Polyphenolic compounds and essential oil analysis of selected species of the genus Thymus / Analýza fenolových zložiek a analýza silice vybraných druhov rodu Thymus

Abstract

Abstract The content of phenolic compounds (total phenolic compounds, tannins, flavonoids and anthocyanidins) of three species of thyme (Thymus pulegioides, Thymus pannonicus, Thymus praecox) of different origin (Bohemian-Moravian highlands, Křivoklat and Považsky Inovec) was determined using spectrophotometric methods of European Pharmacopoeia 8th edition. Furthermore, the determination of the content of essential oil and analysis of its constituents was realised. The amount of total phenolics was determined by a spectrophotometric method using the Folin-Ciocalteu reagent. Their content ranged from 3.87 to 8.86%. The content of tannins was established on a preliminary determination of the total phenolics, followed by adsorption of tannins on hide powder. The amount of tannins in our samples varied from 1.96 to 5.65%. The content of total flavonoids was determined by a spectrophotometric method using aluminium chloride. Quantitative analysis of flavonoids has shown that content in our samples ranged from 0.59 to 1.52% expressed as luteolin-7-O-glucoside (λ = 392 nm) and from 0.41 to 1.12% expressed as rutin (λ = 420 nm). Anthocyanins represent a small amount of total polyphenol content in Thymus species. In our samples, the content of anthocyanins expressed as cyanidin-3-O-glucoside varied from 0.02 to 0.1%. The determination of essential oil was realised by method of European Pharmacopoeia 8th edition. Its contents in our samples ranged from 0.2 to 0.75%. Gas chromatography-mass spectrometry was used for essential oil analysis. According to the presence of main monoterpene in Thymus essential oil, we can distinguish three chemotypes: thymol, carvacrol and linalool. Due to variations of chemical constituents of thyme essential oil, it was possible to observe a relationship between occurrence of certain chemotype and origin of sample. Differences in content of flavonoids have not shown a significant relationship to locality of origin. Slovak abstract Predložena praca bola zamerana na stanovenie obsahu vybranych fenolovych zlučenin (celkove fenoly, triesloviny, flavonoidy a antokyany) troch roznych druhov rodu Thymus (T. pulegioides, T. pannonicus, T. praecox) s rozdielnym povodom (Českomoravska vrchovina, Křivoklat a Považsky Inovec). Na stanovenie tychto zložiek boli využite spektrofotometricke metody Europskeho liekopisu, 8. vydanie. Zaroveň bol stanoveny aj obsah silice a bola vykonana analyza jej zložiek. Obsah celkovych polyfenolov bol stanoveny spektrofotometrickou metodou s využitim Folin-Ciocalteovho činidla. Obsah kolisal od 3.87 % do 8,86 %. Obsah trieslovin bol realizovany na zaklade predošleho stanovenia obsahu celkovych fenolov, a to adsorpciou trieslovin na kožny prašok. Ich obsah sa pohyboval v rozmedzi 1,96 % do 5,65 %. Na stanovenie obsahu flavonoidov bola využita spektrofotometricka metoda s chloridom hlinitym. Obsah flavonoidov vyjadrenych ako luteolin-7-O-glukozid (λ = 392 nm) kolisal od 0,59 % do 1,52 % a obsah flavonoidov vyjadrenych ako rutin (λ = 420 nm) sa pohyboval v rozmedzi od 0,41 % do 1,12 %. Antokyany zaberaju v ramci fenolovych zložiek rodu Thymus len minimalny podiel. V našich vzorkach bol obsah antokyanov vyjadreny ako cyanidin-3- O-glukozid a kolisal od 0,02 % do 0,1 %. Na stanovenie obsahu silice bola využita metoda Europskeho liekopisu, 8.vydanie. Obsah silice sa pohyboval v rozmedzi od 0,2 % do 0,75 %. Na analyzu silice bola nasledne využita metoda plynovej chromatografie s hmotnostnou spektrometriou. Na zaklade tejto analyzy bola zistena pritomnosť troch chemotypov silice, a to tymoloveho, karvakroloveho a linalooloveho chemotypu. Vďaka variaciami chemickeho zloženia silice, bolo možne pozorovať vzťah medzi pritomnosťou určiteho chemotypu a povodom vzorky. Rozdiely v stanoveni obsahu flavonoidov nepreukazali žiadny vyrazny vzťah k lokalite povodu.