Investigation of molecular mechanisms in photodynamic action and radiobiology with nanosecond flash photolysis and pulse radiolysis. Progress report, 1982

Technical Report · Sat Jan 01 04:00:00 EST 1983

OSTI ID:6237802

Grossweiner, L I

Liposomes have been employed as membrane models applicable to photosensitization in phototherapy procedures. The results with 8-methoxypsoralen, the sensitizer in PUVA therapy of psoriasis, show that singlet oxygen generated by near-uv (uv-A) irradiation induces membrane damage leading to lysis. A similar role of singlet oxygen has been shown for photosensitization of liposomes by methylene blue, with the new observation that hydrodynamic forces promote the lytic action initiated by singlet oxygen attack on an unsaturated site of phosphatidylcholine. Liposome photosensitization by hematoporphyrin follows a Type II mechanism mediated by singlet oxygen for low sensitizer concentrations, and a Type I, anoxic, mechanism when the hematoporphyrin is aggregated. Similar concentration effects obtain with hematoporphyrin derivative (hpd), the photosensitizer in photoradiation therapy of malignant tumors. Studies on the components of hpd separated by gel chromatography show that the putative biological active fraction can photosensitize membrane damage under oxic and anoxic conditions. The oxic pathway was suppressed by binding to human serum albumin, as involved in serum transport of hpd prior to localization in tumor tissue. A study on hematoporphyrin photosensitization of targets other than membranes has shown that singlet oxygen is responsible for the photosensitized inactivation of subtilisin BPN' and photooxidation of tryptophan in human and bovine serum albumin. In the case of the serum proteins, the singlet oxygen is generated by the sensitizer-protein complex and it may react with all protein in the system. 11 references.

• Research Organization: Illinois Inst. of Tech., Chicago (USA)
• DOE Contract Number: AC02-76EV02217
• OSTI ID: 6237802
• Report Number(s): DOE/EV/02217-46; COO-2217-46; ON: DE85004290
• Country of Publication: United States
• Language: English

Related Subjects

550200 -- Biochemistry
560400* -- Other Environmental Pollutant Effects
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMINES
ANTI-INFECTIVE AGENTS
ANTIMICROBIAL AGENTS
AZINES
BIOLOGICAL EFFECTS
BIOLOGICAL PATHWAYS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
DECOMPOSITION
DRUGS
ELECTROMAGNETIC RADIATION
ELEMENTS
HALIDES
HALOGEN COMPOUNDS
HEMATOPORPHYRINS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
LASERS
LIPOSOMES
MEMBRANES
METHYLENE BLUE
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANOIDS
OXYGEN
PHENOTHIAZINES
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PHOTOSENSITIVITY
PIGMENTS
PORPHYRINS
RADIATIONS
RADICALS
SENSITIVITY
THERAPY
ULTRAVIOLET RADIATION