EXTRACTION OF ESSENTIAL OILS FROM JUNIPER SPECIES AND STUDY OF THEIR CHEMICAL COMPOSITION (IN THE CLIMATIC CONDITIONS OF UZBEKISTAN)

ABSTRACT

In this article, experimental work was carried out under laboratory conditions at temperatures ranging from 100˚C to 200˚C to extract essential oils from Juniperus communis, which belongs to the Cupressaceae family and grows in the climatic conditions of Uzbekistan. The essential oil yield from J. communis was found to be 2.1% at 187˚C. As the temperature of the working steam increased, the rate of essential oil extraction from the raw material gradually increased, with oil release starting in the range of 150–187˚C. The chromatogram and infrared spectroscopy of the obtained essential oils identified absorption peaks corresponding to the components in its composition.

АННОТАЦИЯ

В данной статье приведены экспериментальные исследования, проведённые в лабораторных условиях при температуре от 100˚C до 200˚C с целью получения эфирных масел из Juniperus communis, относящегося к семейству Cupressaceae и произрастающего в климатических условиях Узбекистана. Выход эфирного масла из J. communis составил 2,1% при температуре 187˚C. По мере повышения температуры рабочего пара скорость выделения эфирного масла из сырья постепенно увеличивалась, причём выделение масла начиналось в интервале температур 150–187˚C. Хроматограмма и инфракрасная спектроскопия полученных эфирных масел выявили пики поглощения, соответствующие компонентам их состава.

Keywords: Juniperus communis, juniper plant, essential oil, terpenes, chromatogram, infrared spectroscopy.

Ключевые слова: Juniperus communis, растение можжевельника, эфирное масло, терпены, хроматограмма, инфракрасная спектроскопия.

Introduction. Essential oils are important natural components that are widely used in the fields of pharmaceuticals, cosmetics, food, chemistry, and perfumery. [1,2]. Today, protecting public health, developing natural sources for medicines, and producing environmentally friendly products are among the most pressing issues. Uzbekistan’s arid climate, abundance of sunny days, and natural resources provide favorable conditions for the successful cultivation of various essential oil plants [3]. However, the quantity and quality of essential oils in plants are strongly influenced by factors such as climate, soil, irrigation, and processing technologies [4].

Materials and Methods. Juniperus communis L. (common juniper) belongs to the Cupressaceae family and is an evergreen, needle-leaved shrub or small tree, with an average height of 1–3 meters (sometimes up to 10 meters). Its leaves are needle-like, pointed, linear, light green on both sides; its fruit—juniper berry (cone)—is round, dark blue-black or purplish, and fragrant [5]. The leaves are sessile, hard, and shaped like a needle. Essential oil from the common juniper, which has three needles arranged in groups on the stem, was obtained by steam distillation, and the effects of temperature and duration on the process were studied [6]. The method of distilling essential oil from plant raw material using water is based on properties such as volatility and insolubility in water. Experimental work was carried out in laboratory conditions at temperatures ranging from 100˚C to 200˚C. The essential oil yield was determined by titration, and the composition of the components was studied using chromatography. Experiments conducted with J. communis leaves showed that the distillation temperature significantly affected the essential oil yield. Subsequently, the plant raw material was treated with water for distillation, which was performed in a distillation apparatus at 178˚C–180˚C in a water bath. Steam generated from the steam generator passed through the plant material, the volatile essential oil condensed in the condenser, and then collected in the receiving vessel.

Results and Discussion.

The distillation results of essential oil obtained by steam distillation at various temperatures using J. communis leaves are shown in fugure 1. Experiments conducted with the leaves demonstrated that the process temperature significantly affected the essential oil yield.

Figure 1. Steam distillation of essential oil from Juniperus communis leaves at different temperatures

As shown in the table, it was found that the essential oil yield depends on the type of raw material and the temperature of the working steam. The obtained data were fully compared with the condition of complete distillation. As the temperature increases, the essential oil yield decreases in this condition (see Figure 1), while other components begin to caramelize, resulting in a sharp increase in the release of monoterpenes. The distillation of essential oil was carried out from both fresh and dried raw materials. At temperatures ranging from 100˚C to 130˚C, the essential oil yield increased, with a slightly higher increase observed in juniper leaves. As the temperature rose (at 180˚C and 200˚C), the essential oil yield decreased, which is explained by the intensified oxidation and polycondensation changes of terpenoids, transforming them into resinous products. The essential oil yield obtained from J. communis was 2.1% at 187˚C. With an increase in the working steam temperature, the rate of essential oil separation from the raw material gradually increased, meaning the oil release started in the range of 150–187˚C.

According to experimental data, complete distillation of the essential oil is achieved in 180 minutes at 100˚C, 120 minutes at 130˚C, 100–110 minutes at 150˚C, and 70–80 minutes at 180˚C. This relationship shows similar parameters in the initial stage and is determined by the steam temperature. Analysis results indicate that the necessary temperature for the essential oil to be released from the raw material ranges between 178˚C and 186˚C, and changes in temperature also affect the rate of oil separation.

As a result of the research, we identified a total of 37 components in the essential oil of J. communis (common juniper). The total mass percentage of these components in the essential oil was 89% (Table 2). The majority of them were terpenic hydrocarbons with low boiling points—monoterpenes (82.3%), which included α-pinene (24.5–32.6%), β-pinene (15.0–20.3%), and α-phellandrene (6.4–8.8%). The share of sesquiterpenes in the essential oil accounted for 0.5% of the total composition (see Table 3.4.2). Among the terpenoid group, alcohols had the largest proportion—3.5%. It was also found that the concentration of nine components in the essential oil exceeded 1%.

Figure 2. Chromatographic analysis of J. Communis

Table 1.

Relative composition of identified components in Juniperus communis essential oil as a percentage of their total, %

The essential oil of common juniper is a light yellow liquid. The amount of essential oil in the needle-like shoots was 0.81 ± 0.04%. Out of 110 compounds detected in the essential oil of common juniper, 39 were identified. The mass fraction of the identified components in the essential oil was 86% (see Table 3.4.1). Among the identified components, monoterpenes accounted for 90.5%, sesquiterpenes for 0.4%, alcohols for 7.5%, and esters for 1.6%. In the essential oil of common juniper, 96 compounds were present at concentrations below 1%, 10 compounds were in the range of 1–5%, and four compounds were found at concentrations above 5%. The highest concentrations were recorded for the following components: α-pinene – 27.2%, β-pinene – 22.4%, 3-carene – 7%, and β-phellandrene – 5.7%.

The obtained essential oils are complex because they contain many terpenes, alcohols, esters, and other components, so their IR spectra are also complex. Below are the most important absorption bands in the wavenumber regions and their corresponding functional groups:

Table 2.

Infrared (IR) absorption spectra of the obtained essential oils

This IR spectrum corresponds to the main components of Juniperus communis essential oil, namely α-Pinene, Sabinene, Myrcene, Limonene — these are monoterpene hydrocarbons that cause strong absorption in the 2850–2950 cm⁻¹ region in the IR spectrum. Additionally, Bornyl acetate or other esters produce a strong C=O peak around 1700 cm⁻¹, and alkenes and cyclic terpenes give C=C peaks around 1650–1600 cm⁻¹.

Figure 3. IR spectra of the essential oil obtained from J. communis

Conclusion. During the extraction of essential oil by steam distillation and hydrodistillation methods, external factors such as temperature (95–105°C), distillation duration (2–3 hours), raw material quantity, and ratio with water (1:3) were identified as the main influencing parameters. Optimization of these parameters increased the essential oil yield up to 1.6–2.3%. Significant variations in essential oil content were observed in local juniper varieties depending on the season. Samples collected in spring and summer showed higher relative amounts of essential oils, with main components such as α-pinene, sabinene, limonene, and β-myrcene identified by chromatographic methods. The chemical composition of essential oils was analyzed using gas chromatography (GC) and infrared spectroscopy (IR), which confirmed significant differences in component composition among juniper samples from different regions. In particular, the content of α-pinene ranged from 35% to 52%, showing variability depending on location and season. The studied juniper essential oils demonstrated high biological activity, with their main components exhibiting antiseptic, antimicrobial, and anti-inflammatory properties. This highlights their promising potential for applications in pharmaceutical and cosmetic industries.

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