Abstract: A compound consisting of a base, a ribose and a fucose, in which the base is a purine or a pyrimidine, the ribose has R.sub.1 and R.sub.2 attached respectively to any two of 2'-O, 3'-O and 5'-O, and the fucose has R.sub.3, R.sub.4 and R.sub.5 attached respectively to any three of 1"-O, 2"-O, 3"-O and 4"-O, wherein each R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 is H, acetate, sulfate, phosphate, or a metallic salt of acetate, sulfate or phosphate; and the base is linked to the ribose via a bond between 9-N of the base and 1'-O of the ribose when the base is a purine or via a bond between 1-N of the base and 1'-C of the ribose when the base is a pyrimidine and the ribose is linked to the fucose via a bond between any one of 2'-O, 3'-O and 5'-O of the ribose and 1"-C of the fucose.

Abstract: A substantially pure compound of the formula: ##STR1## wherein each of R.sub.1 and R.sub.2, independently, is H, CH.sub.3, CF.sub.3, F, Cl, Br, I, OH, OCH.sub.3, OCF.sub.3, SH, SCH.sub.3, NH.sub.2, N.sub.3, NO.sub.2, CN, COOH, CONH.sub.2, CH.sub.2 CONH.sub.2, or SO.sub.2 NH.sub.2 ;R.sub.3 is H, CH.sub.3, COOH, CONH.sub.2, or COOR where R is C.sub.1-4 alkyl;each R.sub.4, independently, is H or C.sub.1-6 alkyl;X is CH.sub.2, CH.sub.2 CH.sub.2, CH.dbd.CH, or CH.sub.2 CH.sub.2 CH.sub.2 ; ##STR2## each Z, independently, is H, CH.sub.3, or Q where Q is a hydrophobic acyl, benzoyl, phenacetyl, benzyloxycarbonyl, alkoxycarbonyl, or N-methyl-dihydropyridine-3-carbonyl linked to N by an amide bond which is cleavable by an endogenous central nervous system enzyme;D is H or ##STR3## where R.sub.5 is H or C.sub.