Evaluation of biological activity of cosmetic formulations with propolis for skin healthcare

Acknowledgements: This work was supported by project BG05SFPR001-3.004-0004-С01, Interdisciplinary training of doctoral students to develop knowledge and competencies in various branches of modern research for healthy life and clean technologies (INTERDOC), funded within procedure “Support for development of doctoral projects” of Executive agency “Programme EDUCATION” , co-funded by the European Union Centre of Competence “Sustainable Utilization of Bio-resources and Waste of Medicinal and Aromatic Plants for Innovative Bioactive Products” (BIORESOURCES BG), project BG16RFPR002-1.014-0001, funded by the Program “Research, Innovation and Digitization for Smart Transformation” 2021-2027, co-funded by the EU, is greatly acknowledged and SU-project 80-10-79 / 27.05.2025. P r o g r a m m e EDUCATION 2021-2027 Vanina Lozanova1* , Georgi Pramatarov1,2, Denis Borisov1,2, Dilyana Nikolova1,2 , Liliya Vinarova3 1Faculty of Biology at Sofia university St. Kliment Ohridski, 1164 Sofia, 8 Dragan Tsankov Blvd, Bulgaria 2Centre of Competence “Sustainable Utilization of Bio-Resources and Waste of Medicinal and Aromatic Plants for Innovative Bioactive Products” (BIORESOURCES BG), 1000 Sofia, Bulgaria 3Faculty of Chemistry and Pharmacy at Sofia university St. Kliment Ohridski, 1164 Sofia, 1 James Bourchier Blvd, Bulgaria *Corresponding author: e-mail: [email protected] Introduction Evaluation of biological activity of cosmetic formulations with propolis for skin healthcare Beyond merely concealing imperfections and serving as a form of social expression, cosmetic products can also have therapeutic properties. As a result, a new interdisciplinary field focused on the development of innovative formulations that combine cosmetic and pharmaceutical benefits has emerged. The creation of such products requires in-depth knowledge in topical application of formulations, properties of the active ingredients, proper incorporation into the base formulation, and the evaluation of the safety of the final product. Materials and Methods Five model formulations - 1-5, with different component composition were prepared (Fig.1) Their biological activity was tested against skin pathogenic strains: Cutibacterium acnes, Staphylococcus epidermidis, Staphylococcus aureus, Malassezia furfur and Candida albicans. All formulations were tested for initial activity using the agar well diffusion method and subsequently determining the minimum inhibitory concentration (MIC) and the optimum contact time for inhibiting growth. Filtration and evaporation of 70% ethanol extract of propolis Addition of base solution containing surfactants Addition of ZnCl2 Final product Fig. 1 Preparation method Results Pathogen strain growth S. epidermidis (108 McFarland) S. aureus (108 McFarland) C. acnes (108 McFarland) C. albicans (108 McFarland) M. furfur (108 McFarland) Formulation Time of contact 2 4 2 4 2 4 2 4 2 4 1‘ 102104103104NG NG 102102NG NG 2‘ 102104101102NG NG 102102NG NG 5‘ 102103101NG NG NG 102102NG NG 10‘ 101102NG NG NG NG 102102NG NG 20‘ 101102NG NG NG NG 102102NG NG Conclusions All model formulations are stable and exhibit antimicrobial properties, especially against M. furfur and C. acnes. Two of the five test pathogens showed total growth suppression after just one minute of incubation, indicating a trend toward decreased pathogen viability at longer contact times. Compared to a commercial product, the formulations demonstrate significant effectiveness and represent a solid foundation for the development of personal hygiene products. Table 1. Мinimum inhibitory concentration of formulations 2 and 4 Table 2. Time of contact (NG = No Growth) Among the five formulations, 2 (with ZnCl2) and 4 (with Propolis and ZnCl2) demonstrate significant potential, exhibiting a minimum inhibitory concentration (MIC) at a 128fold dilution and effectively inhibiting the growth of C. acnes and M. furfur after one minute of contact time (Table 1 and 2). The role of surfactants in suppressing pathogen growth is evident across all strains. Furthermore, the addition of propolis and zinc as inhibitory agents has the potential to maintain and enhance formulation activity. Formulation 2 Formulation 4 Dilution Strain 8x 16x 32x 64x 128x 8x 16x 32x 64x 128x S. epidermidis –––+ + – – + + + S. aureus –––+ + – – – – + C. acnes – – – – – – – – – – C. albicans –––+ + – – – + + M. furfur – – – – – – – – – –