# Comparative analysis of metabolite signatures and hypoglycemic effects in Toona sinensis leaves processed by two distinct methods

## TL;DR

This study compares processed Toona sinensis leaves using black tea techniques versus traditional drying, finding that the former improves flavor and health benefits like hypoglycemic effects.

## Contribution

The study introduces black tea processing for Toona sinensis leaves, revealing enhanced bioactive metabolites and improved hypoglycemic activity.

## Key findings

- Black tea processing significantly alters 41 metabolites in Toona sinensis leaves.
- Processed leaves show increased flavonoids and amino acids, and reduced phenolic acids.
- Processed leaves demonstrate better hypoglycemic effects in vitro and in vivo compared to traditionally dried leaves.

## Abstract

The tender buds of “Heiyouchun” (Toona sinensis), a traditional Chinese specialty variety, are highly favored as a unique woody vegetable. However, the mature leaves exhibit distinct bitterness and lack aromatic compounds, resulting in low resource utilization. This study innovatively developed toon leaf tea (TLT) using black tea processing techniques. Through integrated metabolomic analysis and health benefit evaluation, we systematically compared the differences in chemical composition and hypoglycemic effect between TLT and traditionally dried mature toon leaves (TOL). Metabolomic analysis revealed that the two processing methods induced significant changes in 41 metabolites. Compared with TOL, TLT demonstrated significant enrichment in functional components including flavonoids (e.g., quercetin derivatives), limonoids, and amino acids, along with a marked reduction in phenolic acids and organic acids. The synergistic effects of these components effectively improved product flavor and enhanced bioactivity. In vitro and in vivo experiments confirmed that the α – glucosidase/α – amylase inhibitory activity of TLT and the hypoglycemic effect on diabetes model mice are significantly better than that of TOL. This study not only elucidates the transformation patterns of chemical constituents in mature toon leaves under different processing methods but also provides a scientific basis for the resource utilization of mature toon leaves.

•A total of 41 differential metabolites were identified between toon leaf (TOL) and toon leaf tea (TLT).•TLT vs. TOL showed enriched flavonoids, limonoids, and amino acids, with reduced phenolic/organic acids.•Black tea processing boosts hypoglycemic efficacy in toon leaves compared to direct drying.

A total of 41 differential metabolites were identified between toon leaf (TOL) and toon leaf tea (TLT).

TLT vs. TOL showed enriched flavonoids, limonoids, and amino acids, with reduced phenolic/organic acids.

Black tea processing boosts hypoglycemic efficacy in toon leaves compared to direct drying.