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A series of novel aza vinyl sulfones were designed, synthesized in good yields and evaluated as antiplasmodial agents. Tested compounds did not show activity against papain or the Plasmodium falciparum cysteine protease falcipain-2. However, a number of the new compounds effectively inhibited the in vitro development of P. falciparum. Compounds containing a squaramide group were the most active, with IC(50) values between 0.95 and 4.5 μM, suggesting that these are potential lead compounds for the development of new antimalarial agents., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

In this article we describe an expanded structure-activity relationship study for vinyl sulfones as caspase-3 inhibitors, a topic virtually unexplored in the existing literature. Most remarkably, and to our surprise, tripeptidyl vinyl sulfones were not active for caspase-3, opposite to other examples described in literature for peptidyl vinyl sulfones as potent cysteine protease inhibitors of clan CA. Moreover, the caspase-3 inhibitory activity of vinyl sulfones using an in vitro assay was then confirmed using a yeast cell-based assay. The results show that Fmoc-protected vinyl sulfones containing only the Asp moiety are inhibitors of a caspase-3-dependent pathway and the IC50 values obtained in the yeast assay are in the same order of magnitude of that obtained with the caspase-3 inhibitor tetrapeptidyl chloromethyl ketone, Ac-DEVD-CMK. This observation is consistent with appropriate cell permeability properties displayed by the vinyl sulfone inhibitors, as reflected by logP values ranging from 1.1 to 3.4. Overall, these results suggest that vinyl sulfones containing Asp at P1 should be considered for further optimization as caspase inhibitors and modulators of caspase-3-dependent pathways., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

The first structure-activity relationship study of vinyl sulfones as caspase-3 inhibitors is reported. A series of 12 vinyl sulfones was synthesized and evaluated for two downstream caspases (caspases-3 and -7). Dipeptidyl derivatives were significantly superior to their counterparts containing only Asp at P(1), as caspase-3 inhibitors. Fmoc-Val-Asp-trans-CH=CH-SO(2)Me was the most potent inhibitor of caspase-3 in the series, with a IC(50) of 29 microM and a second-order rate constant of inactivation, k(inact)/K(i), of 1.5 M(-1) s(-1). Computational studies suggest that the second amino acid occupies position S(3) of the enzyme. In addition, Fmoc-Val-Asp-trans-CH=CH-SO(2)Ph was inactive for caspase-7 for the tested concentrations., (2010 Elsevier Masson SAS. All rights reserved.)

A series of artemisinin-vinyl sulfone hybrid molecules with the potential to act in the parasite food vacuole via endoperoxide activation and falcipain inhibition was synthesized and screened for antiplasmodial activity and falcipain-2 inhibition. All conjugates were active against the Plasmodium falciparum W2 strain in the low nanomolar range and those containing the Leu-hPhe core inhibited falcipain-2 in low micromolar range.