Polydatin improves mitochondrial dynamics dysrhythmia by regulating BMAL1 to prevent and treat metabolic dysfunction-associated fatty liver disease.

Polygonum cuspidatum, a traditional Chinese medicine indicated for "blood stasis" and "damp-heat" disorders (e.g., arthralgia, jaundice, amenorrhea), has modern relevance as these conditions correlate with dyslipidemia, inflammation, and microcirculatory issues. Its main constituent, polydatin (PD), exhibits multiple bioactivities, yet its role in metabolic dysfunction-associated fatty liver disease (MAFLD) remains unclear. To elucidate the mechanisms by which PD alleviates MAFLD through BMAL1-mediated mitochondrial dynamics. FFA-induced HepG2 cells and HFD-induced MAFLD rats were used to evaluate the effects of PD on hepatic lipid accumulation, mitochondrial function, and oxidative stress immune imbalance via histological staining and biochemical assays. Additionally, molecular docking, molecular dynamics simulations, and BMAL1 knockdown experiments were conducted to identify potential upstream regulators. PD significantly suppressed lipid accumulation, reduced levels of ROS, MDA, NLRP3, TNF-α, and IL-1β, while enhancing SOD activity, thereby alleviating oxidative stress-immune imbalance. PD increased mitochondrial membrane potential (MMP), ATP content, and mtDNA copy number, reversing mitochondrial dysfunction. Notably, PD improved expression rhythms of BMAL1 and mitochondrial dynamics-related genes (DRP1, OPA1, MFN1, MFN2, FIS1), normalizing their amplitude and phase. Concurrently, PD activated the mitochondrial autophagy pathway by upregulating PINK1 and PARKIN expression, thereby facilitating timely clearance of impaired mitochondria. Most importantly, all the aforementioned therapeutic benefits of PD were abolished upon BMAL1 knockdown, establishing BMAL1 as an essential target for PD's action. This is the first study to demonstrate that PD alleviates MAFLD by mediating BMAL1-regulated circadian rhythms of mitochondrial dynamics, positioning PD as a potential therapeutic candidate for MAFLD.