Structure-reactivity relationships between the fluorescent chromophores and antioxidant activity of grain and sweet sorghum seeds.
Polyphenolic structures are the putative cause of a variety of seed functions including bird/insect resistance and antioxidant activity. Structure-reactivity relationships are necessary to understand the influence of polyphenolic chromophore structures on the tannin content and free radical quenching ability determined by the traditional calorimetric methods. This study investigated the relationships between the structural attributes of fluorescent chromophore and the following seed characterization methods: procyanidin (by acid-butanol assay) and flavonoid (by vanillin assay) contents, radical quenching (by DPPH assay), electron-donating capacity (by FeIIIreduction), andλmax(by UV/visible spectrophotometry). Distinctively different response was observed for different seed categories: U.S. grain sorghum hybrids, African grain sorghum, and sweet sorghum. The U.S. grain sorghum varieties (low-tannin to maximize the livestock digestion) responded only to the DPPH assay. For sweet sorghum and African grain sorghum, linear correlation was observed between (1) the antioxidant activity (2) the amounts of procyanidins and flavonoids, and (2) the aromaticity of fingerprint fluorescent structures.
USDA-ARS Southern Regional Research Center 1100 Robert E. Lee Boulevard New Orleans Louisiana 70124.
Minori
M
Uchimiya
USDA-ARS Crop Genetics and Breeding Research Unit 2747 Davis Road Tifton Georgia 31793.
Xinzhi
X
Ni
USDA-ARS Plant Genetic Resources Conservation Unit Griffin Georgia 30223.
Ming Li
ML
Wang
Cereal; colorimetric method; proanthocyanidin; sweet sorghum; transition metal