Abstract: The invention relates to 2-mercaptoimidazole derivatives substituted in the 4(or 5)-position.These 2-mercaptoimidazole derivatives are of the general formula (I) below: ##STR1## wherein: R.sub.1, R.sub.2, R.sub.5, R.sub.7 and R.sub.8 are hydrogen, a lower alkyl, an aralkyl or a substituted aralkyl, wherein at least one of R.sub.1 and R.sub.2 is hydrogen;R.sub.3 is (CH.sub.2).sub.n COR.sub.4, --(CH.sub.2).sub.n N.sup.+ (R.sub.5 R.sub.6 R.sub.7).X.sup.- or --CH.sub.2 CH(COR.sub.4)N.sup.+ (R.sub.5 R.sub.6 R.sub.7).X.sup.- ;R.sub.4 is OR.sub.8, --NHR.sub.5, --.alpha.-amino acid,--NHCH.sub.2 CH.sub.2 SO.sub.3.sup.-.Y.sup.+, --NHCH.sub.2 CH.sub.2 CO.sub.2.sup.- Y.sup.+, --OCH.sub.2 CH.sub.2 N.sup.+ (CH.sub.3).sub.3.X.sup.- ; ##STR2## n=1 or 2; X.sup.31 is an anion of an acid acceptable in cosmetics, pharmaceuticals or foodstuffs; andY.sup.+ is a cation of a base acceptable in cosmetics, pharmaceuticals or foodstuffs.

Abstract: The method for assaying the SOD (super oxide dismutase) activity in liquid medium is based on the activation of self-oxidization, by SOD activity, of a reactive agent having the general formula (I) wherein either n is 1 or 2, R.sup.1 is --OR.sup.4 or --NR.sup.5 R.sup.6 ; R.sup.2 is H, --OR.sup.4, alkyl (1-6C), --CH.sub.2 -- or --CH.sub.2 --CH.sub.2 --, to form a ring by binding to the phenyl substituent, at meta with respect to R.sup.1 ; and R.sup.3 is H, alkyl (1-6C) or --OR.sup.4 (if R.sup.2 is different from --OR.sup.4); with R.sup.4 being H or alkyl (1-6C); R.sup.5 being H, alkyl (1-6C), --CH.sub.2 COOH, --C.sub.6 H.sub.5 COOH or --C.sub.6 H.sub.5 SO.sub.3 H; and R.sup.6 is H, alkyl (1-6C) or --CH.sub.2 COOH; or n is 1, R.sup.1 is --OR.sup.4, R.sup.2 is --CH.sub.2 --O--, in order to form a ring by bonding of O with the phenyl substituent, at meta with respect to R.sup.1 ; and R.sup.3 is H or --OR.sup.4.