St. John's Wort extracts are used for the treatment of mild to moderately severe depression, and
their composition and standardization have been thoroughly investigated. Standardization of
St. John's Wort extracts has to cope with several factors that affect the phytochemical profile of
the plant, with geographic location, seasonal variations and subspecies all being important. To
address this issue, three different subspecies of Hypericum perforatum L. were profiled in
relation to different maturation phases, evaluating the variations in the context of the major
secondary metabolites from this plant. HPLC analysis indicated that H. perforatum subsp.
perforatum is richer in secondary metabolites than the other subspecies, and that the three
subspecies show a different profile during the developmental stages. Hypericins, hyperforins
and flavonoids peak at quite different stages, and the standardization of Hyperici extracts based
only on the contents of hypericin is not adequate to guarantee batch reproducibility of the
extracts.