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Hypericin: A Photodynamic
Drug
Trevithick, Colleen1
and Foote, Christopher1
University of California Los Angeles1
Abstract-
Hypericin, which is found in many plants including St. John's Wort,
has many therapeutic activities, but also has harmful side effects.
Exposing hypericin to light gives excited-state intermediates that can
produce singlet oxygen, superoxide, and other radical species. Investigation
of hypericin reactivity will lead to an understanding of the potential
harmful side effects of hypericin therapy. It is extremely important
to establish all harmful side effects of any drug, especially those
with photodynamic properties. Using laser light to excite hypericin,
we attempted to observe its transient species in both aqueous and organic
media. We observed no transient species of hypericin in aqueous media.
Hypericin forms aggregates in aqueous media that give no long-lived
excited state. In organic media, we observed the transient species of
hypericin. Observation of this excited state is a very important step
towards elucidating the potential dangerous side effects of hypericin
therapy.
Keywords: hypericin,
photodynamic drug, excited-state intermediates, transient spectrum
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