Comparative metabolomics, network analysis, and fraction-based in vitro evaluation of three Lagerstroemia species reveal bioactive compounds and potential for sustainable industrial applications

Lagerstroemia plants are widely cultivated as ornamental trees, while also being traditionally used in China and Southeast Asia as functional tea beverages, fragrant flowering trees, and herbal medicines, indicating their potential as industrial crops enriched with high-value bioactive compounds. However, insufficient understanding of how interspecific differences in metabolite composition has limited their broader application. Here, we performed metabolomics analysis on Lagerstroemia speciosa (LS), Lagerstroemia caudata (LC), and Lagerstroemia indica ‘Dallas Red’ (LI) by UPLC-MS/MS, detecting 2016 metabolites. Network-based analysis further identified 268 bioactive compounds, predominantly phenolics and triterpenoids, of which 39 potential core components were found to share common targets closely linked to type 2 diabetes–related therapeutic pathways. To validate their functional potential, crude extracts were fractionated and evaluated for phytochemical contents, antioxidant capacity, and α-glucosidase and α-amylase inhibitory activities, with Eriobotrya japonica (EJ) leaves used as an industrial reference. Although EJ showed higher total triterpenoids, several Lagerstroemia fractions exhibited stronger antioxidant capacity and α-glucosidase inhibition. Notably, the aqueous fraction of LS combined relatively high yield, abundant phenolics and flavonoids, strong antioxidant activity, and potent α-glucosidase inhibition. The aqueous fraction of LI showed similar functional potential, whereas LC displayed broader polarity-dependent bioactivity. Correlation analysis indicated that total phenolics, rather than total triterpenoids, were more closely associated with antioxidant and enzyme inhibitory activities. These results suggest that Lagerstroemia leaves are natural resources rich in water-soluble bioactive constituents, with potential for functional tea development and value-added utilization of ornamental industrial plant.