Background/Objectives: Sarcopenia is an age-related disease resulting in muscle mass deterioration and declining strength and functional ability. Muscle protein degradation pathways are activated through the ubiquitin–proteasome system, which is integral to the pathogenesis of sarcopenia. This study examined the capability of Lactobacillus plantarum beLP1 as a postbiotic ingredient of kimchi that prevents sarcopenia. Methods: We evaluated cell viability and measured diameters in a C2C12 myotube damage model and muscle volume, muscle weight, muscle strength, and the expression of muscle degradation proteins MuRF1 and Atrogin-1 in dexamethasone-induced sarcopenic model rats using a heat-killed beLP1 strain. Results: beLP1 had no cytotoxic effects on C2C12 and prevented dexamethasone-induced cellular damage, suggesting its role in muscle protein degradation pathways. beLP1 treatment significantly prevented the dexamethasone-induced reduction in myotube diameter. In a dexamethasone-induced sarcopenic rat model, oral beLP1 significantly mitigated muscle mass decline and prevented grip strength reduction. Microcomputed tomography demonstrated that beLP1 reduced dexamethasone-induced muscle volume loss. beLP1 treatment reduced Atrogin-1 and Muscle RING-finger protein-1 (MuRF1) and the transcription factor Forkhead box O3 alpha (FoxO3α), which triggers muscle protein breakdown. beLP1 exerts protective effects by inhibiting the ubiquitin-proteasome system and regulating FoxO3α signaling. It increased AKT (Ser473) phosphorylation, which affected muscle protein synthesis, degradation, and cell survival, suggesting its potential to prevent sarcopenia. Conclusions: Heat-killed Lactobacillus plantarum beLP1 alleviates muscle mass wasting and weakness in a dexamethasone-induced sarcopenia model by regulating muscle protein degradation pathways and signaling molecules. Thus, postbiotics may be functional ingredients in sarcopenia prevention.

Sarcopenia is characterized by a reduction in muscle function and skeletal muscle mass relative to that of healthy individuals. In older adults and those who are less resistant to sarcopenia, glucocorticoid secretion or accumulation during treatment exacerbates muscle protein degradation, potentially causing sarcopenia. This study assessed the preventive effects and mechanisms of heat-killed Lactobacillus plantarum postbiotic beLP-K (beLP-K) against dexamethasone (DEX)-induced sarcopenia in C2C12 myotubes and Sprague-Dawley rats. The administration of beLP-K did not induce cytotoxicity and mitigated cell damage caused by DEX. Furthermore, beLP-K significantly reduced the expression of forkhead box O3 α (FoxO3α), muscle atrophy f-box (MAFbx)/atrogin-1, and muscle RING-finger protein-1 (MuRF1), which are associated with muscle protein degradation. DEX induced weight loss in rats; however, in the beLP-K group, weight gain was observed. Micro-computed tomography analysis revealed that beLP-K increased muscle mass, correlating with weight and grip strength. beLP-K alleviated the DEX-induced reduction in grip strength and increased the mass of hind leg muscles. The correlation between beLP-K administration and increased muscle mass was associated with decreased expression levels of muscle degradation-related proteins such as MAFbx/atrogin-1 and MuRF1. Therefore, beLP-K may serve as a treatment for sarcopenia or as functional food material.

Background/Objectives: Recently, concerns about age-related conditions, such as sarcopenia and chronic inflammation, have increased owing to the global acceleration of population aging. Notably, these conditions are interrelated and further exacerbate functional decline in older adults. Therefore, this study aimed to evaluate the efficacy of a novel bioactive compound, DuoX (a mixture of the postbiotic beLP1 and Cichorium intybus L.), in alleviating muscle wasting and chronic inflammation. Specifically, the mixture consisted of inulin-rich C. intybus L. root extract, known for its anti-inflammatory effects, and beLP1, a postbiotic previously shown to exert anti-sarcopenic effects. Methods: To assess the multifunctional effects of the DuoX, dexamethasone-induced sarcopenia models (C2C12 myotubes and an in vivo rat model) and a lipopolysaccharide-stimulated RAW 264.7 macrophage inflammation model were established. Results: Pretreatment with DuoX prevented the dexamethasone-induced reduction in myotube diameter and effectively inhibited muscle degradation by downregulating the expression of atrogin-1 caused by dexamethasone treatment. In rats with DEX-induced sarcopenia, DuoX prevented muscle weight loss, grip strength reduction, and the upregulation of atrogin-1 expression in vivo. In lipopolysaccharide-stimulated RAW 264.7 macrophages, DuoX significantly reduced nitric oxide production and cyclooxygenase-2 protein expression and suppressed p38 and ERK phosphorylation in the MAPK signaling pathway, thereby alleviating inflammatory responses. Conclusions: DuoX holds promise as a dual-functional candidate with both anti-sarcopenic and anti-inflammatory properties. Further preclinical and clinical studies are required to validate its therapeutic efficacy and safety in humans, which may contribute to the development of preventive strategies for healthy aging.

Background/Objectives: Estrogen deficiency-related menopause is associated with various physical and psychological symptoms. Although hormone replacement therapy (HRT) effectively alleviates these symptoms, its long-term use is associated with several side effects such as an increased risk of breast cancer and cardiovascular disease. Consequently, there is a growing interest in some plant-derived phytoestrogens that are considered safer alternatives to estrogen. Recent studies on Scrophularia buergeriana confirmed their anti-inflammatory and antioxidant properties; however, their effects on menopausal health remain unclear. Therefore, the aim of this study was to investigate the estrogen-like effects of S. buergeriana root (SB-R) extract, a potential phytoestrogen. Methods: Briefly, the MCF-7 cell line, a widely used in vitro model for assessing estrogen-like activity, was treated with SB-R extract and 17β-estradiol (E2; positive control) in the presence or absence of ICI 182,780 (Fulvestrant), an estrogen receptor antagonist. An E-screen assay and flow cytometry were performed to assess the effects of the treatments on cell proliferation and the cell cycle, respectively. Additionally, Western blotting and immunofluorescence assays were performed to elucidate the potential mechanisms underlying the estrogen-like effects of SB-R. Result: Treatment with SB-R extract promoted MCF-7 cell proliferation in a manner similar to E2. However, ICI 182,780 co-treatment inhibited the SB-R extract-induced increase in MCF-7 cell proliferation. Additionally, SB-R extract promoted cell cycle progression by increasing the proportion of cells in the S and G2/M phases. Moreover, Western blotting and immunofluorescence assays showed that SB-R extract increased the expression of estrogen receptor alpha (ERα). Furthermore, SB-R treatment activated downstream signaling pathways by enhancing AKT and ERK phosphorylation and upregulated the expression of cell cycle regulators, including cyclin D1, cyclin dependent kinase 4 (CDK4), cyclin E1, and cyclin dependent kinase 2 (CDK2). Conclusions: SB-R exhibits estrogen-like activity by activating ERα-mediated AKT and ERK pathways and thereby increasing the expression of proteins involved in cell cycle regulation. This makes it a promising phytoestrogen candidate and a safer alternative to conventional hormonal therapy for alleviating menopausal symptoms.