Radical Intermediates in the Degradation of Hop Acids.

Radical formation in isohumulones was investigated under different types of stress, including temperature, transition metal ions, and hydrogen peroxide. Including dihydroisohumulones and tetrahydroisohumulones, as relevant analogues, allowed us to evaluate critical functionalities in radical formation. Using spin-trapping methodology with 5,5-dimethyl-1-pyrroline -oxide and --butyl-α-phenylnitrone as relevant traps, followed by simulation of corresponding spin adducts, identification of incipient radicals was attempted.