Purification of cynaroside 7-O-beta-D-glucosidase from the herbal drug Cynarae folium (artichoke leaves)

The enzymatic degradation of cynaroside (luteolin 7-O-glucoside), a dominan t flavonoid in artichoke, has been investigated in the herbal drug Cynarae folium (artichoke leaves). Various drug samples obtained from several suppl iers were shown to behave extremely variable in terms of their ability to h ydrolyse endogenous flavone 7-O-glucosides under fermentative conditions. C ynaroside was best hydrolysed by protein extracts prepared Rom the drug at pH 5.0 and 55 degrees C. The responsible cynaroside 7-O-beta-D-glucosidase was purified 250-fold in about 3 % yield by the combination of ammonium sul phate Fractionation, hydrophobic interaction chromatography on Phenylsephar ose 6EF, anion exchange on Source 30Q, and gel filtration chromatography on Superdex 200. Kinetic constants were determined using partially purified e nzyme. Cynaroside and other flavonoid 7-O-glucosides were all well hydrolys ed by the enzyme preparation, whereas the 3-O-glycosides tested were either barely deglycosylated (isoquercitrin) or not hydrolysed at all (rutoside). During drug processing with a view to producing phytopharmaceuticals the c ynaroside 7-O-beta-D-glucosidase described here may become active, thus rel easing luteolin from its precursor cynaroside. This in turn might be of som e relevance with regard to the pharmaceutical quality of artichoke preparat ions since luteolin is regarded as one of the important active principles o f artichoke herbal preparations.