Muaj ib qho kev tsis sib haum xeeb hauv cov metabolism hauv cov kab mob. Txawm hais tias feem ntau cov kab mob hauv ntiaj teb xav tau cov pa oxygen kom ciaj sia, oxygen yog cov khoom siv hluav taws xob zoo heev uas tuaj yeem rhuav tshem cov kab mob los ntawm kev tsim cov pa oxygen reactive. Yog li ntawd, ib tug complex network system tsim los ntawm antioxidant metabolites thiab enzymes tau tsim nyob rau hauv lub cev. Los ntawm kev sib koom tes ntawm kev sib koom tes ntawm antioxidant metabolic intermediates thiab cov khoom thiab cov enzymes, cov khoom tseem ceeb ntawm tes xws li DNA, protein thiab lipids raug tiv thaiv los ntawm kev puas tsuaj oxidative. Cov kab mob antioxidant yeej ua tiav cov txiaj ntsig antioxidant hauv ob txoj hauv kev, ib qho yog los tiv thaiv kev tsim cov tshuaj oxygen nquag, thiab lwm yam yog tshem tawm cov tshuaj nquag ua ntej lawv ua rau kev puas tsuaj rau cov khoom tseem ceeb ntawm tes kom ua tiav cov tshuaj tiv thaiv oxidation. Siv tau. Txawm li cas los xij, cov hom pa oxygen reactive no tseem muaj cov haujlwm tseem ceeb hauv cellular, xws li ua yeeb yam redox signaling molecules hauv cov tshuaj biochemical. Yog li ntawd, lub luag haujlwm ntawm cov kab mob antioxidant hauv lub cev tsis yog kom tshem tawm tag nrho cov tshuaj oxidizing, tab sis kom cov tshuaj no nyob rau theem tsim nyog.
Cov tshuaj reactive oxygen uas tsim nyob rau hauv hlwb muaj xws li hydrogen peroxide (H2O2), hypochlorous acid (HClO), dawb radicals xws li hydroxyl radicals (·OH) thiab superoxide anions (O2). Hydroxyl radicals tshwj xeeb yog tsis ruaj khov thiab tuaj yeem hnov mob nrog feem ntau biomolecules sai thiab tsis muaj qhov tshwj xeeb. Cov hom no yog tsim los ntawm cov hlau-catalyzed hydrogen peroxide txo qis (xws li Fenton cov tshuaj tiv thaiv). Cov oxidants no rhuav tshem cov hlwb los ntawm kev pib cov tshuaj tiv thaiv xws li lipid peroxidation, lossis oxidizing DNA thiab cov proteins. Yog tias DNA puas tsis kho, nws tuaj yeem ua rau muaj kev hloov pauv thiab ua rau mob qog noj ntshav. Kev puas tsuaj rau cov protein tuaj yeem cuam tshuam kev ua haujlwm ntawm cov enzyme, thiab cov protein yuav denatured lossis degraded.
Tib neeg lub cev yuav tsum tau siv cov pa oxygen los tsim cov pa oxygen reactive nyob rau hauv cov txheej txheem ntawm lub zog tsim. Hauv cov txheej txheem no, ob peb kauj ruam hauv cov saw hlau thauj khoom tuaj yeem tsim cov khoom lag luam superoxide anions. Nws yog ib qho tseem ceeb tshwj xeeb uas cov coenzyme Q nyob rau hauv complex III ua ib tug heev active dawb radical intermediate (Q·) thaum lub sij hawm txo. Qhov nruab nrab tsis ruaj tsis khov no yuav ua rau hluav taws xob "tawg" (tsawg ntawm cov hluav taws xob), thiab cov hluav taws xob "kua" yuav dhia tawm ntawm cov khoom siv hluav taws xob thauj mus los thiab ncaj qha txo cov pa oxygen molecules los tsim superoxide anions. Peroxide kuj tuaj yeem tsim los ntawm oxidation ntawm txo cov flavoproteins xws li complex I. Txawm li cas los xij, txawm hais tias cov enzymes tsim oxidants, nws tsis paub meej tias cov saw hlau thauj hluav taws xob tseem ceeb dua li lwm cov txheej txheem biochemical uas tuaj yeem tsim cov peroxides. Nyob rau hauv cov txheej txheem ntawm photosynthesis ntawm cov nroj tsuag, algae thiab cyanobacteria, tshwj xeeb tshaj yog nyob rau hauv high irradiation siv, reactive oxygen hom kuj raug tsim, tab sis carotenoids yog siv raws li photoprotective agents kom nqus tau ntau zog lub teeb los tiv thaiv hlwb. Cov algae thiab cyanobacteria muaj ntau ntawm iodine thiab selenium tuaj yeem cuam tshuam cov oxidative puas tsuaj los ntawm kev siv hluav taws xob ntau. Carotenoids, iodine thiab selenium ua raws li antioxidants kom tsis txhob tsim cov pa oxygen reactive hom los ntawm reacting nrog lub tshaj-txo photosynthetic cov tshuaj tiv thaiv chaw.
