Dihydromyricetin Improves Physical Performance under Simulated High Altitude

The effect of vine tea (Ampelopsis grossedentata) extract on fatigue alleviation via improving muscle mass

ETHNOPHARMACOLOGICAL RELEVANCE

Vine Tea (VT, Ampelopsis grossedentata), boasts a venerable tradition in China, with a recorded consumption history exceeding 1200 years. Predominantly utilized by ethnic groups in southwest China, this herbal tea is celebrated for its multifaceted therapeutic attributes. Traditionally, VT has been employed to alleviate heat and remove toxins, exhibit anti-inflammatory properties, soothe sore throats, lower blood pressure, and fortify bones and muscles. In the realm of functional foods derived from plant resources, VT has garnered attention for its potential in crafting anti-fatigue beverages or foods, attributed to its promising efficacy and minimal side effects. Currently, in accordance with the Food Safety Standards set forth by the Monitoring and Evaluation Department of the National Health and Family Planning Commission in China, VT serves as a raw material in various beverages.

AIM OF THE STUDY

VT has an anti-fatigue or similar effect in folk. However, the underlying molecular mechanisms contributing to VT's anti-fatigue effects remain elusive. This study endeavors to investigate the influence of Vine Tea Aqueous Extract (VTE) on fatigue mitigation and to elucidate its operative mechanisms, with the objective of developing VTE as a functional beverage.

MATERIALS AND METHODS

The preparation of VTE involved heat extraction and freeze-drying processes, followed by the identification of its metabolites using UPLC-QTOF-MS to ascertain the chemical composition of VTE. A fatigue model was established using a forced swimming test in mice. Potential molecular targets were identified through network pharmacology, transcriptome analysis, and molecular docking. Furthermore, RT-PCR and Western blot techniques were employed to assess mRNA and protein expressions related to the AMPK and FoxO pathways.

RESULTS

VTE significantly prolonged the duration of swimming time in an exhaustive swimming test in a dose-dependent manner, while simultaneously reducing the concentrations of blood lactic acid (LA), lactate dehydrogenase (LDH), serum urea nitrogen (SUN), and creatine kinase (CK). Notably, the performance of the high-dose VTE group surpassed that of the well-recognized ginsenoside. VTE demonstrated a regulatory effect akin to ginsenoside on the AMPK energy metabolism pathway and induced downregulation in the expression of Gadd45α, Cdkn1a, FOXO1, and Fbxo32 genes, suggesting an enhancement in skeletal muscle mass. These findings indicate that VTE can improve energy metabolism and muscle mass concurrently.

CONCLUSIONS

VTE exhibits significant anti-fatigue effects, and its mechanism is intricately linked to the modulation of the AMPK and FoxO pathways. Crucially, no caffeine or other addictive substances with known side effects were detected in VTE. Consequently, vine tea shows substantial promise as a natural resource for the development of anti-fatigue beverages within the food industry.

SIRT1 regulates mitochondrial fission to alleviate high altitude hypoxia inducedcardiac dysfunction in rats via the PGC-1α-DRP1/FIS1/MFF pathway

High-altitude exposure has been linked to cardiac dysfunction. Silent information regulator factor 2-related enzyme 1 (sirtuin 1, SIRT1), a nicotinamide adenine dinucleotide-dependent deacetylase, plays a crucial role in regulating numerous cardiovascular diseases. However, the relationship between SIRT1 and cardiac dysfunction induced by hypobaric hypoxia (HH) remains unexplored. This study aims to assess the impact of SIRT1 on HH-induced cardiac dysfunction and delve into the underlying mechanisms, both in vivo and in vitro. In this study, we have demonstrated that exposure to HH results in cardiomyocyte injury, along with the downregulation of SIRT1 and mitochondrial dysfunction. Upregulating SIRT1 significantly inhibits mitochondrial fission, improves mitochondrial function, reduces cardiomyocyte injury, and consequently enhances cardiac function in HH-exposed rats. Additionally, HH exposure triggers aberrant expression of mitochondrial fission-regulated proteins, with a decrease in PPARγ coactivator 1 alpha (PGC-1α) and mitochondrial fission factor (MFF) and an increase in mitochondrial fission 1 (FIS1) and dynamin-related protein 1 (DRP1), all of which are mitigated by SIRT1 upregulation. Furthermore, inhibiting PGC-1α diminishes the positive effects of SIRT1 regulation on the expression of DRP1, MFF, and FIS1, as well as mitochondrial fission. These findings demonstrate that SIRT1 alleviates HHinduced cardiac dysfunction by preventing mitochondrial fission through the PGC-1α-DRP1/FIS1/MFF pathway.

5-Hydroxymethylfurfural reduces skeletal muscle superoxide production and modifies force production in rats exposed to hypobaric hypoxia

Decreased blood-tissue oxygenation at high altitude (HA) increases mitochondrial oxidant production and reduces exercise capacity. 5-Hydroxymethylfurfural (5-HMF) is an antioxidant that increases hemoglobin's binding affinity for oxygen. For these reasons, we hypothesized that 5-HMF would improve muscle performance in rats exposed to a simulated HA of ~5500 m. A secondary objective was to measure mitochondrial activity and dynamic regulation of fission and fusion because they are linked processes impacted by HA. Fisher 344 rats received 5-HMF (40 mg/kg/day) or vehicle during exposure to sea level or HA for 72 h. Right ankle plantarflexor muscle function was measured pre- and post-exposure. Post-exposure measurements included arterial blood gas and complete blood count, flexor digitorum brevis myofiber superoxide production and mitochondrial membrane potential (ΔΨm), and mitochondrial dynamic regulation in the soleus muscle. HA reduced blood oxygenation, increased superoxide levels and lowered ΔΨm, responses that were accompanied by decreased peak isometric torque and force production at frequencies >75 Hz. 5-HMF increased isometric force production and lowered oxidant production at sea level. In HA exposed animals, 5-HMF prevented a decline in isometric force production at 75-125 Hz, prevented an increase in superoxide levels, further decreased ΔΨm, and increased mitochondrial fusion 2 protein expression. These results suggest that 5-HMF may prevent a decrease in hypoxic force production during submaximal isometric contractions by an antioxidant mechanism.

Sarcopenic Obesity: Involvement of Oxidative Stress and Beneficial Role of Antioxidant Flavonoids

Sarcopenic obesity, which refers to concurrent sarcopenia and obesity, is characterized by decreased muscle mass, strength, and performance along with abnormally excessive fat mass. Sarcopenic obesity has received considerable attention as a major health threat in older people. However, it has recently become a health problem in the general population. Sarcopenic obesity is a major risk factor for metabolic syndrome and other complications such as osteoarthritis, osteoporosis, liver disease, lung disease, renal disease, mental disease and functional disability. The pathogenesis of sarcopenic obesity is multifactorial and complicated, and it is caused by insulin resistance, inflammation, hormonal changes, decreased physical activity, poor diet and aging. Oxidative stress is a core mechanism underlying sarcopenic obesity. Some evidence indicates a protective role of antioxidant flavonoids in sarcopenic obesity, although the precise mechanisms remain unclear. This review summarizes the general characteristics and pathophysiology of sarcopenic obesity and focuses on the role of oxidative stress in sarcopenic obesity. The potential benefits of flavonoids in sarcopenic obesity have also been discussed.

Effect of hypobaric hypoxia on the fiber type transition of skeletal muscle: a synergistic therapy of exercise preconditioning with a nanocurcumin formulation

Hypobaric hypoxia (HH) leads to various adverse effects on skeletal muscles, including atrophy and reduced oxidative work capacity. However, the effects of HH on muscle fatigue resistance and myofiber remodeling are largely unexplored. Therefore, the present study aimed to explore the impact of HH on slow-oxidative fibers and to evaluate the ameliorative potential of exercise preconditioning and nanocurcumin formulation on muscle anti-fatigue ability. C2C12 cells (murine myoblasts) were used to assess the effect of hypoxia (0.5%, 24 h) with and without the nanocurcumin formulation (NCF) on myofiber phenotypic conversion. To further validate this hypothesis, male Sprague Dawley rats were exposed to a simulated HH (7620 m) for 7 days, along with NCF administration and/or exercise training. Both in vitro and in vivo studies revealed a significant reduction in slow-oxidative fibers (p < 0.01, 61% vs. normoxia control) under hypoxia. There was also a marked decrease in exhaustion time (p < 0.01, 65% vs. normoxia) in hypoxia control rats, indicating a reduced work capacity. Exercise preconditioning along with NCF supplementation significantly increased the slow-oxidative fiber proportion and exhaustion time while maintaining mitochondrial homeostasis. These findings suggest that HH leads to an increased transition of slow-oxidative fibers to fast glycolytic fibers and increased muscular fatigue. Administration of NCF in combination with exercise preconditioning restored this myofiber remodeling and improved muscle anti-fatigue ability.

Konjac glucomannan-dihydromyricetin complex improves viscosity and hydration capacity of konjac glucomannan as well as the thermal stability of dihydromyricetin

The nutritional benefits of soluble dietary fiber were mainly attributed to its viscosity and hydration capacity. This study was aimed to investigate the effects of the interaction between konjac glucomannan (KGM) and dihydromyricetin (DMY) on the viscosity and hydration capacity of KGM and the thermal stability of DMY. In contrary to most reports, the addition of DMY to KGM resulted in an increase of viscosity and hydration capacity determined via rheology and nuclear magnetic resonance spectroscopy characterization. Meanwhile the prototype retention of DMY in the presence of heating condition at 60 °C and 100 °C were improved. The radical scavenging capacity of DMY under heating condition was improved at 100 °C via the quantification of ABTS⁺ and DPPH. KGM-DMY complex was a non-covalent compound connected by hydrogen bonds which was characterized with particle size analyses, zeta potential analyses, transmission electron microscopy, infrared spectroscopy, X-ray diffraction, and isothermal titration calorimetry. This study was beneficial to the development of polyphenol-enriched nutrition based on KGM, especially in the aspects of satiety, appetite regulation and glucose regulation.

Anti-fatigue Effect of Traditional Chinese Medicines: A Review

A third of the world's population suffers from unexplained fatigue, hugely impacting work learning, efficiency, and health. The fatigue development may be a concomitant state of a disease or the side effect of a drug, or muscle fatigue induced by intense exercise. However, there are no authoritative guides or clinical medication recommendations for various fatigue classifications. Traditional Chinese medicines (TCM) are used as dietary supplements or healthcare products with specific anti-fatigue effects. Thus, TCM may be a potential treatment for fatigue. In this review, we outline the pathogenesis of fatigue, awareness of fatigue in Chinese and western medicine, pharmacodynamics mechanism, and substances. Additionally, we offer a comprehensive summary of fatigue and forecast the potential effect of novel herbal-based medicines against fatigue.

Dihydromyricetin Attenuates High-Intensity Exercise-Induced Intestinal Barrier Dysfunction Associated with the Modulation of the Phenotype of Intestinal Intraepithelial Lymphocytes

BACKGROUND

Exercise-induced gastrointestinal syndrome (GIS) has symptoms commonly induced by strenuous sports. The study aimed to determine the effect of dihydromyricetin (DHM) administration on high-intensity exercise (HIE)-induced intestinal barrier dysfunction and the underlying mechanism involved with intestinal intraepithelial lymphocytes (IELs).

METHODS

The HIE model was established with male C57BL/6 mice using a motorized treadmill for 2 weeks, and DHM was given once a day by oral gavage. After being sacrificed, the small intestines of the mice were removed immediately.

RESULTS

We found that DHM administration significantly suppressed HIE-induced intestinal inflammation, improved intestinal barrier integrity, and inhibited a HIE-induced increase in the number of IELs and the frequency of CD8αα⁺ IELs. Meanwhile, several markers associated with the activation, gut homing and immune functions of CD8αα⁺ IELs were regulated by DHM. Mechanistically, luciferase reporter assay and molecular docking assay showed DHM could activate the aryl hydrocarbon receptor (AhR).

CONCLUSIONS

These data indicate that DHM exerts a preventive effect against HIE-induced intestinal barrier dysfunction, which is associated with the modulation of the quantity and phenotype of IELs in the small intestine. The findings provide a foundation to identify novel preventive strategies based on DHM supplementation for HIE-induced GIS.

Anti-Fatigue Effects of Lycium barbarum Polysaccharide and Effervescent Tablets by Regulating Oxidative Stress and Energy Metabolism in Rats

The purpose of this study was to investigate the anti-fatigue effect of natural Lycium barbarum polysaccharide (LBP) during exercise, develop a functional anti-fatigue effervescent tablet by applying LBP to practical products, and help patients who have difficulty swallowing conventional tablets or capsules. LBP was extracted with water, and DEAE-52 cellulose was used for purification. The chemical structure and monosaccharide composition of LBP by Fourier transform infrared spectroscopy (FI-IR) and ion chromatography (IC). Lycium barbarum polysaccharide effervescent tablets (LBPT) were prepared by mixing LBP and an excipient. Animal experiments showed that LBP and LBPT significantly increased the exhaustive swimming time in rats. LBP and LBPT improved biochemical markers in rat serum, such as lactic acid and creatine kinase, enhanced the antioxidant capacity of rat muscle, and reversed the decrease in serum glucose, ATP and glycogen content caused by exercise. Transmission electron microscopy showed that LBP and LBPT increased the density of mitochondria in rat liver. In addition, molecular experiments showed that LBP and LBPT could improve oxidative stress caused by exercise by regulating the Nrf2/HO-1 signaling pathway and regulating energy metabolism via the AMPK/PGC-1α signaling pathway.

Metabolic response provides insights into the mechanism of adaption to hypoxia in largemouth bass (Micropterus salmoides) under intermittent hypoxic conditions

In metabolism, molecular oxygen is a necessary substrate. Oxygen imbalances are linked to a variety of circumstances in the organism's homeostasis. Recently, the positive effects of hypoxia treatment in improving exercise ability and hypoxia tolerance have become a research focus. We explored the effects of intermittent hypoxia exposure (IHE, for one hour or three hours per day) on the hypoxia tolerance of largemouth bass in this study. The results showed that (1) IHE significantly reduced the LOEcrit (the critical O₂ tension for loss of equilibrium) value of largemouth bass, indicating that its hypoxia tolerance was enhanced. (2) The level of oxidative stress in the liver decreased in the HH3 group (exposed to a hypoxic condition for 3 h per day) compared to HH1 group (exposed to a hypoxic condition for 1 h per day). (3) IHE reduced the content of lactic acid and enhanced the process of gluconeogenesis in the liver. (4) Importantly, lipid mobilization and fatty acid oxidation in the liver of largemouth bass were significantly enhanced during IHE. In short, the results of this study indicate that IHE can improve hypoxia tolerance by regulating the energy metabolism of largemouth bass.

Pterostilbene attenuates intestinal epithelial barrier loss induced by high loading intensity of exercise

Mounting evidence suggested that high loading intensity of exercise might be detrimental to human health, especially the gastrointestinal tract. Pterostilbene (PTE), derived from grapes and blueberries, might reach a high concentration of intestinal contents. Our study aimed to evaluate PTE’s ability to prevent the loss of intestinal epithelial barrier in high loading intensity of exercise. The exercise model was established by the forced running of mice. An effective HPLC-UV method was developed to quantify PTE concentration in intestinal content. The mRNA changes were detected by quantitative polymerase chain reaction (qPCR). The structure of intestinal flora was analyzed by 16S rRNA sequencing. The PTE (100 mg/kg/d) could significantly attenuate exercise-induced intestinal epithelial barrier loss. Moreover, the HPLC-UV assay showed that the PTE concentration of intestinal content could last 12 h. Furthermore, the exercise increased the abundance of Alistipes, which was related to lipopolysaccharide (LPS) production but could not be reversed by PTE intervention. Besides, cell experiments showed that PTE could promote the expression of intestinal epithelial tight junction (TJ) molecules in vitro. In conclusion, PTE has a significant interest in preventing exercise-induced intestinal damage.

Dihydromyricetin resists inflammation-induced muscle atrophy via ryanodine receptor-CaMKK-AMPK signal pathway

Skeletal muscle plays a pivotal role in the maintenance of physical and metabolic health. Skeletal muscle atrophy usually results in physical disability, inferior quality of life and higher health care costs. The higher incidence of muscle atrophy in obese and ageing groups is due to increased levels of inflammatory factors during obesity and ageing. Dihydromyricetin, as a bioactive polyphenol, has been used for anti‐inflammatory, anti‐tumour and improving insulin sensitivity. However, there are no published reports demonstrated the dihydromyricetin effect on inflammation‐induced skeletal muscle atrophy. In this study, we first confirmed the role of dihydromyricetin in inflammation‐induced skeletal muscle atrophy in vivo and in vitro. Then, we demonstrated that dihydromyricetin resisted inflammation‐induced skeletal muscle atrophy by activating Ca²⁺‐CaMKK‐AMPK through signal pathway blockers, Ca²⁺ probes and immunofluorescence. Finally, we clarified that dihydromyricetin activated Ca²⁺‐CaMKK‐AMPK signalling pathway through interaction with the ryanodine receptor, its target protein, by drug affinity responsive target stability (DARTS). Our results not only demonstrated that dihydromyricetin resisted inflammation‐induced muscle atrophy via the ryanodine receptor‐CaMKK‐AMPK signal pathway but also discovered that the target protein of dihydromyricetin is the ryanodine receptor. Our results provided experimental data for the development of dihydromyricetin as a functional food and new therapeutic strategies for treating or preventing skeletal muscle atrophy.

Benefit of a single simulated hypobaric hypoxia in healthy mice performance and analysis of mitochondria-related gene changes

Simulated hypobaric hypoxia (SHH) training has been used to enhance running performance. However, no studies have evaluated the effects of a single SHH exposure on healthy mice performance and analyzed the changes of mitochondria-related genes in the central nervous system. The current study used a mouse decompression chamber to simulate mild hypobaric hypoxia at the high altitude of 5000 m or severe hypobaric hypoxia at 8000 m for 16 h (SHH5000 & SHH8000, respectively). Then, the mouse behavioral tests were recorded by a modified Noldus video tracking. Third, the effects of SHH on 8 mitochondria-related genes of Drp1, Mfn1, Mfn2, Opa1, TFAM, SGK1, UCP2 and UCP4, were assessed in cerebellum, hippocampus and gastrocnemius muscles. The results have shown that a single mild or severe HH improves healthy mice performance. In cerebellum, 6 of all 8 detected genes (except Mfn2 and UCP4) did not change after SHH. In hippocampus, all detected genes did not change after SHH. In muscles, 7 of all 8 detected genes (except Opa1) did not change after SHH. The present study has indicated the benefit of a single SHH in healthy mice performance, which would due to the stabilized mitochondria against a mild stress state.

Exhaustive Exercise Induces Gastrointestinal Syndrome through Reduced ILC3 and IL-22 in Mouse Model

PURPOSE

This study was to investigate the mechanism of intestinal physical and immune barriers in the occurrence of high-intensive exercise-induced gastrointestinal symptoms.

METHODS

An overtraining model of male C57BL/6 mice was established by running-to-exhaustive exercise. Then, the mice were sacrificed, and a series of evaluation indicators, including the routine blood analysis as well as histological examinations, inflammatory factors, ultrastructure observation, and intestinal permeability of the gut, were measured based on this model. The expressions of inflammatory factors tumor necrosis factor α, interferon-γ, and interleukin (IL)-6 as well as the tight junction and adherence junction proteins ZO-1, Occludin, Claudin-1, and E-cadherin were measured, respectively. Furthermore, the mRNA level of IL-22 and the proportion of ILC3 and IL-22 produced in CD4 T cells in lamina propria lymphocytes (LPL) were analyzed by flow cytometry. Besides, the liver glycogen and the expressions of sirtuins-3 and hypoxia-inducible factor-1a, which were associated with the intestinal metabolism phenotype, were analyzed by Western blotting.

RESULTS

Exhaustive exercise induced a disrupted intestinal barrier integrity, an aggravated intestinal inflammation, increased gut permeability, and the reduced IL-22 mRNA level. Compared with the nonexercise mice, the IL-22 produced in LPL was reduced followed by exhaustive exercise, whereas the proportion of IL-22 produced in CD4 T cells was still unchanged. Significantly, the proportion of ILC3 in the LPL was decreased obviously, including the NCR ILC3. Furthermore, the intestinal metabolism phenotype assessment showed lower liver glycogen and blood glucose as well as higher blood lactic acid and hypoxia-inducible factor-1a, respectively.

CONCLUSIONS

The data indicated that the acute high-intensity running-induced gastrointestinal symptom is closely associated with a reduced percentage of ILC3 and IL-22 level in the LPL, possibly due to the glycogen exhaustion and intestinal mucosa hypoperfusion.

Dihydromyricetin Protects Against Gentamicin-Induced Ototoxicity via PGC-1α/SIRT3 Signaling in vitro

Aminoglycoside-induced ototoxicity can have a major impact on patients’ quality of life and social development problems. Oxidative stress affects normal physiologic functions and has been implicated in aminoglycoside-induced inner ear injury. Excessive accumulation of reactive oxygen species (ROS) damages DNA, lipids, and proteins in cells and induces their apoptosis. Dihydromyricetin (DHM) is a natural flavonol with a wide range of health benefits including anti-inflammatory, antitumor, and antioxidant effects; however, its effects and mechanism of action in auditory hair cells are not well understood. The present study investigated the antioxidant mechanism and anti-ototoxic potential of DHM using House Ear Institute-Organ of Corti (HEI-OC)1 auditory cells and cochlear explant cultures prepared from Kunming mice. We used gentamicin to establish aminoglycoside-induced ototoxicity models. Histological and physiological analyses were carried out to determine DHM’s pharmacological effects on gentamicin-induced ototoxicity. Results showed DHM contributes to protecting cells from apoptotic cell death by inhibiting ROS accumulation. Western blotting and quantitative RT-PCR analyses revealed that DHM exerted its otoprotective effects by up-regulating levels of peroxisome proliferator activated receptor γ-coactivator (PGC)-1α and Sirtuin (SIRT)3. And the role of PGC-1α and SIRT3 in the protective effects of DHM was evaluated by pharmacologic inhibition of these factors using SR-18292 and 3-(1H-1,2,3-triazol-4-yl) pyridine, respectively, which indicated DHM’s protective effect was dependent on activation of the PGC-1α/SIRT3 signaling. Our study is the first report to identify DHM as a potential otoprotective drug and provides a basis for the prevention and treatment of hearing loss caused by aminoglycoside antibiotic-induced oxidative damage to auditory hair cells.

Kefir Supplementation Modifies Gut Microbiota Composition, Reduces Physical Fatigue, and Improves Exercise Performance in Mice

The present study evaluated the potential beneficial effect of kefir (KF) against fatigue. Furthermore, the composition of the gut microbiota is related to health benefits in the host; therefore, the study also investigated the effect of KF on the gut microbiota composition. Male ICR mice from four groups (n = 8 per group) were orally administered KF once daily for four weeks at 0, 2.15, 4.31, and 10.76 g/kg/day and were designated as the vehicle, KF-1X, KF-2X, and KF-5X groups, respectively. The gut microbiota was analyzed using 16S rRNA gene sequencing. The results showed a significant clustering of cecum after treatment in the vehicle, KF-1X, KF-2X, and KF-5X groups. The KF-2X and KF-5X groups showed a decreased Firmicutes/Bacteroidetes ratio compared with the vehicle group. In addition, anti-fatigue activity and exercise performance were evaluated on the basis of exhaustive swimming time, forelimb grip strength, and levels of serum lactate, ammonia, glucose, blood urea nitrogen (BUN), and creatine kinase (CK) after a swimming exercise. The exhaustive swimming time for the KF-1X, KF-2X, and KF-5X groups was significantly longer than that for the vehicle group, and the forelimb grip strength of the KF-1X, KF-2X, and KF-5X groups was also significantly higher than that of the vehicle group. KF supplementation also decreased serum lactate, ammonia, BUN, and CK levels after the swimming test. However, tissue glycogen content, an important energy source for exercise, increased significantly with KF supplementation. Thus, KF supplementation can alter the gut microbiota composition, improve performance, and combat physical fatigue.

Determination of dihydromyricetin in rat plasma by LC-MS/MS and its application to a pharmacokinetic study

CONTEXT

The pharmacokinetics properties of dihydromyricetin (DHM) are still unknown.

OBJECTIVE

This study investigates the pharmacokinetic characteristics of DHM using a sensitive and reliable LC-MS/MS method.

MATERIALS AND METHODS

A rapid and sensitive LC-MS/MS method was developed for the determination of DHM in male Sprague-Dawley rat plasma. Twelve rats were equally randomized into two groups, including the intravenous group (2 mg/kg) and the oral group (20 mg/kg). Blood samples (250 μL) were collected at designated time points and analyzed using this method. The pharmacokinetic parameters were calculated using DAS 3.0 pharmacokinetic software.

RESULTS

The calibration curve was linear within the range of 0.5-200 ng/mL (r > 0.998) with the lower limit of quantification at 0.5 ng/mL. After the intravenous injection, DHM reached a maximum concentration of 165.67 ± 16.35 ng/mL, and t_1/2 was 2.05 ± 0.52 h. However, DHM was not readily absorbed and reached C_max 21.63 ± 3.62 ng/mL at approximately 2.67 h following the oral administration of DHM, and t_1/2 was 3.70 ± 0.99 h. The MRT for the intravenous group and the oral group were 2.62 ± 0.36 and 5.98 ± 0.58 h, respectively. The AUC_(0-t) for the intravenous group and the oral group were 410.73 ± 78.12 and 164.97 ± 41.76 ng·L/mL, respectively, so the absolute bioavailability of DHM was 4.02% which was poor.

DISCUSSION AND CONCLUSION

The results indicated that the bioavailability was poor. Further work needs to be conducted to investigate the reason for poor bioavailability and improve this situation.

Dihydromyricetin prevents monocrotaline-induced pulmonary arterial hypertension in rats

Pulmonary artery hypertension (PAH) is a chronic and deadly disease, for which effective medical treatments are lacking. Here, we investigated whether 2R,3R-dihydromyricetin (DHM) could prevent monocrotaline (MCT)-induced PAH in rats. The MCT-injected rats were treated with normal saline or DHM (100mg/kg body weight/d) for 4 weeks, followed by measurements of right ventricular systolic pressure (RVSP), right ventricular hypertrophy index (RVHI), pulmonary arterial remodeling (PAR), and expression levels of IL-6, TNF-α, and IL-10. In vitro, we assessed the role of DHM on IL-6-induced migration of primary human pulmonary arterial smooth muscle cells (HPASMCs). We found that DHM treatment attenuated changes in RVSP, RVHI, and PAR in MCT-injected PAH rats. The observed increase of IL-6 levels in PAH rats was inhibited by DHM treatment. In vitro, DHM pretreatment reduced IL-6-induced HPASMC migration. Furthermore, MCT- and IL-6-mediated increases in MMP9 and P-STAT3 (tyr705) PY-STAT3 levels were suppressed by DHM treatment in vivo and in vitro. These results suggest that DHM could prevent MCT-induced rat PAH and IL-6-induced HPASMC migration through a mechanism involving inhibiting of the STAT3/MMP9 axis.

Tissue Distribution, Excretion, and Metabolic Profile of Dihydromyricetin, a Flavonoid from Vine Tea (Ampelopsis grossedentata) after Oral Administration in Rats

Dihydromyricetin (DMY), a flavanonol compound found as the most abundant and bioactive constituent in vine tea (Ampelopsis grossedentata), possesses numerous biological activities. In the present study, an HPLC-MS/MS method for the determination of DMY in tissues, urine, and feces was developed and applied to the tissue distribution and excretion study after oral administration in rats, and the metabolic profile of DMY was further investigated using UPLC-QTOF-MS. The results indicated that DMY could be distributed rapidly in various tissues and highly in the gastrointestinal tract. The elimination of DMY occurred rapidly as well, and most unconverted forms were excreted in feces. A total of eight metabolites were identified in urine and feces, while metabolites were barely found in plasma. The predicted metabolic pathways including reduction, dehydroxylation, methylation, glucuronidation, and sulfation were proposed. The present findings may provide the theoretical basis for evaluating the biological activities of DMY and will be helpful for its future development and application.

Ampelopsin attenuates the atrophy of skeletal muscle from d-gal-induced aging rats through activating AMPK/SIRT1/PGC-1α signaling cascade

The atrophy of skeletal muscle is highly correlated with oxidative damage, excessive apoptosis and dysfunctional autophagy. Ampelopsin, a natural flavonoid, has multiple biological functions including anti-inflammatory, anti-oxidative, and hepatoprotective functions. Sprague-Dawley (SD) rats subjected to intraperitoneal injection of d-galactose (d-gal) at the dose of 150mg/kg·d revealed an obvious atrophy of skeletal muscle with significantly reduced muscle mass/body mass ratio, cross-sectional area and fiber diameter of skeletal muscle in d-gal-induced aging rats when compared to normal control rats without d-gal administration for 6 consecutive weeks. In contrast, the combinatorial administration of d-gal at the identical dose and DHM at the dose of 100 or 200mg/kg·d could alleviate the reduction of these hallmarks associated with the atrophy of skeletal muscle. In addition, d-gal administration could result in obvious apoptosis and impaired autophagy in skeletal muscle, which could be mitigated upon DHM treatment due to its role in decreasing ubiquitin and Atrogin-1/MAFbx and up-regulating AMPK and SIRT1 signal pathways. Therefore, DHM may be a potential candidate for the prevention and treatment of skeletal muscle atrophy associated aging process.

Dihydromyricetin prevents obesity-induced slow-twitch-fiber reduction partially via FLCN/FNIP1/AMPK pathway

Obesity is often accompanied by decreases in the proportion of skeletal muscle slow-twitch fibers and insulin sensitivity. Increased plasma non-esterified fatty acids (NEFA) levels are responsible for obesity-associated insulin resistance. Palmitate, one of the most elevated plasma NEFA in obesity, has been recognized as the principle inducer of insulin resistance. The present study showed that increased plasma NEFA levels were negatively linked to slow-twitch fiber proportion and insulin sensitivity, while slow-twitch fiber proportion was positively correlated to insulin sensitivity in high fat diet (HFD)-fed and ob/ob mice. Dihydromyricetin (DHM) intervention increased slow-twitch fiber proportion and improved insulin resistance. In cultured C2C12 myotubes, palmitate treatment resulted in decrease of slow-twitch fiber specific Myh7 expression and insulin resistance, concomitant with folliculin (FLCN) and folliculin-interacting protein 1 (FNIP1) expression increase, AMP-activated protein kinase (AMPK) inactivation and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) expression decrease. Those palmitate-induced effects could be blocked by knock-down of FLCN expression or DHM intervention. Meanwhile, the protective effects of DHM were alleviated by over-expression of FLCN. In addition, the changes in AMPK activity and expression of FLCN and FNIP1 in vivo were consistent with those occurring in vitro. These findings suggest that DHM treatment prevents palmitate-induced slow-twitch fibers decrease partially via FLCN-FNIP1-AMPK pathway thereby improving insulin resistance in obesity.

Ampelopsin Improves Insulin Resistance by Activating PPARγ and Subsequently Up-Regulating FGF21-AMPK Signaling Pathway

Ampelopsin (APL), a major bioactive constituent of Ampelopsis grossedentata, exerts a number of biological effects. Here, we explored the anti-diabetic activity of APL and elucidate the underlying mechanism of this action. In palmitate-induced insulin resistance of L6 myotubes, APL treatment markedly up- regulated phosphorylated insulin receptor substrate-1 and protein kinase B, along with a corresponding increase of glucose uptake capacity. APL treatment also increased expressions of fibroblast growth factor (FGF21) and phosphorylated adenosine 5’-monophosphate -activated protein kinase (p-AMPK), however inhibiting AMPK by Compound C or AMPK siRNA, or blockage of FGF21 by FGF21 siRNA, obviously weakened APL -induced increases of FGF21 and p-AMPK as well as glucose uptake capacity in palmitate -pretreated L6 myotubes. Furthermore, APL could activate PPAR γ resulting in increases of glucose uptake capacity and expressions of FGF21 and p-AMPK in palmitate -pretreated L6 myotubes, whereas all those effects were obviously abolished by addition of GW9662, a specific inhibitor of peroxisome proliferator- activated receptor –γ (PPARγ), and PPARγsiRNA. Using molecular modeling and the luciferase reporter assays, we observed that APL could dock with the catalytic domain of PPARγ and dose-dependently up-regulate PPARγ activity. In summary, APL maybe a potential agonist of PPARγ and promotes insulin sensitization by activating PPARγ and subsequently regulating FGF21- AMPK signaling pathway. These results provide new insights into the protective health effects of APL, especially for the treatment of Type 2 diabetes mellitus.

Understanding the Role of ECM Protein Composition and Geometric Micropatterning for Engineering Human Skeletal Muscle

Skeletal muscle lost through trauma or disease has proven difficult to regenerate due to the challenge of differentiating human myoblasts into aligned, contractile tissue. To address this, we investigated microenvironmental cues that drive myoblast differentiation into aligned myotubes for potential applications in skeletal muscle repair, organ-on-chip disease models and actuators for soft robotics. We used a 2D in vitro system to systematically evaluate the role of extracellular matrix (ECM) protein composition and geometric patterning for controlling the formation of highly aligned myotubes. Specifically, we analyzed myotubes differentiated from murine C2C12 cells and human skeletal muscle derived cells (SkMDCs) on micropatterned lines of laminin compared to fibronectin, collagen type I, and collagen type IV. Results showed that laminin supported significantly greater myotube formation from both cells types, resulting in greater than twofold increase in myotube area on these surfaces compared to the other ECM proteins. Species specific differences revealed that human SkMDCs uniaxially aligned over a wide range of micropatterned line dimensions, while C2C12s required specific line widths and spacings to do the same. Future work will incorporate these results to engineer aligned human skeletal muscle tissue in 2D for in vitro applications in disease modeling, drug discovery and toxicity screening.

Lactobacillus plantarum TWK10 Supplementation Improves Exercise Performance and Increases Muscle Mass in Mice

Lactobacillus plantarum (L. plantarum) is a well-known probiotic among the ingested-microorganism probiotics (i.e., ingested microorganisms associated with beneficial effects for the host). However, few studies have examined the effects of L. plantarum TWK10 (LP10) supplementation on exercise performance, physical fatigue, and gut microbial profile. Male Institute of Cancer Research (ICR) strain mice were divided into three groups (n = 8 per group) for oral administration of LP10 for six weeks at 0, 2.05 × 10⁸, or 1.03 × 10⁹ colony-forming units/kg/day, designated the vehicle, LP10-1X and LP10-5X groups, respectively. LP10 significantly decreased final body weight and increased relative muscle weight (%). LP10 supplementation dose-dependently increased grip strength (p < 0.0001) and endurance swimming time (p < 0.001) and decreased levels of serum lactate (p < 0.0001), ammonia (p < 0.0001), creatine kinase (p = 0.0118), and glucose (p = 0.0151) after acute exercise challenge. The number of type I fibers (slow muscle) in gastrocnemius muscle significantly increased with LP10 treatment. In addition, serum levels of albumin, blood urea nitrogen, creatinine, and triacylglycerol significantly decreased with LP10 treatment. Long-term supplementation with LP10 may increase muscle mass, enhance energy harvesting, and have health-promotion, performance-improvement, and anti-fatigue effects.

Investigations on the antifatigue and antihypoxic effects of Paecilomyces hepiali extract

Paecilomyces hepiali, one of the most valuable and effective Chinese medicinal herbs, possesses potential antioxidant, immunomodulatory, antitumor and anti‑inflammatory properties. The present study aimed to investigate the antifatigue and antihypoxic effects of Paecilomyces hepiali extract (PHC) in a mouse model. Using a rotating rod, forced swimming and running assessment, the antifatigue activity of PHC was determined. PHC administration for 7 days had no effect on mouse horizontal or vertical movement, indicating no neurotoxicity at the selected doses was observed. Using a normobaric hypoxia, sodium nitrite toxicosis and acute cerebral ischemia assessments, PHC was confirmed to possess antihypoxic effects. PHC treatment for 7 days significantly enhanced the serum and liver levels of adenosine triphosphate, superoxide dismutase and glutathione peroxidase, prior to and following 60 min of swimming. The levels of antioxidant‑associated proteins in the livers of the mice were analyzed using western blotting. PHC effectively increased the expression levels of phosphorylated (p)‑5'‑monophosphate (AMP)‑activated protein kinase (AMPK), p‑protein kinase B (AKT) and p‑mammalian target of rapamycin (mTOR). The results of the present study demonstrated that PHC efficiently enhanced endurance from fatigue and had antihypoxic effects through elevation of the antioxidant capacity in the serum and liver, at least in part through the AMPK and AKT/mTOR pathways. These results indicate the potential of this natural product as an antioxidant in the treatment of fatigue, hypoxia and their associated diseases.

Dihydromyricetin Improves Hypobaric Hypoxia-Induced Memory Impairment via Modulation of SIRT3 Signaling

Inadequate oxygen availability-for instance at high altitudes-leads to hippocampal neurodegeneration and memory impairment. Although oxidative stress is one factor, the mechanism underlying the effects of hypobaric hypoxia (HH) are unclear, and effective strategies for preventing the resultant damage to the brain are limited. In the present study, we demonstrate that ingesting dihydromyricetin (DM) protects against memory impairment in adult rats subjected to HH for 7 days, equivalent to an altitude of 5000 m above sea level. Moreover, DM treatment stimulated mitochondrial biogenesis and improved mitochondrial morphology and function, suppressed the generation of reactive oxygen species, and reduced lipid peroxidation in the hippocampus. In HT-22 cells exposed to hypoxic conditions, the neuroprotective effects of DM were shown to be exerted via attenuation of oxidative stress through sirtuin 3-induced forkhead box O3 deacetylation.

Dihydromyricetin stimulates irisin secretion partially via the PGC-1α pathway

Irisin, derived from FNDC5, is an exercise-induced myokine that can stimulate the 'browning' of white adipose tissue, which is regulated by peroxisome proliferator-activated receptor γ coactivator 1 α (PGC-1α). Dihydromyricetin (DHM), a natural flavonoid, exerts its activities through PGC-1α activation. Here, we explored whether DHM could mimic the effects of exercise on irisin secretion. DHM administration increased circulating irisin in rats and humans. Notably, the serum irisin level had a greater correlation to the level of circulating DHM than to the amount of exercise. DHM treatment upregulated PGC-1α and FNDC5 expression, enhanced energy metabolism, as evidenced by NMR-based metabonomics analysis, and partially abolished the suppressive effects of Pgc-1α siRNA on FNDC5 expression. These results suggest that DHM can stimulate irisin secretion partially via the PGC-1α pathway. As a potent exercise mimetic, DHM is expected to benefit patients suffering from metabolic diseases, especially those who cannot undergo rigorous exercise.

Dihydromyricetin improves skeletal muscle insulin resistance by inducing autophagy via the AMPK signaling pathway

Skeletal muscle insulin resistance (SMIR) plays an important role in the pathogenesis of type 2 diabetes. Dihydromyricetin (DHM), a natural flavonoid, exerts various bioactivities including anti-oxidative and hepatoprotective effects. Herein, we intended to determine the effect of DHM on SMIR and the underlying mechanisms. We found that DHM increased the expression of phosphorylated insulin receptor substrate-1, phosphorylated Akt and glucose uptake capacity in palmitate-treated L6 myotubes under insulin-stimulated conditions. The expression of light chain 3, Beclin 1, autophagy-related gene 5 (Atg5), the degradation of sequestosome 1 and the formation of autophagosomes were also upregulated by DHM. Suppression of autophagy by 3-methyladenine and bafilomycin A1 or Atg5 and Beclin1 siRNA abolished the favorable effects of DHM on SMIR. Furthermore, DHM increased the levels of phosphorylated AMP-activated protein kinase (AMPK) and Ulk1, and decreased phosphorylated mTOR levels. AMPK inhibitor compound C (CC) and AMPK siRNA abrogated DHM-induced autophagy, subsequently suppressed DHM-induced SMIR improvement. Additionally, DHM inhibited the activity of F1F0-ATPase thereby activating AMPK. Finally, the results of in vivo study conducted in high fat diet-fed rats were consistent with the findings of in vitro study. In conclusion, DHM improved SMIR by inducing autophagy via the activation of AMPK signaling pathway.

Dihydromyricetin improves glucose and lipid metabolism and exerts anti-inflammatory effects in nonalcoholic fatty liver disease: A randomized controlled trial

Ampelopsis grossedentata, a medicinal and edible plant, has been widely used in China for hundreds of years, and dihydromyricetin is the main active ingredient responsible for its various biological actions. We investigated the effects of dihydromyricetin on glucose and lipid metabolism, inflammatory mediators and several biomarkers in nonalcoholic fatty liver disease. In a double-blind clinical trial, sixty adult nonalcoholic fatty liver disease patients were randomly assigned to receive either two dihydromyricetin or two placebo capsules (150 mg) twice daily for three months. The serum levels of alanine, aspartate aminotransferase, γ-glutamyl transpeptidase, glucose, low-density lipoprotein-cholesterol and apolipoprotein B, and the homeostasis model assessment of insulin resistance (HOMA-IR) index were significantly decreased in the dihydromyricetin group compared with the placebo group. In the dihydromyricetin group, the serum levels of tumor necrosis factor-alpha, cytokeratin-18 fragment and fibroblast growth factor 21 were decreased, whereas the levels of serum adiponectin were increased at the end of the study. We conclude that dihydromyricetin supplementation improves glucose and lipid metabolism as well as various biochemical parameters in patients with nonalcoholic fatty liver disease, and the therapeutic effects of dihydromyricetin are likely attributable to improved insulin resistance and decreases in the serum levels of tumor necrosis factor-alpha, cytokeratin-18, and fibroblast growth factor 21.

Fucoidan supplementation improves exercise performance and exhibits anti-fatigue action in mice

Fucoidan (FCD) is a well-known bioactive constituent of seaweed extract that possess a wide spectrum of activities in biological systems, including anti-cancer, anti-inflammation and modulation of immune systems. However, evidence on the effects of FCD on exercise performance and physical fatigue is limited. Therefore, we investigated the potential beneficial effects of FCD on ergogenic and anti-fatigue functions following physiological challenge. Male ICR mice from three groups (n = 8 per group) were orally administered FCD for 21 days at 0, 310 and 620 mg/kg/day, which were, respectively, designated the vehicle, FCD-1X and FCD-2X groups. The results indicated that the FCD supplementations increased the grip strength (p = 0.0002) and endurance swimming time (p = 0.0195) in a dose-depend manner. FCD treatments also produced dose-dependent decreases in serum levels of lactate (p < 0.0001) and ammonia (p = 0.0025), and also an increase in glucose level (p < 0.0001) after the 15-min swimming test. In addition, FCD supplementation had few subchronic toxic effects. Therefore, we suggest that long-term supplementation with FCD can have a wide spectrum of bioactivities on health promotion, performance improvement and anti-fatigue.

Dihydromyricetin ameliorates the oxidative stress response induced by methylglyoxal via the AMPK/GLUT4 signaling pathway in PC12 cells

Dihydromyricetin (DMY), the major bioactive flavonoid ingredient extracted from the leaves of Ampelopsis grossedentata (Hand.-Mazz) W.T. Wang, displays multiple pharmacological activities, including oxidation resistance, antitumor properties and free radical scavenging capacities. However, the role of DMY in methylglyoxal (MG)-induced diabetes-associated cognitive decline and its underlying molecular mechanisms are unclear. The aim of the present study was to evaluate the effects of DMY on oxidative stress and glucose transport activity in a MG-induced PC12 cell line and to explore the related mechanisms. The effects of DMY on cell survival and apoptosis were examined, and the dysregulation of intracellular Ca(2+) was determined. Oxidative stress was evaluated by monitoring ROS production and the glutathione to glutathione disulfide ratio. The effects of DMY on glucose metabolism were investigated using a fluorescently labeled deoxyglucose analog and by measuring ATP and lactate production. Western blot analysis was performed to examine the protein levels of glyoxalase I (Glo-1), glucose transporter 4 (GLUT4), AMP-activated protein kinase (AMPKα) and phosphorylated AMPKα (p-AMPKα). The results revealed that DMY suppressed cellular oxidative stress in PC12 cells and balanced glucose metabolism. Additionally, DMY reduced GLUT4 translocation dysfunction and increased Glo-1 and p-AMPKα expression. We found that DMY protected PC12 cells against MG-induced apoptosis and glycometabolic disorders, at least in part by restraining the hyperactivation of p-AMPK activity and normalizing the translocation of GLUT4 from the intracellular compartment, resulting in a balance in glucose uptake. This result indicates that DMY may serve as a novel and effective candidate agent to treat diabetic encephalopathy by reducing the toxicity of MG.