The invention relates to the use of a compound of formula (I), or salts thereof, as a preserving agent, in particular in a cosmetic, dermatological or pharmaceutical composition:in which R1 and R2 represent H, methyl, ethyl, phenyl or benzyl.The invention also relates to a method of preserving a cosmetic, dermatological or pharmaceutical composition, consisting in incorporating said compound of formula (I) therein and also to the compositions thus obtained.