The present invention relates to a compound of general formula (I) below in which R.sub.1, R.sub.2 and R.sub.3 represent, independently of one another, a hydrogen atom or a C.sub.1-C.sub.6 alkyl group or a (C.sub.1-C.sub.6 alkyl)carbonyl group, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 represent a hydrogen or a C.sub.1-C.sub.6 alkyl group, a C1-C6 alkoxy group or a (C.sub.1-C.sub.6 alkyl)carbonyloxy group, and n is an integer between 8 and 20, or its pharmaceutically acceptable addition salts, isomers, enantiomers and diastereoisomers, and also mixtures thereof. The invention also relates to a pharmaceutical composition comprising the compound and to the use thereof as a neurotrophic agent. ##STR00001##