Determination of the total polyphenolic content in Cirsium palustre (L.) leaves extracts with manganese(IV) chemiluminescence detection.

It was found that weak chemiluminescence of manganese(IV)-hexametaphosphate-formaldehyde system was greatly enhanced by plant polyphenolic compounds. Based on this finding, a new flow injection chemiluminescence method (FI-CL) was developed for the determination of the total content of polyphenols in plant extracts. The calibration graph obtained for standard solutions of 6-hydroxyluteolin 7-O-glucoside (6OHLG) was linear in the range 0.001-0.8 μg mL(-1). The method was simple, rapid (203 samples h(-1)) and sensitive with a detection limit of 0.25 ng mL(-1). The FI-CL method was successfully applied to the determination of the total polyphenols content (as 6OHLG equivalents) in methanolic, ethyl acetate and aqueous extracts from leaves of Cirsium palustre (L.). Two types of solvent extraction methods (reflux and ultrasound assisted extraction) were used and compared in terms of extraction efficiency. A positive, significant linear correlation between the results obtained by FI-CL method and spectrophotometric methods was observed.