Cytotoxicity, Microbial Stability, and Sensory Evaluation of a SynbioticPowder Designed for Athletes with Circadian Disruption

Introduction: Circadian desynchronization occurs when rapid transmeridian travel disrupts the body’s internal clock and gut-brain axis. This study evaluates the cytotoxicity, microbial stability, and sensory acceptability of a synbiotic formulation combining pearl millet, Carica papaya pulp, and selected probiotic strains. Materials and Method: Ten synbiotic formulations were developed containing Lactobacillus fermentum, Lactobacillus plantarum, and Pediococcus acidilactici. Cytotoxicity was assessed using the MTT assay on Vero cell lines. Microbial stability was evaluated over 60 days by measuring total bacterial count (TBC), total yeast and mold count (TYMC), and the presence of Salmonella spp. and Escherichia coli. Sensory evaluation was performed by a semi-trained panel (n = 10). Statistical analysis included ANOVA and Duncan’s Multiple Range Test (p < 0.05). Principal component analysis (PCA) and 3D response surface plots were used to interpret microbial trends. Results: The MTT assay indicated that all formulations were safe, with IC50 values ranging from 101.3 to 290.5 μg/mL; formulation F3 was the least cytotoxic. Triple-strain formulations received the highest sensory scores. TBC increased significantly by day 60 (from 2.7 × 103 to 7.09 × 104 CFU/mL), particularly in F1 and F2. TYMC and E. coli were absent throughout storage, whereas Salmonella appeared from day 30, with F2 showing the highest count. Formulation F3 demonstrated optimal microbial safety, probiotic viability, and low toxicity. Discussion: These findings highlight the potential of plant-based synbiotics to modulate circadian rhythms via the gut-brain axis. The F3 formulation may support gastrointestinal function, and plant-based diets, prebiotics, or probiotics could beneficially modulate microbial populations and circadian regulation in high-risk groups. Conclusion: The F3 synbiotic formulation demonstrated optimal safety, stability, and sensory acceptability, making it a promising intervention for supporting circadian rhythm alignment during transmeridian travel. Plant-based synbiotics may serve as effective dietary strategies to enhance gut health and circadian synchronization.