Molecular and Biochemical Aspects of Photodynamic Action

Hypericin and Its Photodynamic Action

“…Whether or not this narrow definition is applicable to the underlying molecular mechanism of hypericism (Giese, 1971) remains to be seen. A comprehensive review of the literature on the molecular basis of photodynamic action is available (Spikes, 1968;Spikes and Livingston, 1969;Foote, 1976;Krinsky, 1977;Ito, 1978;Lochmann and Micheler, 1979;Duran, 1982). In this section, some of the published results on photodynamic action of hypericin will be reviewed.…”

Dye Binding and Photodynamic Action

“…Several good reviews on the complex formation of acridine dyes are available [32,69,70,93]. However, little is known about the relationship between the structure or modes of the dye-nucleic acid complex and photodynamic potentiality.…”

Crosslinking of double-helical nucleic acids with a photoreactive analog of ethidium

“…The advantages of ethidium diazide as a cross-linker lie in (i) its easy preparation and purification, as described above, (ii) the high ratio of cross-linking to strand breakage obtainable under correct conditions, (iii) its comparability to the well-documented ethidium ion, and (iv) the fact that it can be activated by long-wavelength ultraviolet or blue light, thus avoiding the absorption bands of most biological molecules and protecting the system against photodegradation. A particular advantage over psoralen is that the photolysis of psoralen appears to produce singlet oxygen as a biologically damaging side product (Singh & Vadasz, 1978;Lochman & Micheler, 1979). Disadvantages of ethidium diazide vis-a-vis the psoralens are that the photoreaction is less controllable (both ends react at once) and is irreversible.…”