Drug design and discovery最新文献

Enzymatic acylation of the antitubercular isoniazid (INH) by N-acetyl transferases reduces the therapeutic effectiveness of the drug. Because it represents a major metabolic pathway for INH in human beings, such acetylation has serious consequences for tuberculosis treatment regimens. Among patients in whom this process is efficient, the "rapid acetylators," the resultant chronic underdosing of INH may give rise to the development of resistance, as well as inadequate therapy. Not much work has been done previously to characterize the antitubercular properties of other N2-acylisoniazids. In order to address the fundamental issue of the activities of these acylated derivatives of INH, a number of such compounds 1a-f were chemically synthesized for investigation by a method providing good yield and purity. In experiments in vitro against Mycobacterium tuberculosis, these compounds displayed minimum inhibitory concentration (MIC) values between several fold and several hundred fold greater than that of INH itself, on a molar basis, with some of the more active compounds having higher calculated values of log P. Among these derivatives, compound 1b, closely homologous to the INH metabolite 1a, N2-acetylisoniazid, provided unexpected protection in tuberculosis-infected mice. The authors conclude that such close structural congeners of metabolites of INH may serve as significant leads in antitubercular drug discovery and in the exploration of the mode of action of INH.

3-Deoxy-D-manno-octulosonate 8-phosphate (KDO8P) is the phosphorylated precursor of KDO, an essential sugar of the lipopolysaccharide of Gram negative bacteria. KDO8P is produced by a specific synthase (KDO8PS) by condensing arabinose 5-phosphate (A5P) and phosphoenolpyruvate (PEP), with release of inorganic phosphate. As KDO8PS is present in bacteria and plants, but not in mammalian cells, and mutations that inactivate KDO8PS also block cell replication, KDO8PS is a promising target for the design of new antimicrobials that act by blocking lipopolysaccharide biosynthesis. Previous studies have shown that a compound mimicking an intermediate of the condensation reaction is a good ligand and a powerful inhibitor. Here we report on the crystallographic investigation of the binding to KDO8PS of new derivatives of this original inhibitor. The structures of the enzyme in complex with these compounds, and also with the PEP analogs, 2-phosphoglyceric acid (2-PGA) and Z-methyl-PEP, point to future strategies for the design of novel inhibitors of KDO8PS.

The energies and physical descriptors for the binding of 21 novel 1-(2,6-difluorobenzyl)-2-(2,6-difluorophenyl)-benzimidazole (BPBI) analogs to HIV-1 reverse transcriptase (RT) variants Y181C, L100I, V106A, and K103N have been determined using Monte Carlo (MC) simulations. The crystallographic structure of the lead compound, 4-methyl BPBI, was used as a starting point to model the inhibitors in both the mutant bound and the unbound states. The energy terms and physical descriptors obtained from the calculations were reasonably correlated with the respective experimental EC50 values for the inhibitors against the various mutant RTs. Using the linear response correlations from the calculations, 2 novel BPBI inhibitors have been designed and simulations have been carried out. The results show the computed deltaG(binding) values match the experimental data for the analogs. Given the ongoing problem with drug resistance, the ability to predict the activity of novel analogs against variants prior to synthesis is highly advantageous.

Neonicotinoids are the most important class of synthetic insecticides increasingly used in agriculture and veterinary medicine. Fundamental differences between the nicotinic acetylcholine receptors (nAChRs) of insects and mammals confer remarkable selectivity of the neonicotinoids at insect nAChR over mammalian nAChR. To identify pharmacophoric requirements of azidopyridinyl neonicotinoids for their efficacy and selectivity towards the insect nAChR over the mammalian one, quantitative structure-activity relationship (QSAR) study was performed using electrotopological state atom (ETSA) indices. This study clearly showed that nitroimines, nitromethylenes, and cyanoimines are more selective to Drosophila nAChR and safe for human being, whereas N-substituted imines have affinity to mammalian receptor. Pharmacophore mapping for both the activities was done.