Abstract: Novel tetrahydro-.beta.-carboline derivatives of the formula: ##STR1## wherein R.sup.1 is carboxyl, a lower alkoxycarbonyl, carbamoyl, an N,N-di-lower alkylcarbamoyl, an N-(phenyl-substituted lower alkylidenamino)carbamoyl, a [N,N-di(lower alkyl)amino]-lower alkyl, or a nitrogen-containing monocyclic heterocyclic group;R.sup.2 is hydrogen atom, a lower alkyl, or a hydroxy-lower alkyl group, or R.sup.2 is combined with R.sup.1 to form a group: --CO--O--CH.sub.2 --;R.sup.3 is hydrogen atom, a lower alkyl, a phenyl-lower alkyl, or a group: --CSS--R.sup.4 ;R.sup.4 is hydrogen atom, an alkyl, or a group: --(CH.sub.2).sub.n Y.sup.1 ;n is 0, 1 or 2,Y.sup.

Abstract: Tetrahydro-.beta.-carboline derivative of the formula: ##STR1## wherein R.sup.2 is lower alkyl, and either (A)R.sup.1 is hydroxymethyl or carboxy,R.sup.3 and R.sup.4 are both hydrogen, andX is halogen, lower alkyl, lower alkoxy, hydroxy or benzyloxy; or(B)R.sup.1 is hydrogen, carboxy-lower alkyl or a group of the formula: --CH.sub.2 OY,Y is lower alkyl, lower alkanoyl or an oxygen-containing monocyclic heterocyclic group,R.sup.3 is hydrogen, hydroxy-lower alkyl or carboxy,R.sup.4 is hydrogen or hydroxy-lower alkyl, andX is hydrogen,or a salt thereof, which has excellent activities for alleviating, curing and preventing hepatic damages and is useful as a therapeutic or prophylactic agent for hepatic diseases.

Abstract: Tetrahydro-.beta.-carboline derivatives of the formula: ##STR1## wherein R.sup.1 is hydrogen atom, a lower alkyl group, a cycloalkyl group, phenyl group or a hydroxy-substituted lower alkyl group, R.sup.2 is hydrogen atom, an alkyl group, or a group of the formula: --(CH.sub.2).sub.m Y, Y is thienyl or a substituted or unsubstituted phenyl group, and m and n are an integer of 1 or 2, which have excellent alleviating, curing and preventing hepatic damages and are useful as a therapeutic or prophylactic agent for hepatic diseases, and a process for the preparation of said compounds.

Abstract: A compound of the formula: ##STR1## wherein R.sup.1 is hydrogen or hydroxy, R.sup.2 is a group of the formula: --CO-CH(NH.sub.2)-CH.sub.2 COR.sup.3 or --COCH.sub.2 -CH(NH.sub.2)-COR.sup.3, and R.sup.3 is selected from the group consisting of hydroxy, lower alkylamino, di-lower alkylamino, lower alkoxy and hydroxy-lower alkylamino, or R.sup.3 is amino when R.sup.2 is hydroxy. Several methods of preparing the compound [I] are also disclosed. The compound [I] and a pharmaceutically acceptable salt thereof are useful as antimicrobial agents.