Tae Hee Kim

We investigated the effects of Rhododendron mucronulatum branch extract (RMB) on dexamethasone (DEX)-induced muscle atrophy in young adult male C57BL/6 mice. Mice received oral RMB (100, 200, or 400 mg/kg) for 4 weeks and intraperitoneal DEX (5 mg/kg) during the final 2 weeks. RMB significantly improved exercise duration and capacity at 200 and 400 mg/kg (400 mg/kg vs. DEX control: time to exhaustion, 29.5 vs. 21.3 min), and grip strength showed an increasing trend. Muscle fiber cross-sectional area and gastrocnemius weight were preserved at all doses. RMB increased the phospho-Akt/Akt ratio at 200 mg/kg, the phospho-mTOR/mTOR ratio at 400 mg/kg, and the phospho-FoxO3α/FoxO3α ratio at all doses. Atrogin-1 was suppressed at all doses and MuRF1 at 400 mg/kg, whereas MyoD and Myogenin were increased at 400 mg/kg and IGF-1 at 200 and 400 mg/kg. RMB also reduced intramuscular TNF-α and IL-6, restored antioxidant defense in muscle and serum, and increased Bcl-2. These findings suggest that RMB ameliorates DEX-induced muscle atrophy mainly by partially restoring Akt/mTOR signaling, promoting FoxO3α phosphorylation, and suppressing Atrogin-1 and MuRF1, with additional anti-inflammatory, antioxidant, and anti-apoptotic effects.

Sarcopenia, an age-related muscle atrophy disease, is a major health concern in aging societies and is closely associated with severe chronic diseases. Its primary pathogenesis involves oxidative stress-induced apoptosis in muscle cells and an imbalance in protein metabolism. This study evaluated the potential of Rhododendron mucronulatum branch extract (RMB) and its major flavonoids, taxifolin-3-O-arabinopyranoside (Tax-G) and taxifolin (Tax-A), as natural therapeutic agents for sarcopenia. Phytochemical analyses were performed using TLC, HPLC, LC-MS/MS, and NMR, and Tax-G and Tax-A were isolated from RMB. In vitro models of apoptosis and muscle atrophy were established in C2C12 cells using H₂O₂ and dexamethasone (DEX), respectively. Cell viability, myotube diameter, and protein expression related to apoptosis and muscle differentiation were assessed. All three substances reduced H₂O₂-induced apoptosis by increasing Bcl-2 and inhibiting cleaved caspase-3 and PARP. They also attenuated DEX-induced muscle atrophy by suppressing Atrogin-1, MuRF1, and FoxO3α while promoting MyoD, Myogenin, Akt, and mTOR. Although Tax-A showed the highest activity, Tax-G exhibited comparable effects with lower cytotoxicity. These findings demonstrate that RMB and its active compounds protect muscle cells by regulating apoptosis and muscle metabolism, suggesting their potential as safe and functional natural materials for the prevention of sarcopenia.

This study investigates the effects of pilot scale Alnus japonica hot water extract (AJHW) on muscle loss and muscle atrophy. Building on previous in vitro studies, in vivo experiments were conducted to evaluate muscle strength, mass, fiber size, protein synthesis, and antioxidant activity. The results showed that AJHW significantly restored muscle strength, increased muscle mass, enhanced the expression of muscle synthesis markers, such as Akt and mTOR, and apoptosis inhibition markers, such as Bcl-2, compared to the muscle atrophy control. Muscle degradation markers, such as Atrogin1, MuRF1, FoxO3α, and the apoptosis activation marker Bax, were decreased compared to the muscle atrophy control. Additionally, AJHW significantly boosted the activity of antioxidant factors like SOD, catalase, and Gpx, suggesting its protective role against oxidative stress-induced muscle damage. The enhanced effects were attributed to the high content of hirsutanonol and hirsutenone, which synergized with oregonin, compounds, identified through phytochemical analysis. While these findings support the potential of AJHW as a candidate for preventing muscle loss, further studies are needed to confirm its efficacy across diverse atrophy models and to elucidate its exact mechanisms.

Background/Objectives: Sarcopenia is characterized by the loss of muscle mass and function, increases in mortality rate, and risk of comorbidities in the elderly. This study evaluated the effects of Alnus japonica hot water extract (AJHW) and its active compound, oregonin, on muscle atrophy and apoptosis in vitro. Methods: AJHW underwent phytochemical analysis. C2C12 cells were subjected to H₂O₂ and dexamethasone to induce oxidative stress and muscle loss, after which AJHW and oregonin were administered to assess their impacts on cell viability, apoptosis, muscle protein synthesis stimulation, and muscle protein degradation inhibition. Cell viability was assessed via an MTT assay, and apoptosis was analyzed by measuring Bcl-2, Bax, cleaved caspase-3, and cleaved PARP through Western blotting. Western blotting and RT-PCR were utilized to analyze MyoD, Myogenin, Atrogin-1, and MuRF1 protein and gene expression in a muscle atrophy model, as well as the Akt/mTOR and FoxO3α pathways. Results: AJHW was confirmed to contain oregonin, an active compound. AJHW and oregonin significantly increased cell viability and reduced apoptosis by upregulating Bcl-2 and downregulating Bax, cleaved caspase-3, and cleaved PARP. They significantly enhanced muscle protein synthesis through the upregulation of MyoD and Myogenin, while diminishing muscle degradation by downregulating Atrogin-1 and MuRF1. The activation of the Akt/mTOR pathway and inhibition of the FoxO3α pathway were also observed. Conclusions: AJHW and oregonin effectively prevented muscle cell apoptosis, promoted muscle protein synthesis, and inhibited muscle protein degradation in vitro. These results suggest that AJHW and oregonin could serve as therapeutic agents to prevent and treat sarcopenia.

Muscle atrophy is known to be one of the symptoms leading to sarcopenia, which significantly impacts the quality of life, mortality, and morbidity. Therefore, the development of therapeutics for muscle atrophy is essential. This study focuses on addressing muscle loss and atrophy using Ulmus macrocarpa extract and its marker compound, catechin 7-O-β-D-apiofuranoside, by investigating their effects on biomarkers associated with muscle cell apoptosis. Additionally, protein and gene expression in a muscle atrophy model were examined using Western blotting and RT-PCR. Ulmus macrocarpa has been used as food or medicine due to its safety, including its roots, barks, and fruit. Catechin 7-O-β-D apiofuranoside is an indicator substance of plants of the Ulmus genus and has been reported to have various effects such as antioxidant and anti-inflammatory effects. The experimental results demonstrated that catechin glycoside and Ulmus macrocarpa extract decreased the expression of the muscle-degradation-related proteins Atrogin-1 and Muscle RING-Finger protein-1 (MuRF1) while increasing the expression of the muscle-synthesis-related proteins Myoblast determination (MyoD) and Myogenin. Gene expression confirmation experiments validated a decrease in the expression of Atrogin and MuRF1 mRNA and an increase in the expression of MyoD and Myogenin mRNA. Furthermore, an examination of muscle protein expression associated with the protein kinase B (Akt)/forkhead box O (FoxO) signaling pathway confirmed a decrease in the expression of FoxO, a regulator of muscle protein degradation. These results confirm the potential of Ulmus macrocarpa extract to inhibit muscle apoptosis, prevent muscle decomposition, and promote the development of functional materials for muscle synthesis, health-functional foods, and natural-product-derived medicines.

Aging leads to tissue and cellular changes, often driven by oxidative stress and inflammation, which contribute to age-related diseases. Our research focuses on harnessing the potent anti-inflammatory and antioxidant properties of Korean Ulmus macrocarpa Hance, a traditional herbal remedy, to address muscle loss and atrophy. We evaluated the effects of Ulmus extract on various parameters in a muscle atrophy model, including weight, exercise performance, grip strength, body composition, muscle mass, and fiber characteristics. Additionally, we conducted Western blot and RT-PCR analyses to examine muscle protein regulation, apoptosis factors, inflammation, and antioxidants. In a dexamethasone-induced muscle atrophy model, Ulmus extract administration promoted genes related to muscle formation while reducing those associated with muscle atrophy. It also mitigated inflammation and boosted muscle antioxidants, indicating a potential improvement in muscle atrophy. These findings highlight the promise of Ulmus extract for developing pharmaceuticals and supplements to combat muscle loss and atrophy, paving the way for clinical applications.

Paulownia tomentosa is a representative deciduous tree in South Korea. After 10 years of growth, its wood can be used to make various products through chemical modifications, such as impregnation with a polymer, substitution with chemicals, and physical compression. However, research on the biological resistance of the sapwood and heartwood parts of P. tomentosa xylem is lacking. To ensure the complete utilisation of Paulownia wood, this study aimed to collect baseline data on the necessity of xylem extraction before chemical modification to enhance wood porosity. First, we assessed the decay and termite resistance of sapwood and heartwood blocks. Furthermore, we evaluated the anti-microbial effect of sapwood and heartwood extracts after solvent fractionation. Quantitative and qualitative analyses of the active substances of the fractions with anti-microbial activity were also conducted. The hexane and chloroform solvent fractions of sapwood and heartwood extracts showed fungal resistance against Trametes versicolor and Fomiptosis palustis. Paulownin and sesamin were the main compounds showing anti-microbial activity, and their content in the extracts varied, depending on the wood part. These results provide valuable data for advancing research on porous wood materials and the utilisation of xylem-derived active compounds from Paulownia wood.