Production and Characterization of Polyclonal Antibodies against the Bitter Sesquiterpene Lactones of Chicory (Cichorium intybus L.)

Polyclonal antisera against lactucin and lactucopicrin, two bitter-tasting principles of chicory (Cichorium intybus L.), were obtained after immunization of rabbits with KLH−lactucin and KLH−lactucopicrin conjugates, respectively. In competitive ELISA, the sera from KLH−lactucopicrin-immunized rabbits showed a very low cross-reactivity with other sesquiterpene lactones containing a guaiane skeleton, 0.5% with lactucin, 1% with a mixture of lactucin and 11β,13-dihydrolactucin, and 5% with 8-deoxylactucin and 11β,13-dihydro-8-deoxylactucin. The sera from rabbits immunized with KLH−lactucin showed 50% cross-reaction with 8-deoxylactucin and its 11β,13-dihydro derivative and only 0.4% cross-reaction with lactucopicrin. In competitive ELISAs, chicory extracts spiked with free sesquiterpene lactones showed an expected increase in inhibition level. These ELISAs seem useful in the assessment of chicory bitterness. Keywords: Sesquiterpene lactones; chicory (Cichorium intybus); lactucin; lactucopicrin; bitter taste...