The objective of this study was to assess the biological activity of essential oils (EOs) of four Juniperus species obtained via two different distillation methods and their potential as biopesticides. The studied factors were juniper species (Juniperus communis L., J. oxycedrus L., J. pygmaea C. Koch., and J. sibirica Burgsd), plant sex (male (M) and female (F)), and distillation method (hydrodistillation via a standard Clevenger apparatus (ClevA) and semi-commercial (SCom) steam distillation). The hypothesis was that the EO will have differential antioxidant, antimicrobial, and insecticidal activities as a function of plant species, plant sex, and distillation method. The two distillation methods resulted in similar EO composition within a given species. However, there were differences in the EO content (yield) due to the sex of the plant, and also differences in the proportions of some EO components. The concentration of α-pinene, β-caryophyllene, δ-cadinene and δ-cadinol was dissimilar between the EO of M and F plants within all four species. Additionally, M and F plants of J. pygmaea, and J. sibirica had significantly different concentrations of sabinene within the respective species. The EOs obtained via ClevA extraction showed higher antioxidant capacity within a species compared with those from SCom extraction. All of the tested EOs had significant repellent and insecticidal activity against the two aphid species Rhopalosiphum padi (bird cherry-oat aphid) and Sitobion avenae (English grain aphid) at concentrations of the EO in the solution of 1%, 2.5%, and 5%. The tested EOs demonstrated moderate activity against selected pathogens Fusarium spp., Botrytis cinerea, Colletotrichum spp., Rhizoctonia solani and Cylindrocarpon pauciseptatum. The results demonstrate that the standard ClevA would provide comparable EO content and composition in comparison with SCom steam distillation; however, even slight differences in the EO composition may translate into differential bioactivity.

Hemp (Cannabis sativa L.) is currently one of the most controversial and promising crops. This study compared nine wild hemp (C. sativa spp. spontanea V.) accessions with 13 registered cultivars, eight breeding lines, and one cannabidiol (CBD) hemp strain belonging to C. sativa L. The first three groups had similar main essential oil (EO) constituents, but in different concentrations; the CBD hemp had a different EO profile. The concentration of the four major constituents in the industrial hemp lines and wild hemp accessions varied as follows: β-caryophyllene 11–22% and 15.4–29.6%; α-humulene 4.4–7.6% and 5.3–11.9%; caryophyllene oxide 8.6–13.7% and 0.2–31.2%; and humulene epoxide 2, 2.3–5.6% and 1.2–9.5%, respectively. The concentration of CBD in the EO of wild hemp varied from 6.9 to 52.4% of the total oil while CBD in the EO of the registered cultivars varied from 7.1 to 25%; CBD in the EO of the breeding lines and in the CBD strain varied from 6.4 to 25% and 7.4 to 8.8%, respectively. The concentrations of δ9-tetrahydrocannabinol (THC) in the EO of the three groups of hemp were significantly different, with the highest concentration being 3.5%. The EO of wild hemp had greater antimicrobial activity compared with the EO of registered cultivars. This is the first report to show that significant amounts of CBD could be accumulated in the EO of wild and registered cultivars of hemp following hydro-distillation. The amount of CBD in the EO can be greater than that in the EO of the USA strain used for commercial production of CBD. Furthermore, this is among the first reports that show greater antimicrobial activity of the EO of wild hemp vs. the EO of registered cultivars. The results suggest that wild hemp may offer an excellent opportunity for future breeding and the selection of cultivars with a desirable composition of the EO and possibly CBD-rich EO production.

The hypothesis of this study was that we can modify the essential oil (EO) profile of hemp (Cannabis sativa L.) and obtain fractions with differential composition and antimicrobial activity. Therefore, the objective was to evaluate the effects of grinding of hemp biomass before EO extraction and fractionation during distillation on EO profile and antimicrobial activity. The study generated a several EO fractions with a diversity of chemical profile and antimicrobial activity. The highest concentrations of β-pinene and myrcene in the EO can be obtained in the 5–10 min distillation time (DT) of ground material or in the 80–120 min DT of nonground material. High δ-3-carene and limonene EO can be obtained from 0–5 min DT fraction of nonground material. High eucalyptol EO can be sampled either in the 0–5 min DT of the ground material or in the 80–120 min of nonground material. Overall, the highest concentrations of β-caryophyllene, α-(E)-bergamotene, (Z)-β-farnesene, α-humulene, caryophyllenyl alcohol, germacrene D-4-ol, spathulenol, caryophyllene oxide, humulene epoxide 2, β-bisabolol, α-bisabolol, sesquiterpenes, and cannabidiol (CBD) can be obtained when EO is sampled in the 80–120 min DT and the material is nonground. Monoterpenes in the hemp EO can be increased twofold to 85% by grinding the material prior to distillation and collecting the EO in the first 10 min. However, grinding resulted in a slight but significant decrease in the CBD concentration of the EO. CBD-rich oil can be produced by collecting at 120–180 min DT. Different EO fractions had differential antimicrobial activity. The highest antimicrobial activity of EO fraction was found against Staphylococcus aureus subsp. aureus. THC-free EO can be obtained if the EO distillation is limited to 120 min. The results can be utilized by the hemp processing industry and by companies developing new hemp EO-infused products, including perfumery, cosmetics, dietary supplements, food, and pharmaceutical industries.