Relationship between mycotoxin contamination of colored corn types and phenolic acid evolution during kernel development.

Corn is one of the most cultivated and consumed cereal in the world. There is renewed interest in the identification of naturally occurring mechanisms which can reduce deoxynivalenol (DON) and fumonisin (FB) accumulation. Phenolic acids, could play a role in this type of resistance mechanism as suggested by their ability to reduce in vitro fungal growth and mycotoxin accumulation. In this investigation, total antioxidant activity (TAA), free and cell wall-bound phenolic acids were analyzed during kernel development of six maize genotypes characterized by a wide range of kernel traits (kernel color, size and hardness). Maize ears were handpicked from plants at four growth stages, namely: end of the silking stage, blister stage, dough stage and harvest maturity. TAA and phenolic acids were determined using QUENCHER and LC-MS/MS methods, respectively. Finally, an evaluation of the mycotoxin contamination at harvest maturity was employed by LC-MS/MS. TAA, free and cell wall-bound phenolic acids showed significant differences among corn types at different developmental stages. On average, a significant decrease in TAA, free and cell wall-bound phenolic acid content was observed during kernel development. Ferulic, p-coumaric and caffeic acids were the main cell wall-bound phenolic acids, while chlorogenic acid was the main free phenolic acid. A significant negative correlation was observed between free phenolic acids and TAA at the beginning of kernel development and DON contamination at harvest maturity, while no significant correlation was observed with FB contamination. The findings on phenolic acids provide insight into their evolution during kernel development, evidence of their role in the resistance to Fusarium and to mycotoxin contamination and information about bioactive compound content of maize varieties and hybrids characterized by a wide range of color.