Antioxidant and antimicrobial activity of propolis extracts

¹ Department of Meat and Fish Technology, Technological Faculty, University of Food Technologies, 26 Maritza Blvd., 4002 Plovdiv, Bulgaria;
² Assambly of Academicians and Corresponding Members; Bulgarian Academy of Sciences, 1040 Sofia, Bulgaria;
³ InnoSolv Ltd., 4 Skayler Str., 4000 Plovdiv, Bulgaria

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

This study aimed to compare the antioxidant and antimicrobial properties of four propolis extracts: two subcritical water extracts (WP1 and WP2 at 105°C and 135°C), a 10% propylene glycol extract (PGP, w/v, 70°C), and a 10% ethanol extract (ETOHP, w/v, 22°C). The novelty of this work lies in the direct comparative evaluation of these extraction methods under comparable experimental conditions and in assessing their impact on biological activity. Antioxidant capacity was determined using DPPH, ABTS, FRAP, and CUPRAC assays and interpreted in relation to total phenolic content (TPC). Significant differences (p≤0.05) were observed among the extracts. ETOHP exhibited the highest DPPH inhibition (75.73±0.76%) and TPC (37574.71±4451.55 mg GAE·L⁻¹), while PGP showed the highest FRAP (28973.67±1500.52 μmol TE·L⁻¹) and CUPRAC values (14945.53±138.59 μmol TE·L⁻¹). WP1 demonstrated the strongest ABTS scavenging activity (95.61±1.22%). Antimicrobial activity, evaluated by the agar well diffusion method, revealed that ethanol and propylene glycol extracts exhibited the strongest antibacterial effects, particularly against Staphylococcus aureus and Listeria monocytogenes. Antifungal activity was also observed, with Penicillium chrysogenum showing the highest sensitivity. These results indicate that propolis extracts possess significant bioactive potential for application in food systems, although further validation in real food matrices is required.