Pharmaceutical availability of hydrogels with extracts of Arnica montana, Aesculus hippocastanum and Ruscus aculeatus and their potential use as antioxidant polyphenol-rich material

Introduction
Plant extracts are important sources of natural bioactive compounds, commonly used in the pharmaceutical and cosmeceutical industries. Phytochemical and antioxidant screening of plant extracts provides valuable information about their potential use. In the case of polyphenol-rich plant raw materials for external use, it is extremely important to test the ability of active substances to permeate the skin.

Aim of the research
To determine the polyphenolic content and antioxidant activity of horse chestnut, butcher’s broom, and mountain arnica glycerol-water extracts and to assess the diffusion capacity of plant extracts from hydrogel formulations.

Material and methods
The content of polyphenols was determined using a spectrophotometric method. Antioxidant properties were analysed using DPPH-EPR assay and the FRAP method. The pharmaceutical availability of the extracts in the hydrogels was tested using a simplified model of human skin represented by a cellulose dialysis membrane.

Results and conclusions
The total polyphenol content in the extracts was highest in horse chestnut, followed by butcher’s broom and mountain arnica, whereas the arnica extract had the highest flavonoid content. The obtained results indicate that the extracts have high antioxidant potential, which can be ranked as follows: A. montana > A. hippocastanum > R. aculeatus. The pharmaceutical availability analysis showed that the extract from A. hippocastanum is released most efficiently. Analyses of the kinetics of active substance release from hydrogel formulations have proven to be a useful tool for assessing the efficacy of semi-solid products. Tested plant extracts can be used as polyphenol-rich natural materials with antioxidant properties.