NEW MATERIAL: The N-acyl-lysogangliosdides derived from 2-24C aliphatic acid with its acyl group substituted by Cl, Br, F, OH, SH, COOH, sulfonic acid, nitrile, amino group or their derivatives, etc., as well as their derivatives obtained by esterification (amidification), internal esterification or peracylation of sialic acid carboxyl groups and salts.

EXAMPLE: N-dichloroacetyl lysoganglioside GM1.

USE: A therapeutic agent for metabolic encephalopathyl, injuries, neurodegenertion, mental disorders, etc.

PROCESS: Lysoganglioside derivatives are obtained, e.g. by acylating lysoganglioside, de-N-acetyl lysoganglioside, etc., with 2-24C aliphatic acid substituted by a polar group, after the functional group of the compound to be acrylated is tentatively protected. The functional carboxy group of the reaction product is esterified (amidified), internally esterified or peracylated upon occasions.