Determination of major constituents in St. John's Wort under different extraction conditions

Different extraction procedures have been evaluated to quantify the major constituents (hypericins, hyperforins and flavonoids) of H. perforatum drug samples. The total amount of hypericins has been determined by UV and HPLC. Analysis of hyperforins and flavonoids has been performed by HPLC. Sonication with MeOH resulted the best extraction method to obtain a homogenous drug sample, representative of all the major metabolites and with less degradation products. The procedure was standardized with a commercial drug sample and then applied to quantify the active metabolites in H. perforatum plants collected in various localities in South Italy. Two of the drug samples resulted particularly rich in hypericin, namely, Altamura, 0.21% and Casamassima, 0.27%. Analysis of the flavonoid content confirmed the presence, in Italy, of a chemotype of H. perforatum without rutin.