N-Nitrosamines and N-nitrosamides have been reported to be mutagenic. N-Nitrosamides are direct mutagens that need no activation to be mutagenic, whereas N-nitrosamines need to be enzymatically activated to exert their mutagenicity. Oxidative demethylation of nitrosamines is a commonly accepted activation mechanism. Another pathway of nitroso compounds, denitrosation, has recently been proposed. The mechanism of denitrosation, however, is still unknown.
The purpose of this study was to use a photo -reaction model to explore the possible denitrosation mechanism of N-nitroso compounds. An N-nitrosamine, N-nitrosomorpholi ne (NMOR), and an N-nitrosamide, N-methyl-N'-nitrosoguanidine (MMNG), were irradiated with long-wavelength UV light in the presence of phosphate. Denitrosation of these nitroso compounds occurred, and free radicals were generated during the photolysis of N-nitroso compounds. The free radical from NMOR is carbon centered, and the free radical from MNNG is nitrogen centered. They have different responses to phosphate. A stable mutagen is formed during the photolysis of NMOR in the presence of phosphate. The formation of this stable mutagen is through a free-radical mechanism. MNNG appears to be inactivated in terms of mutagenicity by the photodenitrosation. Free radicals produced during the photolysis of NMOR and MNNG are mutagenic through a direct radical interaction mechanism.
The results of this study indicate that the newly found pathway of N-nitroso compounds, denitrosation, may be related to a free-radical mechanism.
Identifer | oai:union.ndltd.org:UTAHS/oai:digitalcommons.usu.edu:etd-8290 |
Date | 01 May 1989 |
Creators | Wang, Zhenyu J. |
Publisher | DigitalCommons@USU |
Source Sets | Utah State University |
Detected Language | English |
Type | text |
Format | application/pdf |
Source | All Graduate Theses and Dissertations |
Rights | Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact digitalcommons@usu.edu. |
Page generated in 0.0017 seconds