The Protective Effects of Membrane‐Separated Ripe Pu‐Erh Tea Extracts Against Chronic Alcoholic Liver Injury

ABSTRACT Excessive alcohol consumption in contemporary society induces alcoholic liver disease (ALD). Previous laboratory studies demonstrated hepatoprotective and gut microbiota–modulating effects of ripe Pu‐erh tea. To identify the key bioactive components responsible for these effects and to support the development of functional beverages, we investigated the preventive effects of various membrane‐separated Pu‐erh tea extracts on a chronic ALD mouse model. The extracts included an 800‐Da nanofiltration fraction, a fraction isolated via a 50‐nm ceramic membrane, the retentate from the 50‐nm ceramic membrane filtration, and unfiltered Pu‐erh tea. The results revealed that the fraction isolated via a 50‐nm ceramic membrane (T4) significantly improved alcohol‐induced intestinal barrier dysfunction, reduced lipopolysaccharide (LPS) release, and suppressed the release of proinflammatory cytokines, including tumor necrosis factor‐α (TNF‐α), interleukin‐6 (IL‐6), and interleukin‐1β (IL‐1β). Furthermore, T4 attenuated hepatic lipid accumulation, oxidative stress, and inflammatory responses by modulating the Nrf2/NQO1 antioxidant pathway and inhibiting toll‐like receptor 4 (TLR4)/MyD88‐mediated proinflammatory signaling. Notably, T4 restored microbial homeostasis by increasing the relative abundance of beneficial bacteria, such as Dubosiella , Muribaculum , and Lactobacillus , and significantly regulated tryptophan metabolism and its related metabolite, indole‐3‐acetic acid (IAA). Overall, the membrane separation technology enriched T4 with polyphenols and flavonoids, which further regulated tryptophan metabolism by regulating liver oxidative stress and promoting probiotic colonization and ultimately alleviates ALD. The membrane‐fractionated Pu‐erh tea, particularly T4, represents a promising functional beverage to combat alcohol‐induced metabolic disorders.