|Garcia-Conesa, Maria - IFR, NORWICH, UK|
|Wilson, P - IFR, NORWICH, UK|
|Plumb, G - IFR, NORWICH, UK|
|Williamson, Gary - IFR, NORWICH, UK|
Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 15, 1998
Publication Date: N/A
Interpretive Summary: Ferulic acid is a compound in the cell walls of plants that has important roles in wall architecture. It is found attached to certain of the polysaccharides as ferulates. Two such ferulates can react with each other (to form dimers) and, in this way, the wall's polysaccharides become linked. This adds strength and rigidity and various other crucial properties to the cell wall. These ferulates and dimers are quite powerful natural antioxidants with potential applications in pharmaceutical and food industries. We have been studying the antioxidant properties of the range of dimers produced in grasses. Here we report that one of the major dimers (that is one of the hardest to artificially synthesize) is a more powerful antioxidant than all of the others. Such findings are hoped to provide alternative uses and enhanced value for our forage and grain crops. Such research is ultimately aimed at improving agricultural sustainability and maximizing our plant resources.
Technical Abstract: 8-8-diferulic acid (non cyclic form) (4,4'-dihydroxy-3,3'-dimethoxy-beta- beta'-bicinnamic acid) was chemically synthesized and the antioxidant properties were assessed using (a) inhibition of ascorbate/iron-induced peroxidation of phosphatidylcholine liposomes and (b) scavenging of the radical cation of ABTS (2,2'-azinobis (3-ethyl-benzothiazoline-6- sulphonate)) relative to the water-soluble vitamin E analogue, Trolox C. The structure of the chemically synthesized 8-8 dimer was confirmed by 1H- NMR, UV, and mass spectrometry. The 8-8 dimer showed the best antioxidant properties in the aqueous phase assay among the dimers present in plant cell walls. Like the other ferulic acid dimers, 8-8-diferulic acid is a better inhibitor of lipid peroxidation than ferulic acid. Some of the factors possibly involved in the antioxidant effect of these compounds (number of free hydroxyl groups, stability of transient radical and partition coefficient) are also discussed.