A compound having the chemical structure: or a pharmaceutically-acceptable salt thereof; wherein: R 3 is H, NHCH 2 CH=CH 2, NHCH 2 CH 2 N(CH 3) 2, NHCH 2 CH 2 NC 4 H 8, alkoxy, azetidinyl, furfuryl, morpholinyl, piperazinyl, piperidinyl, piperazinyl, pyrrolidinyl, tetrahydrofurfuryl, 2-methyl-1-aziridinyl, (dimethylamino)methyl-1-aziridinyl, 3-(dimethylamino)-1-azetidinyl, 3-hydroxy-1-pyrrolidinyl, 3,4-dihydroxy-1-pyrrolidinyl, or NR 8 R 9, OR 8, SR 8, wherein R 8 and R 9 are independently H, C 1-10 alkyl, alkenyl, alkynyl, alkoxy, alkylhalide, alkyldihalide, amine, cycloalkyl, carboxyalkyl, (acetylamino)alkyl, (dimethylamino)alkyl, 1 -(methoxymethyl)alkyl, 2-(1,3-dioxolan-2-yl)alkyl, 4,4-dimethoxybutyl, [[(1,1-dimethylethoxy)carbonyl]amino]alkyl, [[(1,1-dimethylethoxy)carbonyl]alkylamino]alkyl, 1-(hydroxymethyl)alkyl, 1-(hydroxymethyl)-2-methylalkyl, 2-(hydroxymethyl)cycloalkyl, (diethylamino)alkyl, 2-(dimethylamino)-1-methylethyl, (ethylmethylamino)alkyl, [(2-fluoroethyl)methylamino]alkyl, [(2,2-difluoroethyl)methylamino]alkyl, [bis(2-hydroxyethyl)amino]alkyl, (dimethyloxidoamino)alkyl, (trimethylammonio)alkyl, (1-aziridinyl)alkyl, (1-aziridinylmethyl)alkyl, (1-azetidinyl)alkyl, (2-deoxy-D-glucos-2-yl), (6-deoxy-D-glucos-6-yl), (1H-imidazol-4-yl)alkyl, (1-methyl- 1H-imidazol-4-yl)alkyl, (1-methyl-1H-imidazol-5-yl)alkyl, (4-morpholinyl)alkyl, (4-pyridinyl)alkyl, (1-piperidinyl)alkyl, (1-piperazinyl)alkyl, (1-pyrrolidinyl)alkyl, (1-ethyl-2-pyrrolidinyl)methyl, or 2-(N-methylpyrrolidin-2-yl)ethyl; R 4 and R 5 are independently H, C 1-6 alkyl, C 3-8 cycloalkyl, C(=O)C 1-10 alkyl, C(=O)(CH 2) n -aryl, C(=O)(CH 2) n -cycloalkyl, alkoxy, alkylthiol, glycoside, glucuronide or sulfate, wherein n = 1-10; R 6 is O, OC(=O)NH 2, OC(=O)C 1-10 alkyl, OSO 2 OH, OC(=O)OSO 2 OH and OC(=O)NR 10 R 11 wherein R 10 and R 11 are independently H and C 1-10 alkyl; and R 7 is OH, CN, C 1 -C 4 alkyl, C 1 -C 6 cycloalkyl, alkylhalide, or alkylthiol. R 3 is H, NHCH 2 CH=CH 2, NHCH 2 CH 2 N(CH 3) 2, NHCH 2 CH 2 NC 4 H 8, alkoxy, azetidinyl, furfuryl, morpholinyl, piperazinyl, piperidinyl, piperazinyl, pyrrolidinyl, tetrahydrofurfuryl, 2-methyl-1-aziridinyl, (dimethylamino)methyl-1-aziridinyl, 3-(dimethylamino)-1-azetidinyl, 3-hydroxy-1-pyrrolidinyl, 3,4-dihydroxy-1-pyrrolidinyl, or NR 8 R 9, OR 8, SR 8, wherein R 8 and R 9 are independently H, C 1-10 alkyl, alkenyl, alkynyl, alkoxy, alkylhalide, alkyldihalide, amine, cycloalkyl, carboxyalkyl, (acetylamino)alkyl, (dimethylamino)alkyl, 1 -(methoxymethyl)alkyl, 2-(1,3-dioxolan-2-yl)alkyl, 4,4-dimethoxybutyl, [[(1,1-dimethylethoxy)carbonyl]amino]alkyl, [[(1,1-dimethylethoxy)carbonyl]alkylamino]alkyl, 1-(hydroxymethyl)alkyl, 1-(hydroxymethyl)-2-methylalkyl, 2-(hydroxymethyl)cycloalkyl, (diethylamino)alkyl, 2-(dimethylamino)-1-methylethyl, (ethylmethylamino)alkyl, [(2-fluoroethyl)methylamino]alkyl, [(2,2-difluoroethyl)methylamino]alkyl, [bis(2-hydroxyethyl)amino]alkyl, (dimethyloxidoamino)alkyl, (trimethylammonio)alkyl, (1-aziridinyl)alkyl, (1-aziridinylmethyl)alkyl, (1-azetidinyl)alkyl, (2-deoxy-D-glucos-2-yl), (6-deoxy-D-glucos-6-yl), (1H-imidazol-4-yl)alkyl, (1-methyl- 1H-imidazol-4-yl)alkyl, (1-methyl-1H-imidazol-5-yl)alkyl, (4-morpholinyl)alkyl, (4-pyridinyl)alkyl, (1-piperidinyl)alkyl, (1-piperazinyl)alkyl, (1-pyrrolidinyl)alkyl, (1-ethyl-2-pyrrolidinyl)methyl, or 2-(N-methylpyrrolidin-2-yl)ethyl; R 4 and R 5 are independently H, C 1-6 alkyl, C 3-8 cycloalkyl, C(=O)C 1-10 alkyl, C(=O)(CH 2) n -aryl, C(=O)(CH 2) n -cycloalkyl, alkoxy, alkylthiol, glycoside, glucuronide or sulfate, wherein n = 1-10; R 6 is O, OC(=O)NH 2, OC(=O)C 1-10 alkyl, OSO 2 OH, OC(=O)OSO 2 OH and OC(=O)NR 10 R 11 wherein R 10 and R 11 are independently H and C 1-10 alkyl; and R 7 is OH, CN, C 1 -C 4 alkyl, C 1 -C 6 cycloalkyl, alkylhalide, or alkylthiol.