Stephen C. Grace

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Environmental stresses such as high light, low temperatures, pathogen infection and nutrient deficiency can lead to increased production of free radicals and other oxidative species in plants. A growing body of evidence suggests that plants respond to these biotic and abiotic stress factors by increasing their capacity to scavenge reactive oxygen species.(More)
Plant phenolic compounds such as flavonoids and lignin precursors are important constituents of the human diet. These dietary phytophenolics have been recognized largely as beneficial antioxidants that can scavenge harmful active oxygen species including O(2)(.-), H(2)O(2), .OH, and (1)O(2). Here we review our current understanding of the antioxidant and(More)
Oxygen radicals play both pathological and physiological roles in biological systems. The detection of such radicals is difficult due to their transient nature and the presence of highly efficient antioxidant mechanisms. In plants the physiological role of oxygen is twofold, oxygen is produced by the oxidation of water and consumed as an electron acceptor.(More)
to those exhibited by xanthophyll cycle-dependent energy dissipation. The patterns of acclimation of The acclimation of photochemistry, xanthophyll cycleglutathione reductase are discussed in the context of dependent energy dissipation, and antioxidants was the multiple roles for reduced glutathione. Catalase characterized in leaves of Cucurbita pepo L. and(More)
Adverse health effects of airborne toxicants, especially small respirable particles and their associated adsorbed chemicals, are of growing concern to health professionals, governmental agencies, and the general public. Areas rich in petrochemical processing facilities (e.g., eastern Texas and southern California) chronically have poor air quality.(More)
Chlorogenic acid (CGA; 3-o-caffeoylquinic acid), a phenylpropanoid metabolite of plants, was oxidized by H2O2 in the presence of horseradish peroxidase. The primary and secondary oxidized products both were free radicals which gave EPR multiline signals at g = 2.0044 and 2.0042 in the presence of zinc as a spin stabilizing agent. The EPR kinetics showed(More)
We examined the ability of horseradish peroxidase (HRP), an analog of human myeloperoxidase, to protect DNA against oxidative damage caused by peroxynitrite in the presence of chlorogenic acid (CGA), a naturally occurring polyphenol. Chlorogenic acid inhibits the formation of single strand breaks in supercoiled pBR322 DNA by acting as a scavenger of(More)
We investigated differences between summer and winter in photosynthesis, xanthophyll cycle-dependent energy dissipation, and antioxidant systems in populations of Mahonia repens (Lindley) Don growing in the eastern foothills of the Colorado Rocky Mountains in deep shade, full exposure, and under a single-layered canopy of Pinus ponderosa (partially shaded).(More)
Rice (Oryza sativa L.) is a major grain in the human diet and carotenoids are valuable antioxidants. However, little is known about varietal differences in the carotenoid contents of the rice bran. The objective of this study is to determine the relative differences in bran carotenoid levels among all the five subgroups of rice. Measurements were made by a(More)