Influence of cyclodextrins on the kinetics of oxidation of amino acids andBSA by hydrazyl radicals

The kinetics of oxidation of amino acids (Arg, His, Lys, Phe, Thr and Tyr), a dipeptide (Gly-His), and BSA (bovine serum albumin) by two persistent wa ter soluble free radicals of the hydrazyl type has been studied. The rate d ecreases in the order Arg > Lys > Tyr > Thr > His similar to BSA similar to Phe similar to Gly-His with both free radicals. Addition to the reaction m ixture of alpha- and beta -cyclodextrin decreases the oxidation rate, proba bly due to amino acid encapsulation in the cyclodextrin cavity. beta -Cyclo dextrin protects more efficiently against oxidation than alpha -cyclodextri n.