Stages of free radical reactionsInitiation,Propagation,andTerminationInitiationOxygen (O2)is reduced in mitochondria in one electronsteps. Oxygen with an unpaired electron often escapesas:O2-",called superoxide radical.2-3%oftheoxygenatomstakenupbymitochondriaescapeas free radicals!PropagationFree radicals canpropagate indefinitelyR·+O,>ROO-ROO·->ROOH+R
Initiation, Propagation, and Termination Initiation • Oxygen (O2 ) is reduced in mitochondria in one electron steps. Oxygen with an unpaired electron often escapes as: O2¯·, called superoxide radical. • 2–3% of the oxygen atoms taken up by mitochondria escape as free radicals! Propagation • Free radicals can propagate indefinitely: R·+ O2 -> ROO· ROO· -> ROOH + R· Stages of free radical reactions
Stages of free radical reactionsInitiation,Propagation,and TerminationTerminationR.+R·->R:RR.+ROO.->ROOR2ROO:->ROOR+O2AntioxidantH+ROO-->Antioxidant-+ROOHTermination occurs when free radicals react withotherfreeradicalsorantioxidantmolecules
Initiation, Propagation, and Termination Termination R· + R· -> R:R R· + ROO· -> ROOR 2 ROO· -> ROOR + O2 Antioxidant H + ROO· -> Antioxidant· + ROOH Termination occurs when free radicals react with other free radicals or antioxidant molecules. Stages of free radical reactions
Reactive oxygen species (ROSSuperoxideHydroxylH202e'e'e'e
• Superoxide • Hydroxyl • H2O2 Reactive oxygen species (ROS)
Mitochondria:Major sites of ROSgeneratione'e"eCytoplasmO H OH HgoHHHCooUCP1NADHIV办迎baoaFODHADPATPO2H20PiFADH2HtH+NADHMatrix
Mitochondria: Major sites of ROS generation
Radicalsdetected byelectron(ESR)spinresonance（电子自旋共振检测自由基）BARegrapex-R(mg/ml)1000e800.6604012202400.110100481Regrapex-R(mg/ml)REJUVENATIONRESEARCHFig.EffectsofRegrapex-RonhydroxylVolume12,Number4,2009radicalsdetected byESRMaryAnnLiebert,Inc.DOl:10.1089/rej.2009.0877
Radicals detected by electron spin resonance (ESR) （电子自旋共振检测自由基） Fig. Effects of Regrapex-R on hydroxyl radicals detected by ESR