Novel cyclic tetrapeptide derivatives and pharmaceutical uses thereof

Abstract

The present invention provides a cyclic tetrapeptide derivative represented by the following general formula (I) or a pharmaceutically acceptable salt thereof: 1 wherein each of R21 and R22 independently denotes hydrogen, a linear C1-C6-alkyl group to which a non-aromatic cycloalkyl group or an optionally substituted aromatic ring may be attached, or a branched C3-C6-alkyl group to which a non-aromatic cycloalkyl group or an optionally substituted aromatic ring may be attached; and each of R1 and R3 independently denotes a linear C1-C5-alkylene group which may have a C1-C6 side chain, in which the side chain may form a condensed ring structure on the alkylene chain. The present invention also provides a histone deacetylase inhibitor, an MHC class-I molecule expression-promoting agent and a pharmaceutical composition, each of which comprises the above cyclic tetrapeptide derivative or pharmaceutically acceptable salt thereof as an active ingredient.

Dependencies are inferred from the claim text.