytokines. TLB also decreased the Bax/Bcl-2 ratio and cleaved-caspase 3 levels along with a reduced number of apoptotic neurons. Molecular docking and transcriptomics predicted MMP9 as a prominent gene evoked by TLB treatment. The protective effects of TLB on cerebral I/R-induced BBB breakdown was largely abolished by overexpression of MMP9, and the beneficial effects of TLB on OGD/R-induced loss of BBB integrity in human brain microvascular endothelial cells and astrocyte co-cultures was markedly reinforced by knockdown of MMP9.

CONCLUSIONS AND IMPLICATIONS

Our findings reveal a novel property of TLB: preventing BBB disruption following cerebral I/R via targeting MMP9 and inhibiting APOE4/CypA/NF-κB axis.

Trilobatin contributes to the improvement of myopathy in a mouse model of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) occurs due to genetic mutations that lead to a deficiency in dystrophin production and consequent progressive degeneration of skeletal muscle fibres, through oxidative stress and an exacerbated inflammatory process. The flavonoid trilobatin (TLB) demonstrates antioxidant and anti-inflammatory potential. Its high safety profile and effective action make it a potent therapy for the process of dystrophic muscle myonecrosis. Thus, we sought to investigate the action of TLB on damage in a DMD model, the mdx mouse. Eight-week-old male animals were treated with 160 mg/kg/day of trilobatin for 8 weeks. Control animals were treated with saline. Following treatment, muscle strength, serum creatine kinase (CK) levels, histopathology (necrotic myofibres, regenerated fibres/central nuclei, Feret's diameter and inflammatory area) and the levels of catalase and NF-κB (western blotting) of the quadriceps (QUA), diaphragm (DIA) and tibialis anterior (TA) muscles were measured. TLB was able to significantly increase muscle strength and reduce serum CK levels in dystrophic animals. The QUA of mdx mice showed a reduction in catalase and the number of fibres with a centralized nucleus after treatment with TLB. In the DIA of dystrophic animals, TLB reduced the necrotic myofibres, inflammatory area and NF-κB and increased the number of regenerated fibres and the total fibre diameter. In TA, TLB increased the number of regenerated fibres and reduced catalase levels in these animals. It is concluded that in the mdx experimental model, treatment with TLB was beneficial in the treatment of DMD.

Signaling pathways regulated by natural active ingredients in the fight against exercise fatigue-a review

Exercise fatigue is a normal protective mechanism of the body. However, long-term fatigue hinders normal metabolism and exercise capacity. The generation and recovery from exercise fatigue involves alterations in multiple signaling pathways, mainly AMPK, PI3K/Akt, Nrf2/ARE, NF-κB, PINK1/Parkin, and BDNF/TrkB, as well as MAPK signaling pathways that mediate energy supply, reduction of metabolites, oxidative stress homeostasis, muscle fiber type switching, and central protective effects. In recent studies, a rich variety of natural active ingredients have been identified in traditional Chinese medicines and plant extracts with anti-fatigue effects, opening up the field of research in new anti-fatigue drugs. In this review we give an overview of the signaling pathways associated with the activity of natural food active ingredients against exercise fatigue. Such a comprehensive review is necessary to understand the potential of these materials as preventive measures and treatments of exercise fatigue. We expect the findings highlighted and discussed here will help guide the development of new health products and provide a theoretical and scientific basis for future research on exercise fatigue.

A novel electrochemical sensor based on gold nanobipyramids and poly-L-cysteine for the sensitive determination of trilobatin

Trilobatin is a flavonoid that has wide application prospects due to its various pharmacological effects, such as anti-inflammation and anti-oxidation. In this work, a novel electrochemical sensor based on gold nanobipyramids (AuNBs) and L-cysteine (L-cys) was constructed for the sensitive and selective determination of trilobatin. The AuNBs, which were prepared by a seed-mediated growth method, had large specific surface areas and excellent electrical conductivity. A layer of L-cys film, which provided more active sites through the amino and hydroxyl groups, was modified on the surface of the AuNBs by electropolymerization. Significantly, the Au-S bond between the L-cys film and AuNBs could improve the stability of the sensor and it exhibited satisfactory electrocatalytic oxidation activity for trilobatin. Under optimized conditions, the sensor based on poly-L-cys/AuNBs/GCE was used to determine trilobatin by differential pulse voltammetry (DPV). Two wide linear ranges between the current peak and the concentration of trilobatin were obtained in the range from 5 to 100 μM and 100 to 1000 μM, and the low detection limit (LOD) was up to 2.55 μM (S/N = 3). The sensor demonstrated desirable reproducibility, stability, and selectivity and was applied to detect real trilobatin samples extracted from Lithocarpus polystachyus Rehd.'s leaves, showing recoveries of 98.36%-104.96%, with satisfactory results.

Suppression of SIRT1/FXR signaling pathway contributes to oleanolic acid-induced liver injury

Oleanolic acid (OA) is a pentacyclic triterpenoid compound used clinically for acute and chronic hepatitis. However, high dose or long-term use of OA causes hepatotoxicity, which limits its clinical application. Hepatic Sirtuin (SIRT1) participates in the regulation of FXR signaling and maintains hepatic metabolic homeostasis. This study was designed to determine whether SIRT1/FXR signaling pathway contributes to the hepatotoxicity caused by OA. C57BL/6J mice were administered with OA for 4 consecutive days to induce hepatotoxicity. The results showed that OA suppressed the expression of FXR and its downstream targets CYP7A1, CYP8B1, BSEP and MRP2 at both mRNA and protein levels, breaking the homeostasis of bile acid leading to hepatotoxicity. However, treatment with FXR agonist GW4064 noticeably attenuated hepatotoxicity caused by OA. Furthermore, it was found that OA inhibited protein expression of SIRT1. Activation of SIRT1 by its agonist SRT1720 significantly improved OA-induced hepatotoxicity. Meanwhile, SRT1720 significantly reduced the inhibition of protein expression of FXR and FXR-downstream proteins. These results suggested that OA may cause hepatotoxicity through SIRT1 dependent suppression of FXR signaling pathway. In vitro experiments confirmed that OA suppressed protein expressions of FXR and its targets through inhibition of SIRT1. It was further revealed that silencing of HNF1α with siRNA significantly weakened regulatory effects of SIRT1 on the expression of FXR as well as its target genes. In conclusion, our study reveals that SIRT1/FXR pathway is crucial in OA-induced hepatotoxicity. Activation of SIRT1/HNF1α/FXR axis may represent a novel therapeutic target for ameliorating OA and other herb-induced hepatotoxicity.

Nuclear Factor Erythroid 2-Related Factor 2 and Its Targets in Skeletal Muscle Repair and Regeneration

Significance: Skeletal muscles have a robust regenerative capacity in response to acute and chronic injuries. Muscle repair and redox homeostasis are intimately linked; increased generation of reactive oxygen species leads to cellular dysfunction and contributes to muscle wasting and progression of muscle diseases. In exemplary muscle disease, Duchenne muscular dystrophy (DMD), caused by mutations in the DMD gene that encodes the muscle structural protein dystrophin, the regeneration machinery is severely compromised, while oxidative stress contributes to the progression of the disease. The nuclear factor erythroid 2-related factor 2 (NRF2) and its target genes, including heme oxygenase-1 (HO-1), provide protective mechanisms against oxidative insults. Recent Advances: Relevant advances have been evolving in recent years in understanding the mechanisms by which NRF2 regulates processes that contribute to effective muscle regeneration. To this end, pathways related to muscle satellite cell differentiation, oxidative stress, mitochondrial metabolism, inflammation, fibrosis, and angiogenesis have been studied. The regulatory role of NRF2 in skeletal muscle ferroptosis has been also suggested. Animal studies have shown that NRF2 pathway activation can stop or reverse skeletal muscle pathology, especially when endogenous stress defence mechanisms are imbalanced. Critical Issues: Despite the growing recognition of NRF2 as a factor that regulates various aspects of muscle regeneration, the mechanistic impact on muscle pathology in various models of muscle injury remains imprecise. Future Directions: Further studies are necessary to fully uncover the role of NRF2 in muscle regeneration, both in physiological and pathological conditions, and to investigate the possibilities for development of new therapeutic modalities. Antioxid. Redox Signal. 38, 619-642.

Ferroptosis and its role in skeletal muscle diseases

Ferroptosis is characterized by the accumulation of iron and lipid peroxidation products, which regulates physiological and pathological processes in numerous organs and tissues. A growing body of research suggests that ferroptosis is a key causative factor in a variety of skeletal muscle diseases, including sarcopenia, rhabdomyolysis, rhabdomyosarcoma, and exhaustive exercise-induced fatigue. However, the relationship between ferroptosis and various skeletal muscle diseases has not been investigated systematically. This review’s objective is to provide a comprehensive summary of the mechanisms and signaling factors that regulate ferroptosis, including lipid peroxidation, iron/heme, amino acid metabolism, and autophagy. In addition, we tease out the role of ferroptosis in the progression of different skeletal muscle diseases and ferroptosis as a potential target for the treatment of multiple skeletal muscle diseases. This review can provide valuable reference for the research on the pathogenesis of skeletal muscle diseases, as well as for clinical prevention and treatment.