Sideritis Species Research Articles

Chromatographic profile and antioxidant and enzyme inhibitory activity of Sideritis leptoclada: An endemic plant from Turkey

Sideritis species have been used for centuries for their antimicrobial, digestive, anti-ulcerogenic and anti-inflammatory properties. Therefore, in this study, it was aimed to evaluate the chemical composition, antioxidant and enzyme inhibitory activities of solvent extracts of S. leptoclada O. Schwarz & P.H. Davis, an endemic species. It was determined that methanol (MeOH) and water extracts contained high amounts of chlorogenic acid and verbascoside, while the ethyl acetate (EtOAc) extract contained high amounts of 4-hydroxybenzoic and vanilic acids. The water extract showed the highest antioxidant activity in almost all parameters. Inhibitory activity of the MeOH extract on tyrosinase was 1.04 mg/ml, which was the highest value in this experiment. On the other hand, in α-amylase inhibitory assay, the EtOAc extract showed an activity of 2.21 mg/ml. Docking analysis showed that verbascoside can be an effective tyrosinase and α-amylase inhibitory agent.

Essential oil composition of endemic plant Sideritis rubriflora Hub. Mor

Background: The genus Sideritis L.is mostly found in habitats dominated by the Mediterranean climate and is represented by approximately 150 taxa in the world. Turkey is among few countries where Sideritis includes about 52 species and the endemic rate of this genus goes up to almost 80%. Sideritis species are generally known as ‘sage or ironwood worth’ or as a tea plant is widely used in folk medicine in Turkey. There are important studies in the literature on Sideritis species due to their widespread use in ethnobotanical and related uses. Materials and Methods: Plant samples were collected from their natural habitats, dried following the herbarium technique, and then identified and stored at the Department of Pharmaceutical Botany, Faculty of Pharmacy, Adıyaman University with the number ÖK 6854. The essential oil was obtained from 100 g of plant samples by the water distillation method. Essential oil composition was determined by gas chromatography–mass spectrometry (GC-MS). Results: It was found that the studied plant is rich in essential oil with 0.4 ml oil content in the sample. Forty components were determined from the essential oil of the plant and the main components were found as carvacrol (33.26%), β-caryophyllene (12.5%), α-pinene (7.32%), and β-pinene (6.13%). The results were discussed in terms of natural products, renewable resources, usage areas, and culture of Sideritis taxa. Conclusions: With this study, the economic values of the members of the genus were emphasized by referring to the characteristics of Sideritis members such as aromatherapeutic, phytotherapy, ethnobotanical, and biological activity. In order to better evaluate the S. rubriflora plant and to continue the activities related to this endemic plant of high economic value more efficiently, basic data were obtained and it was tried to contribute to the sector. It is important to take the necessary precautions and show the necessary sensitivity in order to protect and conserve Sideritis members, especially S. rubriflora. In this way, Sideritis members and S. rubriflora will have the opportunity to continue their existence and spread more in nature. This will easily make available sufficient raw materials for the sectors they are used.

Antioxidant and Anticholinesterase Properties of Sideritis perfoliata subsp. athoa (Papan. &Kokkini) Baden and Sideritis trojana Bornm. Teas from Mount Ida-Turkey and Their Phenolic Characterization by LC-MS/MS

The phenolic profile, antioxidant and anticholinesterase activities of teas prepared from two Sideritis(L.) species: Sideritis perfoliata subsp. athoa (Papan. &Kokkini) Baden. and Sideritis trojana Bornm, collected from Mount Ida (Kaz Dağı) Turkey, were determined. The teas were prepared by infusion and decoction methods. The quantitative amounts of the phenolic contents were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The major phytochemicals were found to be fumaric acid for infusion and decoction samples of S. trojana and infusion of S. perfoliata subsp. athoa, chlorogenic acid for decoction of S. perfoliata subsp. athoa. The tea samples prepared by decoction method were found to be rich in phenolics. Apart from the fact that the decoction sample of S. trojana exhibited the best antioxidant effect in 2, 2-diphenyl-1-picrylhydrazyl (DPPH), β -carotene bleaching and cupric (Cu2+) ion reducing power assay (CUPRAC) methods among the tested samples at all concentrations, and showed significant inhibition effect at 200 μg/mL against acetylcholinesterase and butyrylcholinesterase enzymes (59.74%, 64.99%, respectively).

NMR-Based Chemical Profiling, Isolation and Evaluation of the Cytotoxic Potential of the Diterpenoid Siderol from Cultivated Sideritis euboea Heldr.

Diterpenes are characteristic compounds from the genus Sideritis L., possessing an array of biological activities. Siderol is the main constituent of the ent-kaurene diterpenes in Sideritis species. In order to isolate the specific compound and evaluate for the first time its cytotoxic activity, we explored the dichloromethane extract of cultivated Sideritis euboea Heldr. To track the specific natural bioactive agent, we applied NMR spectroscopy to the crude plant extract, since NMR can serve as a powerful and rapid tool both to navigate the targeted isolation process of bioactive constituents, and to also reveal the identity of bioactive components. Along these lines, from the rapid 1D 1H NMR spectrum of the total crude plant extract, we were able to determine the characteristic proton NMR signals of siderol. Furthermore, with the same NMR spectrum, we were able to categorize several secondary metabolites into chemical groups as a control of the isolation process. Therefore, this non-polar extract was explored, for the first time, revealing eleven compounds—one fatty acid ester; 2-(p-hydroxyphenyl)ethylstearate (1), three phytosterols; β-sitosterol (2), stigmasterol (3), and campesterol (4); one triterpenoid; ursolic acid (5), four diterpenoids; siderol (6), eubol (7), eubotriol (8), 7-epicandicandiol (9) and two flavonoids; xanthomicrol (10) and penduletin (11). The main isolated constituent was siderol. The antiproliferative potential of siderol was evaluated, using the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay, on three human cancer cell lines DLD1, HeLa, and A549, where the IC50 values were estimated at 26.4 ± 3.7, 44.7 ± 7.2, and 46.0 ± 4.9 μΜ, respectively. The most potent activity was recorded in the human colon cancer cell line DLD1, where siderol exhibited the lowest IC50. Our study unveiled the beneficial potential of siderol as a remarkable cytotoxic agent and the significant contribution of NMR spectroscopy towards the isolation and identification of this potent anticancer agent.

Traditionally Used Sideritis cypria Post.: Phytochemistry, Nutritional Content, Bioactive Compounds of Cultivated Populations.

Sideritis species are recognized as important medicinal plants and their commercial demand is continuously on the rise both in the European and in the global market. Consequently, the cultivation of Sideritis species has been occurred to successfully meet the need for mass production of high-quality plant material. The present study was undertaken in order to investigate the chemical composition of cultivated S. cypria. Infusions of flowers and leaves were prepared separately, according to the European Medicine Agency (EMA) monograph. The infusion of the flowers revealed the presence of four flavones, isoscutellarein-7-O-[6′″-O-acetyl-β-D-allopyranosyl-(1→2)-β-D-glucopyranoside, its 4′-O-methyl-derivative, 4′-O-methyl-hypolaetin-7-O-[6′″-O-acetyl-β-D-allopyranosyl-(1→2)-β-D-glucopyranoside, and isoscutellarein-7-O-[6′″-O-acetyl-β-D-allopyranosyl-(1→2)]-6″-O-acetyl-β-D-glucopyranoside; four phenylethanoid glucosides, acteoside, leucosceptoside A, lamalboside, and leonoside A; one iridoid, melittoside, and one phenolic acid, chlorogenic acid, while the infusion of the leaves of the same population afforded the same first two flavones; five phenylethanoid glucosides, acteoside, leucosceptoside A, lavandulifolioside, leonoside A, and lamalboside; melittoside and chlorogenic acid. The structural elucidation of the isolated compounds was undertaken by high-field NMR spectroscopy. Moreover, the essential oils of the flowers and leaves were studied by GC-MS, separately. In addition, the mineral, bioactive compounds, protein and carbohydrate contents were evaluated for both plant materials.

Synthesis, molecular structure, DFT calculations and biological activity of acetoxy linearol

Acetoxy linearol (ent-3β,7α,18-triacetoxykaur-16-ene), a natural compound was synthesized from linearol isolated from endemic Sideritis species and structurally characterized using diverse spectroscopic techniques such as 1H, 13C NMR and FT-IR. The geometrical parameters, vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of acetoxy linearol (1) in the ground state have been calculated using the density functional theory (DFT) method at the B3LYP and X3LYP with the 6-31+G (d) basis set. The calculated vibrational frequencies and 1H and 13C NMR chemical shifts have been compared with that of obtained experimental values. A combined study based on NMR data and theoretical calculations using DFT/GIAO indicate that (1) is the correct structure of title molecule. The experimental and theoretical results confirmed the proposed molecular structure of the synthesized (1) compound. Weak inhibitory activity of linearol and acetoxy linearol against acetyl- and butyryl-cholinesterase was determined. Also, the antioxidant capacity of the title molecule was determined by DPPH free radical scavenging and β-carotene linoleic acid assays.

Diterpenoid and phenolic contents of Sideritis hololeuca Boiss & Heldr. Apud Bentham with antioxidant and anticholinesterase activity

Abstract The objective of this study is to determine essential oil, diterpenoid and phenolic contents of Sideritis hololeuca along with their biological activities. Phytol was found to be the main component of the essential oil. Seven known kaurane diterpenoids, siderol (140 mg, 0.16%, w/w), 7-acetoxy sideroxol (15 mg, 0.02%, w/w), eubol (6 mg, 0.01%, w/w), eubotriol (5 mg, 0.03%, w/w), 7-epicandicandiol (3 mg, 0.02%, w/w), ent-7α-acetoxy-18-hydroxykaur-16-ene (5 mg, 0.01%, w/w) and linearol [by liquid chromatography-tandem mass spectrometry (LC-MS/MS)] were determined from the species. Moreover, vanillin (21 mg, 0.10%, w/w), which was not isolated from any Sideritis species earlier, was isolated from an acetone extract of S. hololeuca. Quantitative amounts of some phenolic compounds in n-hexane, dichloromethane, acetone, methanol extracts and infusion and decoction of the plants were also investigated by LC-MS/MS. Antioxidant capacity and acetylcholinesterase, butyrylcholinesterase inhibition effects of the species were evaluated. The extracts of methanol and infusion and decoction of species showed moderate butyrylcholinesterase inhibition activity. The highest inhibition was observed from the decoction of species. The Cu2+ reducing power of infusion was determined as 1.435 mmol TR g−1.

Antioxidative capacities of some GABAA receptor modulating food plants

Reactive oxygen species cause oxidative stress associated with some health issues such as neurodegenerative diseases. Some antioxidants show neuroprotective activity and regulate neuronal activity through positive modulation of GABA A receptors. In this study, the antioxidative capacity of some novel GABA A receptor modulating food plants, including lavender, clove and four Sideritis species ( S. arguta , S. sipylea , S. condensata , and S. stricta) was investigated using ABTS assay. The aqueous clove extract showed the most potent antioxidant effect and its IC 50 value was found to be 3.76 μg/mL. The antioxidant capacity of Trolox was lower (IC 50 : 4.63 μg/mL) than that of the clove extract, but higher than those of the other food extracts. The aqueous lavender extract exhibited less antioxidant activity compared to Sideritis species, except S. sipylea that had the least antioxidant capacity (IC 50 : 20.75 μg/mL). In conclusion, these results confirm that GABA A receptor modulating food plants possess strong antioxidative activity.

Synthesis, Structural Characterization, Spectroscopic Properties, and Theoretical Investigation of Siderol Acetate

In the present study, siderol acetate (1) was synthesized from siderol isolated from endemic Sideritis species, then its chemical structure was determined by using various spectroscopic methods (FT-IR, 1H NMR, and 13C NMR). The geometrical parameters, vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values for siderol acetate in the ground state have been calculated using the Density Functional Theory (DFT) and Hartree–Fock (HF) methods with the 6-31G(d) basis set. The calculated vibrational frequencies and 1H and 13C NMR chemical shifts have been compared with experimental values. A combined study based on NMR data and quantum-mechanical calculations using DFT/GIAO indicate that 1 is the correct structure of the title molecule.

Phytochemical contents, antioxidant effects, and inhibitory activities of key enzymes associated with Alzheimer's disease, ulcer, and skin disorders of Sideritis albiflora and Sideritis leptoclada.

In this study, urease, tyrosinase, cholinesterase inhibitory, and antioxidant activities of various extracts of Sideritis albiflora and Sideritis leptoclada were determined together with the phytochemical contents. In addition, the fatty acid compositions and phenolic compounds were investigated by gas chromatography(GC), gas chromatography-mass spectrometry(GC-MS), and high performance liquid chromatography-diode array detector (HPLC-DAD). Rosmarinic acid and caffeic acid in both Sideritis species were identified as the most abundant phenolic compounds whereas palmitic acid was found as a major fatty acid. The acetone extract of S. leptoclada indicated the highest antioxidant activity in β-carotene-linoleic acid (IC50 : 17.23±0.11µg/ml), DPPH• (IC50 : 28.14±0.05µg/ml) and ABTS•+ (IC50 : 15.18±0.02µg/ml) assays. The acetone extract of S. albiflora (A0.50 : 32.71±0.44µg/ml) was found as the best reductant in cupric reducing antioxidant capacity(CUPRAC) assay. Against acetylcholinesterase (AChE)and butyrylcholinesterase(BChE), only the hexane extracts of Sideritis species showed moderate inhibitory activity. Moreover, all extracts of S. albiflora and the hexane extract of S. leptoclada exhibited significantly higher urease inhibitory activity than that of thiourea. Further, in vivo activity studies on extracts and isolated constituents obtained from these species are needed to understand the activity in biological systems. PRACTICAL APPLICATIONS: Multiple pharmacological studies have proven that Sideritis species is precious with significant bioactive properties. This is the first comprehensive research to determine the enzyme inhibitory and antioxidant activities of various extracts of S. albiflora and S. leptoclada with phytochemical contents. Both Sideritis species were found to be rich in rosmarinic and caffeic acids. The acetone extracts showed the highest activity in terms of antioxidant activity, while the hexane extracts exhibited superior urease inhibitory activity. These results show that Sideritis species could be used as urease inhibitors' agents and source of antioxidants in food, pharmaceutical, and cosmetic industries.

Cultivation strategy to improve chemical profile and anti-oxidant activity of Sideritis perfoliata L. subsp. perfoliata

Due to the remarkable medicinal properties of Sideritis spp, the commercial demand for the plant is continuously on the rise both in the European and in the global market. Cultivation of Sideritis species have been occurred to successfully meet the need for mass production of high-quality plant material. The present study was undertaken in order to investigate the impact of different cultivation practices (conventional versus organic cultivation; full versus deficit irrigation) in the yield and phytochemical profile of S. perfoliata L. subsp. perfoliata from Cyprus, under two harvestings for biomass production. Deficit irrigation decreased plant growth, but increased dry matter content. The content of chlorophylls and the nitrogen and potassium content decreased in organically grown plants. Both organic cultivation and/or deficit irrigation increased total phenolics, flavonoids, vitamin C and antioxidants. Essential oil yield increased under deficit irrigation at the 2nd harvest, while essential oil composition fluctuated among the treatments. Infusions of each plant material were prepared according to the European Medicines Agency (EMA) monograph. Based on their NMR spectra, the deficit-irrigated plants from conventional cultivation were the most rich in secondary metabolites and chosen for further chemical analysis. Six iridoids such as three flavonoids, two phenylethanoid glucosides and one phenolic acid have been isolated indicating new knowledge on the effects of cultivation practices on plant secondary metabolisms with putative industrial applications and interest.

Genus Sideritis, section Empedoclia in southeastern Europe and Turkey - studies in ethnopharmacology and recent progress of biological activities.

Over the last two decades there has been a substantial increase of the number of studies on the species of genus Sideritis. Species of section Empedoclia, occurring in the Eastern Mediterranean region and in part of Western Asia possess some remarkable characteristics and are known as valuable medicinal plants used by local people in the traditional medicine and for herbal tea. The objective of the review is to make a survey on the recent studies on the ethnopharmacology and biological activity of the species in Southeastern Europe and in Turkey, which is the center of distribution and their main occurrence. The review focuses on the ethnopharmacology and biological activities of the species of interest. The survey revealed that a total of 47 species belonging to section Empedoclia have been studied either in ethnopharmacological aspect, or in relation to their biological activities, or both. Most species have been used traditionally by the local people as herbal tea or for treatment of various health problems, most frequently flu, cold and respiratory diseases. Sideritis species demonstrate numerous biological activities and are promising for use in the therapy of many diseases and health disorders. Antioxidant activity was found in 40 species, antimicrobial and antibacterial activity - in 27 species, anti-inflammatory - in 14 species, antifungal - in 8 species, cytotoxic - in 7 species. There were also some other, more specific biological activities, found in a few species, but considered promising for further studies and application. The species of genus Sideritis, section Empedoclia have been used by local people as herbal tea and in traditional medicine since long time ago. People are taking advantage of the high species diversity and are aware of their useful properties. Much more information is available on the biological activities of the target species than on their traditional uses. Most species demonstrate various biological activities and are of substantial interest for further studies on their pharmacological properties and their potential for pharmacy and medicine. Graphical abstract Schematic illustration of traditional uses and biological activities of some Sideritis species. Arrows with different colors represent biological activities of different species. The species and their corresponding color can be seen at the right part of the figure. The colors correspond also to the squares placed in the different parts of human body.

Chemical Composition, Antioxidant, Anticholinesterase and Anti-Tyrosinase Activities of Essential Oils of Two Sideritis Species from Turkey.

Sideritis species have been known as medicinal plants since ancient times, and used as tea in Mediterranean countries such as Turkey, Greece, and Spain. They are also used for the treatment of several ailments such as a cough, common cold, and gastrointestinal disorders. The aim of the present study was to perform the chemical composition, antioxidant, anticholinesterase, and anti-tyrosinase activities of the essential oils of Sideritis albiflora and S. leptoclada. β-caryophyllene (21.2%) and Germacrene D (17.9%) were identified as the major compounds in S. albiflora and S. leptoclada essential oils, respectively. The essential oil of S. albiflora showed the highest lipid peroxidation inhibitory (IC50: 73.8 ± 0.8 µg/mL), DPPH free radical scavenging (28.3±0.1%), ABTS cation radical scavenging (IC50: 50.6 ± 1.0 µg/mL), reducing power (A0.05: 181.7 ± 0.6 µg/mL), acetylcholinesterase (22.1 ± 0.4%), butyrylcholinesterase (IC50: 157.2 ± 0.9 µg/mL) and tyrosinase (15.2 ± 0.4%) inhibitory activities. Moreover, S. albiflora essential oil had rich total phenolic and flavonoid contents indicating 41.5 ± 0.8 µg PEs/mg and 21.4 ± 1.0 µg QEs/mg respectively. This study suggests that consumption of Sideritis species as tea may protect one against melanogenesis, amnesia, and oxidative stress without any observable side effect.

Comparative and phylogenetic analysis of RuBisCO large subunit (rbcL) proteins in some Sideritis L. (Lamiaceae) species: A bioinformatic approach

The large subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) protein, which plays an important role in the photosynthesis reaction, are encoded by the chloroplast genome. Sideritis L., a medical and aromatic plant group, belongs to Lamiaceae family. In this study, we performed sequence, physicochemical, phylogenetic and three-dimensional (3D) bioinformatic analyses of RuBisCO large subunit (rbcL) proteins in the Sideritis ssp. using various bioinformatics tools. Physicochemical analyzes were performed by ExPASy - ProtParam. The putative phosphorylation sites of the rbcL proteins were determined by NetPhos 2.0 and NetPhos 3.1. Phylogenetic analyses were performed with the MEGA 6.0 software. To estimate 3D protein structures, PyMol program was used. At the end of the study, it was found that the amino acid number of stilbene synthase proteins ranged between 171 and 456, molecular weight ranged between 19002.67 and 50420.44 Da, instability index ranged between 27.30 to 40.70 and GRAVY values ranged between -0.394 to -0.226. While the highest average amino acid rate in the rbcL proteins was Gly (10.00%), the lowest amino acid ratio (1.4%) was determined as Trp. In phylogenetic analyses performed using protein sequences, maximum likelihood (ML) tree consisted of 2 large clades. Pairwise distance analysis based on Sideritis species? rbcL protein sequences was performed using MEGA 6.0. The lowest pairwise distance was 0.000, while the highest pairwise distance was 0.024. When the estimated 3D structures of the proteins were examined, the Gly residue, which plays an important role in the structure and function of the proteins, was detected as the least in S. libanotica subsp. kurdica species while it was the most abundant residue in S. cretica subsp. spicata. The results of our study provide insights into fundamental characteristics of rbcL proteins in Sideritis taxa.

Biochemical Fingerprint of Greek Sideritis spp.: Implications for Potential Drug Discovery and Advanced Breeding Strategies

Plant species of the Sideritis genus are native to the Mediterranean region and widely used through millennia for their medicinal and culinary properties. They are mostly known as mountain tea or Shepard tea and in the last few years, they are on the spotlight due to the production of an enormous variety of bioactive secondary metabolites exerting a wide range of pharmaceutical applications. In the present study the biochemical value and the health promoting components of various indigenous Sideritis species was assessed: S. perforiata subsp. perfoliata, S. perfoliata subsp. athoa, S. syriaca, S. raeseri, S. scardica. A thorough biochemical analysis was conducted, including total phenols and flavonoid content, antioxidant activity, amino acids, elemental and polar/non polar metabolite profiling. S. perfoliata subsp. perfoliata had the most diverse and rich terpene profile among the studied species, while its infusion had the highest phenol and flavonoid content thus, showed the highest antioxidant activity. The diverse chemotype of Sideritis species can be used as a guide on the preparation of tea mixes with the desired metabolite content targeting specialized medical applications or may assist on the design of breeding strategies.

Morphometric studies of Sideritis scardica Grsb. and S. syriaca L. in their natural populations in Bulgaria

The paper aimed at studying the morphometric variation in eight natural populations of two rare Sideritis species occurring in Bulgaria. Thirteen measured traits and four ratios were used to reveal the degree and distribution of variation. Most traits exhibited moderate to high variation and the most differentiating one was the length of the acumen. Cluster analysis and Principal component analysis revealed that the two taxa, S. scardica and S. syriaca are well distinguished but the population Chervenata stena, classified as S. scardica differed significantly from the remaining ones of the same species. Results of the morphometric study indicate the necessity of further studies for revealing the taxonomic relationships among the taxa.

Essential Oil Composition of Five Sideritis Species Endemic to Turkey

In this study, dried aerial parts of Sideritis phrygia Bornm., Sideritis pisidica Boiss. & Heldr., Sideritis brevibracteata P. H. Davis, Sideritis bilgerana P. H. Davis and Sideritis hispida P. H. Davis, collected from different regions of Turkey, were investigated the essential oil compositions obtained by hydrodistillation and they were analyzed by using GC-MS/MS. The main compounds in the essential oils of five Sideritis species were found as follows : caryophyllene oxide (11.4%), limonene (10.6%) and p -cymene (10.1%) in S. phrygia; β - caryophyllene (32.8%), germacrene D (10.7%) and (E) -β-farnesene (10.0%) in S. pisidica ; β - caryophyllene (43.1%), germacrene D (10.6%) and α-cadinene (10.3%) in S. brevibracteata ; α-cadinol (28.1%), α-cadinene (11.0%) and undecane (8.5%) in S. bilgerana ; α-cadinol (41.1%), α-cadinene (13.3%) and β - caryophyllene (5.0%) in S. hispida .

Experimental and Theoretical Vibrational Spectra of Sideridiol Isolated from Sideritis Species

Sideridiol (ent-7α,18β-dihydroxykaur-15-ene) one of the ent-kaurene diterpenoid, is isolated from the genus Sideritis L. belongs to the family of Lamiaceae. The vibrational frequencies of sideridiol in the ground state have been calculated using the Density Functional Theory (DFT) method with the 6-31G(d) and 6 31+G(d,p) basis sets. The calculated vibrational frequencies have been compared with that of obtained experimental IR spectrum.

Pharmacologically active fractions of Sideritis spp. and their use in inherited eye diseases

Abstract The main constituents of the genus Sideritis are various terpenoids, sterols, coumarins, flavonoid aglycones and glycosides. Sideritis species have been traditionally used as infusions or flavoring agents and in medicine as anti-inflammatory, antiulcer, antimicrobial, antioxidant, antispasmodic and analgesic agents. This paper includes the following sections: Introduction, Description and distribution of Sideritis spp, Pharmacological effects, Toxicity tests, Rationale for use of Sideritis spp. in ophthalmology and Conclusions. The aim is to provide a comprehensive overview on the botanical, phytochemical and pharmacological aspects of the genus Sideritis, and to establish the scientific basis of its pharmacological use. New approaches to using officinal plants have recently yielded significant results. The paper also reviews this information and provides a critical view on the options for exploiting the potential of Sideritis spp. in ophthalmology.

Effect of acidic and enzymatic pretreatment on the analysis of mountain tea (Sideritis spp.) volatiles via distillation and ultrasound-assisted extraction

A number of beneficial medicinal properties are attributed to the extract and essential oil of the aerial parts of Sideritis species (Lamiaceae). Hydrodistillation of the aerial parts of wild Sideritis clandestina ssp. peloponnesiaca (an endemic taxon in northern Peloponnesus, Greece) gave a low essential oil yield (<0.12%); about 65 components, mainly α-pinene, β-caryophyllene, β-pinene, globulol, caryophyllene oxide, were identified via GC–MS. Internal and external standards were used for quantification. For miniaturization of the procedure, we studied side-by-side maceration (MAC) and ultrasound-assisted extraction (UAE) methods, as well as the effect of preincubation in acidic medium (pH 4.8) for 75min at 37°C with or without a mixture of cellulase, hemicellulase and pectinase. Maceration and UAE provide consistent chemoprofiling of the main volatile compounds (about 20); UAE has lower demands on time, solvent, plant material (3g) and results in higher yields. Pretreatment with enzymes can increase the respective yields of hydrodistillation and UAE, but this effect is definitely attributed to the concurrent acidic pretreatment. In conclusion, incubation of plant material prior to hydrodistillation or UAE in citrate buffer, pH 4.8, significantly enhances the overall yield and number of components obtained and is recommended for the analysis of Sideritis volatiles. The acidic pre-treatment method was also successfully applied to analysis of cultivated Sideritis raeseri Boiss. & Heldr. in Boiss. ssp. raeseri; α-pinene, α- and γ-terpinene and β-thujene were predominant albeit in different percentages in flowers and leaves.