| abstract |
Sialic acid derivatives represented by the general formula (I): <IMAGE> (I) wherein R1 is a steroidal compound residue; R2 is H or alkyl; R3 is alkyl; <IMAGE> wherein each of R6 and R7 is H, alkyl or the like and I is an integer of 0 to 6; or the like; X is O or S; R4 is H or acyl; and R5 is R14O- (R14 is H or acyl) or R15NH-(R15 is acyl or the like); their salts, hydrates or solvates are provided. Sialic acid derivatives of the present invention are expected to be effective medicines for the prevention and therapy of senile dementia including Alzheimer's disease and the like, because they increase ChAT activity in cholinergic neurons. |