The invention relates to compounds having general formula I ##STR00001## in which X represents an optically detectable moiety, n is an integer with 1.ltoreq.n.ltoreq.20, R.sub.1 is an unbranched or branched alkyl group having 1 to 20 carbon atoms, and R.sub.2 is hydrogen or --CH.sub.2--O--R.sub.3 group, wherein R.sub.3 has the same meaning as R.sub.1. These compounds are useful as inhibitors of lipolytic enzymes and can be used as tools for analysis as well as discrimination of lipolytic enzymes in biological samples.