# Aloysia citrodora Polyphenolic Extract: From Anti-Glycative Activity to In Vitro Bioaccessibility and In Silico Studies

## TL;DR

This study explores the anti-glycative properties of Aloysia citrodora extract and its potential as a natural ingredient to combat aging-related diseases.

## Contribution

The study provides new insights into the anti-glycative and RAGE-binding potential of Aloysia citrodora metabolites.

## Key findings

- The extract strongly inhibits AGE formation and traps harmful compounds like methylglyoxal.
- Digestion reduces the extract's bioaccessibility and anti-glycative activity by about 60%.
- Molecular modeling shows the extract's compounds can bind to the RAGE receptor.

## Abstract

Background: The in vivo accumulation of Advanced Glycation End products (AGEs) is associated with the development of several chronic aging-related and degenerative diseases, as they alter protein structures and activate oxidative and inflammatory processes through interactions with the receptor for AGEs (RAGE). Plant secondary metabolites play a key role in counteracting the glycation process through various mechanisms of action. Therefore, Aloysia citrodora leaf polyphenolic extract could represent a source of anti-glycative compounds. Methods: The methanolic extract was characterized by RP-HPLC-DAD-MSn, and its anti-glycative properties were investigated using several in vitro assays mimicking the different steps of the glycation reaction. In parallel, molecular docking studies were carried out to evaluate potential interactions between the identified metabolites and RAGE. Furthermore, A. citrodora metabolites’ stability under simulated in vitro digestion was assessed, and the anti-glycative activity of the bioaccessible fraction was investigated. Results:
A. citrodora extract, rich in iridoid glycosides, phenylethanoid glycosides, and flavones, strongly inhibited AGE formation (from 10% to 100%) in both the middle and end step of the reaction and had high methylglyoxal and glyoxal trapping capacity. However, the digestion process affected extract stability, particularly under intestinal conditions, yielding an overall bioaccessibility of about 40% and leading to a subsequent reduction in anti-glycative properties. Finally, molecular modeling analysis highlighted the ability of the studied metabolites to bind RAGE. Conclusions:
A. citrodora represents a promising source of natural anti-glycative agents with potential applications as food ingredients. However, it is essential to improve the extract bioaccessibility and to preserve its anti-glycative properties by developing a suitable formulation.