Novel compounds of the following formula have restorative pharmacological activities in immuno-deficient hosts, ##STR1## wherein R.sup.1 is amino or a protected amino group, R.sup.2 is hydrogen, carboxy or a protected carboxy group, R.sup.3 is hydrogen, carboxy or a protected carboxy group, R.sup.4 is lower alkyl, amino(lower)alkyl, protected amino(lower)alkyl, carbamoyl(lower)alkyl or protected carbamoyl(lower)alkyl, R.sup.5 is hydrogen or lower alkyl, and R.sup.6 is hydrogen, hydroxyphenyl(lower)alkyl, imidazolyl(lower)alkyl or indolyl(lower)alkyl.
以下式子的新化合物在免疫缺陷宿主中具有修复药理活性,其中,R1为
氨基或保护
氨基基团,R2为氢、羧基或保护羧基基团,R3为氢、羧基或保护羧基基团,R4为较低的烷基、
氨基(较低)烷基、保护
氨基(较低)烷基、
氨基甲酰基(较低)烷基或保护
氨基甲酰基(较低)烷基,R5为氢或较低的烷基,R6为氢、羟基苯基(较低)烷基、
咪唑基(较低)烷基或
吲哚基(较低)烷基。