A compound of Formula I and the pharmaceutically acceptable salts and esters thereof, wherein Ar 1 is selected from the group consisting of aryl and R 4 -substituted aryl; X, Y and Z are independently selected from the group consisting of -CH 2 -, -CH(C 1-6 alkyl)- and -C(C 1-6 alkyl) 2 -; R is selected from the group consisting of -OR 6, -O R 6, -O OR 9, -O NR 6 R 7, a sugar residue, a disugar residue, a trisugar residue and a tetrasugar residue; R 1 is selected from the group consisting of -H, -C 1-6 alkyl and aryl, or R and R 1 together are oxo; R 2 is selected from the group consisting of -OR 6, -O R 6, -O OR 9 and -O NR 6 R 7; R 3 is selected from the group consisting of -H, -C 1-6 alkyl and aryl or R 2 and R 3 together are oxo; q, r and t are each independently selected from 0 and 1; m, n and p are each independently selected from 0, 1, 2, 3 and 4; R 4 is 1-5 substituents independently selected at each occurrence from the group consisting of: -OR 5, -O R 5, -O OR 8, -O-C 1-5 alkyl-OR 5, -O NR 5 R 6, -NR 5 R 6,-NR 5 R 6, -NR 5 OR 8, -NR 5 NR 6 R 7, -NR 5 SO 2 R 8, -COOR 5, -CONR 5 R 6,-COR 5, -SO 2 NR 5 R 6, -S t R 8, -O-C 1-10 alkyl-COOR 5, -O-C 1-10 alkyl-CONR 5 R 6 and fluoro; R 5, R 6 and R 7 are independently selected at each occurrence from the group consisting of -H, C 1-6 alkyl, aryl and aryl-substituted C 1-6 alkyl; R 8 is independently selected from the group consisting of C 1-6 alkyl, aryl and aryl-substituted C 1-6 alkyl; R 9 is selected from the group consisting of -C≡C-CH 2 -NR 10 R 11, -C≡C-C R 13, and -(CH 2) 3 -NR 10 R 14; R 10 is independently selected at each occurrence from -H and -C 1-3 alkyl; R 11 is selected from the group consisting of -C -C 1-3 alkyl, -C -NR 10 R 10, -SO 2 -C 1-3 alkyl, and -SO 2 -phenyl; and R 12 is selected from -H, R 13 is -NR 10 R 11; and R 14 is selected from the group consisting of -C -C 1-3 alkyl, -C -NR 10 R 10, -SO 2 -C 1-3 alkyl and -SO 2 -phenyl. Ar 1 is selected from the group consisting of aryl and R 4 -substituted aryl; X, Y and Z are independently selected from the group consisting of -CH 2 -, -CH(C 1-6 alkyl)- and -C(C 1-6 alkyl) 2 -; R is selected from the group consisting of -OR 6, -O R 6, -O OR 9, -O NR 6 R 7, a sugar residue, a disugar residue, a trisugar residue and a tetrasugar residue; R 1 is selected from the group consisting of -H, -C 1-6 alkyl and aryl, or R and R 1 together are oxo; R 2 is selected from the group consisting of -OR 6, -O R 6, -O OR 9 and -O NR 6 R 7; R 3 is selected from the group consisting of -H, -C 1-6 alkyl and aryl or R 2 and R 3 together are oxo; q, r and t are each independently selected from 0 and 1; m, n and p are each independently selected from 0, 1, 2, 3 and 4; R 4 is 1-5 substituents independently selected at each occurrence from the group consisting of: -OR 5, -O R 5, -O OR 8, -O-C 1-5 alkyl-OR 5, -O NR 5 R 6, -NR 5 R 6,-NR 5 R 6, -NR 5 OR 8, -NR 5 NR 6 R 7, -NR 5 SO 2 R 8, -COOR 5, -CONR 5 R 6,-COR 5, -SO 2 NR 5 R 6, -S t R 8, -O-C 1-10 alkyl-COOR 5, -O-C 1-10 alkyl-CONR 5 R 6 and fluoro; R 5, R 6 and R 7 are independently selected at each occurrence from the group consisting of -H, C 1-6 alkyl, aryl and aryl-substituted C 1-6 alkyl; R 8 is independently selected from the group consisting of C 1-6 alkyl, aryl and aryl-substituted C 1-6 alkyl; R 9 is selected from the group consisting of -C≡C-CH 2 -NR 10 R 11, -C≡C-C R 13, and -(CH 2) 3 -NR 10 R 14; R 10 is independently selected at each occurrence from -H and -C 1-3 alkyl; R 11 is selected from the group consisting of -C -C 1-3 alkyl, -C -NR 10 R 10, -SO 2 -C 1-3 alkyl, and -SO 2 -phenyl; and R 12 is selected from -H, R 13 is -NR 10 R 11; and R 14 is selected from the group consisting of -C -C 1-3 alkyl, -C -NR 10 R 10, -SO 2 -C 1-3 alkyl and -SO 2 -phenyl.