Salinosporamides and Methods for Use Thereof

An isolated compound having the structure (I):

• wherein:
• R1 is —H, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, heterocyclic, substituted heterocyclic, cycloalkyl, substituted cycloalkyl, alkoxy, substituted alkoxy, thioalkyl, substituted thioalkyl, hydroxy, halogen, amino, amido, carboxyl, —C(O)H, acyl, oxyacyl, carbamate, sulfonyl, sulfonamide or sulfuryl;
• wherein when R1 is a substituted alkyl, the alkyl group can further bear one or more substituents selected from alkoxy, mercapto, cycloalkyl, substituted cycloalkyl, heterocyclic, substituted heterocyclic, aryl, substituted aryl, heteroaryl, substituted heteroaryl, aryloxy, substituted aryloxy, cyano, nitro, amino, amido, —C(O)H, acyl, oxyacyl, carboxyl, sulfonyl, sulfonamide, and sulfuryl;
• R2 is —H, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, heterocyclic, substituted heterocyclic, cycloalkyl, substituted cycloalkyl, alkoxy, substituted alkoxy, thioalkyl, substituted thioalkyl, hydroxy, halogen, amino, amido, carboxyl, —C(O)H, acyl, oxyacyl, carbamate, sulfonyl, sulfonamide or sulfuryl;
• R3 is —H, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, heterocyclic, substituted heterocyclic, cycloalkyl, substituted cycloalkyl, alkoxy, substituted alkoxy, thioalkyl, substituted thioalkyl, hydroxy, halogen, amino, amido, carboxyl, —C(O)H, acyl, oxyacyl, carbamate, sulfonyl, sulfonamide or sulfuryl;
• each R4 is independently alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, cycloalkyl, substituted cycloalkyl;
• E1 to E4 are each independently O, —NR5, or —S, wherein R5 is —H or C1-C6 alkyl;
• and
• X is 0 to 8.