Structure-dependent lipid peroxidation by photoirradiation of pyrene and its mono-substituted derivatives

Abstract

Pyrene, one of the most studied polycyclic aromatic hydrocarbons, can damage biological macromolecules and cause toxicity when irradiated by light. The effect of substituents, 1-amino, 1-hydroxy, 1-nitro, and 1-bromo, on light-induced lipid peroxidation is studied. Degradation kinetics and photoproduct analyses were conducted to test how these substituents affect the photoreaction. All five compounds have widely different photodegradation rates, with degradation half-lives, ranging from 8 min to 495 min. These rates parallel their light absorptivity. Four out of the five compounds induce lipid peroxidation when irradiated with UVA light, whereas 1-aminopyrene causes minimum or no lipid peroxidation. The relative amount of lipid peroxidation caused is: 1-bromopyrene > pyrene > 1-nitropyrene ≈ 1-hydroxypyrene > 1-aminopyrene. This relative lipid peroxidation is dependent on the substituent due to the following factors: light absorptivity, relative rates of the competing processes in the excited states, nature of the photoreaction, and nature of the photoproducts.

Keywords:

• Mono-substituted pyrene
• photoreaction rate
• UVA radiation
• lipid peroxidation.

Acknowledgments

Use of Research Core Facilities was made possible by NIH grant number G12 RR13459 from the NCRR/RCMI NSF CHE 0840450. Financial support for TEP was from the U.S. Department of Education Grant number P031B090210-11 through Title III-HBGI. The authors wish to thank Dr. Peter Fu of the National Center for Toxicological Research for useful discussions.