Propenone derivatives represented by general formula (I) or pharmacologically acceptable salts thereof: wherein R1 represents substituted lower alkyl or YR5 (where Y represents S or O and R5 represents optionally substituted lower alkyl, optionally substituted aryl, optionally substituted aromatic heterocyclic group, or optionally substituted cyclic ether residue); R?2 and R3¿ may be the same or different and each represents hydrogen, lower alkyl, or optionally substituted aralkyl, or R?2 and R3¿ may be bonded to each other to thereby form optionally substituted methylene or ethylene; R4 represents hydrogen, hydroxy, lower alkyl, optionally substituted aralkyl, lower alkoxy, optionally substituted aralkyloxy, or halogeno; and X represents optionally substituted indolyl.