Subchronic toxicity of Sideritis scardica, Lamiaceae on male Wistar rats.

INTRODUCTION: Sideritisscardica, Lamiaceae, is a plant with anti-inflammatory, antirheumatic, digestive, and antimicrobial properties that is widely used in folk medicine throughout the Balkan Peninsula. The name derives from the Greek word 'sideros', meaning iron, and it is believed that the plant was also used by soldiers to heal wounds caused by cutting weapons.

Plant Growth Regulators and Activated Charcoal Selectively Affect Phenylethanoid and Flavone Glycoside Accumulation in Sideritis scardica Griseb. Tissue Culture.

Sideritis scardica Griseb. is a Balkan endemic species traditionally used for the treatment of pulmonary emphysema and angina pectoris. Recent research has also shown its phytotherapeutic potential as an anticancer and neuroprotective agent. These findings, as well as the endangered status of the species in its wild habitats, have motivated the present research on application of plant cell tissue and organ culture for the purposes of both valuable germplasm conservation and secondary metabolites production. Shoot cultures of the plant were initiated from sterile germinated seeds and the effects of activated charcoal (AC), as well benzyl adenine and 1-naphthaleneacetic acid treatments, were experimented. The phenolic profile analysis was performed by HPLC/DAD/MSn. Comparison with samples collected from wild plants in their natural habitat was performed. It was established that in vitro multiplication induced by plant growth regulators (PGRs) was accompanied by a higher impairment of leaf morphology and trichome formation, as well as by the occurrence of plantlet hyperhydricity and callus formation, as compared with the AC treatments. Shoot culture-derived plant material was shown to produce two phenylethanoids and five flavone glycosides, not detected in the wild collected plant material. In addition, the two types of in vitro culture treatments led to the stimulation of either flavone glycosides or phenylethanoids in the in vitro cultivated plants. Thus, AC stimulated, to a higher extent, flavone glycosides' accumulation, leading to an elevated flavone/phenylethanoid ratio, as compared with PGR treatments.

Comparative Study on Assisted Solvent Extraction Techniques for the Extraction of Biologically Active Compounds from Sideritis raeseri and Sideritis scardica.

The plants in the Sideritis genus are postulated to exhibit several important medicinal properties due to their unique chemical composition. To isolate the targeted phytochemical compounds, the selection of a suitable extraction method is of primary importance. In this work, a comparative study on the phytochemical profiles of various Sideritis raeseri and Sideritis scardica extracts has been carried out. An untargeted metabolomics approach based on ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry was applied to investigate the metabolic differences between extracts obtained by conventional extraction and extractions assisted by microwaves, ultrasounds and high pressure. Additionally, the influence of extraction solvents on HPLC antioxidant profiles obtained following the derivatization of analytes with ABTS reagent was evaluated. A total of 102 metabolites have been putatively identified. The major secondary metabolites groups were classified as flavonoids, terpenoids, phenylethanoid glycosides and phenolic acids. The main antioxidants in the extracts were isoscutellarein and hypolaetin derivatives as well as verbascoside and chlorogenic acid. The results showed that 70% ethanol was the most effective extractant for different classes of phytochemicals including antioxidants. In addition, extraction supported with microwaves, ultrasounds or high pressure improved the overall recovery of metabolites by about 3 times compared to the conventional extraction method.

Sideritis scardica Extracts Demonstrate Neuroprotective Activity against Aß25-35 Toxicity.

Alzheimer's disease (AD) is the most prevalent neurodegenerative condition, primarily affecting seniors. Despite the significant time and money spent over the past few decades, no therapy has been developed yet. In recent years, the research has focused on ameliorating the cytotoxic amyloid beta (Aß) peptide aggregates and the increased elevated oxidative stress, two interconnected main AD hallmarks. Medicinal plants constitute a large pool for identifying bioactive compounds or mixtures with a therapeutic effect. Sideritis scardica (SS) has been previously characterized as neuroprotective toward AD. We investigated this ability of SS by generating eight distinct solvent fractions, which were chemically characterized and assessed for their antioxidant and neuroprotective potential. The majority of the fractions were rich in phenolics and flavonoids, and all except one showed significant antioxidant activity. Additionally, four SS extracts partly rescued the viability in Aß25-35-treated SH-SY5Y human neuroblastoma cells, with the initial aqueous extract being the most potent and demonstrating similar activity in retinoic-acid-differentiated cells as well. These extracts were rich in neuroprotective substances, such as apigenin, myricetin-3-galactoside, and ellagic acid. Our findings indicate that specific SS mixtures can benefit the pharmaceutical industry to develop herbal drugs and functional food products that may alleviate AD.

A Comprehensive Phytochemical Analysis of Sideritis scardica Infusion Using Orbitrap UHPLC-HRMS.

Sideritis scardica Griseb, also known as "mountain tea" and "Olympus tea" (Lamiaceae family) is an endemic plant from the mountainous regions of the Balkan Peninsula. In this study, we focused on an in-depth phytochemical analysis of S. scardica infusion using ultra-high-performance liquid chromatography hyphenated with high-resolution mass spectrometry (UHPLC-HRMS). Quantitative determination of the main secondary metabolites was carried out by UHPLC-HRMS analyses using the external standard method. The results revealed more than 100 metabolites, including five sugar acids and saccharides, 21 carboxylic, hydroxybenzoic, hydroxycinnamic acids, and derivatives, 15 acylquinic acids, 10 phenylpropanoid glycosides, four iridoid glycosides, 28 flavonoids, seven fatty acids, and four organosulfur compounds. Furthermore, a dereplication and fragmentation patterns of five caffeic acids oligomers and four acylhexaric acids was performed for the first time in S. scardica. Regarding the quantitative analysis, the phenylethanoid verbascoside (53) (151.54 ± 10.86 mg/g lyophilized infusion, li), the glycosides of isoscutellarein (78) (151.70 ± 14.78 mg/g li), methylisoscutelarein (82) (107.4 ± 9.07 mg/g li), and hypolaetin (79) (78.33 ± 3.29 mg/g li), as well as caffeic acid (20) (87.25 ± 6.54 mg/g li), were found to be the major compounds in S. scardica infusion. The performed state-of-the-art phytochemical analysis of S. scardica provides additional knowledge for the chemical constituents and usage of this valuable medicinal plant.

Phytochemical Study and In Vitro Screening Focusing on the Anti-Aging Features of Various Plants of the Greek Flora.

Skin health is heavily affected by ultraviolet irradiation from the sun. In addition, senile skin is characterized by major changes in the collagen, elastin and in the hyaluronan content. Natural products (NPs) have been shown to delay cellular senescence or in vivo aging by regulating age-related signaling pathways. Moreover, NPs are a preferable source of photoprotective agents and have been proven to be useful against the undesirable skin hyperpigmentation. Greek flora harvests great plant diversity with approximately 6000 plant species, as it has a wealth of NPs. Here, we report an extensive screening among hundreds of plant species. More than 440 plant species and subspecies were selected and evaluated. The extracts were screened for their antioxidant and anti-melanogenic properties, while the most promising were further subjected to various in vitro and cell-based assays related to skin aging. In parallel, their chemical profile was analyzed with High-Performance Thin-Layer Chromatography (HPTLC) and/or Ultra-Performance Liquid Chromatography High-Resolution Mass Spectrometry (UPLC-HRMS). A variety of extracts were identified that can be of great value for the cosmetic industry, since they combine antioxidant, photoprotective, anti-melanogenic and anti-aging properties. In particular, the methanolic extracts of Sideritis scardica and Rosa damascena could be worthy of further attention, since they showed interesting chemical profiles and promising properties against specific targets involved in skin aging.

Extracts of medicinal plants with natural deep eutectic solvents: enhanced antimicrobial activity and low genotoxicity.

Natural deep eutectic solvents (NADES) are a new alternative to toxic organic solvents. Their constituents are primary metabolites, non-toxic, biocompatible and sustainable. In this study four selected NADES were applied for the extraction of two medicinal plants: Sideritis scardica, and Plantago major as an alternative to water-alcohol mixtures, and the antimicrobial and genotoxic potential of the extracts were studied. The extraction efficiency was evaluated by measuring the extracted total phenolics, and total flavonoids. Best extraction results for total phenolics for the studied plants were obtained with choline chloride-glucose 5:2 plus 30% water; but surprisingly these extracts were inactive against all tested microorganisms. Extracts with citric acid-1,2-propanediol 1:4 and choline chloride-glycerol 1:2 showed good activity against S. pyogenes, E. coli, S. aureus, and C. albicans. Low genotoxicity and cytotoxicity were observed for all four NADES and the extracts with antimicrobial activity. Our results confirm the potential of NADESs for extraction of bioactive constituents of medicinal plants and further suggest that NADES can improve the effects of bioactive extracts. Further studies are needed to clarify the influence of the studied NADES on the bioactivity of dissolved substances, and the possibility to use such extracts in the pharmaceutical and food industry.

Polyphenols and Other Bioactive Compounds of Sideritis Plants and Their Potential Biological Activity.

Due to the growing problem of obesity associated with type 2 diabetes and cardiovascular diseases, causes of obesity are extensively investigated. In addition to a high caloric diet and low physical activity, gut microbiota disturbance may have a potential impact on excessive weight gain. Some reports indicate differences in the composition of the intestinal microflora of obese people in comparison to lean. Bioactive compounds of natural origin with beneficial and multifaceted effects on the body are more frequently used in prevention and treatment of many metabolic diseases including obesity. Sideritis scardica is traditionally consumed as mountain tea in the Balkans to strengthen the body and improve mood. Many reports indicate a positive effect on digestive system, weight loss, and prevention of insulin resistance. Additionally, it exhibits antioxidant activity and anti-inflammatory effects. The positive effect of Sideritis scardica extracts on memory and general cognitive abilities is indicated as well. The multilevel positive effect on the body appears to originate from the abundant occurrence of phenolic compounds, especially phenolic acids in Sideritis scardica extracts. However, mechanisms underlying their action require careful discussion and further research. Therefore, the objective of this review is to summarize the available knowledge on the role and mechanism of action of biologically active compounds of Sideritis scardica and other related species from the genus Sideritis.

The Acute and Chronic Cognitive and Cerebral Blood Flow Effects of a Sideritis scardica (Greek Mountain Tea) Extract: A Double Blind, Randomized, Placebo Controlled, Parallel Groups Study in Healthy Humans.

BACKGROUND: The presence of polyphenols such as hydroxy-cinnamic acids and flavonoids in Sideritis scardica (Greek mountain tea) are likely responsible for the cognitive and mood effects of its consumption and this could be underpinned by the ability of such polyphenols to prevent monoamine neurotransmitter reuptake and to increase cerebral blood flow (CBF). OBJECTIVE: The current study extends the small amount of Sideritis scardica literature in humans by assessing both cognitive and mood outcomes in a sample of older adults, as well as blood pressure (BP) and CBF, in a subsample, utilizing near-infrared spectroscopy (NIRS). DESIGN: This randomized, double-blind, placebo-controlled, parallel groups trial randomized N = 155, 50⁻70-year-old male and female participants who were assessed for the cognitive (N = 140), mood (N = 142), BP (N = 133) and CBF (N = 57) effects of two doses of Greek mountain tea (475 and 950 mg) as well as an active control of 240 mg Ginkgo biloba, and a placebo control, following acute consumption (Day 1) and following a month-long consumption period (Day 28). RESULTS: Relative to the placebo control, 950 mg Greek mountain tea evinced significantly fewer false alarms on the Rapid Visual Information Processing (RVIP) task on Day 28 and significantly reduced state anxiety following 28 days consumption (relative also to the active, Ginkgo control). This higher dose of Greek mountain tea also attenuated a reduction in accuracy on the picture recognition task, on Day 1 and Day 28, relative to Ginkgo and both doses of Greek mountain tea trended towards significantly faster speed of attention on both days, relative to Ginkgo. Both doses of Greek mountain tea, relative to placebo, increased oxygenated haemoglobin (HbO) and oxygen saturation (Ox%) in the prefrontal cortex during completion of cognitively demanding tasks on Day 1. The higher dose also evinced greater levels of total (THb) and deoxygenated (Hb) haemoglobin on Day 1 but no additional effects were seen on CBF on Day 28 following either dose of Greek mountain tea. Ginkgo biloba led to lower levels of Ox% and higher levels of Hb on Day 1 and lower levels of both HbO and THb on Day 28. CONCLUSIONS: The significantly improved cognitive performance following Greek mountain tea on Day 1 could be due to significant modulation of the CBF response. However, these improvements on Day 28 are more likely to be due to the reductions in state anxiety and, taken together, suggests that the former mechanism is more likely to facilitate acute cognitive effects and the latter more likely to underpin more prolonged cognitive improvements.

Assessment of the Acute and Subchronic Toxicity and Mutagenicity of Sideritis scardica Griseb. Extracts.

Sideritis scardica Griseb. has a long history of collection from the wild as a traditional remedy for respiratory and gastrointestinal complaints. It has also been investigated for its promising pharmacological activities in the central nervous system. However, its toxicological data is entirely missing. This study investigated the acute and repeated-dose oral toxicity of a S. scardica 20% (v/v) ethanol extract in Sprague Dawley rats, and mutagenicity using the Ames test. No gross pathological abnormalities and no toxicity signs or mortality were detected in animals treated with the dose of 2000 mg/kg bw during 14 days of observation. The tested extract was assigned to category 5 of the GHS. To evaluate a repeated-dose toxicity, an extract has been tested over a 28-day period followed by a 14-day recovery period. No mortality and no changes in body/organ weight or food consumption have been observed. The no-observed-adverse-effect-level of the extract was determined at 1000 mg/kg bw. The results of Ames tests conducted on extracts of different polarity (water; 20% (v/v) ethanol; 50% (v/v) ethanol; n-heptane), were unequivocally negative. The study reveals no toxicity of S. scardica and no concerns for its mutagenic effects, supports its positive safety profile, and confirms the acknowledged traditional medicinal use in human.

Beneficial Effects of Sideritis scardica and Cichorium spinosum against Amyloidogenic Pathway and Tau Misprocessing in Alzheimer's Disease Neuronal Cell Culture Models.

BACKGROUND: Natural products are a significantly underutilized source of potential treatments against human disease. Alzheimer's disease (AD) is a prime example of conditions that could be amenable to such treatments as suggested by recent findings. OBJECTIVE: Aiming to identify novel potentially therapeutic approaches against AD, we assessed the effects of Cichorium spinosum and Sideritis scardica extracts, both distinct components of the Mediterranean diet. METHODS/RESULTS: After the detailed characterization of the extracts' composition using LC-HRMS methods, they were evaluated on two AD neuronal cell culture models, namely the AßPP overexpressing SH-SY5Y-AßPP and the hyperphosphorylated tau expressing PC12-htau. Initially their effect on cell viability of SH-SY5Y and PC12 cells was examined, and subsequently their downstream effects on AßPP and tau processing pathways were investigated in the SH-SY5Y-AßPP and PC12-htau cells. We found that the S. scardica and C. spinosum extracts have similar effects on tau, as they both significantly decrease total tau, the activation of the GSK3ß, ERK1 and/or ERK2 kinases of tau, as well as tau hyperphosphorylation. Furthermore, both extracts appear to promote AßPP processing through the alpha, non-amyloidogenic pathway, albeit through partly different mechanisms. CONCLUSIONS: These findings suggest that C. spinosum and S. scardica could have a notable potential in the prevention and/or treatment of AD, and merit further investigations at the in vivo level.

Sideritis scardica Griseb., an endemic species of Balkan peninsula: traditional uses, cultivation, chemical composition, biological activity.

ETHNOPHARMACOLOGICAL RELEVANCE: Sideritis scardica Griseb. is an endemic species in the Balkan Peninsula. It is used in traditional medicine as a loosening agent in bronchitis and bronchial asthma; against the common cold and lung emphysema; in the treatment of inflammation, gastrointestinal disorders and coughs; and as an active constituent of dietary supplements for the prevention of anemia. This review aims to provide a comprehensive overview of the traditional use, phytochemistry, biological activity, cultivation, and extraction of Sideritis scardica and to highlight the gaps in our knowledge which deserves further research. MATERIALS AND METHODS: The present review is based on information collected from scientific journals, books, and electronic search. These sources include Scopus, Pubmed, Web of Science, and Google scholar as well as local books on ethnopharmacology and botany of this plant. RESULTS: The reported data on phytochemical studies, biological activity, cultivation, extraction, and traditional uses have been reviewed. Variability in essential oil composition of wild growing and cultivated taxa depending on ecological conditions was discussed. Flavonoids, phenylethanoids, diterpenoids, aliphatic compounds, etc. identified so far have been summarized. A comparative study on the effectiveness of different methods, solvents, and parameters of extraction has also been discussed. A broad range of activities of plant extracts and fractions as antimicrobial, anti-inflammatory, cytotoxic, antioxidant, gastroprotective, antiglioma, and triple monoamine reuptake inhibition as well as cultivation of the species as an approach for conservation of the natural habitats and provision of herb with high and permanent quality has also been presented. CONCLUSIONS: Sideritis scardica has become very popular and widely advertised herb in Europe. Although some of ethnobotanical uses have been proved through in vitro experiments, further studies of the individual compounds or chemical class of compounds responsible for the pharmacological effects and the mechanisms of action are necessary. In addition, the toxicity and the side effects from the use of Sideritis scardica as well as clinical trails need attention. The variability in the chemical composition of this medicinal plant depending on the origin requires development of a protocol for its standardization. For the practice it is important to improve cultivation conditions in order to increase the accumulation of biologically active compounds and to obtain herb with permanent and good quality.

Bioactive-rich Sideritis scardica tea (mountain tea) is as potent as Camellia sinensis tea at inducing cellular antioxidant defences and preventing oxidative stress.

BACKGROUND: In several countries, tea (hot-water infusions of dried Camellia sinensis (CS) leaves) is a major source of antioxidant flavonoids, and its consumption has been associated with several favourable outcomes. Other plants used for the preparation of herbal teas are sources of phenolic antioxidant compounds; among them Sideritis scardica (SS) is used for the preparation of a popular drink throughout Eastern and Central Europe. We have compared the effects of an SS extract to a CS extract in HepG2 cells to set the scientific basis for the exploitation of other herbal teas in counteraction of oxidative stress. RESULTS: Although SS extract had a lower phenolic concentration and total antioxidant capacity than CS extract, their cellular antioxidant effects were similar. The different phenolic pattern of the extracts suggests that the protective activity is not limited to catechins. CONCLUSION: Although further research is needed, our data represent a first contribution for the evaluation of the potential effect of SS in increasing antioxidant defences. © 2013 Society of Chemical Industry.