A compound of the formula:whereinR3 represent a C1-8
alkyl which is unbranched or branched and unsubstituted or substituted with OH, alkoxy, CO2H, =NOH, =NOCONH2, or =O; C3-8 cycloalkyl which is unsubstituted or substituted with OH, alkoxy, CO2H, =NOH, =NOCONH2, or =O; C4-8 cycloalkylalkyl wherein the cycloalkyl portion is unsubstituted or substituted with OH, alkoxy, CO2H, =NOH, =NOCONH2, or =O;
aryl which is unsubstituted or substituted with Cl, NH2, alkylamino, dialkylamino, amido, C1-C8 alkylamido, C1-C3 dialkylamido, OH, alkoxy, HC=NOH, HC=NOCONH2, C1-C3
alkyl, phenyl or benzyl; aralkyl (C1-4); heterocyclyl; heterocyclylalkyl (C1-C4); and heteroaryl;R8 represents H or a C1-8
alkyl which is unbranched or branched and unsubstituted or substituted with OH, alkoxy, CO2H, =NOH, =NOCONH2, or =O; C3-8 cycloalkyl which is unsubstituted or substituted with OH, alkoxy, CO2H, =NOH, =NOCONH2, or =O; C4-8 cycloalkylalkyl wherein the cycloalkyl portion is unsubstituted or substituted with OH, alkoxy, CO2H, =NOH, =NOCONH2, or =O;
aryl which is unsubstituted or substituted with Cl, NH2, alkylamino, dialkylamino, amido, C1-C8 alkylamido, C1-C3 dialkylamido, OH, alkoxy, HC=NOH, HC=NOCONH2, C1-C3 alkyl, phenyl or benzyl; aralkyl (C1-4); heterocyclyl; heterocyclylalkyl (C1-C4); and heteroaryl.