.
Endogenous free radicals are, for the most part, formed intracellularly. These compounds may then act either exclusively within the cell or exert some effect after being released into the extracellular matrix. Intracellular free radical production typically involves either enzymatic or non enzymatic electron transfer reactions. Besides electron transport system leakage, radicals may result from the activity of certain oxidases, cyclooxygenases, lipoxygenases, dehydrogenases, and peroxidases. In addition, accidental intracellular generation may occur through the autoxidation and consequent inactivation of various small molecules. These can include reduced flavins, thiols (e.g., glutathione, cysteine), and adrenaline. Such reactions can take place practically anywhere within the cell in
...