Antioxidant, Antibacterial, and Probiotic Effects of Ajuga chamaecistus on Honeybee Enterococcus durans

Abstract

Medicinal plants are recognized as important sources of bioactive compounds with significant pharmaceutical potential. In the present study, the antioxidant and antibacterial properties of different solvent extracts of Ajuga chamaecistus were investigated, along with their potential effects on the growth of the probiotic bacterium Enterococcus durans isolated from Apis mellifera meda.

The plant material was extracted using five different solvents (methanol, ethanol, acetone, ethyl acetate, and water) in order to evaluate the influence of solvent polarity on bioactive compound extraction. Total phenolic content was determined using the Folin–Ciocalteu method, while antioxidant activity was assessed using the DPPH radical scavenging assay. Antibacterial activity was evaluated using the agar well diffusion method against Escherichia coli, Staphylococcus aureus, and E. durans. Additionally, the effect of plant extracts on probiotic growth was examined by measuring optical density (OD600) at different concentrations and incubation times. The results showed that methanolic extract exhibited the highest total phenolic content and strongest antioxidant activity, followed by ethanolic, acetone, ethyl acetate, and aqueous extracts. Similarly, methanolic and ethanolic extracts demonstrated the highest antibacterial activity against pathogenic bacteria, while showing minimal inhibitory effects on the probiotic strain. Furthermore, low concentrations of plant extracts enhanced the growth of E. durans, whereas higher concentrations exerted a mild inhibitory effect, indicating a concentration-dependent dual role. The findings suggest that A. chamaecistus is a promising source of natural antioxidants and antimicrobial agents with potential probiotic-modulating properties. This study highlights its possible application in the development of functional foods and natural pharmaceutical formulations.