Cultivar-Dependent Metabolite Signatures and Effects on Lipid Metabolism of Teas Processed from Three Varieties of Toona sinensis

Background: The edible and medicinal plant Toona sinensis holds promise for functional food development, yet how cultivar variation affects the metabolite profiles and lipid-modulating effects of its processed leaf teas remains poorly understood. Methods: We systematically prepared and compared teas from three dominant cultivars—Green Toon (GT), Red Toon (RT), and Black Toon (BT)—using a standardized black tea processing procedure. Untargeted metabolomics combined with chemometric analysis was used to characterize cultivar-dependent metabolite signatures. Quantitative analysis was performed for total flavonoids, total polyphenols, and free amino acids. The lipid-modulating effects were evaluated in high-fat-diet-fed mice after 12-week oral administration of RT or BT (equivalent to 2.67 mg/g body weight per day, corresponding to ~14 g tea/day for a 60 kg adult), with GT as the comparison group. Results: Untargeted metabolomics with chemometric analysis revealed distinct cultivar-dependent metabolite signatures. RT and BT contained significantly higher levels of flavonoids and phenolic acids than GT. Notably, BT was putatively rich in flavonoid sulfates and chlorogenic acid derivatives, whereas RT putatively accumulated acylated flavonoid glycosides and theogallin. Quantitative analysis confirmed that RT and BT had higher contents of total flavonoids, total polyphenols, and free amino acids than GT. In high-fat-diet-fed mice, 12-week oral administration of RT or BT markedly attenuated body weight gain, hepatic steatosis, and dyslipidemia (improving triglycerides, total cholesterol, and LDL cholesterol), while GT showed only mild beneficial effects. Correlation analysis further demonstrated that polyphenols and flavonoids, particularly quercetin derivatives and specific phenolic acids, were significantly correlated with improvements in lipid metabolism parameters. Conclusions: These results highlight that cultivar selection is strongly associated with the chemical composition and lipid-regulatory effects of T. sinensis leaf teas, and suggest RT and BT as superior cultivars for the development of functional teas targeting metabolic health; these findings provide actionable data for evidence-based cultivar selection in the food industry.