# Formulation and Biological Evaluation of Glycyrrhiza glabra L. Methanolic Extract: An Exploratory Study in the Context of Rosacea

## TL;DR

This study explores the use of licorice root extract in hydrogel formulations for treating rosacea, showing safety and potential anti-inflammatory and antioxidant benefits.

## Contribution

The study introduces a novel licorice-based hydrogel formulation with demonstrated anti-angiogenic, antimicrobial, and antioxidant properties for rosacea treatment.

## Key findings

- Glycyrrhiza glabra hydrogels showed sustained release and strong antioxidant activity.
- Formulation S2 exhibited improved cytocompatibility and reduced neovascularization in assays.
- Immunohistochemistry indicated modulation of inflammatory pathways relevant to rosacea.

## Abstract

Rosacea is a chronic inflammatory skin disorder characterized by oxidative stress, innate immune dysregulation, vascular instability, and microbiome-related triggers. Glycyrrhiza glabra (Gg, licorice) root contains phenolics and triterpenoids with antioxidant, anti-inflammatory, antimicrobial, and anti-angiogenic properties that may benefit rosacea-prone skin. Xanthan-gum hydrogels containing 2% methanolic Gg extract (S1, S2) were prepared and characterized. Rheology, in vitro release, and in vitro permeation were evaluated, with the aim of assessing their suitability as topical formulations for rosacea-prone skin. Antioxidant activity was assessed using DPPH, ABTS, and FRAP assays. Antimicrobial effects were tested against S. pyogenes, S. aureus, and C. acnes. Safety and bioactivity were examined through HaCaT keratinocyte assays (MTT, Neutral Red, LDH), the HET-CAM irritation test, and the CAM angiogenesis assay. Immunocytochemistry was performed on rosacea-related inflammatory markers. Both hydrogels showed suitable rheology, sustained release, and preserved strong antioxidant activity. Moderate antimicrobial effects were observed, particularly against S. pyogenes and C. acnes. HaCaT cell viability remained above 84% for the S2 formulation at the highest concentration (200 µg/mL), indicating improved cytocompatibility compared with formulation S1. The hydrogels were non-irritant in the HET-CAM model and reduced neovascularization in the CAM assay, with a more sustained effect observed for formulation S2. Immunohistochemistry supported potential modulation of inflammatory pathways relevant to rosacea, evidencing suppressed VEGF expression and preserved CD44-mediated integrity, particularly in the Labrasol-based formulation (S2), while Caspase-3 staining indicated a controlled apoptotic profile. Overall, Gg hydrogels are safe, biocompatible, non-irritant, and exhibit antioxidant, antimicrobial, and anti-angiogenic activities, supporting their potential as biocompatible topical formulations with antioxidant and pathway-modulating properties relevant to the biological features associated with rosacea, while underscoring the importance of formulation design.