The anodic oxidation mechanism of the Vinca alkaloids vinblastine, its
semisynthetic derivatives vindesine and 5'-noranhydrovinblastine, and
of vincristine, all with closely similar structures, was studied at a
glassy carbon disk electrode in buffered aqueous media using differen
tial pulse and cyclic voltammetry. The effect of pH on the mechanism s
howed that it is a complex multistep electron transfer with deprotonat
ion steps involved and that the final products, dimers or polymers, ad
sorb strongly to the electrode, forming an unreactive film on the elec
trode surface. The electrochemical differential pulse voltammograms sh
owed a correlation between the vinblastine derivatives, whereas vincri
stine reacts at different potentials. These differences in the anodic
oxidation mechanisms of the compounds studied can be related to their
neurotoxicity and myelosuppression effects. These effects may be due t
o the metabolite and/or degradation products of the compounds and resu
lt from how they are attached to, or transported across, cellular stru
ctures such as cell membranes.