Characterization of Sideritis clandestina subsp. peloponnesiaca Polar Glycosides and Phytochemical Comparison to Other Mountain Tea Populations

Sideritis clandestina (Bory & Chaub.) Hayek subsp. peloponnesiaca (Boiss. & Heldr.) Baden (SCP) is endemic to the mountains of the Northern Peloponnese (Greece). This and other Sideritis taxa, collectively known as mountain tea, are widely ingested as beverages for refreshment or medicinal purposes. We describe a methodology for the characterization of SCP. Four iridoid glycosides (monomelittoside, melittoside, ajugoside, and 7-O-acetyl-8-epiloganic acid), two phenolic acid glycosides (vanillic and salicylic acid glycosides), and three caffeoyl ester glycosides (chlorogenic acid, verbascoside, and isoverbascoside) were isolated from SCP for the first time. We used ultrasound-assisted extraction of 3 g of plant material to produce petroleum ether and aqueous extracts, which we then analyzed using GC/MS and LC/MS. This was applied to eight samples from four different taxa. In total, 70 volatile and 27 polar metabolites were determined. The S. clandestina samples had a lower phenolic content and weaker antioxidant properties than S. raeseri and S. scardica. However, S. clandestina ssp. clandestina seemed to be the most aromatic taxon, with almost double the number of volatiles as the others. Τhis study could contribute to authentication and chemotaxonomic studies of Sideritis taxa.

Comparison of Volatile Organic Compounds of Sideritis romana L. and Sideritis montana L. from Croatia

A study on the headspace volatile organic compounds (VOCs) profile of native populations of Sideritis romana L. and Sidertis montana L., Lamiaceae, from Croatia is reported herein, to elucidate the phytochemical composition of taxa from this plant genus, well-known for traditional use in countries of the Mediterranean and the Balkan region. Headspace solid-phase microextraction (HS-SPME), using divinylbenzene/carboxene/polydimethylsiloxane (DVB/CAR/PDMS) or polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber, coupled with gas chromatography-mass spectrometry (GC-MS) was applied to analyze the dried aerial parts of six native populations in total. Furthermore, principal component analysis (PCA) was conducted on the volatile constituents with an average relative percentage ≥1.0% in at least one of the samples. Clear separation between the two species was obtained using both fiber types. The VOCs profile for all investigated populations was characterized by sesquiterpene hydrocarbons, followed by monoterpene hydrocarbons, except for one population of S. romana, in which monoterpene hydrocarbons predominated. To our knowledge, this is the first report on the VOCs composition of natural populations of S. romana and S. montana from Croatia as well as the first reported HS-SPME/GC-MS analysis of S. romana and S. montana worldwide.

Volatile aroma compounds in infusions of stems and rosette leaves of Sideritis raeseri Boiss. & Heldr. from R. Macedonia, Albania and Greece

The composition of the volatile aroma components was defined in the infusion prepared by stems of Sideritis raeseri (SR-S) from R. Macedonia, Albania and Greeсe and in the infusion of rosette leaves of S. raeseri (SR-R) from R. Macedonia. Analysis were made by gas chromatography (GC/FID/MS) equipped with a headspace (HS) sampler. Twenty components (12 monoterpenes representing 76.70- 94.84% and 8 sesquiterpenes representing 5.16-18.55% of the entire volatiles) were identified as aroma components in SR-S samples. The predominant components in all samples were β-pinene, α-pinene and trans-сaryophyllene. The high abundance of limonene and δ-3-сarene were characteristic for the samples from Greeсe and 1,8-сineole was for the samples from R. Maсedonia and Albania. In the infusions of SR-R, ten components were identified, 5 monoterpenes (73.20-83.89%) and 5 sesquiterpenes (16.10-26.80%). Prevailing components in all tested samples of SR-R were β-pinene, α-pinene, 1,8-cineole and α-epi-murolol. There was almost no difference in the chemical profiles of the aroma compounds between SR-S and SR-R. Infusion of rosette leaves exhibit very similar aroma compounds profile with the infusion of stems of S. raeseri.