Antimicrobial Assessment of Prunus spinosa L. Fruit Extracts

Prunus spinosa L., commonly known as blackthorn or sloe, is a member of the Rosaceae family that typically grows as a shrub on the slopes of uncultivated, wild terrain. In late autumn, fresh fruits were collected from three distinct habitats in Bosnia and Herzegovina: Borije, Vareš, and Trnovo. This study investigated the antibacterial activity of fruit extracts prepared using the Soxhlet method, employing n-hexane, ethanol, diethyl ether, and dichloromethane. Antibacterial activity was assessed in vitro using the agar well diffusion method against standard bacterial strains: Gram-positive (Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Enterococcus faecalis ATCC 29212), Gram-negative (Pseudomonas aeruginosa ATCC 9027, Salmonella enterica ATCC 31194, Escherichia coli ATCC 25922), and fungus (Candida albicans ATCC 1023). Four solvents served as negative controls, while the antibiotic streptomycin and the antimycotic nystatin served as positive controls. All the blackthorn extracts demonstrated varying degrees of antimicrobial activity against the bacterial strains tested. Ethanol fruit extracts from Borije, Trnovo, and Vareš exhibited the strongest antibacterial activity against the Gram-positive bacterial strain S. aureus, with inhibition zones measuring 21.00, 23.50, and 25.00 mm, respectively. Compared to the control sample, the extracts from Trnovo and Vareš displayed greater potency against this bacterial strain. The diethyl ether extract from Vareš was more effective than streptomycin against E. faecalis, exhibiting a highly sensitive inhibition zone of 22.00 mm. These results suggest that the blackthorn fruit extracts studied possess strong antibacterial activity.