Abstract: The present invention relates to synthetic green tea derived polyphenolic compounds, their modes of syntheses, and their use in inhibiting proteasomal activity and in treating cancers. The present invention is also directed to pharmaceutical compositions useful in methods of inhibiting proteasomes and of treating cancers.

Abstract: The subject invention concerns N-thiolated ?-lactam compounds of formula A, wherein R1is a hydrocarbon group having 1-8 carbon atoms; R3 is an organothio group; and R4 is alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, heterocycloalkyl, cycloalkenyl, or heterocycloalkenyl, and analogs and pharmaceutically acceptable salts, esters and amides thereof. The subject invention also concerns methods for inducing tumor cell death or inhibiting tumor cell proliferation, and methods for inducing DNA damage, inhibiting DNA replication, activating p38 MAP kinase, or activating caspase cascade activation, or releasing cytochrome C from mitochondria into the cytoplasm in a tumor cell. Methods for treating cancer using N-thiolated ?-lactam compounds, as well as pharmaceutical compositions comprising the same are further disclosed.