1. A compound of the formula: ##STR7## wherein: R.sup.1 and R.sup.2 indepently are: hydrogen; lower alkyl; halogen; acyl; nitro; sulfonic acid; --CH.dbd.NR.sup.4, wherein R.sup.4 is guanidino, heterocyclic, or --NR.sup.5 R.sup.6, wherein R.sup.5 or R.sup.6 is hydrogen or lower alkyl, and the other is hydrogen, lower alkyl, acyl, aryl, heterocyclic, carbamoyl or lower alkylaminocarbonyl; --NR.sup.5 R.sup.6 ; --CH(SR.sup.7).sub.2, wherein R.sup.7 is lower alkyl or alkylene; --(CH.sub.2).sub.j R.sup.8, wherein j is 1-6, and R.sup.8 is halogen; substituted aryl; unsubstituted aryl; substituted heteroaryl; unsubstituted heteroaryl; N.sub.3 ; --CO.sub.2 R.sup.9, wherein R.sup.9 is hydrogen, substituted lower alkyl, unsubstituted lower alkyl, substituted aryl, unsubstituted aryl, substituted heteroaryl, or unsubstituted heteroaryl; --C(.dbd.O)NR.sup.10 R.sup.11, wherein R.sup.10 and R.sup.11 independently are hydrogen, substituted lower alkyl, unsubstituted lower alkyl, substituted aryl, unsubstituted aryl, substituted heteroaryl, unsubstituted heteroaryl, substituted aralkyl, unsubstituted aralkyl, lower alkylaminocarbonyl, or lower alkoxycarbonyl, or R.sup.10 and R.sup.11 are combined with a nitrogen atom to form a heterocyclic group; --OR.sup.12, wherein R.sup.12 is hydrogen, substituted lower alkyl, unsubstituted lower alkyl, substituted aryl, unsubstituted aryl; or --C(.dbd.O)R.sup.13, wherein R.sup.13 is hydrogen, NR.sup.10 R.sup.11, substituted lower alkyl, unsubstituted lower alkyl, substituted aryl, unsubstituted aryl, substituted heteroaryl, unsubstituted heteroaryl, substituted aralkyl, or unsubstituted aralkyl; --NR.sup.10 R.sup.11 ; --C(.dbd.O)R.sup.14, wherein R.sup.14 is hydrogen, lower alkyl, substituted aryl, unsubstituted aryl, substituted heteroaryl, or unsubstituted heteroaryl; --S(.dbd.O).sub.r R.sup.15, wherein r is 0 to 2, and R.sup.15 is hydrogen, substituted lower alkyl, unsubstituted lower alkyl, substituted aryl, unsubstituted aryl, substituted heteroaryl, unsubstituted heteroaryl, substituted aralkyl, unsubstituted aralkyl, thiazolinyl, (CH.sub.2).sub.a CO.sub.2 R.sup.16, wherein a is 1 or 2, and R.sup.16 is hydrogen or lower alkyl, or --CH.sub.2).sub.a C(.dbd.O)NR.sup.10 R.sup.11 ; --OR.sup.17, wherein R.sup.17 is hydrogen, lower alkyl, or --C(.dbd.O)R.sup.18, wherein R.sup.18 is substituted lower alkyl, unsubstituted lower alkyl, substituted aryl, or unsubstituted aryl; --C(.dbd.O)(CH.sub.2).sub.j R.sup.19, wherein R.sup.19 is hydrogen, halogen, NR.sup.10 R.sup.11, N.sub.3, SR.sup.15, or OR.sup.20, wherein R.sup.20 is hydrogen, substituted lower alkyl, unsubstituted lower alkyl, or C(.dbd.O)R.sup.14 ; --CH(OH)(CH.sub.2).sub.j R.sup.19 ; --(CH.sub.2).sub.d CHR.sup.21 CO.sub.2 R.sup.16A, wherein d is 0-5, and R.sup.21 is hydrogen, CONR.sup.10 R.sup.11, or CO.sub.2 R.sup.16A, wherein R.sup.16A is the same as R.sup.16 ; --(CH.sub.2).sub.d CHR.sup.21 CONR.sup.10 R.sup.11 ; --CH.dbd.CH(CH.sub.2).sub.m R.sup.22, wherein m is 0-4, and R.sup.22 is hydrogen, lower alkyl, CO.sub.2 R.sup.9, substituted aryl, unsubstituted aryl, substituted heteroaryl, unsubstituted heteroaryl, OR.sup.12, or NR.sup.10 R.sup.11 ; --CH.dbd.C(CO.sub.2 R.sup.16A).sub.2 ; --C.tbd.C(CH.sub.2).sub.m R.sup.22 ; --SO.sub.2 NR.sup.23 R.sup.24, wherein R.sup.23 and R.sup.24 independently are hydrogen, lower alkyl, or groups that form a heterocycle with the adjacent nitrogen atoms; --OCO.sub.2 R.sup.13A, wherein R.sup.13A is the same as R.sup.13 ; or --OC(.dbd.O)NR.sup.10 R.sup.11 ; R.sup.3 is hydrogen; lower alkyl; carbamoyl; amino; tetrahydropyranyl; hydroxyl; C(.dbd.O)H; aralkyl; lower alkanoyl; or CH.sub.2 CH.sub.2 R.sup.25, wherein R.sup.25 is halogen, amino, di-lower alkylamino, hydroxyl, or hydroxysubstituted lower alkylamino; X is hydrogen; formyl; carboxyl; lower alkoxycarbonyl; lower alkylhydrazinocarbonyl; --CN; lower alkyl; --C(.dbd.O)NR.sup.26 R.sup.27, wherein R.sup.26 and R.sup.27 independently are hydrogen, unsubstituted lower alkyl, or unsubstituted aryl; or R.sup.26 and R.sup.27 are combined with a nitrogen atom to form a heterocyclic group; --CH(R.sup.34)W, wherein R.sup.34 is hydrogen or lower alkyl, and W is --N.dbd.CHN(alkyl).sub.2 ; guanidino; N.sub.3 ; NR.sup.28 R.sup.29, wherein R.sup.28 or R.sup.29 is hydrogen or lower alkyl, and the other is hydrogen, allyl, alkanoyl, aryloxycarbonyl, unsubstituted alkyl, or the residue of an .alpha.-amino acid in which the hydroxy group of the carboxyl group is excluded; --CO.sub.2 R.sup.9 ; --C(.dbd.O)NR.sup.10 R.sup.11 ; --S(.dbd.O).sub.r R.sup.30, wherein R.sup.30 is substituted or unsubstituted lower alkyl, aryl, or heteroaryl; or --OR.sup.31, wherein R.sup.31 is hydrogen, substituted or unsubstituted alkyl, or substituted or unsubstituted alkanoyl; --CH.dbd.N--R.sup.32, wherein R.sup.32 is hydroxyl, lower alkoxy, amino, guanidino, ureido, imidazolylamino, carbamoylamino, or NR.sup.26A R.sup.27A (wherein R.sup.26A is the same as R.sup.26 and R.sup.27A is the same as R.sup.27); or --CH.sub.2 Q wherein Q is a sugar residue represented by ##STR8## wherein V represents hydrogen, methyl, ethyl, benzyl, acetyl, or trifluoroacetyl; Y is hydrogen; --OH; --OC(.dbd.O)R.sup.33, wherein R.sup.33 is alkyl, aryl, or amino; --OCH.sub.2 O-alkyl; -O-alkyl; aralkyloxy; or X and Y are combined as -X-Y- to form, --CH.sub.2 OCO.sub.2 -- or --CH.sub.2 N(R.sup.16B)CO.sub.2 -- (wherein R.sup.16B is the same as R.sup.16); A.sup.1 and A.sup.2 are hydrogen, or both are combined to represent O; or B.sup.1 and B.sup.2 are hydrogen, or both are combined to represent O; or a pharmaceutically acceptable salt thereof; with the proviso that at least one of A.sup.1,A.sup.2 or B.sup.1,B.sup.2 represents O; and with the further proviso that both X and Y are not simultaneously hydrogen.