Novel acylflavones from Sideritis syriaca ssp. syriaca

In the framework of the detailed phytochemical analysis of the aerial parts of Sideritis syriaca, two novel acylflavones were isolated together with three acetylated flavone glycosides and acylated flavone glycosides. The novel acylflavones were identified as isoscutellarein 7-trans-p-coumarate and apigenin 7-,4′-bis(trans-p-coumarate). Their structures were elucidated by means of UV, 1D and 2D NMR, LC–DAD–MS and confirmed by HR-MS spectroscopy.     

Antioxidant activity screening of extracts from Sideritis species (Labiatae) grown in Bulgaria

Plant samples from several species and populations of the genus Sideritis (Labiatae) grown in Bulgaria (S scardica, S syriaca and S montana) were extracted with different solvents. Their antioxidant activities were determined by the β‐carotene bleaching test (BCBT), 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH^?) radical scavenging method and static headspace gas chromatography (HS‐GC) and compared with the antioxidant activity of two reference compounds of different polarity, viz butylated hydroxytoluene (BHT) and rosmarinic acid. The pure reference compounds were applied in a ten‐times lower concentration than the plant extracts. The highest antioxidant activity in the BCBT, close to that of BHT, was observed for the more apolar extracts. The inhibitory effect on β‐carotene bleaching of the polar extracts and rosmarinic acid was much lower than that of BHT. The inhibition of hexanal formation in bulk safflower oil by most of S syriaca and S scardica extracts was as effective as BHT but less so than rosmarinic acid. S montana extracts showed weak antioxidant or even pro‐oxidant properties. Extracts from butanol and from ethyl acetate and the total methanol extracts from all Sideritis plants studied showed a strong radical scavenging activity against DPPH^?, close to that of rosmarinic acid. S montana extracts were, as a whole, slightly weaker radical inhibitors than the extracts from the other two species. The antioxidant activity of Sideritis extracts was attributed to the presence of flavonoid and phenylpropanoid glycosides. Copyright © 2003 Society of Chemical Industry     

Metabolic profile and biological activity of Sideritis brevibracteata P. H. Davis endemic to Turkey

Essential oil and phenolic compositions of Sideritis brevibracteata P.H. Davis, which is an endemic species in Turkey and commonly used as a herbal tea for some diseases, were determined by GC-MS and Liquid chromatography–mass spectrometry (LC-MS/MS) techniques. While the main components of the essential oil were determined as caryophyllene, germacrene-D, and α-cadinene, the phenolic compounds quercetagetin-3,6-dimethylether and chlorogenic acid were found to be the main compounds in the extracts of the species. The characteristic diterpenoids of Sideritis species such as siderol, linearol, eubotriol, sideridiol, and athonolone were isolated and their structures were elucidated by 1D and 2D NMR (Nuclear Magnetic Resonance) techniques. Weak inhibitory activity of species against butyryl-cholinesterase was determined. Antioxidant capacity of the acetone and methanol extracts was determined by DPPH free radical scavenging activity, β-carotene linoleic acid assays, and CUPRAC assays.     

Spray drying of the mountain tea (Sideritis stricta) water extract by using different hydrocolloid carriers

The water extract of the mountain tea was spray-dried by using different food hydrocolloids viz. β-cyclodextrin (BCD), arabic gum (AG), and maltodextrins (MD19 and MD12) as carrier materials. Powdered samples were then subjected to product yield, moisture content, water activity, bulk density, solubility, color (Lab) and SEM particle microstructure analyses. Furthermore, color (Lab), turbidity (NTU), total phenolic content (TPC), total antioxidant activity (TAA) and volatile compound (β-pinene) analyses were performed on the reconstituted mountain tea samples. The product yield increased with the addition of the carrier materials whereas decreased at higher drying temperatures. The inlet air temperature of 155 °C provided the better retention for β-pinene. Almost all physicochemical properties of the spray-dried mountain tea samples were significantly (P < 0.05) affected by the inlet air temperature, the type and concentration of the carrier materials.     

Phenolic profile,antioxidant, anticholinesterase,and anti-tyrosinase activities of the various extracts of Ferula elaeochytris and Sideritis stricta

In this study, the antioxidant, anticholinesterase, and anti-tyrosinase properties of (hexane, acetone, methanol, and water) extracts of Ferula elaeochytris and Sideritis stricta were determined with the total phenolic and flavonoid contents. The phenolic profile of the methanol and water extracts was analysed using HPLC-DAD. Protocatechuic acid was found as the major phenolic compound in the methanol (116.3 ± 3.1 µg/g) and water extracts (69.4 ± 1.3 µg/g) of F. elaeochytris. Coumarins (253.9 ± 4.1 µg/g) and catechin hydrate (175.2 ± 2.9 µg/g) were the most abundant phenolic compounds in the methanol and water extracts of S. stricta. β-carotene–linoleic acid, DPPH^?, ABTS^?+, CUPRAC, and metal-chelating assays were used to evaluate antioxidant properties of the extracts. The methanol and water extracts of F. elaeochytris and the acetone and methanol extracts of S. stricta containing the highest amount of total phenolic and flavonoid contents showed the highest antioxidant activities in β-carotene–linoleic acid, DPPH^?, ABTS^?+, and CUPRAC assays. The enzyme inhibitory potential of extracts was investigated against key enzymes involved in neurodegenerative (acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)) and skin (tyrosinase) disorders. In the cholinesterase inhibitory assays, the hexane extracts of two species exhibited the best activity against AChE, while the hexane extract of F. elaeochytris and the methanol extract of S. stricta observed to be the most active against BChE. As for anti-tyrosinase activity results of extracts, the only acetone and methanol extracts showed mild inhibitory activity for both species.     

Traditional uses,chemical composition and biological activities of Sideritis raeseri Boiss. & Heldr.

Sideritis species have been used in folk medicine for their antimicrobial, antiulcerogenic, digestive and anti‐inflammatory properties. Over the years, the phytochemistry of the genus Sideritis has been studied, and various terpenoids, sterols, coumarins and especially flavonoid aglycones and glycosides have been identified. In particular, species from the Balkan Peninsula have been studied and were found to be rich in flavonoids, with valuable antioxidant activity. In the folk medicine of the Balkan countries, Sideritis raeseri is used as a herbal tea in the treatment of inflammation, gastrointestinal disorders and coughs, and also as a tonic, whereas extracts are used as a component of dietary supplements for anaemia. Its dried inflorescences are used to prepare a beverage called ‘mountain tea’. In light of the considerable interest generated in the chemistry, pharmacological properties and commercial value of S. raeseri Boiss. & Heldr., we review and summarise the available literature on these plants. The review details the chemical composition of the essential oil, its mineral and polyphenol contents, the naming of these plants and their physicochemical characterisation, and the nuclear magnetic resonance spectral data and biological properties associated with the plant extracts, with a focus on their potential chemotherapeutic applications. © 2016 Society of Chemical Industry     

Chemical properties of the cultivated Sideritis raeseri Boiss. & Heldr. subsp. raeseri

Phytochemical analyses of the cultivated Sideritis raeseri subsp. raeseri in four different stages of flower development were performed. Traditionally used infusion and decoction were also prepared from aerial parts in full flowering stage, and analyses of active compounds and radical scavenging capacity were performed. The highest yield of the essential oil, obtained by hydrodistillation, was noticed in the full flowering phase (0.11%), with sesquiterpene bicyclogermacrene as the main constituent (42.5%). All examined extracts contained phenolic compounds and their amounts varied from 15.3 to 34.1 mg GAE/g DW. The amounts of total phenolics in infusion and decoction were similar (46.5 and 43.9 mg GAE/100 ml, respectively). LC–ESI-MS analyses of all samples allowed the characterisation of 22 phenolic compounds. Two dominant flavone glycosides, 4′-O-methylhypolaetin-7-O-[6?-O-acetyl-β-d-allopyranosyl (1 → 2)-β-d-glucopyranoside (17) and 4′-O-methylisoscutellarein-7-O-[6?-O-acetyl-β-d-allopyranosyl-(1 → 2)]-β-d-glucopyranoside (19) were quantified using HPLC. Moreover, the mineral content and the percent of transportation were investigated.     

Investigations of anti-inflammatory,antinociceptive, antioxidant and aldose reductase inhibitory activities of phenolic compounds from Sideritis brevibracteata

The Sideritis species are widely used in the treatment of gastrointestinal disorders, rheumatism, cough, the common cold and as a diuretic, and they are commonly used as an herbal tea in folk medicine in Turkey. The teas of Sideritis have unique tastes, pleasant aromas and a transparent yellow colour, and are preferred as a hot beverage. In order to evaluate this information, the crude methanolic extract and the water soluble part of the methanolic extract after partition with chloroform and n-butanol were investigated for their anti-inflammatory and antinociceptive activities. Phytochemical studies performed on the n-butanol extract of the overground parts of Sideritis brevibracteata, which is rich in phenolic compounds with promising activities, resulted in the isolation of six acetylated allose containing 8-hydroxyflavone glycosides and a phenylethanoid glycoside. The structures of the compounds were established by spectroscopic evidence (UV, IR, NMR, MS). Furthermore, these phenolic compounds of S. brevibracteata were studied for anti-inflammatory, antinociceptive, antioxidant and aldose reductase inhibitory activities. The experimental data demonstrated that S. brevibracteata displayed remarkable anti-inflammatory, antinociceptive and antioxidant activities.