ABSTRACT
This chapter presents a synopsis of some radical-mediated processes, focuses on phenomena related to biochemistry and medicine. While much attention has been given to both the in vivo and in vitro redox activity of l-ascorbic acid, the literature addressing the structures of species involved as intermediates has been somewhat unsettled. In an electrochemical cell, oxidation corresponds to loss of electrons from the anode while reduction refers to a gain of electrons by the cathode. Any process affording the necessary starting radicals can be an initiating step, while any process destroying the species in the chain can be a terminating step. The tocopherols may be viewed as derivatives of tocol, the principal changes being in the nature of the bicyclic ring system. The mode(s) of action of ubiquinone–ubiquinol as an antioxidant remains a matter of discussion. The chapter concludes with a presentation of radical chain reactions and mechanisms whereby antioxidants can interfere with the processes.
