PHOTOCHEMISTRY OF METAL NITROSYL COMPLEXES - DELIVERY OF NITRIC-OXIDETO BIOLOGICAL TARGETS

The discoveries that nitric oxide serves important roles in mammalian bioregulation and immunology have stimulated intense interest in the c hemistry and biochemistry of NO and derivatives such as metal nitrosyl complexes. Also of interest are strategies to deliver NO to biologica l targets on demand. One such strategy would be to employ a precursor which displays relatively low thermal reactivity but is photochemicall y active to give NO. This proposition led the authors to investigate p hotochemical properties of metal nitrosyl complexes such as the iron-s ulfur-nitrosyl Roussin cluster anions Fe2S2(NO)(4)(2--) and Fe4S3(NO)( 7)(-) as well as metalloporphyrin nitrosyls including ferriheme comple xes (with M. Hoshino of the Institute of Physical and Chemical Researc h, Japan) and nitrosyl nitrito complexes of ruthenium porphyrins Ru(P) (ONO)(NO). Continuous and flash photolysis studies of these compounds are reviewed here as are studies (with D.A. Wink and J.B. Mitchell of the Radiation Biology Branch of the US National Cancer Institute) usin g metal nitrosyl photochemistry as a vehicle for delivering NO to hypo xic cell cultures in order to sensitize gamma-radiation damage. (C) 19 98 Elsevier Science S.A.