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Free Radical Scavenging Capacities of Winter Wheat
Reference
Yu, L., Haley, S., Perret, J. and Harris, M. 2004. Comparison of wheat flours grown at different locations for their antioxidant properties. Food Chemistry 86: 11-16.

Background
Reactive oxygen species (ROS) generated during cellular metabolism or peroxidation of lipids and proteins play a causative role in the pathogenesis of cancer and coronary heart disease (CHD), as demonstrated by Slaga et al. (1987), Frenkel (1992), Marnett (2000) and Zhao et al. (2000). However, and fortunately so, as noted by Yu et al., "antioxidant treatments may terminate ROS attacks and reduce the risks of CHD and cancer, as well as other ROS-related diseases such as Parkinson's disease (Neff, 1997; Chung et al., 1999; Wong et al., 1999; Espin et al., 2000; Merken and Beecher, 2000)." As a result, the four Colorado State University scientists from Fort Collins (CO, USA) say that "developing functional foods rich in natural antioxidants may improve human nutrition and reduce the risks of ROS-associated health problems."

In light of these observations, it is only natural to wonder how global warming might affect crop ROS scavenging activities and chelating capacities, the latter of which may inhibit radical mediated oxidative chain reactions by stabilizing transition metals that are required to catalyze the formation of the first few radicals needed to initiate the radical reactions (Nawar, 1996). In one of the few studies to broach this subject, Wang and Zheng (2001) examined the effects of a group of day/night temperature combinations on the antioxidant activities of the juice of two strawberry varieties, finding, in the words of Yu et al., that "the highest day/night temperature resulted in fruits with the greatest phenolic content as well as antioxidant activities." Encouraged by this finding, the Fort Collins scientists decided to explore the subject further in a study of winter wheat.

What was done
Flour extracts of three hard winter wheat varieties that were grown at five different locations in Colorado were examined and compared for their radical scavenging properties, chelating capacities and total phenolic contents.

What was learned
No statistically significant correlations were found, but the scientists report that "a correlation coefficient of 0.890 (P = 0.110) was detected for the chelating activity of Akron flour and the total hours of the growth location exceeding 32C during the 6-week grain-filling period."

What it means
Although no firm conclusions could be drawn from the results of their study, in contrast to the study of Wang and Zheng (2001), Yu et al.'s findings were intriguing enough to lead them to state that "more research is needed to clarify how varieties and growing conditions alter the antioxidant properties of wheat, wheat flour and bran." We agree. This is a subject of enormous importance that has been largely neglected in the global warming debate of the past several years; and it is a deficiency that must be remedied.

References
Chung, H.S., Chang, L.C., Lee, S.K., Shamon, L.A., Breemen, R.B.V., Mehta, R.G., Farnsworth, N.R., Pezzuto, J.M. and Kinghorn, A.D. 1999. Flavonoid constituents of chorizanthe diffusa with potential cancer chemopreventive activity. Journal of Agricultural and Food Chemistry 47: 36-41.

Espin, J.C., Soler-Rivas, C. and Wichers, H.J. 2000. Characterization of the total free radical scavenger capacity of vegetable oils and oil fractions using 2,2-diphenyl-1-picryhydrazyl radical. Journal of Agricultural and Food Chemistry 48: 648-656.

Frenkel, K. 1992. Carcinogen-mediated oxidant formation and oxidative DNA damage. Pharmacology and Therapeutics 53: 127-166.

Marnett, L.J. 2000. Oxyradicals and DNA damage. Carcinogenesis 21: 361-370.

Merken, H.M. and Beecher, G.R. 2000. Measurement of food flavonoids by high-performance liquid chromatography: A review. Journal of Agricultural and Food Chemistry 48: 577-599.

Nawar,W.W. 1996. Lipids. In: Fennema, O.R. (Ed.). Food Chemistry. Marcel Dekker, New York, NY, USA, pp. 225-313.

Neff, J. 1997. Big companies take nutraceuticals to heart. Food Processing 58(10): 37-42.

Slaga, T.J., O'Connell, J., Rotstein, J., Patskan, G., Morris, R., Aldaz, M. and Conti, C. 1987. Critical genetic determinants and molecular events in multistage skin carcinogenesis. Symposium on Fundamental Cancer Research 39: 31-34.

Wang, S.Y. and Zheng, W. 2001. Effect of plant growth temperature on antioxidant capacity in strawberry. Journal of Agricultural and Food Chemistry 49: 4977-4982.

Wong, S.S., Li, R.H.Y. and Stadlin, A. 1999. Oxidative stress induced by MPTP and MPP+: Selective vulnerability of cultured mouse astocytes. Brain Research 836: 237-244.

Zhao, J., Lahiri-Chatterjee, M., Sharma, Y. and Agarwal, R. 2000. Inhibitory effect of a flavonoid antioxidant silymarin on benzoyl peroxide-induced tumor promotion, oxidative stress and inflammatory responses in SENCAR mouse skin. Carcinogenesis 21: 811-816.


Reviewed 19 May 2004