Glucosamine derivatives and pharmaceutical uses thereof

A compound of Formula (A), or a pharmaceutically acceptable salt or ester thereof:

• where:
• X is O, N, or S;
• R is a substituted or unsubstituted C2 to C18 substituent selected from linear or branched alkyl, alkenyl, alkynyl, aryl, heteroaryl, arylalkyl, alkylaryl, cycloalkyl, and alkyl comprising a cyclic or a heterocyclic moiety, or R is a substituted or unsubstituted C2 to C12 substituent selected from linear or branched alkyl, alkenyl, alkynyl, aryl, heteroaryl, arylalkyl, alkylaryl, cycloalkyl, and alkyl comprising a cyclic or a heterocyclic moiety;
• R2 is hydrogen, acyl, or alkyl;
• and
• R1, R3, R4, and R5 are independently hydrogen, substituted or unsubstituted alkyl, aryl, arylalkyl, alkylaryl, cyclic or heterocyclic moiety, or acyl group derived from a carboxylic acid, an amino acid, or a peptide, optionally with a protecting group, a phosphonyl group, or a sulfonyl group, provided that R1, R3, R4, and R5 are not all hydrogen at the same time, or
• one or more of R1, R3, R4, and R5 are independently selected from alkoxycarbonyl, aryloxycarbonyl, and arylalkoxycarbonyl, or
• R3 and R4, taken together with the atoms to which they are attached, form a substituted or unsubstituted heterocyclic ring, or
• R4 and R5, together with the atoms to which they are attached, form a substituted or unsubstituted heterocyclic ring;
• and
• n is an integer from 1 to 6.