Houseleek (Sempervivum tectorum L., Crassulaceae) has been used in folk medicine as an anti-inflammatory remedy. Some studies have described its antinociceptive, liver- protecting and membrane stabilizing effects [1, 2, 3]. These may correlate with diverse phenolic compounds such as polyphenols, proanthocyanidines, flavonols and flavonol- glycosides, which act as potent antioxidant agents. The aim of our study was to evaluate phenolic composition and content of Sempervivum tectorum L. Further purpose was to reveal the contribution of these compounds in radical scavenger action. Polyphenol, tannin, proanthocyanidine and flavonoid contents of lyophilized houseleek leaves were determined by spectrophotometry according to the instructions of the European Pharmacopoeia 5.08 (2007). Contents are, respectively: 4,9mg*g-1, 2,0mg*g-1, 2,7mg*g-1 and 9,4mg*g-1. Flavonoid fingerprints of extracts before and after acidic hydrolysis have been evaluated by TLC and HPLC methods. Also numerous catechin and proanthocyanidine compounds were detected by TLC. HPLC separations were performed on a Supelcosil C18 (250*4,6mm; 5µm) column. For elution, acetonitrile and 2,5 v/v% acetic acid were used. The main flavonoid aglycone was kaempferol, its presence has been proven by standard addition and UV spectra. The antioxidant activity of different extracts was determined by neutralization of the free radicals ABTS [2,2'-azinobis-(3-ethyl-benzothiazoline-6-sulfonic acid)] and DPPH (2,2-diphenyl-1-picrylhydrazyl) [4]. We have found that the scavenger activity of extracts containing flavonoid aglycones was the highest (EC50DPPH=1,29*10-5 g*ml-1, EC50ABTS=0,75*10-5 g*ml-1), similar to that of kaempferol standard (EC50DPPH=1,91*10-5 g*ml-1, EC50ABTS=0,85*10-5 g*ml-1). Extracts with different chromatographic profiles of flavonoid glycosides were less effective scavengers of DPPH and ABTS free radicals (EC50DPPH=7,87*10-5 g*ml-1, EC50ABTS=3,73*10-5 g*ml-1).
References: [1] Kekesi, I. et al. (2003) Phytother Res 17: 1032–1036. [2] Blázovics, A. et al. (1993) Phytother Res 7: 98–100. [3] Blázovics, A. et al. (2000) J Ethnopharmacol 73: 479–485. [4] Re, R. et al. (1999) Free Rad Biol Med 26: 1231–1237.
