HPLC-DAD and TLC-densitometry for quantification of hypericin in Hypericum perforatum L. extracts

Hypericum perforatum L. is a spontaneous perennial herbaceous plant. widely distributed in Europe, Asia, Northern Africa, and North America. The dried flowers or dried aerial parts are used to prepare the drug Hyperici Herba or St. John's Wort. Nowadays this drug is largely used as a natural antidepressant; hypericin and hypericin-like substances are considered the main active ingredients. In this work the hypericin and pseudohy-pericin content of hydroalcoholic extracts both of Hyperici Herba and of Hypericum perforatum L. dried flowers were measured by two techniques, TLC-densitometry with fluorescence detection and reversed-phase HPLC-DAD (diode-array detection). The quantitative data obtained by applying these techniques were compared and the identification of the main flavonoid constituents was performed by HPLC-DAD for characterization of the extracts. The quantitative data obtained by use of the two techniques were in good agreement and statistical analysis of the findings was indicative of the equivalence of the techniques.