Patent ID: 7608611

Claim:
A purified compound having the chemical structure: or a pharmaceutically-acceptable salt thereof; wherein: R 1 and R 2 are independently C 2-6 alkyl, C 3-8 cycloalkyl, C(═O)C 1-10 alkyl, C(═O)(CH 2 ) n -cycloalkyl, C(═O)(CH 2 ) n -aryl, wherein n=1-10, alkoxy, alkylthiol, glycoside, glucuronide or sulfate, C(═O)CH(X)NH 2 , and C(═O)CH(X)OH wherein X=an amino acid side chain; 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 , azetidinyl, furfuryl, morpholinyl, 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 7 R 8 , OR 7 , SR 7 , wherein R 7 and R 8 are independently 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-methyl-pyrrolidin-2-yl)ethyl; and wherein when R 1 and R 2 are both H, R 3 is not NH 2 ; 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 or sulfate, wherein n=1-10; and, 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 9 R 10 wherein R 9 and R 10 are independently H and C 1-10 alkyl.