DOI 10.1007/s11094-015-1267-z Pharmaceutical Chemistry Journal, Vol. 49, No. 4, July, 2015 (Russian Original Vol. 49, No. 4, April, 2015)
MEDICINAL PLANTS PHYTOCHEMICAL STUDY OF ESSENTIAL OIL FROM TURKISH OREGANO (ORIGANUM ONITES L.) BY GAS CHROMATOGRAPHY/MASS SPECTROMETRY D. O. Bokov,1,* S. L. Morokhina,1 and D. M. Popov1 Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 49, No. 4, pp. 44 – 61, April, 2015.
Original article submitted July 17, 2013. The chemical composition of essential oil from Turkish oregano growing in southeastern Turkey was studied by gas chromatography/mass spectrometry. More than 70 constituents, of which 57 were identified, were detected. Oregano essential oil from this Turkish region was characterized by a high content of phenolic compounds including thymol and carvacrol (75.72% total) belonging to the menthane biosynthetic type. In addition, essential oil contained linalool (4.42%), p-cymene (3.36%), borneol (2.35%), 4-terpineol (1.74%), a-bisabolene (1.24%), anethole (1.12%), caryophyllene oxide (1.10%), b-caryophyllene (0.68%), b-terpineol (0.55%), spathulenol (0.55%), carvone (0.51%), t-terpinene (0.44%), o-acetylthymol (0.43%), etc. Taking into account the high contents of these compounds in essential oil, Turkish oregano could be recommended for further study as a promising aromatic plant for non-black-earth zones of the RF. Keywords: Turkish oregano (Origanum onites L.), essential oil, thymol, carvacrol.
ent composition is a serious hindrance to standardization, for which only physicochemical parameters become insufficient. Therefore, the International Organization for Standardization (ISO) recommends that modern methodical methods for recording the chromatographic profile be used for quality control [2]. This method of fingerprints allows the studied sample to be clearly characterized and the product quality to be subsequently evaluated [3]. Specifications for EOs are contained in the European Pharmacopoeia (7th Ed.), the British Pharmacopoeia (BP), and the USA pharmacopeia (USP) [4 – 6]. EOs corresponding to pharmacopoeial standards should contain a constant amount of principal BAC to ensure stable therapeutic activity. Chromatographic analysis is the most promising and informative method for studying EOs. Gas chromatography (GC), being an effective separation method, makes it possible to study terpenoids of EOs in the minimum amount of time, with highly accurate identification of compounds in multicomponent mixtures, and with an insignificant analyzed sample volume [7]. The emergence of the mass-spectrometric detector made it possible to identify EO components automatically during the analytical cycle [8]. The fact that a
Essential oils (EOs) that are used as antifungal, antibacterial, and immunostimulating drugs are currently of great interest in Russia. The uncontrolled use of antibacterial chemotherapeutics led to the spread of resistant microorganism strains. It was also noted in clinical practice that such drugs are often the cause of allergic and immunological diseases. Biologically active compounds (BACs) of plant origin, in particular EOs, lack such drawbacks. This fact was explained by the variable chemical compositions of EOs. The fraction of each constituent changes over rather broad limits even for plants belonging to the same species and depends on the habitat, vegetation stage, collection time, raw-material storage times and conditions, and processing technology. The risk of developing resistant pathogenic microorganisms decreases significantly owing to the broad variability of the EO composition. This allows several basic problems related to the selection of effective therapeutic agents to be resolved [1]. However, the variable EO constitu1 *
I. M. Sechenov First Moscow State Medical University, Ul. Trubetskaya 8, Moscow, 119991 Russia. e-mail:
[email protected]
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certain set of constituents (e.g., thymol and carvacrol in oregano) is present simultaneously in EOs due to biogenetic relationships and the occurrence of rather unique biochemical processes in the plants that relate eventually all EO constituents into a single polyfunctional biological cycle should be considered during the identification [9 – 11]. Today, about 2500-3000 EO plant species are known worldwide. About 1100-1300 new species belonging to 77 families were determined during the time of the USSR. The most numerous of these were the families Asteraceae Bercht. & J. Presl, Apiaceae Lindl., and Lamiaceae Lindl. The pathways for using EO plants are extremely varied. From them, EOs are obtained; collections are formulated; and tinctures, decoctions, infusions, and complex phytopreparations are prepared [12]. EOs are widely used to adjust the taste and aroma of drugs. According to experimental results, the majority of EOs exhibit pronounced antimicrobial activity. EOs from plants of the family Lamiaceae exhibit the greatest bactericidal activity [1]. At present, special attention is paid to expanding the production of EOs for the chemical and pharmaceutical industries. Meanwhile, the number of EO plants cultivated in the non-black-earth zones remains exceedingly small. In addition to broadening the areas of these plants in the Russian Federation, the introduction of new species of EO plants mostly from the aforementioned family is also being actively pursued [13 – 15]. The genus Origanum L. (Lamiaceae Lindl. or Labiatae Juss.) has a rather complicated taxonomic structure. Ietswaart gave the most complete classification [16]. Plants of this genus are divided based on morphological features into 10 sections consisting of 42 species or 49 taxons (species, subspecies, varieties). A total of 46 of the 49 taxons have limited distributions within the Mediterranean basin with 21 representatives of the taxon endemic to Turkey. One of the economically important species is O. onites L., which belongs to the section Majorana. The plant originated in western and southern Anatolia and its islands and also grows on islands of the Aegean Sea, Cypress, Crete, Asia Minor, and Syria. O. onites is a perennial herbaceous plant reaching heights of 45 cm with bright-green leaves and a thickly pubescent stem. Flowers of length 5 – 7 mm are gathered into inflorescences. The light-green calix has ovate teeth rarely with fibers. The aureole has two teeth and is white or greenish-white and inconspicuous. The bracts are green. The calix with triangular ovate teeth is densely pubescent. All parts of the plant have a characteristic pleasant aroma [17]. Turkey is the leading global exporter of oregano. Over 80% of all exports come from Turkey [18]. Turkish oregano is the most well-known oregano in Europe. Also, synonymous names include O. smyrnaeum Sibth. & Sm., Majorana onites (L.) Benth = pot marjoram, O. pallidum Pers., Cretan oregano, Crete marjoram, Smyrna marjoram, rigani (Greek), and kekik [19]. The raw-material base includes wild populations and cultivated plantations of total area 6,000 ha in the Aegean and Mediterranean regions; the cities of Denizli,
D. O. Bokov et al.
Aydin, Izmir, Isparta, Burdur; and the provinces of Antalya that are capable of satisfying the growing global demand for O. onites [18]. The very first reliable reports of the medicinal properties of Turkish oregano appeared in pharmaceutical sources that were discovered in the vicinity of Anatolia and were dated from the first century CE. The Greek military doctor Pedani Dioscurides mentioned oregano in the third volume of his great work Materia medica that was focused on plant drugs. The book De opsoniis et condimentis sive de re culinaria libri decem by gastronomist M. Gavius Apicius presented a list dishes frequently consumed by famous Romanians. They could not be prepared without using massive amounts of aromatic herbs, among which thyme, caraway, and oregano were notable [20]. Turkish oregano typically accumulates EO, phenolic compounds (rosmarinic acid, acacetin), flavonoids (cinaroside, luteolin, thymusin, thymonin, cosmosiin, apigenin, etc.), tanning agents, phenolic glycosides, ascorbic acid, glycolipids, phospholipids, and steroids (sitosterol) [17, 18, 21 – 23]. Turkish oregano is currently used internally as a spasmolytic, antimicrobial, expectorant, and carminative and externally as an antiseptic and adhesive [18]. Dried oregano and its extracts are widely used in the food industry as spices [22]. Oregano tea is very popular in Turkey. The aerial part of oregano is steam distilled soon after collecting in order to produce EO on industrial scales. Kekik water, i.e., the aromatic water obtained after removal of EO from the distillate, with a high carvacrol content is used internally for gastrointestinal disorders, reduction of blood cholesterol and glucose levels, and in complex therapy of neoplastic diseases. EO from O. onites was rich in carvacrol and was used as an analgesic for rheumatism [18]. As a rule, Turkish oregano is collected in the morning of a bright sunny day. Runners 15 – 30 cm in length must be cut off with a knife, clippers, or scissors so that as few stems as possible remain in the collected material. The material was dried in attics or outside in the shade and also in special dryers by spreading the raw material as a loose layer (5 – 7 cm) on water-resistant cloth or paper. Under urban conditions, material is dried by hanging bunches of small bundles out of drafts and sunshine. The drying temperature should be kept
