Patent ID: 8217047

Claim:
A diketopiperazine of the following formula or a pharmaceutically-acceptable salt thereof: wherein: R 1 is: (a) a side chain of an amino acid, wherein the amino acid is glycine, alanine, valine, norvaline, α-aminoisobutyric acid, 2,4-diaminobutyric acid, 2,3-diaminobutyric acid, leucine, isoleucine, norleucine, serine, homoserine, threonine, aspartic acid, asparagine, glutamic acid, glutamine, lysine, hydroxylysine, histidine, arginine, homoarginine, citrulline, phenylalanine, p-aminophenylalanine, tyrosine, tryptophan, thyroxine, cysteine, homocysteine, methionine, penicillamine or ornithine; (b) —CH 2 —CH 2 —CH 2 — or —CH 2 —CH(OH)—CH 2 — and together with the adjacent ring nitrogen forms proline or hydroxyproline; or (c) a derivative of a side chain of an amino acid, wherein the amino acid is one of those recited in (a), and the derivatized side chain has: (i) an —NH 2 group replaced by an —NHR 3 or —N(R 3 ) 2 group, wherein each R 3 may independently be a substituted or unsubstituted alkyl, cycloalkyl, heterocycloalkyl, aryl, alkylaryl, arylalkyl or heteroaryl; (ii) an —OH group replaced by an —O—PO 3 H 2 or —OR 3 group, wherein each R 3 may independently be a substituted or unsubstituted alkyl, cycloalkyl, heterocycloalkyl, aryl, alkylaryl, arylalkyl or heteroaryl; (iii) a —COOH group replaced by a —COOR 3 group, wherein each R 3 may independently be a substituted or unsubstituted alkyl, cycloalkyl, heterocycloalkyl, aryl, alkylaryl, arylalkyl or heteroaryl; (iv) a —COOH group replaced by a —CON(R 4 ) 2 group, wherein each R 4 may independently be H or a substituted or unsubstituted alkyl, cycloalkyl, heterocycloalkyl, aryl, alkylaryl, arylalkyl or heteroaryl; (v) an —SH group replaced by —S—S—CH 2 —CH(NH 2 )—COOH or —S—S—CH 2 —CH 2 —CH(NH 2 )—COOH; (vi) a —CH 2 — group replaced by a —CH(NH 2 )— or a —CH(OH)— group; (vii) a —CH 3 group replaced by a —CH 2 —NH 2 or a —CH 2 —OH group; and/or (viii) an H which is attached to a carbon atom replaced by a halogen; R 2 has formula II, III or IV: wherein: each R 5 is independently aryl, heteroaryl, alkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryloxy, acyl, carboxyl, hydroxyl, halogen, amino, nitro, sulfo or sylfhydryl, wherein each alkyl is optionally substituted with hydroxyl, amino or sulfhydryl; n is from 0 to 5; and R 6 is hydrogen or lower alkyl.