Plant extracts including secondary metabolites have anti-inflammatory and anti-obesity activities. This study was conducted to investigate the anti-obesity properties of fermented Artemisia annua (AW) and Salicornia herbacea (GW) in vitro and in mice. The metabolite profiling of AW and GW extracts was performed using UHPLC−LTQ−Orbitrap–MS/MS, and gene expression was analyzed using real-time PCR for adipocyte difference factors. The anti-obesity effects in mice were measured using serum AST, ALT, glucose, TG, and cholesterol levels. Metabolites of the plant extracts after fermentation showed distinct differences with increasing anti-obesity active substances. The efficacy of inhibitory differentiation adipogenesis of 3T3-L1 adipocytes was better for GW than AW in a concentration-dependent manner. RT-PCR showed that the GW extract significantly reduced the expression of genes involved in adipocyte differentiation and fat accumulation (C/EBPα, PPARγ, and Fas). In C57BL/6 mice fed the HFD, the group supplemented with AW and GW showed reduced liver weight, NAS value, and fatty liver by suppressing liver fat accumulation. The GW group significantly reduced ALT, blood glucose, TG, total cholesterol, and LDL-cholesterol. This study displayed significant metabolite changes through biotransformation in vitro and the increasing anti-obesity effects of GW and AW in mice. GW may be applicable as functional additives for the prevention and treatment of obesity.

Probiotic fermentation of plant-based materials can lead to the generation of various bioactive substances via bacterial metabolites and the biotransformation of phenolic compounds. We compared the metabolic differences between fermentation by Limosilactobacillus fermentum KCTC15072BP (LFG) and fermentation by Lactiplantibacillus plantarum KGMB00831 (LPG) in guava leaf extract (0%, 0.5%, and 2% (w/v))-supplemented medium via non-targeted metabolite profiling. By performing multivariate statistical analysis and comparing the different guava leaf extract groups, 21 guava-derived and 30 bacterial metabolites were identified. The contents of guava-derived glucogallin, gallic acid, and sugar alcohols were significantly higher in LFG than they were in LPG. Similarly, significantly higher contents of guava-derived pyrogallol, vanillic acid, naringenin, phloretin, and aromatic amino acid catabolites were obtained with LPG than with LFG. LFG led to significantly higher antioxidant activities than LPG, while LPG led to significantly higher antiglycation activity than LFG. Interestingly, the fermentation-induced increase in the guava-leaf-extract-supplemented group was significantly higher than that in the control group. Thus, the increased bioactivity induced by guava fermentation with the Lactobacillaceae strain may be influenced by the synergistic effects between microbial metabolites and plant-derived compounds. Overall, examining the metabolic changes in plant-based food fermentation by differentiating the origin of metabolites provides a better understanding of food fermentation.

Sepsis induces severe immune and metabolic dysfunction driven by mitochondrial failure. Mitochondrial transplantation (MT) has emerged as a promising strategy to restore mitochondrial bioenergetics, but its metabolic impact on immune cells remains unclear. Here, we used gas chromatography–time-of-flight mass spectrometry (GC-TOF-MS)-based metabolomics to evaluate metabolic alterations in peripheral blood mononuclear cells (PBMCs) and splenocytes from a rat polymicrobial sepsis model treated with MT. Principal component and partial least-squares discriminant analyses revealed distinct clustering between sham, sepsis, and MT groups. Sepsis markedly suppressed metabolites related to amino acid, carbohydrate, and lipid metabolism, including aspartic acid, glutamic acid, AMP, and myo-inositol, reflecting mitochondrial metabolic paralysis. MT partially restored these metabolites toward sham levels, reactivating tricarboxylic acid (TCA) cycle, nucleotide, and lipid pathways. Pathway analysis confirmed that exogenous mitochondria reversed sepsis-induced metabolic suppression and promoted bioenergetic recovery in immune cells. These findings provide direct metabolomic evidence that MT reprograms immune metabolism and restores oxidative and biosynthetic function during sepsis, supporting its potential as a mitochondrial-based metabolic therapy.

Branched-chain hydroxy acids (BCHAs) as bioactive metabolites of Lactobacillaceae include 2-hydroxy isovaleric acid (HIVA), 2-hydroxy isocaproic acid (HICA), and 2-hydroxy-3-methyl isovaleric acid (HMVA). Combining targeted and untargeted metabolomics, this study elucidates differences in extracellular BCHA production in Limosilactobacillus fermentum, Ligilactobacillus salivarius, and Latilactobacillus sakei alongside comparing comprehensive metabolic changes. Through targeted metabolomics, BCHA production among 38 strains exhibited strain specificity, except for L. sakei, which showed significantly lower BCHA production. Explaining the lower production in L. sakei, which lacks the branched-chain amino acid (BCAA)-utilizing pathway, comparison of BCHA production by precursor reaction revealed that the pathway utilizing BCAAs is more dominant than the pathway utilizing pyruvate. Expanding upon the targeted approach, untargeted metabolomics revealed the effects of the reaction compound on other metabolic pathways besides BCHAs. Metabolism alterations induced by BCAA reactions varied among species. Significant differences were observed in glycine, serine, and threonine metabolism, pyruvate metabolism, butanoate metabolism, and galactose metabolism (p < 0.05). These results emphasize the importance of the synergy between fermentation strains and substrates in influencing nutritional components of fermented foods. By uncovering novel aspects of BCAA metabolism pathways, this study could inform the selection of fermentation strains and support the targeted production of BCHAs.

Skeletal muscle atrophy is one of the serious complications of diabetes, which increases the risk of frailty, falls, and mortality. However, interventions for muscle atrophy are limited, and research is needed regarding the treatment of muscle wasting. Recently, the bioconversion of natural products by lactic acid bacteria has been highlighted as a possibility to improve the bioavailability of active ingredients. This process also produces metabolites, which are key signaling mediators for a variety of physiological functions. This study investigated the effect of bioconverted guava leaf (Psidium guajava L., GL) by Lactobacillus plantarum on hyperglycemia-induced skeletal muscle atrophy in type 2 diabetes mellites (T2DM) mice. Diabetes was induced by a high-fat diet with a two-time streptozotocin (STZ) injection (60 mg/kg BW) in male C57BL/6J mice. After diabetes was induced (a fasting blood glucose level (FBG) ≥ 300 mg/dL), the mice were administered with GL (100 mg/kg/day) or bioconverted GL (FGL) (50 mg/kg/day) by oral gavage for 14 weeks. FGL contains different substances such as hydroxyl-isocaproic acid and hydroxyl-isovaleric acid compared to GLE itself, which have potential to prevent muscle degradation in T2DM mice. GL and FGL supplementation reduced the FBG level in T2DM mice. In addition, GL and FGL supplementation enhanced muscle strength, the skeletal muscle cross-sectional area, and ameliorated ubiquitin–proteasome system (UPS)-related pathways in T2DM mice. On the other hand, GLE supplementation ameliorated glucose tolerance demonstrated by oral glucose tolerance test and enhanced insulin signaling pathway. In addition, only FGL supplementation attenuated skeletal muscle inflammation and apoptosis with an improved mammalian target of the rapamycin (mTOR)-autophagy-related pathway. Although administered at a half dose of GLE, FGL demonstrated greater efficacy in regulating the expression of these molecular markers. The result suggests that even GL itself has anti-diabetic effects, and the functionality would be enhanced by the bioconversion of GL with L. Plantarum, which has an additive or/and a synergistic effect. Taken together, FGL could be used as a potential nutraceutical to attenuate muscle degradation by the inhibition of inflammation, the UPS, and the apoptosis pathway.

Probiotics are widely consumed as health-promoting agents, with probiotic supplements (PS) and yogurt (YG) representing formulated products and fermented foods, respectively. Despite their broad consumption, systematic comparisons of their biochemical characteristics remain limited. In this study, integrated untargeted and targeted metabolomics approaches were applied to compare the comprehensive metabolite profiles of PS and YG. PS exhibited relatively higher levels of amino acids, dicarboxylic acids, and lysophospholipids, along with short-chain fatty acids such as acetate and propionate, and amino acid-derived bioactive metabolites, including γ-aminobutyric acid, branched-chain hydroxy acids, indole derivatives, and γ-glutamylpeptides. In contrast, YG showed higher relative abundances of carbohydrates, acylcarnitines, sphingolipids, and bioactive metabolites such as butyrate, creatine, carnitine, and orotic acid. Based on these metabolomic differences, 27 PS-specific and 17 YG-specific marker metabolites were identified. To explore their functional relevance, in vitro antioxidant and antiglycation activities were evaluated. PS exhibited significantly higher antioxidant and antiglycation activities than YG, which were positively correlated with amino acids and indole derivatives. Indole-3-acrylic acid, indole-3-acetic acid, and indole-3-propionic acid showed antiglycation activity and were identified as PS-specific bioactive marker metabolites. These findings reveal the distinct biochemical characteristics of PS and YG and highlight potential bioactive candidate metabolites that may contribute to their functional differences.