Vine tea is documented in ancient Chinese books as having the function of promoting blood circulation. However, its effects and mechanisms remain unclear. The aim of this study was to comprehensively investigate the protective potential and mechanisms of vine tea in high-fat diet rat through a combination of in vivo and in vitro experiments. The efficacy of vine tea was evaluated using a high-fat diet rat model and an oxidized low-density lipoprotein-treated cell model, with physiological and biochemical indicators measured in rat serum and cell supernatants. Transcriptomics was utilized to investigate alterations mRNA expression following the administration of dihydromyricetin in cell model. Metabolomics and 16S rRNA sequencing was employed to examine changes in metabolites in the serum and changes in gut microbiota of high-fat diet rats after administering vine tea extract. Vine tea extract and dihydromyricetin can reduce elevated levels of lipids, including total cholesterol and triglycerides, following modeling. Transcriptomic data indicate that dihydromyricetin exerts its effects by regulating ferroptosis signaling pathways. Metabolomic analysis demonstrates that the administration of vine tea extract influences the vitamin K cycle and glutathione, thereby alleviating the progression of ferroptosis. Additionally, 16S rRNA sequencing reveals that vine tea extract increases Lactobacillaceae in the gut microbiota, which subsequently affects the levels of lysophosphatidylcholine, a major phospholipid component of oxidized low-density lipoprotein in serum. Our results indicate that vine tea can regulate ferroptosis signaling pathways and increase Lactobacillaceae in the gut microbiota, thereby exhibiting cardiovascular protective effects in high-fat diet rats.

This study aimed to evaluate the quality attributes and components of instant Pu-erh tea produced by liquid-state fermentation with Pantoea camelliae Z09. Colorimetric analysis and headspace-solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) were used for a comparative evaluation of instant tea samples made from non-fermented sun-dried tea leaves (UIPT), sun-dried tea leaves subjected to natural liquid-state fermentation (NIPT) and inoculated liquid-state fermentation with P. camelliae Z09 (PIPT) for 24 h. Sensory evaluation revealed that PIPT infusion had a reddish brown color, a mellow and slightly sweet taste, and a strong floral and fruity aroma, which was distinct from UIPT and NIPT infusions. A total of 29 volatile components were detected in PIPT infusion, including phenylethanol and methyl nonyl ketone, which contribute to the aroma of rose and citrus oils. In addition, the analysis of the non-volatile composition of PIPT indicated that P. camelliae Z09 promoted the degradation and conversion of theanine and catechins while significantly increasing the synthesis of theabrownins, thereby increasing the mellow taste of instant Pu-erh tea. Correlation analysis showed that theanine, catechin and epigallocatechin gallate were significantly negatively correlated with the synthesis of theabrownins (P＜0.05), indicating that they might be involved in the synthesis of theabrownins. In addition, the contents of theabrownins, theanine, catechin, soluble proteins and total soluble sugars had significant effects on the L^*, a^* and b^* values. The results of multiple batches of scaled-up fermentation showed that instant Pu-erh tea (F-PIPT) prepared in a 100 L fermenter was superior to PIPT with respect to infusion color quality and key ingredient contents, and the scale-up production was feasible and stable. This study fills the gap in the application of bacteria in the liquid-state fermentation of tea and provides a new idea for the development of quality tea products.