Antimicrobial and Antiradical Activities of Individual Fractions of Pinus sibirica Du Tour and Abies sibirica Ledeb. Growing in Siberia

— Essential oil from the spruce branches of Siberian pine ( Pinus sibirica Du Tour) and Siberian fir ( Abies sibirica Ledeb.) growing on the territory of Krasnoyarsk krai has been obtained by exhaustive hydro-steam distillation. Five separate oil fractions have been extracted: the first was collected 45 min after the onset of distillation; the second, at 2 h; the third, at 5 h; the fourth, at 6 h after the onset of distillation, and the fifth fraction was collected after the termination of hydro-steam distillation. The antimicrobial activity of separate fractions of essential oil from P. sibirica and А. sibirica toward the strains of conditionally pathogenic bacteria has been tested: Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus 209р , Micrococcus luteus, Acinetobacter baumanii, and Candida albicans . The results of the study have shown that all samples of essential oils exhibit either bactericidal or bacteriostatic activity toward microbial strains used in the experiment except for Pseudomonas aeruginosa . The type of activity depends on the microbial strain and the sample of essential oil. It has been noted that the sensitivity of the strains to the components of P. sibirica and A. sibirica essential oils diminishes on going from the first to the last fraction. It has been assumed that this is due to a decrease in the content of monoterpenes in the oil composition. The antiradical activity has been examined by the reaction of essential oil components with the stable free 2,2-diphenyl-1-picrylhydrazyl radical. It has been found that both whole essential oils from P. sibirica and А. sibirica and their individual fractions exhibit antiradical activity. It has been noted that the antiradical activity increases with decreasing content of monoterpenes in the composition of the essential oil.