eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2026-03-20 19 1 738 751 10.13005/bpj/3388 71004 article Oksana Barna 1 Nataliia Aponchuk 1 Lidiya Romanyuk 2 Mariia Hrabovets 2 Mariana Fedorovska 3 Mariia Shanaida 4 Department of Pharmacy Management, Economics and Technology, I. Horbachevsky Ternopil National Medical University, Ternopil, Ukraine Department of Microbiology, Virology and Immunology , I. Horbachevsky Ternopil National Medical University, Ternopil, Ukraine. Department of Pharmacy and Pharmacology, Lesya Ukrainka Volyn National University, Lutsk Department of Pharmacognosy and Medical Botany, I. Horbachevsky Ternopil National Medical University, Ternopil, Ukraine Antibiotic resistance in many pathogenic microorganisms has become a serious challenge for medical doctors and scientists. Therefore, researchers are seeking effective natural remedies to address this problem. The research aimed to investigate the influence of technological factors on the selection of the optimal method of extracting bioactive compounds from the Blackthorn (Prunus spinosa L.) fruits and study the antimicrobial activity of the resulting phytosubstance (PSFP). Using the mathematical planning method gave us the possibility to choose the optimal extraction conditions, i.e., factor A: extraction method (a₁ – maceration, a₂ – maceration with stirring, a₃ – re-maceration); factor B: type of extractant (b₁ – 40% ethanol, b₂ – 55% ethanol, b₃ – 70% ethanol); factor C: plant raw material (PRM) to extractant ratio (c₁ – 1:5, c₂ – 1:10, c₃ – 1:15). It was established that the most effective extraction of bioactive compounds occurred using the maceration with stirring method, 40% ethanol as the extractant, and 1:5 as the PRM to extractant ratio. The obtained PSFP was characterized as containing 2.43% flavonoids and 0.03% anthocyanins. During the study of antimicrobial activity of the developed PSFP, it was established that it exhibited a complex antimicrobial effect that extends beyond simple toxicity and exerts a bacteriostatic impact on Staphylococcus aureus. It was found that the antimicrobial effect of the PSFP against S. aureus depends on its concentration. With the simultaneous use of the PSFP and antibiotics such as cephalosporins and chloramphenicol, an increase in their action in vitro was noted, due to the ability of polyphenolic compounds to act as efflux pump inhibitors in Staphylococci. It may contribute to enhancing the activity of selected antibiotics in vitro, warranting further mechanistic and pharmacological investigation. https://biomedpharmajournal.org/vol19no1/optimal-method-selection-for-extracting-bioactive-compounds-from-prunus-spinosa-l-fruits-and-evaluating-the-antimicrobial-activity-of-the-resulting-extract/ Antimicrobial effect  Blackthorn fruits Phenolic compounds Spectrophotometric analysis Staphylococcus aureus  Technological factors Various extraction conditions