ARS | Publication request: Antioxidant and Antimelanogenic activities of polyamine conjugates from corn bran and related hydroxycinnamic acids

Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 20, 2007
Publication Date: May 1, 2007
Citation: Choi, S., Lee, S., Kim, E., Yoon, K., Parris, N., Hicks, K.B., Moreau, R.A. 2007. Antioxidant and Antimelanogenic activities of polyamine conjugates from corn bran and related hydroxycinnamic acids. Journal of Agriculture and Food Chemistry 55, p.3920-3925.

Interpretive Summary: Corn and other grains contain several types of common phenolic compounds that have been recognized to have antioxidant properties. Previously, we identified two new types of phenolic compounds at high levels in corn bran and through collaborative studies with other ARS scientists we determined that these new compounds inhibited the synthesis of aflatoxins in Aspergillis flavus. In the current study we identified a third type of unusual phenolic compound in corn bran and we found that all three of the new corn bran phenolic compounds had antioxidant properties which were more potent than ferulic acid, p-coumaric acid, and other common phenolic compounds. In addition, we found that one of the new phenolic compounds inhibited melanin synthesis and may be useful as a natural skin whitening agent for use in cosmetics. This report contains useful new information which indicates that corn bran could be a valuable source of novel antioxidants and whitening agents for food and cosmetic applications.

Technical Abstract: The antioxidant activity of three major polyamine conjugates, N,N'-dicoumaroyl- putrescine (DCP), N-p-coumaroyl-N'-feruloylputrescine (CFP) and N,N'-diferuloyl- putrescine (DFP) isolated from corn bran, and their related hydroxycinnamic acids, p-coumaric acid (CA) and ferulic acid (FA), were evaluated by three antioxidant in vitro assay systems, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and superoxide and hydroxyl radicals generated by enzymatic and nonenzymatic reactions. Additionally, the five phenolic compounds were evaluated for melanogenesis inhibitory activity using mushroom tyrosinase and B16 melanoma cells. Most of the phenolic compounds significantly scavenged DPPH, superoxide and hydroxyl radicals in a dose-dependent manner. Particularly, DFP showed potent DPPH (IC50=38.46 uM) and superoxide (IC50=291.62 uM) radical scavenging activities, while DCP exhibited the strongest hydroxyl radical scavenging activity (IC50=120.55 uM). CFP also exerted moderate DPPH, superoxide and hydroxyl radical scavenging activities. Meanwhile, DCP (IC50=181.73 uM) showed potent tyrosinase inhibitory activity toward L-tyrosine as the substrate, whereas DFP (IC50=733.64 uM) significantly inhibited melanin synthesis in B16 melanoma cell. These current results indicate that these three polyamine conjugates from corn bran may be useful potential sources of natural antioxidants and skin whitening agents.