A topical issue in modern pharmacy is the study of new types of medicinal plant raw materials and the development of pharmaceuticals based on them. Considerable interest is aroused by promising species of the genus Juniperus, which are cultivated in Ukraine and are widely used in folk medicine, homeopathy, and cosmetology, but remain insufficiently studied.

Aim: to investigate the component composition and determine the antimicrobial activity of the essential oil of Juniperus virginiana L. as an additional source for new antimicrobial herbal medicines.

Materials and methods. The object of the study was the essential oil of Juniperus virginiana cultivated at the educational and experimental plot of medicinal plants of Zaporizhzhia State Medical and Pharmaceutical University. The essential oil was obtained by hydrodistillation. The qualitative and quantitative composition of volatile compounds was determined using gas chromatography – mass spectrometry (GC-MS) on an Agilent 7890B chromatograph. The study of antimicrobial activity of Juniperus virginiana essential oil (experimental sample) and the reference preparation (essential oil of Juniperus communis) was carried out by the disc diffusion method in vitro using standard test strains of microorganisms from various groups: Staphylococcus aureus ATCC 29213/NCTC12973 (Gram-positive cocci), Bacillus subtilis ATCC 6633 (Gram-positive spore-forming rods), Escherichia coli ATCC 25922 (Gram-negative enterobacteria), Pseudomonas aeruginosa ATCC 27853 (non-fermenting Gram-negative microorganisms), and Candida albicans ATCC 885-653 (yeast-like fungi of the genus Candida).

Results. As a result of GC-MS, 57 compounds belonging to 6 different chemical classes were identified. The dominant components were Limonene (14.83 %), Naphthalene, 1,2,3,4,4a,5,6,8a-octahydro-7 (12.65 %), and Safrole (12.42 %). The results of the in vitro disc diffusion method demonstrated a pronounced antibacterial activity of Juniperus virginiana essential oil against the reference strains of Gram-positive microorganisms: Staphylococcus aureus ATCC 29213/NCTC12973 (Gram-positive cocci) and Bacillus subtilis ATCC 6633 (Gram-positive spore-forming rods). High antifungal activity was also established against the reference strain of Candida albicans ATCC 885-653. The tested sample exhibited moderate antibacterial activity against the Gram-negative test strains Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853.

Conclusions. The qualitative composition and quantitative content of volatile compounds in the essential oil of Juniperus virginiana were studied using GC-MS. A total of 57 components were identified in the essential oil, the major ones being Limonene (14.83 %), Naphthalene 1,2,3,4,4a,5,6,8a-octahydro-7 (12.65 %), and Safrole (12.42 %). Experimental testing of Juniperus virginiana essential oil for microbiological purity showed no microbial growth on the surface or within the nutrient media, allowing further investigation of its antimicrobial activity.