Peptidyl beta-homo-aspartals (3-amino-4-carboxybutyraldehydes): new specific inhibitors of caspases.

Interleukin-1 beta (IL-1 beta)-converting enzyme (ICE, caspase-1) processes the IL-1 beta precursor to mature inflammatory cytokine IL-1 beta. ICE has been identified as a unique cysteine protease, which cleaves Asp-X bonds, shows resistance to E-64 (an inhibitor of most cysteine proteases) and has a primary structure that is homologous to CED-3, a protein required for apoptosis (programmed cell death) in the nematode Caenorhabditis elegans, and to mammalian cysteine proteases that initiate and execute apoptosis, e.g.

Peptidyl beta-homo-aspartals: specific inhibitors of interleukin-1 beta converting enzyme and its homologues (caspases).

Inhibition of interleukin-1 beta converting enzyme (ICE), apopain, papain, thrombin and trypsin with substrate like peptidyl L- and D-alpha-aldehydes and their L-beta-homo-aldehyde analogues was investigated. The L-beta-homo-aspartals appear to be specific inhibitors for ICE and its homologues; the other enzymes were not inhibited with such L-beta-homo aldehydes. Papain shows tolerance for D-residues at P1 depending on their chiral stability.

Active site-directed thrombin inhibitors: alpha-hydroxyacyl-prolyl-arginals, new orally active stable analogues of D-Phe-Pro-Arg-H.

D-alpha-Hydroxyacyl-prolyl-arginals, a new type of analogues of D-Phe-Pro-Arg-H (R1), have been prepared and evaluated. Unlike R1, whose terminal group is NH2, the new analogues with a terminal OH group are stable, as are the N-substituted derivatives of R1, that is, D-MePhe-Pro-Arg-H (R2), the highly potent and selective thrombin inhibitor, and Boc-D-Phe-Pro-Arg-H (R3), the much less favorable analogue. The most notable of the new analogues corresponds to the general formula D-Xaa-Pro-Arg-H, wherein Xaa means the acyl residue of mandelic acid (Man, 1), diphenyllactic acid (Dpl, 2), hexahydrophenyllactic acid (Hpl, 3), or hexahydromandelic acid (Hma, 4).

Effect of peptide aldehydes with IL-1 beta converting enzyme inhibitory properties on IL-1 alpha and IL-1 beta production in vitro.

Tripeptide and pentapeptide aldehydes as substrate-base inhibitors of cysteine proteases were designed in our laboratory for the inhibition of interleukin-1 beta converting enzyme (ICE), a recently described cysteine protease responsible for the processing of IL-1 beta. The biological effectivity of the peptide aldehydes was studied in THP-1 cells and human whole blood. The released and cell-associated IL-1 alpha and IL-1 beta levels were determined by ELISA from the supernatants and cell lysates, respectively.

Active site-directed thrombin inhibitors: alpha-hydroxyacyl-prolyl-arginals. New orally active stable analogs of D-Phe-Pro-Arg-H.

D-alpha-Hydroxyacyl-prolyl-arginals have been designed and synthesized as orally active stable analogs of D-Phe-Pro-Arg-H, the active site-directed peptidyl thrombin inhibitor prototype. Many of the new analogs possess high in vitro anticoagulant activity while having little effect on fibrinolysis. Compounds GYKI-66104 (2), -66131 (3) and -66132 (5) effectively delay the clotting time in rabbits ex vivo and prevent thrombus formation in various thrombosis models in rabbits and rats when applied in a single oral dose of 5 mg kg-1.