Correlation between oxidative stress and inflammation with metabolomics profile in skeletal muscle of ageing animal model and its modulation by tocotrienol-rich fraction

Abstract

Introduction: Sarcopenia, characterised by age-associated decline in skeletal muscle mass and function, is driven by multifactorial mechanisms including oxidative stress, chronic inflammation, and genomic instability. The imbalance between reactive oxygen species (ROS) and antioxidant defence contributes to mitochondrial dysfunction and DNA damage, thereby affecting cellular metabolism and promoting muscle degeneration. Tocotrienol-rich fraction (TRF), a potent antioxidant form of vitamin E, has shown potential in modulating oxidative and inflammatory pathways. However, in vivo evidence exploring TRF's multifaceted role in ageing muscle remains limited. This study investigates the correlation between oxidative stress and inflammation with the metabolomics profile in ageing skeletal muscle in a rat model and its modulation by tocotrienols.

Methods: Young (3 months) and old (21 months) male Sprague-Dawley rats were divided into control and TRF-supplemented groups (n = 10). TRF was administered orally (60 mg/kg/day) for 3 months. Antioxidant enzymes, lipid peroxidation products: malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE); and inflammatory markers: C-reactive protein (CRP), Interleukin-6 (IL-6), and tumour necrosis factor alpha (TNF-α) were quantified, alongside DNA damage, using the comet assay. Muscle histology was assessed using hematoxylin and eosin (H&E) staining. Pearson correlation analysis was performed between selected metabolites and biological markers.

Results: Ageing significantly increased oxidative damage, pro-inflammatory markers, and DNA fragmentation, while reducing antioxidant enzyme activities and disrupting metabolic profiles. Although TRF supplementation did not significantly restore muscle mass or overall body composition, it effectively enhanced antioxidant defence by increasing Superoxide dismutase (SOD) and catalase (CAT) activities, reducing lipid peroxidation (MDA and 4-HNE), attenuating inflammatory responses, preserving DNA integrity, and improving muscle histological features. Importantly, correlation analyses revealed that ageing is associated with a coordinated metabolic shift linking amino acid and carnitine metabolism with antioxidant defence, inflammation, and genomic stability. TRF supplementation weakened these maladaptive biomarker and metabolite associations while strengthening correlations between protective metabolites (e.g., taurine, histidine, pantothenic acid) and antioxidant enzymes, alongside inverse relationships between lipid peroxidation and inflammatory markers (e.g., MDA, prostaglandin factor 2-alpha, PGF2α) and redox-supportive metabolites.

Discussion: Collectively, these findings indicate that TRF acts primarily as a preventive intervention by restoring redox balance, dampening inflammatory signalling, and stabilising metabolic and inflammatory coupling, highlighting its potential as a nutritional strategy for preserving muscle health and genomic integrity during ageing.

Keywords: DNA damage; ageing; low-grade inflammation; oxidative stress; sarcopenia.