Abstract: A pyrimidinedione derivative of formula (I) or a pharmaceutically acceptable salt thereof exhibits excellent inhibitory activity against hepatitis C virus.

Abstract: A pyrimidinedione derivative of formula (I) or a pharmaceutically acceptable salt thereof exhibits excellent inhibitory activity against hepatitis C virus.

Abstract: The present invention relates to a new N-cinnamoyl-2-methyl-5-methoxy-3-indoleacetic ester represented by the following general formula (I). It is manufactured by causing N-cinnamoyl-2-methyl-5-metboxy-3-indoleacetic acid represented by the following general formula (II) or a reactive derivative thereof to react with a compound represented by the following general formula (III) ##STR1## wherein, R is ##STR2## The inventive compounds are effective to the same extent as the existing cinmetacin, and are also excellent in greatly reducing fatal side effects like a gastric ulcer, that are associated with cinmetacin or an intestinal ulcer.