N-Myristoylation protein is catalyzed by N-myristoyltransferase (NMT), an essential target in Leishmania donovani, the causative agent of kala-azar. Four-dimensional quantitative structure-activity relationship (4D-QSAR) analysis was applied to a series of 77 Leishmania donovani NMT inhibitors. Then, three new compounds were proposed using QSAR models. In addition, molecular docking was performed to predict the binding affinities and interaction modes among the proposed compounds and the NMT active site. In silico absorption, distribution, metabolism and excretion (ADME) evaluation was performed and potential inhibitors demonstrated satisfactory pharmacokinetic properties.

Com o objetivo de contribuir para o desenvolvimento de produtos para o controle de Meloidogyne exigua, as bactérias Bacillus cereus e B. subtilis foram cultivadas em meio líquido de cultura para produzirem metabólitos ativos contra este nematoide parasita de plantas. Os fracionamentos dos extratos em diclorometano dos meios de cultura produziram uracila, 9H-purina e di-idrouracila. Todos os compostos foram ativos contra M. exigua, sendo o último o mais eficiente. Ele apresentou CL50 de 204 µg/mL contra o nematoide, enquanto uma CL50 de 260 µg/mL foi observada para o nematicida comercial carbofuran. Uma busca por complexos proteína-ligante nos quais o ligante fosse estruturalmente similar à di-idrouracila resultou na seleção de fosforibosiltransferases, cujas sequências foram utilizadas em uma busca in silico no genoma de M. incognita por sequência de aminoácidos semelhante. A sequência resultante foi modelada e di-idrouracila e 9H-purina foram inseridos nos sítios ativos desta provável fosforibosiltransferase, resultando em complexos proteína-ligante que foram submetidos a simulações por dinâmica molecular. Cálculos das energias livres de ligação destes complexos revelaram que a constante de dissociação de di-idrouracila e 9H-purina da enzima é da ordem de 8,3 x 10-7 e 1,6 x 10-6 M, respectivamente. Consequentemente, estas substâncias e a provável fosforibosiltransferase podem ser de grande utilidade para o desenvolvimento de novos produtos para o controle de M. exigua.

To contribute to the development of products to controlMeloidogyne exigua, the bacteria Bacillus cereus and B. subtilis were cultivated in liquid medium to produce metabolites active against this plant-parasitic nematode. Fractionation of the crude dichloromethane extracts obtained from the cultures afforded uracil, 9H-purine and dihydrouracil. All compounds were active against M. exigua, the latter being the most efficient. This substance presented a LC50 of 204 µg/mL against the nematode, while a LC50 of 260 µg/mL was observed for the commercial nematicide carbofuran. A search for protein-ligand complexes in which the ligands were structurally similar to dihydrouracil resulted in the selection of phosphoribosyltransferases, the sequences of which were used in an in silico search in the genome of M. incognita for a similar sequence of amino acids. The resulting sequence was modelled and dihydrouracil and 9H-purine were inserted in the active site of this putative phosphoribosyltransferase resulting in protein-ligand complexes that underwent molecular dynamics simulations. Calculation of the binding free-energies of these complexes revealed that the dissociation constant of dihydrouracil and 9H-purine to this protein is around 8.3 x 10-7 and 1.6 x 10-6 M, respectively. Consequently, these substances and the putative phosphoribosyltransferase are promising for the development of new products to control M. exigua.