A method of treating arteriosclerosis, comprising the steps of:administering to a patient in need thereof an effective amount of a compound represented by formula (I): ##STR7## wherein X is an alkyl group having from 1-4 carbon atoms or an alkoxy group having from 1-4 carbon atoms; Y is a hydrogen atom or an alkoxy group having from 1-4 carbon atoms; Z is an alkyl group having from 1-4 carbon atom