Abstract
(1) Background: The essential oils (EOs) of Sideritis L. have attracted great interest due to their pharmacological activities and potential applications in the cosmetic and perfume industries. The aim of this work was to study the EO chemical composition of three of the most popular, in Greece, mountain tea species: namely, these include Sideritis scardica, Sideritis raeseri, and Sideritis syriaca. (2) Methods: The EOs were obtained from the aerial parts of three Sideritis species that were cultivated in various regions of Greece by hydrodistillation, and the chemical composition was studied by gas chromatography–mass spectrometry (GC-MS) analysis. (3) Results: The EOs of the Sideritis species—S. scardica (SSC1, SSC2, SSC3), S. raeseri (SR1, SR2, SR3), and S. syriaca (SS1, SS2, SS3)—were analyzed by GC-MS, and they showed both qualitatively and quantitatively high variation in their chemical composition. (4) Conclusions: The EOs of S. scardica and S. raeseri from three different regions of Greece, and the S. syriaca from three different localities of Crete Island in Southern Greece, showed high chemical variability. Although 165 different components were found to be present in the nine samples through GC-MS analysis, only 7 (1-octen-3-ol, linalool, trans-pinocarveol, p-mentha-1,5-dien-8-ol, α-terpineol, myrtenol, and verbenone) were common components in the nine EOs, which were identified to be highly variable in different percentages among the samples. Even the EOs of SS1 and SS2, which were cultivated nearby, showed different GC profiles. The composition variation observed might be attributed to differentiations in the soil and climatic conditions.
Keywords: Sideritis, mountain tea, GC-MS analysis, essential oils
1. Introduction
Mountain tea, which belongs to the genus Sideritis spp. (Lamiaceae family), and is also known as Dioscorides siderite, is very popular in the Mediterranean area for its use as an herbal tea. The genus name, which comprises more than 150 species and several subspecies, derives from the Greek word for “iron”, thanks to the plant’s healing action against wounds caused by iron weapons [1]. Siderites, Olympus tea, malotira, good sleeper, Malevos tea, and Taygetus tea, are some of the local names used in Greece to describe mountain tea. In the Mediterranean region and the Balkan Peninsula, many locally endemic species of the genus Sideritis exist. In Greece, apart from the species S. scardica and S. raeseri, which are the most widespread, several species of mountain tea can be found, most of which are collected wild and consumed on a local scale, and they are restricted to narrow mountainous areas or (uniquely to) islands, such as S. syriaca in Crete Island and S. euboea in Evia Island [2].
The therapeutic use of Sideritis species was first mentioned by Dioscorides in his book “De Materia Medica” [3]. Over the years, Sideritis species have found applications in Mediterranean traditional medicine [4] for their anti-inflammatory, antirheumatic, and antimicrobial activities [1,5]. Several investigations into plants belonging to the genus Sideritis L. have revealed a plant-derived source of particular pharmacological and nutritional interest [5].
Essential oils are isolated from aromatic plants using a variety of methods, including hydrodistillation, solvent extraction, cold pressing, and supercritical fluid extraction [6]. EOs find a wide area of applications in the food industry, as they are used as food flavors, natural additives, and in the preservation of foods because of their antioxidant and antimicrobial properties [7]. EOs extracted by several Sideritis species have been studied for their antimicrobial [8,9], antioxidant, anti-inflammatory, and antiproliferative action [9], while their antidiabetic, antiurease, cytoprotective, nematicidal, analgesic, allelopathic, and antirust effects have not been studied sufficiently [10]. A very recent review article summarizes and discusses the chemical composition and pharmacological activities of EOs of the genus Sideritis L. [10].
In that work presented, the pharmacological properties of Sideritis species that have been studied until now have mainly focused on the antibacterial, antifungal, and antioxidant activities. Specifically, the EO of S. raeseri (main compounds: geranyl-p-cymene (25.08%), geranyl-γ-terpinene (15.17%), geranyl-linalool (14.04%), γ-elemene (5.73%)) showed low antibacterial activity, compared to positive controls, gentamycin and ciproxin. Also, the EO of S. scardica (main compounds: hexadecanoic acid (12.92%) and myristicin (5.23%)) showed low activity in Gram-positive and Gram-negative bacteria when compared to the positive control (gentamycin). However, the EO of S. syriaca (main compounds: carvacrol (33.68%), β-(E)-caryophyllene (8.47%), β-phellandrene/limonene (6.84%), and bicyclogermacrene (5.29%)) has shown high antibacterial activity. This EO was shown to be rich in carvacrol (33.68%), which is a widely noted antibacterial agent. The EO of S. raeseri was also studied for its antifungal activity against Saccharomyces cerevisiae and A. niger, and the MIC values were significantly higher than those of the control (voriconazole). In addition, the EO of S. syriaca, which is characterized by the presence of a high carvacrol percentage (33.68%), presented the strongest effect against pathogenic microorganisms. Furthermore, the EO of S. raeseri showed low antioxidant activity when studied by DPPH and ABTS assays [10].
The aim of the present study was to investigate and compare the chemical composition of three of the most popular Sideritis species in Greece: Sideritis scardica, Sideritis raeseri, and Sideritis syriaca, which are mainly cultivated at small scales in Greece and Bulgaria, as previously reported [11], and have not been studied enough until now. According to the existing literature, there is only one reference where an EO of a S. scardica from Greece has been studied, but it originated from a different area of our study: four references where the EOs of S. syriaca have been studied, of which two of them concerned wild samples, and six references where the EOs of S. raeseri have been studied, which three of them concerned cultivated samples from different areas of our study [10]. With our research, we are aiming to reinforce the literature regarding the chemical composition of the EOs from the Sideritis species, which are cultivated in Greece in different geographical areas, such as S. scardica or Olympus tea, which is possibly the most well-known herbal/mountain tea in Greece and the Balkan Peninsula.
2. Materials and Methods
2.1. Chemical and Reagents
Diethyl ether and magnesium sulfate (anhydrous) were purchased from Sigma-Aldrich (Taufkirchen Deutschland and St. Louis, MO, USA, respectively).
2.2. Plant Material
For this study, the aerial parts of three Sideritis species were harvested from different regions of Greece. The first sample of S. scardica (SSC1) was cultivated in the area of Mount Olympus in Central Greece (Olympus tea), while the second sample of S. scardica (SSC2) was cultivated in the area of Mount Mainalo in Peloponnesos; finally, the third sample of S. scardica (SSC3) was cultivated in the area of Kastoria in Northern Greece. The first sample of S. raeseri (SR1) was cultivated in the foothills of Mount Othrys in Central Greece, the second sample of S. raeseri (SR2) was cultivated in the area of Kastoria in Northern Greece, and the third sample of S. raeseri (SR3) was cultivated in the area of Elassona, Larissa, in Central Greece. The three samples of S. syriaca were cultivated in Crete island: the first sample of S. syriaca (SS1) was cultivated in the southern part of the White Mountains (Lefka Ori), the second sample of S. syriaca (SS2) was cultivated in the area of Anopoli Sfakion near to White Mountains (Lefka Ori), and the third sample of S. syriaca (SS3) was cultivated in the area of Omalos Chanion (Figure 1).
Figure 1.
Map of the origin of samples of Sideritis species.
Voucher specimens were deposited (No 012276: SSC1, No 012279: SSC2, No 012293: SSC3, No 012277: SR1, No 012294: SR2, No 012295: SR3, No 012278: SS1, No 012291: SS2, and No 012292: SS3) and maintained at the Herbarium of the Agricultural University of Athens (Table 1).
Table 1.
Geographical origin of Sideritis samples.
| Sample | Species | Geographical Origin | Latitude | Longitude | Elevation (m) |
Voucher Number |
|---|---|---|---|---|---|---|
| SSC1 | Scardica | Mount Olympus, Central Greece |
39°59′ | 22°23′ | 900 | 012276 |
| SSC2 | Scardica | Mount Mainalo, Peloponnesos, Southern Greece |
37°57′ | 22°25′ | 900 | 012279 |
| SSC3 | Scardica | Kastoria, Northern Greece |
40°54′ | 21°34′ | 800 | 012293 |
| SR1 | Raeseri | Mount Othrys, Central Greece |
39°06′ | 22°21′ | 780 | 012277 |
| SR2 | Raeseri | Kastoria, Northern Greece |
40°54′ | 21°34′ | 800 | 012294 |
| SR3 | Raeseri | Elassona, Larissa, Central Greece |
40°02′ | 22°05′ | 625 | 012295 |
| SS1 | Syriaca | White Mountains (Lefka Ori), Crete island, Southern Greece |
35°23′ | 24°08′ | 700 | 012278 |
| SS2 | Syriaca | Anopoli Sfakion, Crete island, Southern Greece |
35°22′ | 24°08′ | 650 | 012291 |
| SS3 | Syriaca | Omalos Chanion, Crete island, Southern Greece |
35°232′ | 23°91′ | 1100 | 012292 |
2.3. Isolation of the Essential Oil
The fresh aerial parts of these plants were subjected to hydrodistillation for 3 h using a Clevenger-type apparatus. The yields of EOs (Table 2) for these 9 samples ranged from 0.01% (v/w) (SS3) to 0.10% (v/w) (SR3). Due to their extremely low oil yield, EOs were obtained by liquid–liquid extraction using diethyl ether. The diethyl ether phase was then concentrated under a gentle flow of nitrogen stream, and the resulting solutions of oils were dried over anhydrous magnesium sulfate and stored in the freezer.
Table 2.
Essential oil yields % (v/w) of Sideritis samples.
| Sample | Oil Yield % (v/w) |
|---|---|
| SSC1 | 0.02 |
| SSC2 | 0.03 |
| SSC3 | 0.05 |
| SR1 | 0.02 |
| SR2 | 0.05 |
| SR3 | 0.10 |
| SS1 | 0.02 |
| SS2 | 0.05 |
| SS3 | 0.01 |
2.4. Gas Chromatography–Mass Spectrometry (GC-MS)
The EOs were analyzed using a gas chromatography instrument (SCION) coupled with a mass spectrometer detector and an autosampler (CP-8400) (Bruker, Carteret (NJ), USA). The capillary column used was OPTIMA-5 MS, 30 m × 0.25 mm, 0.25 μm. Helium (He) was used as the carrier gas, with a flow rate of 1.0 mL/min. The temperature at the injector was 220 °C and at the ionization source was 230 °C. The source was operated with an electric voltage of 70 eV. The analysis program, which had a total duration of 73.33 min, involved a rise in the temperature of the column, which was initially at 60 °C and increased gradually up to 250 °C at a rate of 3 °C/min and at a rate of 5 °C/min up to 300 °C. The volume of the sample to be analyzed was 1 μL.
2.5. Identification of the Components of the Essential Oils
The identification of volatile components of EOs was performed by comparing the mass spectra of the components with those from NIST and Adams mass spectral libraries and by comparing literature and estimated arithmetic (retention) indices that were determined using mixture of homologous series of normal alkanes from C7–C24 in n-hexane under the same conditions.
3. Results
The chemical composition (%) of the EOs of the nine Sideritis samples are summarized in Table 3. In the Sideritis scardica EOs (SSC1 and SSC2), others constituted the main group of components (Figure 2) yielded in a total amount of 45.65% and 52.02%, respectively, while for the essential oil of SSC3, the group of components known as oxygenated monoterpenes was found as the predominant amount in a percentage of 35.46%. In the Sideritis raeseri EOs (SR1, SR2, and SR3), considerable variations were observed (Figure 3). Oxygenated sesquiterpenes constituted the main group of components found in SR1 in a total amount of 35.1%, while in the SR2 and SR3, oxygenated monoterpenes and monoterpene hydrocarbons were estimated in a total amount of 31.91% and 28.12%, respectively. Considerable variations were also observed in the Sideritis syriaca EOs (Figure 4). In the essential oil of SS1, the main group of components was others (49.38%), because of the presence of 1-octen-3-ol (17.90%) and hexanol (16.23%) in a high percentage. In the SS2, oxygenated monoterpenes constituted the main group of components yielded in a total amount of 49.13%, while sesquiterpene hydrocarbons (32.87%) constituted the main group of components found in the SS3.
Table 3.
Chemical composition (%) of the essential oils of Sideritis samples.
| No | Compound | RI Exp a |
RI Lit a |
SSC1 b | SSC2 b | SSC3 b | SR1 b | SR2 b | SR3 b | SS1 b | SS2 b | SS3 b |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | (E)-2-Hexenal | 846 | 846 | - c | 8.75 | - | - | - | - | - | - | - |
| 2 | Hexanol | 860 | 863 | - | 3.59 | 1.89 | - | 1.50 | 0.15 | 16.23 | 0.87 | 9.84 |
| 3 | Heptanal | 897 | 901 | - | - | - | - | - | - | 2.89 | 0.82 | 1.47 |
| 4 | 2,4-(E,E)-Hexadienal | 903 | 907 | 0.57 | 0.30 | - | - | 0.22 | - | - | - | 0.80 |
| 5 | α-Thujene | 926 | 924 | - | - | - | - | 0.20 | 0.75 | 0.89 | - | - |
| 6 | α-Pinene | 933 | 932 | - | 1.12 | 3.86 | 0.14 | 5.33 | 4.46 | 0.40 | 0.53 | 1.62 |
| 7 | Benzaldehyde | 952 | 952 | 1.96 | 0.97 | 2.04 | - | 1.44 | 0.32 | 5.83 | 2.07 | 6.65 |
| 8 | Hexanoic acid | 967 | 967 | - | 0.06 | - | - | - | - | 0.70 | - | - |
| 9 | 1-Octen-3-ol | 974 | 974 | 7.91 | 37.28 | 13.99 | 1.32 | 6.14 | 1.83 | 17.90 | 2.41 | 3.94 |
| 10 | β-Pinene | 976 | 974 | - | - | 1.43 | - | 7.50 | 3.00 | - | - | 1.26 |
| 11 | 5-Hepten-2-one, 6-methyl- | 980 | 981 | - | - | - | - | - | - | - | - | 0.38 |
| 12 | Myrcene | 988 | 988 | - | - | - | - | 0.52 | 1.45 | - | - | - |
| 13 | 3-Octanol | 991 | 988 | - | - | 0.37 | - | - | - | - | - | - |
| 14 | α-Phellandrene | 1004 | 1002 | - | - | - | - | - | 2.90 | - | - | - |
| 15 | (2E,4E)-Heptadienal | 1007 | 1005 | - | 1.07 | 0.21 | - | 0.38 | - | 2.80 | 1.03 | 1.57 |
| 16 | 3-δ-Carene | 1010 | 1008 | - | - | - | - | - | 3.73 | - | 0.38 | 0.30 |
| 17 | α-Terpinene | 1015 | 1014 | - | - | - | - | 0.09 | 1.06 | - | 0.17 | - |
| 18 | p-Cymene | 1022 | 1020 | - | - | - | 0.14 | 0.09 | 2.79 | - | 0.32 | 0.12 |
| 19 | Benzyl alcohol | 1026 | 1026 | - | - | 0.76 | - | - | - | 1.39 | - | - |
| 20 | D-Limonene | 1027 | 1024 | - | - | - | - | 3.32 | 4.44 | - | - | - |
| 21 | β-Phellandrene | 1028 | 1025 | - | - | - | - | - | - | - | 6.64 | 4.29 |
| 22 | Eucalyptol | 1029 | 1026 | - | - | - | - | - | - | 0.84 | - | - |
| 23 | β-Ocimene | 1034 | 1032 | - | - | - | - | - | 1.92 | - | 0.10 | - |
| 24 | Benzene acetaldehyde | 1035 | 1036 | 16.42 | 2.05 | 1.93 | 0.13 | 1.24 | - | 3.58 | 3.16 | 5.15 |
| 25 | (E)-2-Octen-1-al | 1053 | 1049 | - | 0.10 | - | - | - | - | - | 0.18 | - |
| 26 | γ-Terpinene | 1056 | 1054 | - | - | - | - | 0.29 | 1.05 | - | 0.37 | - |
| 27 | Acetophenone | 1061 | 1059 | 0.15 | - | - | - | - | - | 0.48 | - | 0.32 |
| 28 | 2-Methyl-,benzaldehyde | 1061 | - | - | - | - | - | - | - | 0.34 | 0.56 | - |
| 29 | Octanol | 1063 | 1063 | - | - | - | - | 0.29 | - | 1.36 | - | 1.29 |
| 30 | cis-Linalool oxide | 1067 | 1067 | - | - | - | 0.14 | 0.24 | - | 0.37 | 0.29 | 0.28 |
| 31 | Isopinocampheol | 1071 | - | - | - | - | 0.08 | - | - | - | - | - |
| 32 | Tetramethyl-pyrazine | 1081 | 1081 | - | - | - | - | - | - | 0.30 | - | - |
| 33 | trans-Linalool oxide | 1084 | 1084 | 0.21 | - | - | - | - | - | - | - | - |
| 34 | Terpinolene | 1086 | 1086 | - | - | - | - | 0.59 | 0.57 | - | - | - |
| 35 | Linalool | 1096 | 1095 | 1.33 | 4.32 | 1.47 | 1.14 | 1.65 | 0.53 | 4.04 | 1.14 | 2.70 |
| 36 | Nonanal | 1102 | 1100 | - | 0.03 | - | 0.21 | 0.19 | - | - | 1.00 | |
| 37 | Phenylethyl Alcohol | 1110 | 1106 | 5.71 | 0.33 | - | - | - | - | - | - | 0.39 |
| 38 | endo-Fenchol | 1111 | 1114 | - | - | - | - | - | - | 0.12 | - | - |
| 39 | cis-p-Menth-2-en-1-ol | 1119 | 1118 | - | - | - | - | - | - | 0.41 | 1.00 | 0.40 |
| 40 | α-Campholenal | 1123 | 1122 | - | 0.31 | - | 0.24 | 0.11 | 0.14 | 0.17 | 0.13 | 0.13 |
| 41 | Nopinone | 1132 | 1135 | 0.53 | 0.38 | - | 0.10 | 1.92 | 0.15 | 0.48 | - | 0.27 |
| 42 | cis-p-Mentha-1(7),8-dien-2-ol | 1133 | - | - | - | - | - | - | - | - | 0.25 | - |
| 43 | trans-Pinocarveol | 1136 | 1135 | 0.66 | 2.07 | 1.02 | 0.82 | 3.60 | 0.56 | 1.66 | 1.01 | 1.11 |
| 44 | cis-Verbenol | 1142 | 1137 | - | - | 1.29 | 0.12 | 1.52 | 0.28 | 1.00 | 1.42 | 0.20 |
| 45 | trans-Verbenol | 1144 | 1140 | - | 1.36 | - | - | 1.15 | - | 0.97 | - | 0.73 |
| 46 | Sabina ketone | 1151 | 1154 | - | - | - | - | 0.56 | - | - | - | - |
| 47 | Pinocarvone | 1158 | 1160 | - | 0.85 | - | 0.47 | 1.15 | 0.22 | 0.58 | - | 0.46 |
| 48 | p-Mentha-1,5-dien-8-ol | 1167 | 1166 | 2.64 | 4.55 | 1.82 | 0.74 | 2.84 | 0.41 | 1.36 | 1.22 | 0.85 |
| 49 | Terpinen-4-ol | 1174 | 1174 | - | 0.44 | 0.84 | 0.31 | 2.51 | 0.92 | 2.59 | 4.44 | 1.56 |
| 50 | p-Methyl-acetophenone | 1177 | - | - | - | - | - | - | - | 0.28 | - | - |
| 51 | p-Cymen-8-ol | 1183 | 1179 | 0.56 | 0.27 | - | 0.13 | - | - | - | - | - |
| 52 | Cryptone | 1184 | 1183 | - | - | - | - | - | 0.24 | 2.67 | 6.21 | 2.55 |
| 53 | α-Terpineol | 1187 | 1186 | 1.41 | 1.96 | 1.76 | 1.10 | 2.23 | 1.14 | 4.92 | 5.73 | 2.78 |
| 54 | Methyl salicylate | 1188 | 1190 | 0.37 | 0.55 | - | - | - | - | - | - | - |
| 55 | Myrtenol | 1194 | 1194 | 0.48 | 0.19 | 0.52 | 0.52 | 1.37 | 0.29 | 0.59 | 0.15 | 0.41 |
| 56 | Myrtenal | 1195 | 1195 | - | - | 0.39 | - | 2.00 | 0.29 | 0.89 | 0.28 | 0.48 |
| 57 | Verbenone | 1204 | 1204 | 1.55 | 1.12 | 0.42 | 0.16 | 1.08 | 0.20 | 0.58 | 0.60 | 0.24 |
| 58 | Eucarvone | 1206 | - | - | - | - | 0.07 | - | - | - | - | - |
| 59 | trans-Carveol | 1217 | 1215 | 0.37 | - | - | 0.09 | 0.66 | 0.16 | 0.42 | 0.45 | 0.23 |
| 60 | Nerol | 1224 | 1227 | - | - | - | - | - | - | 0.22 | - | - |
| 61 | cis-Carveol | 1226 | 1226 | - | - | - | - | 0.08 | - | - | - | - |
| 62 | cis-3-Hexenyl-α-methylbu-tyrate | 1228 | 1229 | - | - | - | 0.04 | - | - | - | - | - |
| 63 | Pulegone | 1233 | 1233 | - | 1.96 | 0.47 | - | 0.24 | - | 0.53 | - | - |
| 64 | Cumin aldehyde | 1233 | - | - | - | - | - | - | 0.14 | - | 0.65 | 0.38 |
| 65 | Carvone | 1240 | 1239 | - | 0.19 | - | 0.16 | 0.41 | 0.18 | 0.47 | 0.29 | 0.20 |
| 66 | Geraniol | 1251 | 1249 | 1.07 | - | - | 0.12 | 0.35 | - | 0.46 | - | - |
| 67 | trans-2-Decenal | 1258 | - | - | - | - | 0.02 | - | - | - | - | - |
| 68 | Geranial | 1264 | 1264 | - | - | - | 0.01 | - | - | - | - | - |
| 69 | Nonanoic acid | 1275 | 1267 | 3.87 | - | - | 0.66 | 0.22 | - | 0.87 | - | - |
| 70 | Bornyl acetate | 1281 | 1254 | - | - | - | 0.18 | 0.18 | - | - | - | - |
| 71 | Thymol | 1286 | 1289 | 0.56 | - | 1.16 | 0.18 | 0.29 | - | 0.11 | - | - |
| 72 | Carvacrol | 1296 | 1298 | 7.98 | - | 19.91 | 1.54 | 3.88 | 0.22 | 4.52 | 19.75 | 0.19 |
| 73 | 2-Methoxy-4-vinylphenol | 1303 | - | 2.74 | - | - | - | - | - | - | - | - |
| 74 | 2-Methylpropyl ester-Benzoic acid | 1324 | - | - | - | - | 0.03 | - | - | - | - | |
| 75 | δ-Elemene | 1338 | 1335 | - | - | - | 0.40 | - | - | - | - | 0.16 |
| 76 | 4-Methoxy-acetophenone | 1343 | - | - | - | - | - | - | 1.86 | 0.26 | 0.86 | |
| 77 | α-Cubebene | 1344 | 1345 | - | - | - | 0.10 | - | - | - | - | - |
| 78 | Eugenol | 1351 | 1356 | 21.52 | 3.83 | 1.70 | 0.31 | 0.36 | - | 1.30 | - | 0.35 |
| 79 | γ-Nonanolactone | 1354 | - | 0.27 | - | - | - | - | - | - | - | - |
| 80 | Ylangene | 1373 | 1373 | - | - | - | 0.60 | - | - | - | - | - |
| 81 | α-Copaene | 1378 | 1374 | - | - | 0.41 | - | 0.18 | 0.28 | - | 0.12 | 1.42 |
| 82 | (E)-β-Damascenone | 1380 | 1383 | - | - | - | 0.20 | - | - | 0.28 | 0.22 | 0.26 |
| 83 | β-Bourbonene | 1386 | 1387 | - | - | - | 0.12 | 0.11 | - | - | - | - |
| 84 | 4-(2,2-Dimethyl-6-methyle-ne-cyclohexyl)-2-butanone, | 1390 | - | - | - | - | 0.13 | - | - | - | - | - |
| 85 | β-Elemene | 1392 | 1389 | - | - | - | - | 0.22 | - | - | - | 0.43 |
| 86 | 4-Dimethyl-γ-benzenebuta-nal | 1396 | - | - | - | - | 0.24 | - | - | - | - | - |
| 87 | α-Gurjunene | 1404 | 1409 | - | - | - | 0.06 | - | - | - | - | 0.56 |
| 88 | 4-(2,6,6-Trimethyl-1,3-cycl-ohexadien-1-yl)-2-butanone | 1409 | - | - | - | - | 0.30 | - | - | - | - | - |
| 89 | α-Cedrene | 1415 | 1410 | - | - | - | - | - | - | - | - | 0.14 |
| 90 | (E)-Caryophyllene | 1421 | 1417 | - | - | 3.40 | 4.03 | 4.13 | 0.91 | 0.33 | 9.09 | 10.18 |
| 91 | β-Copaene | 1426 | 1430 | - | - | - | 0.07 | - | - | - | - | - |
| 92 | α-Bergamotene | 1430 | 1432 | - | - | - | 0.03 | - | - | - | - | - |
| 93 | 3-Methyl,-1-Butanol, benzoate | 1433 | - | - | - | - | 0.20 | - | - | - | - | - |
| 94 | (Z)-β-Famesene | 1437 | 1440 | - | - | - | 0.04 | - | - | - | - | - |
| 95 | cis-Muurola-3,5-diene | 1445 | 1448 | - | - | - | 0.34 | - | 0.16 | - | - | - |
| 96 | (E)-β-Farnesene | 1454 | 1454 | - | - | 1.34 | 0.56 | 1.29 | 0.43 | - | 1.20 | 1.26 |
| 97 | Alloaromadendrene | 1455 | 1458 | - | - | - | 0.09 | - | - | - | - | - |
| 98 | 2,6,10-Trimethyltridecane | 1461 | - | - | - | - | 0.08 | - | - | - | - | - |
| 99 | epi-β-Caryophyllene | 1463 | 1464 | - | - | - | - | - | 0.13 | - | - | - |
| 100 | α-Acoradiene | 1466 | 1464 | - | - | - | - | - | - | - | - | 0.60 |
| 101 | trans-Cadina-1(6),4-diene | 1468 | - | - | - | - | 0.15 | - | - | - | - | - |
| 102 | Pentyl benzoate | 1471 | 1476 | - | - | - | 0.12 | - | - | - | - | - |
| 103 | γ-Curcumene | 1479 | 1479 | - | - | - | - | - | - | - | - | 1.62 |
| 104 | Phenyl ethyl 2-methylbutanoate | 1480 | 1486 | - | - | - | 0.06 | - | - | - | - | - |
| 105 | D-Germacrene | 1482 | 1484 | - | 0.87 | 3.80 | 1.10 | 5.25 | 0.39 | - | 3.41 | 7.22 |
| 106 | γ-Amorphene | 1487 | 1495 | - | - | - | 0.47 | - | - | - | - | - |
| 107 | α-Zingiberene | 1494 | 1493 | - | - | - | - | - | - | - | - | 2.51 |
| 108 | α-Muurolene | 1494 | 1500 | - | - | - | 0.01 | - | - | - | - | - |
| 109 | Bicyclogermacrene | 1497 | 1500 | - | - | 3.33 | 3.20 | 3.17 | 5.81 | - | - | 2.66 |
| 110 | β-Bisabolene | 1505 | 1505 | - | - | - | 0.74 | 0.53 | 0.98 | - | - | - |
| 111 | β-Curcumene | 1511 | 1514 | - | - | - | - | - | - | - | - | 1.20 |
| 112 | Cubebol | 1515 | 1514 | - | - | - | - | - | 0.09 | - | - | - |
| 113 | trans-Calamenene | 1522 | 1521 | - | - | - | 0.65 | - | - | - | - | - |
| 114 | δ-Cadinene | 1523 | 1522 | - | - | - | 0.94 | 0.45 | - | - | - | 2.91 |
| 115 | trans-Cadina-1,4-diene | 1528 | - | - | - | - | 0.72 | - | 0.42 | - | - | - |
| 116 | α-Calacorene | 1536 | 1544 | - | - | - | 0.37 | - | - | - | - | - |
| 117 | β-Calacorene | 1556 | - | - | - | - | 0.08 | - | - | - | - | - |
| 118 | trans-Nerolidol | 1560 | 1561 | - | - | - | 0.09 | - | 0.14 | - | - | - |
| 119 | (Z)-3-Hexen-1-ol, benzoate | 1568 | - | - | - | - | 0.58 | - | 0.44 | - | - | - |
| 120 | Spathulenol | 1578 | 1577 | - | - | 1.02 | 6.46 | 0.81 | 5.03 | 0.33 | 1.12 | 0.91 |
| 121 | Caryophyllene oxide | 1583 | 1582 | - | - | 1.17 | 2.92 | 0.77 | 1.11 | 0.37 | 4.21 | 1.37 |
| 122 | Globulol | 1590 | 1590 | - | - | - | 0.46 | - | - | - | - | - |
| 123 | Viridiflorol | 1592 | 1592 | - | - | - | 0.97 | - | - | - | - | - |
| 124 | Rosifoliol | 1601 | 1600 | - | - | - | 0.11 | - | - | - | - | - |
| 125 | Humulene epoxide II | 1604 | 1608 | - | - | - | 0.52 | - | - | - | 0.50 | - |
| 126 | Isospathulenol | 1628 | - | - | - | - | 0.35 | - | - | - | - | - |
| 127 | Caryophylladienol II | 1634 | - | - | - | - | 0.21 | - | - | - | 0.48 | - |
| 128 | tau.-Muurolol | 1639 | 1640 | - | - | 1.20 | 2.02 | 0.09 | - | - | - | - |
| 129 | Bisabolol oxide II | 1650 | - | - | - | - | 0.51 | - | 0.41 | - | - | - |
| 130 | α-Cadinol | 1653 | 1652 | - | - | - | - | 0.10 | - | - | - | - |
| 131 | (Z,Z)-1,8,11-Heptadecatrie-ne | 1659 | - | - | - | - | 0.24 | - | - | - | - | - |
| 132 | (Z,Z,Z)-,1,8,11,14-Heptade-catetraene | 1663 | - | - | - | - | 0.28 | - | - | - | - | - |
| 133 | Valeranone | 1668 | 1674 | - | - | - | 1.82 | - | 0.65 | - | - | - |
| 134 | Aromadendrene oxide-(1) | 1671 | - | - | - | - | 0.47 | - | - | - | - | - |
| 135 | α-Bisabolol | 1683 | 1683 | - | - | - | 3.24 | 0.21 | 4.56 | - | - | - |
| 136 | Pentadecanal | 1712 | - | - | - | - | 0.16 | - | - | - | - | - |
| 137 | trans-Nuciferol | 1718 | 1713 | - | - | - | 0.11 | - | - | - | - | - |
| 138 | Benzyl benzoate | 1758 | 1759 | 1.31 | - | - | 0.45 | 0.84 | 0.26 | 0.16 | 0.46 | - |
| 139 | Tetradecanoic acid | 1761 | - | - | - | - | 0.10 | - | - | - | - | - |
| 140 | 6,10,14-Trimethyl-2-Pentadecanone | 1838 | - | - | - | - | 0.55 | 0.19 | - | - | - | - |
| 141 | Geranyl-α-terpinene d | 1845 | - | - | - | - | 0.58 | - | - | - | - | - |
| 142 | Benzyl salicylate | 1859 | 1864 | - | - | - | 0.05 | - | - | - | - | - |
| 143 | Geranyl-α-terpinene d | 1863 | - | - | - | - | 0.23 | - | - | - | - | - |
| 144 | (E,E)-7,11,15-Trimethyl-3-methylene-hexadeca-1,6,10,14-tetraene | 1902 | - | - | - | - | 0.40 | - | - | - | - | - |
| 145 | Geranyl-α-terpinene d | 1910 | - | - | - | - | 1.52 | - | - | - | - | - |
| 146 | Geranyl-α-terpinene d | 1918 | - | - | - | - | 0.30 | - | - | - | - | - |
| 147 | Cembrene | 1922 | 1937 | - | - | - | - | - | 1.39 | - | - | - |
| 148 | Isopimara-9(11),15-diene | 1926 | - | - | - | - | 0.17 | - | - | - | - | - |
| 149 | Pimaradiene | 1936 | - | - | - | - | 0.85 | - | - | - | - | - |
| 150 | Geranyl-p-cymene | 1952 | - | - | 1.15 | 1.88 | 3.60 | 0.20 | 3.13 | - | 0.21 | 0.44 |
| 151 | Sandaracopimaradiene | 1955 | 1968 | - | - | - | 0.17 | - | - | - | - | - |
| 152 | Geranyl-α-terpinene e | 1960 | - | - | - | - | 4.58 | - | - | - | - | - |
| 153 | Hexadecanoic acid | 1962 | - | - | - | 4.54 | 3.10 | 4.16 | 1.96 | - | 1.03 | - |
| 154 | Geranyl-α-terpinene e | 1968 | - | - | - | - | - | - | 5.84 | - | - | - |
| 155 | (Z,Z)-Geranyl linalool | 1977 | - | - | - | - | 1.75 | - | - | - | - | - |
| 156 | Kaur-15-ene | 1987 | 1997 | - | - | - | 1.13 | 0.20 | 0.20 | - | - | - |
| 157 | (E,Z)-Geranyl linalool | 1990 | 1987 | - | - | - | 0.77 | - | - | - | - | - |
| 158 | 13-epi-Manoyl oxide | 2004 | - | - | - | - | 1.20 | - | - | - | - | - |
| 159 | (E,E)-Geranyl linalool | 2018 | 2026 | - | - | - | 0.14 | - | - | - | - | |
| 160 | (Z)-9-Octadecen-1-ol | 2059 | - | - | - | - | 12.00 | 5.13 | 3.23 | - | - | - |
| 161 | (E)-9-Octadecen-1-ol | 2069 | - | - | 3.04 | - | - | - | - | - | - | - |
| 162 | 1-Heneicosene | 2088 | 2100 | - | - | - | 0.36 | - | - | - | - | - |
| 163 | 5-(7a-Isopropenyl-4,5-dimethyl-octahydroinden-4-yl)-3-methyl-pent-2-en-1-ol | 2094 | - | - | - | - | 1.01 | - | - | - | - | - |
| 164 | Linoleic acid | 2131 | 2132 | - | - | 2.11 | - | 2.23 | 1.80 | - | - | - |
| 165 | Cembrenol | 2165 | - | - | - | - | - | - | 1.29 | - | - | - |
| Monoterpene hydrocarbons (%) | - | 1.12 | 5.29 | 0.28 | 17.93 | 28.12 | 1.29 | 8.51 | 7.59 | |||
| Oxygenated monoterpenes (%) | 36.5 | 26.86 | 35.46 | 9.33 | 31.91 | 6.26 | 39.98 | 49.13 | 24.91 | |||
| Sesquiterpene hydrocarbons (%) | - | 0.87 | 12.28 | 15.47 | 15.33 | 9.51 | 0.33 | 13.82 | 32.87 | |||
| Oxygenated sesquiterpenes (%) | - | 3.04 | 3.39 | 35.1 | 8.14 | 15.92 | 0.86 | 6.77 | 2.28 | |||
| Diterpenes (%) | - | 1.15 | 1.88 | 18.76 | 0.40 | 11.85 | - | 0.21 | 0.44 | |||
| Others (%) | 45.65 | 52.02 | 25.15 | 5.21 | 16.29 | 6.06 | 49.38 | 8.49 | 25.51 | |||
| Total intedified (%) | 82.15 | 85.06 | 83.45 | 84.15 | 90 | 77.72 | 91.84 | 86.93 | 93.6 |
a RIexp: experimental retention index calculated against C7-C24 n-alkanes on the OPTIMA-5MS column; RIlit: literature retention index [12]. b SSC1: S. scardica from Olympus; SSC2: S. scardica from Mainalo; SSC3: S. scardica from Kastoria; SR1: S. raeseri from Othrys; SR2: S. raeseri from Kastoria; SR3: S. raeseri from Elassona; SS1: S. syriaca from Lefka Ori; SS2: S. syriaca from Anopoli Sfakion; SS3: S. syriaca from Omalos. c not identified. d correct isomer did not identify. e correct isomer did not identify.
Figure 2.
Group components (%) of Sideritis scardica EOs.
Figure 3.
Group components (%) of Sideritis raeseri EOs.
Figure 4.
Group components (%) of Sideritis syriaca EOs.
In the EOs of SSC1 (Table 3), 25 components were estimated, among which eugenol (21.52%) was the predominant component found, followed by benzene acetaldehyde (16.42%). In the EO of SSC2, 30 components were identified, and the major one was 1-octen-3-ol (37.28%). A total of 32 components were estimated in the EO of SSC3, with carvacrol (19.91%) and 1-octen-3-ol (13.99%) being the principal components.
A total amount of 106 components were observed in the EO of SR1, and (Z)-9-octadecen-1-ol (12.00%) was found to be the predominant component. The chemical composition of SR2 yielded 62 components, with β-pinene (7.50%), 1-octen-3-ol (6.14%) and α-pinene (5.33%) possessing higher percentages among the others. In the essential oil of SR3, 59 compounds were identified, and geranyl-α-terpinene (5.84%) and bicyclogermacrene (5.82%) were present at almost equal percentages.
The chemical composition of the essential oil of SS1 consisted of 48 compounds, where the principal compounds were 1-octen-3-ol (17.90%) and hexanol (16.23%). In the EO of SS2, 46 compounds were identified, and carvacrol (19.75%) was the predominant one. In addition, the essential oil of SS3 yielded 57 components, with (E)-caryophyllene (10.18%) and hexanol (9.84%) being yielded as the predominant components.
Τhe chemical variation and relationship between the Sideritis species are presented in the dendrogram (Figure 5). As can be observed, based on their chemical composition the samples were initially divided into two groups. The 1st group included the sample SR1, and the 2nd group included all the other samples (SSC1, SSC2, SSC3, SR2, SR3, SS1, SS2, and SS3). Then, the samples of the 2nd group were divided into subgroups; the 1st subgroup had only one sample—SR3—and 2nd subgroup included the rest of the other samples (SSC1, SSC2, SSC3, SR2, SS1, SS2, and SS3).
Figure 5.
Dendrogram of the chemical variations and relationships between the Sideritis species (Statistical analysis was conducted through the package Statgraphics, which was performed using Word’s method).
In this second subgroup, the samples were separated into smaller subgroups: one subgroup (3rd subgroup) consisted of the samples SS1, SS2, and SS3, and another subgroup included the samples SR2, SSC1, SSC2, and SSC3 (4th subgroup). The 3rd subgroup samples were also divided into smaller subgroups: the 5th subgroup included SS1 and SS2, and the 6th subgroup included SS3; the 4th subgroup samples were divided into the 7th subgroup—SR2—while the 8th subgroup included SSC1, SSC2, and SSC3. Finally, the 8th subgroup samples were divided into a 9th subgroup—including SSC1—and a 10th subgroup—including SSC2, SSC3.
According to these results, the EO of the SR1 was differentiated due to its chemical composition from the rest of the eight EOs. Both of the other two EOs of the S. raeseri samples were quite different from the rest. The EOs of S. syriaca (SS1, SS2, and SS3) and S. scardica (SSC1, SSC2, and SSC3), showed more similar chemical composition, especially the EOs of SS1 and SS2, as well as SSC2 and SSC3.
In the nine samples studied, 165 different compounds were found in total. However, only seven of them were identified to be present in all of the nine samples. Figure 6 depicts the contents of the seven common components, namely, 1-octen-3-ol, linalool, trans-pinocarveol, p-mentha-1,5-dien-8-ol, α-terpineol, myrtenol, and verbenone. In five out of the nine samples, 1-octen-3-ol was estimated as the most common component (>6%) (Figure 6A). All of the rest of the common components (linalool, trans-pinocarveol, p-mentha-1,5-dien-8-ol, α-terpineol, myrtenol, and verbenone) were found at percentages that were lower than 6% (Figure 6A,B).
Figure 6.
Variation of the seven components in the nine EOs. (subfigure (A) 1-octen-3-ol, linalool, trans-pinocarveol; subfigure (B) p-mentha-1,5-dien-8-ol, α-terpineol, myrtenol, and verbenone). SSC1: S. scardica from Olympus; SSC2: S. scardica from Mainalo; SSC3: S. scardica from Kastoria; SR1: S. raeseri from Othrys; SR2: S. raeseri from Kastoria; SR3: S. raeseri from Elassona; SS1: S. syriaca from Lefka Ori; SS2: S. syriaca from Anopoli Sfakion; SS3: S. syriaca from Omalos. Graphs were created using GraphPad Prism 9.2.0.
4. Discussion
4.1. Sideritis scardica
The EOs of the S. scardica from three different regions of Greece (Central—SSC1, Southern—SSC2, and Northern—SSC3) showed variable chemical composition. The common components of these three EOs were benzaldehyde; 1-octen-3-ol; benzene acetaldehyde; linalool; p-mentha-1,5-dien-8-ol; trans-pinocarveol; α-terpineol; myrtenol; verbenone; and eugenol.
Kouklina et al. have studied EOs of S. scardica from two different locations in Greece and noticed the presence of α-pinene (8.20%, 17.80%), β-pinene (12.80, 13.10%), bicyclogermacrene (6.6%, 7.1%), and D-germacrene (6.60%, 2.20%) [13], which were also identified in our samples: α-pinene (1.12% in the SSC2 and 3.86% in the SSC3), β-pinene (1.43% in the SSC3), bicyclogermacrene (3.33% in the SSC3), D-germacrene (0.87% in the SSC2 and 3.80% in the SSC3). The presence of α-pinene (4.40–25.1%) and β-pinene (2.80–18.00%) were also observed in another study of the EOs of six populations of S. scardica that originated from Bulgaria [14]. The major component of the essential oil of SSC2 was 1-octen-3-ol (37.28%). This component was also identified in the EOs of the SSC1 and SSC3 in a percentage of 7.91% and 13.99%, respectively. These results are in accordance with a previous study, which reported the presence of 1-octen-3-ol in a range of 6.20–29.8% [15]. In addition, Trendafilova et al. reported the presence of 1-octen-3-ol (2.3–8%) in the EOs of S. scardica that originated from Bulgaria [14].
4.2. Sideritis raeseri
The EOs of the S. raeseri from three different regions of Greece (Central—SR1 and SR3 and Northern—SR2) showed different chemical composition. The common components detected in these three EOs were α-pinene; 1-octen-3-ol; linalool; nopinone; trans-pinocarveol; cis-verbenol; pinocarvone; terpinen-4-ol; α-terpineol; myrtenol; verbenone; trans-carveol; carvone; carvacrol; (E)-caryophyllene; (E)-β-farnesene; D-germacrene; bicyclogermacrene; spathulenol; caryohyllene oxide; α-bisabolol; benzyl benzoate; geranyl-p-cymene; hexadecanoic acid; and (Z)-9-Octadecen-1-ol.
Previous studies have reported the presence of α-pinene and β-pinene [8,14], which were also identified in our EOs: α-pinene (0.14% in the SR1, 5.33% in the SR2, and 4.46% in the SR3), β-pinene (7.50% in the SR2 and 3.00% in the SR3). In our samples, (Z)-9-octadecen-1-ol was also identified in a percentage of 12.00% in the SR1, 5.13% in the SR2, and 3.23% in the SR3, and bicyclogermacrene was found in a percentage of 3.20% in the SR1, 3.17% in the SR2, and 5.81% in the SR3. Kouklina et al. analyzed the EOs of the S. raeseri from two different localities of Greece and identified (Z)-9-octadecen-1-ol, (12.4% in one sample) and bicyclogermacrene (11.20% and 4.60%, respectively) [13]. In addition, in our samples, spathulenol was identified in a percentage of 6.46% in the SR1, 0.81% in the SR2, and 5.03% in the SR3. Pljevljakušic et al. also uncovered, the presence of spanthulenol (5.00–15.00%), in the aerial parts of four samples (four different stages of flowering) of S. raeseri, which were cultivated in Serbia [16].
4.3. Sideritis syriaca
The EOs of the S. syriaca from three different localities of Crete Island (Southern Greece—SS1, SS2, and SS3) presented variable chemical composition. However, 25 components were identified in all of the three samples: hexanol; benzaldehyde; 1-octen-3-ol; (2E,4E)-heptadienal; benzeneacetaldeyde; cis-linalool oxide; linalool; cis-p-menth-2-en-1-ol; α-campholenal; trans-pinocarveol; p-mentha-1,5-dien-8-ol; terpinen-4-ol; cryptone; α-terpineol; myrtenol; myrtenal; verbenone; trans-carveol; carvone; carvacrol; 4-methoxy-acetophenone; (E)-β-damascenone; (E)-caryophyllene; spathulenol; and caryophyllene oxide.
Aligiannis et al. reported the presence of 1-octen-3-ol in the essential oil of S. syriaca in a percentage of 2.27% [8]. In the essential oil of the SS1, 1-octen-3-ol was the main compound, identified in a percentage of 17.90%, and in the EOs of the SS2 and SS3, it was identified in a lower percentage (2.41% and 3.94%, respectively). Furthermore, Aligiannis et al. identified carvacrol in a percentage of 33.68% [8]. In the EO of the SS2, carvacrol was the major compound (19.75%), and in the EOs of the SS1 and SS3, it was identified in a percentage of 4.52% and 0.19%, respectively. In addition, in a previous study in the EO of the S. syriaca from Bulgaria, the presence of α-pinene, β-pinene, bicyclogermacrene, and D-germacrene (18.2%, 3.00%, 3.30%, 4.80%, respectively) was reported [17]. These components were also identified in the EOs of our samples: α-pinene was identified in the SS1 in a proportion of 0.40%, 0.53% in the SS2, and 1.62% in the SS3; β-pinene was identified in a proportion of 1.26% in the SS3; bicyclogermacrene was identified in a proportion of 2.66% in the SS3; and D-germacrene was identified in the EOs of the SS2—3.41%—and SS3—7.22%. According to Tirillini et al. [18], the major component of the S. syriaca, collected from Central Italy, was hexadecanoic acid (31.10%), which was also identified in the EO of the SS2 (1.03%). In addition, caryophyllene oxide (4.00%) was reported, which was also determined in the EOs of our samples: SS1 contained 0.37%, SS2 contained 4.21%, and SS3 contained 1.37%. Finally, Kouklina et al. reported in the EO of S. syriaca the presence of β-phellandrene (18.5%), kaur-15-ene (17.3%), hexadecanoic acid (5.9%), α-bisabolol (4.8%), and α-pinene (4.6%) [11]. In our samples, we identified α-pinene, (0.40% in the SS1, 0.53% in the SS2, and 1.62% in the SS3), β-phellandrene (SS2: 6.64% in the SS2 and 4.29% in the SS3), and hexadecanoic acid (1.03% in the SS2).
5. Conclusions
The EOs of three Sideritis species cultivated in different areas in Greece, namely, S. scardica (SSC1, SSC2, and SSC3), S. raeseri (SR1, SR2, and SR3), and S. syriaca (SS1, SS2, and SS3), were analyzed by GC-MS analysis and showed considerably different variability in their chemical composition. Comparing their contents, 1-octen-3-ol, linalool, trans-pinocarveol, p-mentha-1,5-dien-8-ol, α-terpineol, myrtenol, and verbenone were revealed as the common constituents in the nine EOs; however, they were estimated in different percentages among the samples.
Furthermore, it was found that the EOs of the S. scardica and S. raeseri from three different regions of Greece and the S. syriaca from three different localities of Crete Island, in Southern Greece, yielded different major components.
The essential oil’s chemical variability in relation to the examined plant species was presented using a dendrogram dividing the samples into two main groups and of one group to six subgroups. Among the same species of different geographical origins, the observed qualitative and quantitative differences can be attributed to abiotic factors such as soil, temperature, humidity, rainfall, and altitude, which influence the biosynthetic pathways of certain essential oil constituents.
The present work presents new data for the EOs’ chemical composition of the cultivated S. scardica, S. raeseri, and S. syriaca of different geographical origins in Greece, which therefore contribute to the existing literature.
Author Contributions
Conceptualization, E.H.K. and P.A.T.; methodology, E.H.K.; software, E.H.K. and P.A.T.; validation, E.H.K., D.D., C.D.K., E.S., M.G.K. and P.A.T.; formal analysis, E.H.K.; investigation, E.H.K.; resources, E.H.K., D.D., C.D.K., E.S., M.G.K. and P.A.T.; data curation, E.H.K. and P.A.T.; writing—original draft preparation, E.H.K., D.D. and M.G.K.; writing—review and editing, E.H.K., D.D., M.G.K. and P.A.T.; visualization, E.H.K. and P.A.T.; supervision, E.H.K. and P.A.T.; project administration, E.H.K. and P.A.T. All authors have read and agreed to the published version of the manuscript.
Data Availability Statement
The data presented in this study are available upon request from the corresponding author.
Conflicts of Interest
The authors declare no conflict of interest.
Funding Statement
This research received no external funding.
Footnotes
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.
References
- 1.González-Burgos E., Carretero M., Gómez-Serranillos M.P. Sideritis spp.: Uses, chemical composition and pharmacological activities—A review. J. Ethnopharmacol. 2011;135:209–225. doi: 10.1016/j.jep.2011.03.014. [DOI] [PubMed] [Google Scholar]
- 2.Stefanaki A., Van Andel T. In: Mediterranean Aromatic Herbs and Their Culinary Use. Aromatic Herbs in Food: Bioactive Compounds, Processing, and Applications. Galanakis C.M., editor. Volume 3. Elsevier; Amsterdam, The Netherlands: 2021. pp. 93–121. [Google Scholar]
- 3.Font Quer P. Plantas Medicinales. Ediciones Peninsula; Barcelona, Spain: 2000. El Dioscorides Renovado. [Google Scholar]
- 4.Todorova M., Trendafilova A. Sideritis scardica Griseb., an endemic species of Balkan peninsula: Traditional uses, cultivation, chemical composition, biological activity. J. Ethnopharmacol. 2014;152:256–265. doi: 10.1016/j.jep.2014.01.022. [DOI] [PubMed] [Google Scholar]
- 5.Tadic V., Jeremic I., Dobric S., Isakovic A., Markovi´c I., Trajkovic V., Bojovic D., Arsic I. Anti-inflammatory, gastroprotective, and cytotoxic Effects of Sideritis scardica extracts. Planta Med. 2012;78:415–427. doi: 10.1055/s-0031-1298172. [DOI] [PubMed] [Google Scholar]
- 6.El-Molla M.M., El-Ghorab A.H. Extraction of eco-friendly essential oils and their utilization in finishing polyester fabrics for fragrant and medical textiles. J. Eng. Fiber Fabr. 2022;17:15589250221104475. doi: 10.1177/15589250221104475. [DOI] [Google Scholar]
- 7.Božovića M., Garzoli S., Navarra A., Garzoli S., Pepi F., Ragno R. Essential oils extraction: A 24-hour steam distillation systematic methodology. Nat. Prod. Res. 2017;31:2387–2396. doi: 10.1080/14786419.2017.1309534. [DOI] [PubMed] [Google Scholar]
- 8.Aligiannis N., Kalpoutzakis E., Chinou I.B., Mitakou S., Gikas E., Tsarbopoulos A. Composition and antimicrobial activity of the essential oils of five taxa of Sideritis from Greece. J. Agric. Food Chem. 2001;49:811–815. doi: 10.1021/jf001018w. [DOI] [PubMed] [Google Scholar]
- 9.Mitropoulou M., Sidira M., Skitsa M., Tsochantaridis I., Pappa A., Dimtsoulidis C., Proestos C., Kourkoutas Y. Assessment of the antimicrobial, antioxidant, and antiproliferative potential of Sideritis raeseri subps. raeseri essential oil. Foods. 2020;9:860. doi: 10.3390/foods9070860. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Chrysargyris A., Tomou E.-M., Goula K., Dimakopoulou K., Tzortzakis N., Skaltsa H. Sideritis L. essential oils: A systematic review. Phytochemistry. 2023;209:113607. doi: 10.1016/j.phytochem.2023.113607. [DOI] [PubMed] [Google Scholar]
- 11.Kloukina C., Tomou E.-M., Krigas N., Sarropoulou V., Madesis P., Maloupa E., Sklatsa H. Non-polar secondary metabolites and essential oil of ex situ propagated and cultivated Sideritis syriaca L. subsp. syriaca (Lamiaceae) with consolidated identity (DNA Barcoding): Towards a potential new industrial crop. Ind. Crops Prod. 2020;158:112957. [Google Scholar]
- 12.Adams R.P. Identification of Essential Oil Components by Gas Chromatography, Mass Spectrometry. 4.1th ed. Allured Publishing Corporation; Carol Stream, IL, USA: 2017. 804p [Google Scholar]
- 13.Kloukina C., Tomou E.M., Skaltsa H. Essential oil composition of two Greek cultivated Sideritis spp. Nat. Volatiles Essent. Oils. 2019;6:16–23. [Google Scholar]
- 14.Trendafilova A.B., Todorova M.N., Evstatieva L.N., Antonova D.V. Variability in the essential-oil composition of Sideritis scardica Griseb. from native Bulgarian populations. Chem. Biodivers. 2013;10:484–492. doi: 10.1002/cbdv.201200282. [DOI] [PubMed] [Google Scholar]
- 15.Qazimi B., Stefkov G., Karapandzova M., Cvetkovikj I., Kulevanova S. Aroma compounds of mountain tea (Sideritis scardica and S. raeseri) from western balkan. Nat. Prod. Commun. 2014;9:1369–1372. doi: 10.1177/1934578X1400900937. [DOI] [PubMed] [Google Scholar]
- 16.Pljevljakušić D., Šavikin K., Janković T., Zdunić G., Ristić M., Godjevac D., Konić-Ristić A. Chemical properties of the cultivated Sideritis raeseri Boiss. & Heldr. subsp. raeseri. Food Chem. 2011;124:226–233. [Google Scholar]
- 17.Todorova M., Christov R., Evstatieva L. Essential oil composition of three Sideritis species from Bulgaria. J. Essent. Oil Res. 2000;12:418–420. doi: 10.1080/10412905.2000.9699553. [DOI] [Google Scholar]
- 18.Tirillini B., Pellegrino R., Luigi Menghini L., Pagiotti R., Menghini A. Composition of the oil of Siderifis syriaca L. from Italy. J. Essent. Oil Res. 2001;13:444–445. doi: 10.1080/10412905.2001.9699722. [DOI] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data presented in this study are available upon request from the corresponding author.