Metabolomic Profiling Using UPLC‒MS/MS Revealed Differential Changes in Metabolites of Three Tea Plant Varieties and Their Potential Antioxidant Activities

Tea plants, as essential health beverages, are widely recognized for their rich content of antioxidant metabolites. This study utilized metabolomics analysis techniques to compare the metabolic differences between Camellia tachangensis F. C. Zhang, Camellia gymnogyna Hung T. Chang, and Camellia sinensis (L.) O. Kunzte, aiming to reveal their potential antioxidant activities. By applying UPLC–MS/MS technology, we analyzed metabolites in the samples and identified 1056 metabolites. We utilized statistical methods such as orthogonal partial least squares discriminant analysis (OPLS-DA) and principal component analysis to evaluate and compare the variations in the samples. An intersection analysis of metabolites from the three types of tea plants identified 29 major differential metabolites. Functional annotation and pathway analysis of these differential metabolites were conducted, ultimately discussing 24 antioxidant-related metabolites, primarily belonging to flavonoids, phenolic acids, and other categories. Among the three types of tea, C. tachangensis has the highest content of procyanidin B4, which is the most abundant substance in this tea. In terms of the impact of this substance on tea, it is known to have antioxidant properties and contributes to the overall antioxidant capacity of tea. In both C. gymnogyna and C. sinensis, the top 5 antioxidant metabolites include substances such as apigenin-6,8-di-C-glucoside (vicenin-2), epigallocatechin, and apigenin-5-O-glucoside. These substances belong to the flavonoid class and contribute to the antioxidant properties of these teas. Beyond the flavonoids and phenolic acids, other classes of metabolites in tea plants also exhibited significant antioxidant properties. These different metabolites play a key role in the antioxidant function of tea, contributing to their potential health benefits. The metabolites provide crucial insights for exploring and developing high-antioxidant products that occur naturally.