Metabolomics Study Suggests the Mechanism of Different Types of Tieguanyin (Oolong) Tea in Alleviating Alzheimer’s Disease in APP/PS1 Transgenic Mice

Abstract

Previously, we found that three types of Tieguanyin tea (Tgy-Q, Tgy-N and Tgy-C) extracts could alleviate Alzheimer’s disease (AD) in a mouse model among which Tgy-C was more effective. In this study, APP/PS1 transgenic mice were used to investigate the metabolomic changes in the feces of mice treated with Tieguanyin tea extracts. Results showed that the profile of fecal metabolites was obviously changed in AD mice. Metabolomics analysis found the effects of Tgy-C, especially its decreasing effect on the fecal metabolites in AD mice—132 of the 155 differential metabolites were decreased. KEGG enrichment revealed that differential metabolites could participate in functional pathways including protein digestion and absorption, biosynthesis of amino acids and ABC transporters. Further comparisons of the metabolites between groups showed that although Tgy-N and Tgy-Q exerted a decreasing effect on the fecal metabolites, Tgy-C was more effective. Moreover, correlation analysis found that the levels of the fecal metabolites were highly correlated with the contents of functional components in tea extracts. Finally, 16S rDNA sequencing presented that Tieguanyin extracts modified the gut microbiota by targeting diverse bacteria. In this study, we investigated the differences of three types of Tieguanyin tea extracts on the fecal metabolites as well as the bacterial community of the gut microbiota in AD mice. The identified differential metabolites and the changed intestinal bacteria might provide potential diagnostic biomarkers for the occurrence and progression of AD.

Trends and hotspots in tea and Alzheimer's disease research from 2014 to 2023: A bibliometric and visual analysis

“…The presence of theanine in tea appears to correlate with improvements in cognitive function [ 19 , 20 ]. Multiple investigations underscore that diverse tea types—ranging from black tea [ 21 ] and white tea [ 22 ] to green tea [ 23 , 24 ] and Oolong tea [ 25 ] — can positively influence mitigating risk factors linked to AD. Nevertheless, the correlation between tea consumption and AD remains an ongoing subject of inquiry, yielding inconclusive findings.…”

Preparation of angiotensin I-converting enzyme (ACE) inhibitory peptides from Tie Guanyin tea residue protein using two-step enzymatic hydrolysis

“…Tie Guanyin, a kind of semi-fermented oolong tea, is famous for the unique and elegant floral aroma, and ripe fruity flavor (Yao et al, 2021). Research indicated that Tie Guanyin extracts could alleviate Alzheimer's disease (AD) in a mouse model (Tu et al, 2022). Phenolics obtained from Tie Guanyin exhibited strong antioxidant capacity and inhibition of the growth of 4T1 murine breast cancer cells (Wang et al, 2019).…”