Proceedings Article | 27 February 2007
KEYWORDS: Photodynamic therapy, Bladder, Tumors, In vitro testing, Bladder cancer, Leukemia, In vivo imaging, Cell death, Fluorescence correlation spectroscopy, Cancer
In the last three years we have prepared and studied the polar methanolic extract PMF, of the herb Hypericum
perforatum L, and studied as a new, alternative photosensitizing substance for PDT. Hypericum perforatum
L., as well as PMF, contains a number of naphthodianthrone derivatives (hypericins), such as hypericin and
pseudohypericin, as its main photosensitizing constituents. PMF has been tested as a PDT agent in vitro in
bladder cancer cells, leukemia cells, and in vivo in rat tumor bearing urinary bladder.
In order to evaluate the contribution of the hypericins in the overall PDT action, and prepare a better
photosensitizing extract than PMF, we have separated the extract in four main fractions (1,2,3,4), and tested
their PDT effects against the HL-60 leukemic cells. The concentration of hypericins in the extracts was
found 0.08% for fraction 1, 0.09% for fraction 2, 0.8% for fraction 3, and 2,8% for fraction 4. The PDT
activity observed among the fractions was proportional to their hypericins concentration, thus increasing in
the order of increasing number: fraction 4 > fraction 3 > fraction 2 > fraction 1. Fraction 4 proved to be the
most powerful fraction. However, despite its relatively high hypericins concentration (2.8%), compared with
the total extract PMF (1.37%), fraction 4 proved to be less active in the cell line tested. This result indicates
that there are other photosensitizing constituents within the PMF extract which contribute significantly in the
overall PDT action, and therefore the extract should be used as it is for further PDT studies, without any
further purification.
