| 摘要 |
A compound of general formula (I) or a pharmaceutically acceptable salt thereof or its hydrate, wherein R<1> and R<2> are each independently alkyl or alkenyl; R<3> is optionally substituted aryl or an optionally substituted aromatic heterocyclic group having at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur in the aromatic heterocycle; R<4> is hydrogen, acyl, alkoxycarbonyl or optionally mono- or di-alkyl substituted carbamoyl; and R<5> is hydrogen, halogeno or alkyl. |
