Metabolic profiling and antioxidant activity of Sideritis species growing in southeast europe

The genus Sideritis L. (Lamiaceae) comprises more than 150 species occurring mainly in the Mediterranean area and the Balkan Peninsula [1 – 2]. The plants in many locations of Greece are known as “mountain tea” and are used traditionally as herbal teas for treating cold, cough, fever, as well as digestive, diuretic or respiratory problems. Due to the high content of polyphenolic compounds the species have been also associated with potential antioxidant activity [3]. In a continuation of our studies on Sideritis genus [4], six of the most popular Balkan species (S. clandestina subsp. clandestina, S. euboea, S. perfoliata subsp. perfoliata, S. raeseri subsp. raeseri, S. scardica and S. syriaca) have been compared for their phenolic content, their antioxidant activity and their metabolic profiling. In more details, several extracts were prepared by maceration, using H₂O or H₂O/EtOH in different portions with various ratios of solvent to plant material. These extracts were evaluated for their Total Phenolic Content and found values ranging from 70 to 200 mg GAE/g extract, as well as for their Free Radical Scavenging activity and showed that possess significant antioxidant potential. In addition, phytochemical investigation lead to the isolation of the major components that were identified as acteoside, martynoside and glycosides of apigenin, hypolaetin, isoscutelarein, 4′-O-methylisoscutellarein and 4′-O-methyl-hypolaetin. Then, High Performance Thin Layer Chromatography (HPTLC) and Ultra Performance Liquid Chromatography (UPLC) were used for the chemical profiling of the extracts. The results showed that the metabolite profiling and antioxidant activity of all water extracts were identical while the extracts produced by H₂O/EtOH proportion had mainly quantitative differences in their chemical contents.

Keywords: mountain tea, Sideritis, antioxidant activity, secondary metabolites

References:

[1] Heywood V.H. Flora Europaea, Vol 3. Cambridge: Cambridge University Press; 1972: 138 – 143.

[2] Baden C. Mountain Flora of Greece, Vol 3. Edinburgh: Edinburgh University Press; 1991: 84 – 91.

[3] Charami M, Lazari D, Karioti A, Skaltsa H, Hadjipavlou-Litina D, Souleles Ch. Antioxidant and Antiinflammatory Activities of Sideritis perfoliata subsp. perfoliata (Lamiaceae), Phytother Res 2008; 4: 450 – 454.

[4] Aligiannis N, Kalpoutzakis E, Chinou I.B, Mitakou S. Composition and antimicrobial activity of the essential oils of five taxa of Sideritis from Greece, J Agric Food Chem 2001; 49: 811 – 815.