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Robert V. Cooney, Patricia J. Harwood, Laurie J. Custer, and Adrian A. Franke

University of Hawaii, Cancer Research Center of Hawaii, Honolulu, HI 96813 USA

Abstract
Plants are more susceptible to the toxic effects of nitrogen dioxide when exposure takes place in the dark. Beta-carotene and other common carotenoids react with nitrogen dioxide in the dark to yield intermediate nitrosating agents consistent with the formation of nitrite esters. Simultaneous exposure of carotenoids to NO₂ and light significantly reduced formation of nitrosating intermediates and resulted in the release of nitric oxide (NO) into the gas phase. Light-mediated reduction of NO₂ to NO by carotenoids may be an important mechanism for preventing damage in plants exposed to NO₂. The formation of nitrosating agents from the reaction of carotenoids with NO₂ suggests that their ability to prevent nitrosative damage associated with NO₂ exposure in both plants and animals may be limited in the absence of light. Key words: carotenoids, light-mediated reduction, nitric oxide, nitrogen dioxide, plant damage. Environ Health Perspect 102: 460-462 (1994)

http://ehpnet1.niehs.nih.gov/docs/1994/102-5/cooney.html

Address correspondence to R.V. Cooney, University of Hawaii, Cancer Research Center of Hawaii, 1236 Lauhala Street, Honolulu, HI 96813 USA.

This research was supported by grant ES-04302 from the National Institute of Environmental Health Sciences and the Leahi Trust.

Received 13 August 1993 ; accepted 23 February 1994.