PYRIMIDINE NUCLEOSIDE DERIVATIVE AND ANTIVIRAL AGENT CONTAINING THE DERIVATIVE AS ACTIVE INGREDIENT

摘要

The invention is a pyrimidine nucleoside derivative represented by the following formula (I): wherein R1 represents ethyl group or isopropyl group; R2 and R3 independentl y represent hydrogen atom, an C1-C3 alkyl group or chlorine atom; X represents oxygen atom or sulfur atom; and Z represents sulfur atom or methylene group; with the proviso that R2 and R3 do not simultaneously represent hydrogen atoms wh en X represents oxygen atom and Z represents sulfur atom, or a pharmaceutical ly acceptable salt thereof. The pyrimidine nucleoside derivative and pharmaceutically acceptable salt thereof show a markedly higher anti-retroviral activity than conventional analogous compounds and have a relatively low toxicity against the host cells, and therefore, are useful as an active ingredient of antiviral agent.