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.
以下化合物的新型化合物在免疫缺陷宿主中具有修复药理活性,其中,R.sup.1是
氨基或保护的
氨基基团,R.sup.2是氢、羧基或保护的羧基,R.sup.3是氢、羧基或保护的羧基,R.sup.4是较低的烷基、
氨基(较低)烷基、保护的
氨基(较低)烷基、
氨基甲酰(较低)烷基或保护的
氨基甲酰(较低)烷基,R.sup.5是氢或较低的烷基,R.sup.6是氢、羟基苯基(较低)烷基、
咪唑基(较低)烷基或
吲哚基(较低)烷基。