Yawancin kwayoyin suna fuskantar haɗuwa da haɗuwa da ba za su iya amfani da su azaman abinci ba kuma za su zama masu cutarwa idan sun tara a cikin sel, saboda ba su da aikin maye. Wadannan mahadi masu cutarwa ana kiransu xenobiotics. Xenobiotics kamar magungunan roba, gubobi na halitta da kwayoyin cuta suna detoxified ta hanyar saitin enzymes na xenobiotic-metabolizing enzymes. A cikin mutane, waɗannan sun haɗa da cytochrome P450 oxidases, UDP-glucuronosyltransferases, da glutathione S-transferases. Wannan tsarin enzymes a cikin matakai uku na farko ya yi amfani da xenobiotic (phase I) sannan kuma ya haɗu da kwayoyin da ke narkewa a cikin ruwa (phase II). Wadannan kwayoyin da ke narkewa a cikin ruwa za a iya fitar da su daga cikin kwayoyin halitta kuma za a iya cire su daga cikin kwayoyin halitta masu yawa da suka hada da sunadarai masu guba kamar sunadarai masu guba na peroxide da kuma sunadarai masu guba.
mutane