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SENSIBILISIERTE PHOTOOXIDATION DURCH METHYLENBLAU, THIOPYRONIN UND PYRONIN — II. PHYSIKOCHEMISCHE GRUNDLAGEN DER PHOTODYNAMISCHEN WIRKUNG VON THIOPYRONIN
Author(s) -
BERG H.,
GOLLMICK F. A.,
JACOB H.E.,
TRIEBEL H.
Publication year - 1972
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1972.tb07344.x
Subject(s) - chemistry , polarography , flash photolysis , methylene blue , redox , reaction rate constant , photochemistry , kinetics , relaxation (psychology) , inorganic chemistry , catalysis , organic chemistry , photocatalysis , social psychology , psychology , physics , quantum mechanics
— The physical‐chemical properties of thiopyronine which result in its outstanding photodynamic effectiveness (in comparison to methylene blue and pyronine) are: (1) High velocity of free radical generation (kinetics followed by spectroscopy after flash photolysis). (2) High velocity of reoxidation of free radical (rate constant determined by kinetic spectroscopy under aerobic conditions). (3) Fairly positive reduction potential of oxidized free radical (from polarographic analysis of redox behavior). (4) Irreversible oxidation behavior of leuco‐thiopyronin in contrast to leuco‐methylene blue (the structure of leuco‐thiopyronin was elucidated by NMR‐analysis). (5) Fairly high equilibrium constant for complex formation with DN A (determination by high sensitive pulse‐polarography). From the sedimentation behavior and T‐jump relaxation of in vitro photodynamically treated DNA it is shown that not only does guanine photooxidation take place but also single‐ and double‐strand breaks can occur. The mechanism of this phenomenon is not yet elucidated.