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The design and synthesis of a small library of pyrrolidine iminocyclitol inhibitors with a structural similarity to 1,4-dideoxy-1,4-imino-D-arabitol (DAB-1) is reported. This library was specifically designed to gain a better insight into the mechanism of inhibition of glycosidases by polyhydroxylated pyrrolidines or iminocyclitols. Pyrrolidine-3,4-diol 15a and pyrrolidine-3,4-diol diacetate 15b had emerged as the most potent α-glucosidase inhibitors in the series. Docking studies performed with an homology model of α-glucosidase disclosed binding poses for compounds 15a, 15b, 16a, and 16a' occupying the same region as the NH group of the terminal ring of acarbose and suggest a closer and stronger binding of compound 15a and 15b with the enzyme active site residues. Our studies indicate that 2 or 5-hydroxyl substituents appear to be vital for high inhibitory activity.

Cytochrome bc(1) is a validated drug target in malaria parasites. The spread of Plasmodium falciparum strains resistant to multiple antimalarials emphasizes the urgent need for new drugs. We screened in silico the ZINC and MOE databases, using ligand- and structure-based approaches, to identify new leads for development. The most active compound presented an IC(50) value against cultured P. falciparum of 2 μM and a docking pose consistent with its activity.

A series of 1,4-naphthoquinone derivatives diversely substituted at C-2, C-3, C-5 and C-8, prepared by reaction of amines, amino acids and alcohols with commercial 1,4-naphthoquinones, has been evaluated against papain and bovine spleen cathepsin B. These 1,4-naphthoquinone derivatives were found to be irreversible inhibitors for both cysteine proteases, with second-order rate constants, k(2), ranging from 0.67 to 35.4 M-1 s(-1) for papain, and from 0.54 to 8.03 M-1 s(-1) for cathepsin B. Some derivatives display a hyperbolic dependence of the first-order inactivation rate constant, k(obs) with the inhibitor concentration, indicative of a specific interaction process between enzyme and inhibitor. The chemical reactivity of the compounds towards cysteine as a model thiol is dependent on the naphthoquinone LUMO energy, whereas papain inactivation is not. The 1,4-naphthoquinone derivatives are inactive against the serine protease, porcine pancreatic elastase. (c) 2007 Elsevier Ltd. All rights reserved.