Дослідження жирнокислотного складу сировини Cetraria islandica (L.) Ach., заготовленої в Україні

Анотація

Introduction. The study of the component composition of fatty acids in plant raw materials often attracts the attention of scientists, considering the fact that, this group of compounds plays an important role in adapting plants to environmental stress factors and defining their value as food crops and sources of raw materials for industrial use. Modern scientific works are devoted not only to the search for new natural sources of fatty acids, but also to the study of the fatty acids profile and the new potential aspects of the pharmacological activity of plant raw materials, which are already used as medicinal. In recent years, studies of the component composition of fatty acids have been actively conducted not only for higher plants, but also for fungi, algae and lichens, including studies related to their nutritional value and use as functional food products. Fatty acid profiles also have significant importance for lichen studies, because they are used for the taxonomics and the differentiation of their genera. A lot of recent scientific works are devoted to the study of the chemical composition of Iceland moss (Cetraria islandica (L.) Ach.), a member of the Parmeliaceae family, namely such groups of biologically active substances as carbohydrates, compounds of phenolic nature, in particular, lichen acids, and amino acids. Pharmacological studies of C. islandica have demonstrated a wide range of activity, including antibacterial, antiviral, anti-inflammatory, antioxidant, antifungal, anti-ulcer, and immunomodulatory. In the literature sources there are only fragmentary and outdated data regarding the fatty acid composition of C. islandica. Using the method of thin-layer chromatography, dutch scientists have identified in the raw material of C. islandica among others such fatty acids as: palmitic, stearic, oleic, linoleic and linolenic, which are also typical for higher plants. In addition, long-chain fatty acids such as behenic and eicosadienoic were also identified. Therefore, the study of the fatty acid composition of thalli of C. islandica, harvested in Ukraine, is a relevant issue as a part of the comprehensive study of the component composition of biologically active substances of such raw material. The aim of the work was to study the component composition and to determine the quantitative content of fatty acids in thalli of C. islandica, harvested in Ukraine, as a part of the systematic pharmacognostic study of domestic raw material of C. islandica for the elaboration of new substances and medical products on its basis. Materials and methods. For the study, thalli of C. islandica harvested in autumn 2019 in the Rakhiv district of the Zakarpattia region were used. The determination of the component composition of fatty acids in the studied raw material was carried out by the method of gas chromatography with mass spectrometric detection (GC/MS). The chromatographic separation was performed on an Agilent 6890N gas chromatograph with a 5973 inert mass detector (Agilent technologies, USA). A HP-5ms capillary column (30 m×0.25 mm×0.25 μm, Agilent technologies, USA) was used. For the further analysis, methyl esters of fatty acids were obtained. The identification of fatty acid methyl esters was based on their retention times compared to the data of the mass spectral library NIST 02. The quantitative analysis was carried out by the method of internal standards. The undecanoic acid solution was used as an internal standard. Results and discussion. In the raw material of C. islandica, harvested in Ukraine, six fatty acids were identified; among them 3 belonged to saturated. Among the saturated fatty acids arachidic (eicosanoic), pentadecylic (pentadecanoic) and stearic (octadecanoic) acids were found. Among the unsaturated fatty acids, linoleic (octadecadienoic), elaidic and oleic acids were identified. The quantitative content of identified fatty acids differed insignificantly and ranged from 1.57±0.02 mg/g (arachidic acid) to 1.95±0.03 mg/g (linoleic acid). The total content of the sum of fatty acids was 11.10±0.15 mg/g. The content of unsaturated fatty acids was 5.66±0.08 mg/g and slightly exceeded the content of the sum of saturated fatty acids (5.44±0.07 mg/g). The data regarding the quantitative content of saturated arachidic, pentadecylic, stearic and unsaturated linoleic, elaidic and oleic fatty acids in the raw material of C. islandica were presumably given for the first time. Conclusions. For the first time, the fatty acid composition of the raw material of C. islandica, harvested in Ukraine, has been determined. The content of the sum of unsaturated fatty acids (5.66±0.08 mg/g) is comparable to the content of the sum of saturated fatty acids (5.44±0.07 mg/g). Among the saturated stearic acid (1.94±0.03 mg/g) prevailed. Linoleic acid (1.95±0.03 mg/g) predominated among the unsaturated ones.  The results obtained provide an opportunity to deepen knowledge about the component composition of biologically active substances in the raw material of C. islandica, harvested in Ukraine, and will be used for the elaboration of substances and medical products on its basis.

Keywords: Cetraria islandica (L.) Ach. thalli, component composition of fatty acids, GC/MS.