FreerADIcalsandreactiveoxygenspecies(ROS)arehighlyreactivemoleculesthataregeneratedbynormalcellularprocesses,environmentalstresses,andUVirradiation.ROSreactwithcellularcomponents,damagingDNA,carbohydrates,proteins,andlipidscausingcellularandtissueinjury.Excessproductionofreactiveoxygenspeciescanalsoleadtoinflammation,prematureagingdisorders,andseveraldiseasestates,includingcancer,diabetes,andatherosclerosis.Organismshavedevelopedcomplexantioxidantsystemstoprotectthemselvesfromoxidativestress,however,excessROScanoverwhelmthesystemsandcauseseveredamage.

TheZenbioORAC(OxygenRadicalAbsorbanceCapacity)AntioxidantAssayKitcanbeusedtodeterminethetotalantioxidantcapacityofBIOLOGicalfluids,cells,andtissue.Itcanalsobeusedtoassaytheantioxidantactivityofnaturallyoccurringorsyntheticcompoundsforuseasdietarysupplements,topicalprotection,andtherapeutics.Theassaymeasuresthelossoffluoresceinfluorescenceovertimeduetoperoxyl-radicalformationbythebreakdownofAAPH(2,2"-azobis-2-methyl-propanimidamide,dihydrochloride).Trolox[6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylicacid],awatersolublevitaminEanalog,servesasapositivecontrolinhibitingfluoresceindecayinadosedependentmanner.TheORACassayisakineticassaymeasuringfluroesceindecayandantioxidantprotectionovertime.Theantioxidantactivityinbiologicalfluids,cells,tissues,andnaturalextractscanbenormalizedtoequivalentTroloxunitstoquantifythecompositeantioxidantactivitypresent.ThisassaymeasuresantioxidantactivitybyhydrogenatomtransferandwhencombinedwithZenBio"sABTSantioxidantassaykit,providesacomprehensiveanalysisofatestsample"santioxidantactivity.