Effects of a Chemically Characterised Multi-Component Nutraceutical Formulation on Intestinal, Hepatic and Skeletal Muscle Responses in an In Vitro Gut–Liver–Muscle Model

Autophagy plays a central role in cellular homeostasis and metabolic adaptation, and its dysregulation has been implicated in metabolic disorders, including non-alcoholic fatty liver disease (NAFLD). This study investigated the biological effects of a chemically characterised multi-component nutraceutical formulation using an integrated in vitro gut–liver–muscle axis model under lipotoxic and inflammatory conditions induced by free fatty acids (FFAs) and lipopolysaccharide (LPS). The principal bioactive constituents were quantified in both the individual extracts and the final formulation before biological testing. Caco-2, HepG2, and C2C12 cells were sequentially exposed to conditioned media to reproduce inter-organ metabolic interactions. The Supplement preserved intestinal barrier integrity by maintaining transepithelial electrical resistance and tight junction protein expression. In HepG2 cells, it preserved telomerase levels, improved markers of cellular metabolic adaptation, modulated AMPK/mTOR and SIRT1 signalling, and promoted autophagy-related responses, including increased LC3-II/I ratio, reduced p62 accumulation, and preservation of lysosomal markers. In skeletal muscle cells, exposure to conditioned medium derived from formulation-treated compartments was associated with improved cellular bioenergetics, reduced oxidative stress and inflammatory mediators, and enhanced ATP and glycogen levels under exercise-like conditions. Overall, these findings provide preliminary evidence that the chemically characterised formulation modulates interconnected pathways involved in intestinal barrier function, hepatic autophagy-related processes, and skeletal muscle metabolic adaptation under the experimental conditions employed.