Chemical profile of the Anatolian Sideritis species with bioactivity studies

CONTEXT

The genus Sideritis L. (Lamiaceae) is represented by 46 species in Turkey with an 79% endemism ratio, 42 of 46 belonging to the section Empodoclia.

OBJECTIVE

In this review article, Sideritis species growing in Turkey have been evaluated for phytochemical constituents and biological activities.

METHODS

The data for the isolates, components and extracts of the Anatolian Sideritis species and their bioactivity studies were retrieved from the main databases WoS, Scopus and PubMed from 1975 until 31 December 2022.

RESULTS

In this review article, terpenoids, flavonoids, phenolics and other secondary metabolites isolated from Turkish Sideritis species were reported. Anatolian Sideritis species, which primarily consist of monoterpenes and sesquiterpenes, were studied in detail. Sideritis plants are represented by 46 species in Turkey, and 25 of them were investigated for their diterpenoids through isolation or LC-MS studies. Most of the diterpenoids of Turkish Sideritis species have ent-kaurene skeleton, among them linearol, siderol, 7-epicandicandiol and sideridiol were found to be the main compounds. Exceptionally, labdane, pimarane and beyerene diterpenoids were only found in a few species. For phenolics and flavonoids, only 12 species were investigated until now, and they were found to be rich in phenylethanoid glycosides and flavonoid glycosides. In terms of activity, most of the species were tested for antioxidant activity, followed by antimicrobial and anti-ulcer/anti-inflammatory activities. Their cytotoxic, enzyme inhibitory, antinociceptive and antistress activities were less frequently studied.

CONCLUSIONS

Sideritis species should be considered promising therapeutic agents in the treatment of upper respiratory tract and ulcer/inflammatory diseases.

Sideritis L. essential oils: A systematic review

Essential oils are extensively used in the food, cosmetic, perfume, pharmaceutical, and agrochemical industries due to their aroma and pharmacological properties. The Lamiaceae family is mainly represented by widely well-known medicinal and aromatic plants that produce essential oil. Over the years, Sideritis L. essential oils have attracted great interest due to their chemical variability among the different taxa and their pharmacological activities. In-depth research of previously published literature was performed on electronic databases with several key search words for the collection of the available data and a total of 128 scientific studies were used since 1983. To date, 155 accepted Sideritis samples have been studied originating from 15 countries and more than 250 compounds have been reported in 87 Sideritis taxa overall. Furthermore, antimicrobial and antioxidant effects have been the most studied pharmacological activities. This review summarizes and critically discusses the research work on the chemical composition and pharmacological activities of essential oil of the genus Sideritis based on the currently valid taxonomy. Additionally, statistical analysis is encompassed to provide a deeper comprehensive understanding of the high chemical polymorphism of Sideritis essential oils. We expect that this review will encourage researchers to investigate unexplored Sideritis taxa and will contribute to revealing uncharted scientific territory and future perspectives on these plants.

Sideritis spp.: uses, chemical composition and pharmacological activities--a review

The genus Sideritis (Lamiaceae) comprises more than 150 perennial and annual vegetal species widely distributed in the Mediterranean area, together with Canary and Madeira islands. It is a controversial botanic genus, with a complex taxonomical classification due to the high number of hybridizations that occur between species; their study requires a deep research experience. Sideritis species have been traditionally used as teas for feeding, flavoring agents and in folk medicine as antiinflammatory, antiulcerative, antimicrobial, vulnerary, antioxidant, antispasmodic, anticonvulsant, analgesic and carminative agents. The chemical components found in Sideritis genus include terpenes, flavonoids, essential oil, iridoids, coumarins, lignanes and sterols, among others. Diterpenes, flavonoids and essential oil occur in almost every species and are the main compounds responsible for the observed in vivo and in vitro pharmacological activities. The aim of this review is to provide a comprehensive overview on the botanical, phytochemical and pharmacological aspects from the genus Sideritis, with the objective of establishing scientific basis that explains its ethnopharmacological use.

Chemical composition, antimicrobial and antioxidant activities of the essential oils of Sideritis erythrantha Boiss. and Heldr. (var. erythrantha and var. cedretorum P.H. Davis) endemic in Turkey

In the present study, chemical compositions, antimicrobial and antioxidant activities of the essential oils of Sideritis erythrantha var. erythrantha (SE) and Sideritis erythrantha var. cedretorum (SC), which are endemic taxa in Turkey, were investigated. The essential oils obtained by hydrodistillation were analyzed by gas chromatography-mass spectrometry (GC-MS). α-Pinene was the major component of the essential oils of SC and SE. SC essential oil was as effective as antibiotic against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin resistant Enterococcus faecalis (VRE), ampicillin resistant Haemophilusinfluenzae and vancomycin sensitive E. faecalis. Similarly, SE essential oil was also as effective as antibiotic against VRE and ampicillin resistant H. influenzae. Antioxidant activities of the essential oils of SC and SE were determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH), β-carotene/linoleic acid and reducing power. Both essential oils exhibited weak antioxidant activity. This is the first report on antimicrobial and antioxidant activities of the essential oils of SC and SE.