Abstract: Disclosed are derivatives of gangliosides and of N-acyl-N-lyso-gangliosides, of N'-acyl-N'-lyso-gangliosides and N,N'-di- or poly-acyl-N,N'-di-lyso-gangliosides, in which at least one of the hydroxyl groups in the saccharide, sialic or ceramide residues is esterified with sulfuric acid, functional derivatives thereof, and their salts with either inorganic or organic bases and the acid addition salts, except persulfated derivatives at the hydroxyl, sialic and ceramide groups of the GM.sub.1, GD.sub.1a, GD.sub.1b and GT.sub.1b gangliosides. Such compounds have antineurotoxic and neurotogenic activity and may therefore be used in pharmaceutical preparations. Also a marked modulating effect on the expression of the CD.sub.4 molecule in immune system cells has been shown.

Abstract: Semisynthetic analogues of gangliosides selected from the group consisting of N-sulfo-, N-hydrocarbyl-sulfonyl- and N-hydrocarbyloxy-sulfonyl-N,N'-dilyso-gangliosides and the N'-acyl derivatives thereof, N'-sulfo-, N'-hydrocarbylsulfonyl- and N'-hydrocarbyloxy-sulfonyl-N,N'-dilyso-gangliosides and the N-acyl derivatives thereof, N,N'-di or polysulfo-N,N'-di- or poly-lyso-gangliosides, N,N'-di- or polyhydrocarbylsulfonyl-N,N'-di- or poly-lyso-gangliosides and N,N'-di- or polyhydrocarbyloxy-N,N'-di- or poly-lyso-gangliosides, and functional derivatives thereof, and salts of these compounds, have protective activity against neurotoxicity induced by excitatory amino acids and are foreseen to be used in therapy in the nervous system and in modulating of the expression of determinants such as CD.sub.4 on the surface of human cells in the immune system.

Abstract: Provided are new derivatives of neuraminic acid of formula (I), where Ac represents an acyl residue of an aliphatic, araliphatic, aromatic, alicyclic, or heterocyclic carboxylic acid, including carboxylic amides, their 2-hydrocarbyl-glycosides, and their peracylated derivatives at the hydroxy groups of both these series of amides. These compositions are therapeutically useful in providing a protective effect against the neurotoxicity induced by excitatory amino acids, and can therefore be used in therapies of the central nervous system.