Production and Specificity of Polyclonal Antibodies to Hexanal−Lysine Adducts

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Abstract
Hexanal content is a widely used index of lipid oxidation in foods. The objectives of this study were to develop antibodies to hexanal−lysine adducts, devise an ELISA, and characterize antibody specificity. Hexanal was made immunogenic by covalent attachment to lysine side chains of bovine serum albumin via reductive alkylation. Polyclonal antibodies had antiserum titers as high as 6.15 × 105. A competitive indirect ELISA was developed with a detection limit of 0.7 ng of hexanal/mL. Antibodies were carrier-independent, reacting with hexanal conjugates of several proteins but not with the corresponding native proteins. Cross-reactivities with chicken serum albumin conjugates of n-heptanal, n-pentanal, and n-octanal were 86.3, 11.8, and 2.2%, respectively. Antibodies reacted strongly with hexanal-modified lysine and hexanal-modified ε-aminocaproic acid but did not recognize free amino acids or free hexanal. It may be feasible to use this ELISA to monitor lipid oxidation in food provided hexanal is alkylated to a carrier protein prior to analysis. Keywords: Immunoassay; hexanal; polyclonal antibodies; lipid oxidation