# Insights into Bioactive Molecules in Rhododendron tomentosum: From Metabolomics to Biological Applications

## TL;DR

This study identifies bioactive compounds in Rhododendron tomentosum and shows their antioxidant, antimicrobial, and plant health benefits.

## Contribution

The study provides the first tentative identification of aesculin derivatives and links R. tomentosum's chemical profile to its biological activities.

## Key findings

- The extract contains flavonoids like quercetin and catechin, and novel aesculin derivatives.
- It shows antioxidant activity in human keratinocytes and antimicrobial effects against several pathogens.
- The extract promotes growth of the beneficial bacterium Bacillus amyloliquefaciens.

## Abstract

Rhododendron tomentosum is an aromatic plant belonging to the Ericaceae family, widely used for different applications, but still lacking in its molecular signature. This work provides a complete chemical and biological characterization of the hydroalcoholic extract of R. tomentosum tips of twigs. Combining untargeted metabolomic analysis with bioassays, a correlation between chemical composition and biological activity was defined. To this regard, liquid chromatography high-resolution tandem mass spectrometry (LC-MS/MS) revealed a heterogeneous chemical composition, including flavonoids, such as quercetin, catechin, and their derivatives, as well as a first tentative identification of novel aesculin derivatives. Cell-based model experiments on stressed immortalized human keratinocytes demonstrated the antioxidant activity of the extract. Moreover, it exhibited significant antifungal and antibacterial effects against Trichoderma atroviride AGR2, Botrytis cinerea, and Clavibacter michiganensis, while promoting the growth of the beneficial bacterium Bacillus amyloliquefaciens. These findings highlight the rich diversity of bioactive molecules present in R. tomentosum hydroalcoholic extract, bridging its chemical composition to its functional properties. Overall, these results suggest its promising potential for applications in improving plant health, as well as in pharmaceutical, cosmetic, and agricultural industries.