Search

The aims of this study were to (1) establish the intrapopulation and seasonal variation of Juniperus excelsа essential oil (EO); (2) compare the J. excelsa concrete and resinoid composition with its EO composition; and (3) investigate the potential herbicidal activity of J. excelsa EO against seeds of Papaver rhoeas L., Consolida orientalis (J.Gay) Schrödinger, Anthemis arvensis L., Avena fatua L., and Agrostemma githago L. Four independent studies were performed to meet these objectives. Twenty-eight individual trees were analyzed from two populations to establish intrapopulation and interpopulation variability of EOs yield and composition. In the seasonal dynamic study of leaf EO, samples from the same three trees and in the same population were collected in January, March, May, July, October, and December and their EO yield and composition determined. The EOs (intrapopulation and seasonal) were extracted by hydrodistillation, while the EO for the herbicidal test was obtained by steam distillation in a semi-commercial (SCom) apparatus. Overall, the EO yield varied significantly from 0.93% to 2.57%. α-Pinene (8.85-35.94%), limonene (11.81-50.08%), and cedrol (3.41-34.29%) were the predominant EO compounds in all samples (intrapopulation variability); however, trans-2,4-decadienol and β-caryophyllene were predominant in some individual trees. Four chemical groups were identified in the samples collected from two natural populations (intrapopulation). This is the first report on the compositions of J. excelsa concrete and resinoid. Cedrol (15.39%), 7-hydroxy-4-methyl-coumarin (17.63%), 1-octacosanol (36.85%), tritriacontane (16.08%), and tiacontanoic acid were the main compounds in the concrete and resinoid. Juniperus excelsa EO suppressed seed germination and seedling growth of P. rhoeas, C. orientalis, A. arvensis, A. fatua, and A. githago, demonstrating its potential to be used for the development of new biopesticides. The highest EO yield with high content of limonene and cedrol was obtained from samples harvested during the winter months (December, January, and March)., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Semerdjieva et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The cuticle is important in the interaction between the plant and its environment, especially in the dry areas. Four species of junipers from the section Sabina wild growing in the Balkans were selected to study leaf wax composition using GC/MS and GC-FID and its surface morphology under SEM to understand the correlation between the distribution and/or habitat of these species and their cuticles. SEM micrographs showed continuous, smooth epicuticular layers with crusts in all species but with a species-specific distribution of different 3D crystalloid types and different cuticle thickness. n-C33 alkane was the most abundant compound, followed by n-C29, n-C31, and n-C35, depending on the species and the site. The average chain length (N) was the lowest in J. phoenicea, but with the greatest dispersion around it. At the same time, the two most continental species (J. foetidissima and J. excelsa) show the N with the lowest dispersion around it. The statistical analyses confirmed the significance of climate on the evolution of the specific epicuticular wax composition in studied junipers., (© 2023 Wiley-VHCA AG, Zurich, Switzerland.)

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.

Juniperus excelsa M. Bieb and J. sabina L. contain essential oil (EO), while J. sabina also contains podophyllotoxin, which is used as a precursor for anti-cancer drugs. Two studies were conducted. The first assessed the variability in the EO profile and podophyllotoxin concentration of the two junipers, depending on the location and tree gender. The main EO constituents of J. excelsa were α-cedrol, α-limonene and α-pinene, while the constituents in J. sabina were sabinene, terpinen-4-ol, myrtenyl acetate and α-cadinol. The podophyllotoxin yield of 18 J. sabina accessions was 0.07-0.32% ( w/w ), but this was not found in any of the J. excelsa accessions. The second study assessed the effect of hydrodistillation (Clevenger apparatus) and steam distillation (in a semi-commercial apparatus) on the EO profile and bioactivity. The extraction type did not significantly alter the EO composition. The EO profiles of the two junipers and their accessions were different and may be of interest to the industry utilizing juniper leaf EO. Breeding and selection programs could be developed with the two junipers (protected species) in order to identify chemotypes with (1) a high EO content and desirable composition, and (2) a high concentration of podophyllotoxin in J. sabina . Such chemotypes could be established as agricultural crops for the commercial production of podophyllotoxin and EO.

The chemical profile and antioxidant capacity of Juniperus virginiana , J. excelsa , and J. sabina essential oil (EO) fractions as a function of time was the subject of this study. The hypothesis was that, capturing EO in sequential timeframes during hydrodistillation would generate fractions containing unique compositions and antioxidant capacity. In J. virginiana , the highest limonene (43%) was found in the 0⁻5 min oil fraction, with safrole (37%) being highest in the 10⁻20 and 20⁻40 min fractions, and elemol (34%) being highest in the 160⁻240 min fraction. In J. excelsa , α-pinene (34-36%) was the highest in the 0⁻5 min fraction and in the control (non-stop 0⁻240 min distillation) oil, limonene (39%) was the highest in the 0⁻10 min fractions and cedrol (50-53%) was the highest in the 40⁻240 min fractions. In J. sabina , sabinene (80%) was highest in the 0⁻3 min fraction. The highest antioxidant capacity of J. virginiana was demonstrated by the 5⁻10 min fraction; the one in J. sabina by the 3⁻10 min fraction; and, the one in J. excelsa , by the control. The kinetics regression models that were developed can predict EO composition of the three juniper species eluted at different timeframes. Various industries could benefit from the results from this study.

Highlights • There are current efforts on develop some junipers as agricultural crops. • J. communis , J. sibirica , and J. pygmaea are taxonomically controversial. • The essential oil of three species was analyzed for chemistry and antimicrobial activity. • Oil composition varied among and within species, depended on plant sex and location. • The results may help in conservation and development of juniper species as crops. Abstract Juniperus communis L. is one of the widest spread species on earth, while J. pygmaea C. Koch. and J. sibirica Burgsd. are taxonomically controversial with some authors and the official Flora of Bulgaria recognizing them as separate species and other authors considering them sub-species of J. communis. There are current efforts on developing J. communis as agricultural crop to provide consistency of supply and quality of juniper essential oil (EO) and juniper galbuli (cones or berries). The objective of the study was to evaluate the chemical profile and antimicrobial activity of the leaf EO of juniper species collected in Bulgaria, Serbia, and Slovakia. The leaf EO content and EO composition varied among species and within species and also depended on the plant sex and location. In J. communis EO from Slovakia and Serbia, the major oil constituent was α-pinene (25.1–27.0 % and 21.8–22.2% respectively). However, sabinene (19.8–27.9%) was the major constituent in J. communis EO from Bulgaria. Monoterpene hydrocarbons (MHs) were the main group of EO constituents in J. communis from Bulgaria (17–22% α-pinene, 20–27% sabinene, and 8.8–11.7% γ-terpinene) and Serbia (25–27% α-pinene, 23–25% sabinene, and 4.9 to 5.3% γ-terpinene). J. communis oils originating from Slovakia showed more similarity to those from Bulgaria. The main group of EO constituents in J. pygmaea belonged to MHs (26–28% α-pinene, 17–19% sabinene, and 4.8–6.1% β-phellandrene). The oxygenated sesquiterpenes (OSs) were the second largest group of components in the EO of J. pygmaea , a noted difference compared with J. communis. The main group of EO constituents of J. sibirica from Bulgaria were MHs (36–44% α-pinene, 10–13% δ -3 carene, and 4.5–12% limonene). Eleven components found in the EO of J. sibirica from Bulgaria were not detected in the EOs of other species. In J. sibirica originating in Serbia, the main group of EO constituents belonged to MHs (∼ 24%, sabinene, ∼ 19% α-pinene, and 6% γ-terpinene). The results support the concept that the three junipers should be considered separate species. The leaf EOs of J. communis , J. sibirica , and J. pygmaea did not exhibit significant antimicrobial activity. The results contribute to further understanding of juniper leaf EO in Eastern Europe and can be used by policymakers and industry in conservation planning and in the development of juniper species as agricultural crops. [ABSTRACT FROM AUTHOR]