# Efficacy Study of Propolis Eutectic Extract in Gel Formulations for the Treatment of Bacterial Skin Diseases in Dogs

## TL;DR

This study explores the use of propolis extract in gel form to treat bacterial skin infections in dogs, offering a natural alternative to antibiotics.

## Contribution

The study introduces gelled formulations of propolis extract using deep eutectic solvents to enhance antibacterial activity for treating skin infections.

## Key findings

- Hydrogels released the highest amount of active propolis compounds, showing strong antibacterial potential.
- Propolis extract demonstrated significant activity against multiple bacterial and fungal pathogens.
- The developed gels offer a promising alternative to antibiotics for treating skin infections in dogs.

## Abstract

Skin infections are common in veterinary medicine and are often treated with topical preparations. Superficial bacterial folliculitis (SBF) is most commonly caused by Staphylococcus spp., and frequent antibiotic use may contribute to the development of resistant strains. Antimicrobial resistance (AMR) is a major threat to human and animal health and natural compounds with antibacterial properties, such as propolis, are being explored as alternative therapies to combat it. In this study, different types of gels with propolis extract were developed, including hydrogels, oleogels, and bigels. These gels help to deliver active compounds directly to the site of infection. The study investigated the antibacterial activity of propolis extracts. The results showed that propolis extract demonstrated promising antibacterial activity, making it a suitable active ingredient for the treatment of bacterial skin infections.

Skin infections are common in veterinary practice and are often treated with topical agents. Superficial pyoderma (superficial bacterial folliculitis) is a common cause of skin disease in dogs and a reason for treatment, most caused by Staphylococcus spp. strains. The frequent use of antibiotics contributes to the emergence of resistant bacterial strains, making antimicrobial resistance (AMR) one of the most important threats to human and animal health. For this reason, active natural compounds are increasingly being explored as alternative therapies. To contribute to the development of effective treatments for bacterial infectious diseases, researchers are looking for new antimicrobial agents. Topical drug action has many advantages as it avoids systemic reactions and ensures that the active substance reaches the site of the lesion directly. This study aimed to develop gelled dosage forms with propolis extract and to evaluate their antibacterial activity and the release of the active substances. Hydrogels, oleogels, and bigels enriched with eutectic propolis extract were produced. Deep eutectic solvents (DESs) were chosen as an effective tool to extract the active compounds of propolis and to improve their penetration into the skin. The pH values of the semi-solid pharmaceutical forms tested ranged from 3.3 to 6.4. Using modified Franz-type diffusion cells, the release of phenolic compounds from gels, oleogels, and bigels was assessed and quantified spectrophotometrically using the Folin–Ciocalteu method. The highest amount of active compounds was released from the hydrogels, while the lowest amount was released from the castor oil-based oleogel. The study used clinical and reference strains of bacteria. The antimicrobial activity of the gelled dosage forms with propolis extract was tested against six pathogenic bacterial species (S. aureus, S. agalactiae, B. cereus, E. faecalis, E. coli, Ps. aeruginosa) and one pathogenic fungus (C. albicans). The study’s results suggest that the propolis extract obtained by DES has significant antibacterial activity and is a promising component in skin formulations for the treatment of bacterial infections.