Essential oil composition of Pinus heldreichii Christ., P. peuce Griseb., and P. mugo Turra as a function of hydrodistillation time and evaluation of its antimicrobial activity

Pinus heldreichii and P. peuce are Balkan endemics, Tertiary relicts, while Pinus mugo is an edificator in the phytocenoses in the Alpine mountain range. The chemical profile and essential oil (EO) yield and composition of these three species as a function of distillation time (DT) was the subject of this study. The working hypothesis was that EO of P. heldreichii, P. peuce and P. mugo would produce EO with dissimilar composition and antimicrobial activity at different DT. The EO yields in the controls were 0.4% for P. heldreichii, 1.3% for P. peuce and 1.08% for P. mugo. During the first 0–15 min interval of the distillation, up to 70% of the total EO was extracted in P. heldreichii, 53.85% in P. peuce and 54.63% in P. mugo. Overall, the EO of the three species had relatively constant compositional profile at the different DTs, which contradicts the working hypothesis. Most of the quantitative differences in the main components were determined. The EO obtained from 0 to 15 min DT interval had the following major compounds: limonene (76.9%−77.0%) and α-pinene (12.47%−15.54%) in P. heldreichii; α-рinene (34.26–43.75%), limonene (19.2%−22.2%), and β-рinene (9.24%−11.48%) in P. peuce; and α-pinene (16.48%−17.84%), α-phellandrene (23.06–23.76%), and β-phellandrene (28.12%−28.79%) in P. mugo. The obtained results of EO from the three studied species are a prerequisite for obtaining EO with a certain, desired composition while reducing the distillation duration and saving energy and time. The tested EOs demonstrated significant antimicrobial activity against Escherichia coli.