The role of molecular weight on chitosan and chitosan oligosaccharides in sleep regulation: Integrating network pharmacology and multi-omics analysis in Drosophila.

This study aims to investigate the sleep-regulating effects of chitosan (COS) with different molecular weights (1 kDa, 3 kDa and 30 kDa). Network pharmacology predicted the sleep-regulating effects of COS and COS oligosaccharides and identified sleep-related targets. Drosophila sleep analysis demonstrated that COS ameliorated caffeine-induced insomnia, and its efficacy was critically influenced by molecular weight. Specifically, COS30K exhibited superior effects compared to COS1K and COS3K in improving the nighttime sleep time, duration of sleep episode and number of sleep episodes in flies. These differential effects were primarily related to acetate-producing bacteria Acetobacter and polysaccharide-degrading bacteria (Bacteroides and Ruminococcus). Their influence on tryptophan metabolism (serotonin and kynurenine) may contribute to the molecular weight-dependent differences in sleep-regulating effects of COS. Integration of network pharmacology and transcriptomic analyses identified five crucial targets (Insc, Aox1, bgm, Acer and hll). This study provides a strategy for predicting novel biological activity of COS and COS oligosaccharides.