This study explored whether the antiobesity effect of theabrownin (TB) extracted from Fu brick tea (FBT) was associated with the activation of brown adipose tissue (BAT) or browning of the white adipose tissue (WAT) in mice fed a high-fat diet (HFD). Mice were divided into five groups, which received a normal diet, HFD, or HFD plus TB (200, 400, and 800 mg/kg), respectively. A 12-week administration of TB in a dose-dependent manner reduced the body weight and WAT weight and improved lipid and glucose disorders in the HFD-fed mice (p < 0.05). TB also promoted the expression of thermogenic and mitochondrial genes, whereas inflammation genes were reduced in interscapular BAT (iBAT), inguinal WAT (iWAT), and epididymis white adipose tissue (eWAT), accompanied by improvement in the intestinal homeostasis by improving SCFAs, especially butyric acid levels (p < 0.05), which was related to thermogenic and inflammatory factors of iBAT and iWAT. Mechanistically, TB was shown to efficiently promote thermogenesis by stimulating the AMPK-PGC1α pathway with an increase in uncoupling protein 1 (UCP1). Conclusively, these findings suggest that long-term consumption of TB can enhance BAT activity and WAT browning by activating the AMPK-PGC1α pathway and modulating SCFAs; meanwhile, SCFAs regulating TB improved inflammatory disorder in HFD-fed mice.

The antidiabetic effects of Fu brick tea aqueous extract (FTE) and its underlying molecular mechanism in type 2 diabetes mellitus (T2DM) mice were investigated. FTE treatment significantly relieved dyslipidemia, insulin resistance (IR), and hepatic oxidative stress caused by T2DM. FTE also ameliorated the T2DM-induced gut dysbiosis by decreasing the Firmicutes/Bacteroidota (F/B) ratio at the phylum level and promoting the proliferation of Bifidobacterium, Parabacteroides, and Roseburia at the genus level. Besides, FTE significantly improved colonic short-chain fatty acid levels of T2DM mice. Furthermore, the antidiabetic effects of FTE were proved to be mediated by the IRS1/PI3K/Akt and AMPK-mediated gluconeogenesis signaling pathways. Metabolomics analysis illustrated that FTE recovered the levels of 28 metabolites associated with T2DM to the levels of normal mice. Taken together, these findings suggest that FTE can alleviate T2DM by reshaping the gut microbiota, activating the IRS1/PI3K/Akt pathway, and regulating intestinal metabolites.

The regulatory functions of plant miRNAs on mammalian bodies are controversial, mainly because stability of the miRNAs in the digestive tract, as the prerequisite for their cross-kingdom effects, has somehow been overlooked. Hence, as the first stage of food ingestion, stability of plant miRNAs in human saliva has been investigated. The results show that plant miRNAs are of considerable resistance against salivary digestion, as surviving miRNAs more than 20 fM are detected. The stability varies dramatically, which can be explained by the difference in tertiary structure, governing their affinities to RNase. Surprisingly, miRNAs of low initial concentrations can end up with high survival rates after digestion. Plant miRNAs can be loaded into exosome-like nanoparticles (ELNs) and microcapsules formed by food components, both of which protect the miRNAs from being degraded in human saliva. Overall, plant miRNAs can apply certain strategies to maintain constant concentrations, paving the way for their potential cross-kingdom effects.

This study aimed to investigate the amendatory effects of Fu brick tea aqueous extract (FTE) on constipation and its underlying molecular mechanism. The administration of FTE by oral gavage (100 and 400 mg/kg•bw) for 5 weeks significantly increased fecal water content, improved difficult defecation, and enhanced intestinal propulsion in loperamide (LOP)-induced constipated mice. FTE also reduced colonic inflammatory factors, maintained the intestinal tight junction structure, and inhibited colonic Aquaporins (AQPs) expression, thus normalizing the intestinal barrier and colonic water transport system of constipated mice. 16S rRNA gene sequence analysis results indicated that two doses of FTE increased the Firmicutes/Bacteroidota (F/B) ratio at the phylum level and increased the relative abundance of Lactobacillus from 5.6 ± 1.3 to 21.5 ± 3.4% and 28.5 ± 4.3% at the genus level, subsequently resulting in a significant elevation of colonic contents short-chain fatty acids levels. The metabolomic analysis demonstrated that FTE improved levels of 25 metabolites associated with constipation. These findings suggest that Fu brick tea has the potential to alleviate constipation by regulating gut microbiota and its metabolites, thereby improving the intestinal barrier and AQPs-mediated water transport system in mice.

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