Phytochemical Composition and Biological Activities of Essential Oils from Pinus nigra J. F. Arnold and Pinus sylvestris L.

This research aimed to examine the chemical composition, as well as the antioxidant, antibacterial, and antibiofilm properties of essential oils (EOs) derived from black pine (Pinus nigra J. F. Arnold) and white pine (Pinus sylvestris L.). The essential oils were extracted using the hydrodistillation method and analyzed using gas chromatography-mass spectrometry (GC-MS). The dominant components identified in the EOs were monoterpenes and sesquiterpenes. The antioxidant capacity was assessed using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method, which revealed that both EOs exhibited moderate antioxidant activity. The antibacterial activity was evaluated against Staphylococcus aureus ATCC 6538 and Extended-Spectrum Beta-lactamase (ESBL) - producing Escherichia coli ATCC 35218, using the agar diffusion method and the microdilution technique. Antibiofilm activity was assessed using the Tissue Culture Plate (TCP) method. The results of the agar diffusion method suggested that P. sylvestris exhibited stronger antibacterial activity compared to P. nigra. This finding aligns with the results of the broth microdilution method, which showed lower minimum inhibitory concentration (MIC) values for the essential oil of P. sylvestris. Staphylococcus aureus investigated in this study formed a moderately adherent biofilm, while ESBL E. coli was identified as strong biofilm former. Tested EOs performed the capacity to change the biofilm-forming category in a species-specific and concentration-dependent manner, with P. nigra EO showing more pronounced antibiofilm effects