29B-38 |
Vitamin C equivalent antioxidant capacity of various polyphenolics, fruits, and vegetables and the polyphenolic structure-bioactivity relationship |
D. O. KIM1, O. K. Chun1, H. Y. Moon2, and C. Y. Lee1. (1) Food Science & Technology, Cornell Univ., New York State Agricultural Experiment Station, 630 W. North St., Geneva, NY 14456-1371, (2) Division of Food, Biological and Chemical Engineering, Daegu University, # 15 Neriri Jinryang, Gyeongsan, 712-714, South Korea Antioxidants are compounds that can delay, inhibit, or prevent the oxidation of oxidizable matters by scavenging free radicals and diminishing oxidative stress. Oxidation in a biological system may lead to quality loss in foods, coronary heart disease, cancers, and DNA damage. Polyphenolics act as free radical scavengers and have shown beneficially health-promoting effects in the chronic and degenerative diseases. Only limited information is available in the area of the relationship between antioxidant capacity and chemical structure of polyphenolics. In particular, there are no available accounts of the structural relationship of antioxidants evaluated on the basis of vitamin C. Our objectives were to evaluate the antioxidant capacity of various polyphenolics, fruits, and vegetables as vitamin C equivalent antioxidant capacity (VCEAC) and to explain the polyphenolic structure-bioactivity relationship. The ABTS radicals were used to evaluate antioxidant capacity. The polyphenolics tested are categorized at follows: phenolics acids, flavonoids, synthetic food additives, vitamins, and other miscellaneous polyphenolics. Polyphenolics commonly showed a higher VCEAC compared to monophenolics. Among phenolic acids test, gallic acid showed the highest VCEAC, whereas delphinidin, myricetin, and epigallocatechin were the highest among flavonoids. There was a strong linear correlation between VCEAC and the number of free OH groups around the flavonoid aglycone. Two characteristic chemical structures, the catechol moiety in the B ring and the 3-OH group in a chroman ring, were found to be very important. Synthetic food additives conventionally used in food industry were less effective antioxidants than ascorbic acid. Other naturally occurring polyphenolics followed the general trends as phenolic acids and flavonoids. Overall, natural polyphenolics exhibited high antioxidant activities. Fruits and vegetables that contain high amount of phenolic phytochemicals (chlorogenic acid, rutin, various anthocyanins, etc.) will exert high antioxidant activities. A higher consumption of fruits and vegetables might be able to inhibit, prevent or delay such age-related diseases.
Session 29B, Food Chemistry: Lipids, antioxidants and emulsifiers
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