Abstract: A substituted pyridine derivative represented by the general formula ##STR1## wherein R.sup.1 represents a phenyl or naphthyl group which may optionally be substituted by a substituent selected from the class consisting of a hydroxyl group, lower alkyl groups, lower alkoxy groups, cycloalkyl groups, lower alkoxycarbonyl groups, a phenyl group and halogen atoms; X represents an oxygen atom, a sulfur atom, a carbonyl group, or a group of the formula --CH(OH)-- or --N(R.sup.a)-- in which R.sup.a is a hydrogen atom or a lower alkyl group; Y represents a linear or branched lower alkylene group or a vinylene group which may optionally be substituted by a lower alkyl group, with the proviso that when X is an oxygen or sulfur atom, Y represents the lower alkylene group; R.sup.2 and R.sup.3 are identical or different and each represents a hydrogen atom or a lower alkyl group; R.sup.