Disclosed are 1,4-dihydropyridine derivatives represented by the general formula (I) and salts thereof, as well as optical active 1,4-dihydropyridine derivatives represented by the general formula (II) and salts thereof which are obtained from the derivative by biochemical reactions using microorganisms or enzymes and useful as preventive and therapeutic agents for ischemic heart diseases and hypertension. ##STR1## (wherein x and Y are H, NO.sub.2, CN, halogen; R.sup.1 and R.sup.2 are H, CHO, substituted alkylcarbonyl, crotonyl, cinnamoyl, alkoxycarbonyl, aryloxycarbonyl, benzyloxycarbonyl, carboxybenzoyl, or R.sup.1 and R.sup.2 taken together represent phthaloyl; n is an integer of 1 to 3).