Triterpenoid saponins in tea plants: A spatial and metabolic analysis using UPLC-QTOFMS, molecular networking, and DESI-MSI

Abstract

Triterpenoid saponins, bioactive compounds with pharmaceutical relevance and functional food potential, are abundant in tea plants (Camellia sinensis), yet their structural diversity and tissue-specific distribution remain insufficiently explored. Using high-resolution mass spectrometry, Feature-based Molecular Networking, and imaging mass spectrometry (IMS), we profiled 52 tea saponins, including two novel trisaccharide saponins with unique glycosylation patterns. Aerial tissues, particularly buds and leaves, were enriched with cinnamoyl-decorated tetrasaccharide saponins, whereas roots predominantly accumulated di- and trisaccharide saponins, with significant cultivar-specific variation. IMS further revealed a compartmentalized root distribution, with di- and trisaccharide saponins localized in the epidermis and cortex, while tetrasaccharide saponins were concentrated in the stele. These findings advance understanding of the structural complexity and spatial accumulation of tea saponins, offering insights for bioactive compound extraction and informing breeding strategies to enhance saponin yield and diversity.