RESUMO
The heme enzyme myeloperoxidase (MPO) participates in innate immune defense mechanism through formation of microbicidal reactive oxidants. However, evidence has emerged that MPO-derived oxidants contribute to propagation of inflammatory diseases. Because of the deleterious effects of circulating MPO, there is a great interest in the development of new efficient and specific inhibitors. Here, we have performed a novel virtual screening procedure, depending on ligand-based pharmacophore modeling followed by structure-based virtual screening. Starting from a set of 727842 compounds, 28 molecules were selected by this virtual method and tested on MPO in vitro. Twelve out of 28 compounds were found to have an IC50 less than 5 µM. The best inhibitors were 2-(7-methoxy-4-methylquinazolin-2-yl)guanidine (28) and (R)-2-(1-((2,3-dihydro-1H-imidazol-2-yl)methyl)pyrrolidin-3-yl)-5-fluoro-1H-benzo[d]imidazole (42) with IC50 values of 44 and 50 nM, respectively. Studies on the mechanism of inhibition suggest that 28 is the first potent mechanism-based inhibitor and inhibits irreversibly MPO at nanomolar concentration.
Assuntos
Benzimidazóis/farmacologia , Inibidores Enzimáticos/farmacologia , Guanidinas/farmacologia , Peroxidase/antagonistas & inibidores , Quinazolinas/farmacologia , Benzimidazóis/síntese química , Benzimidazóis/toxicidade , Linhagem Celular , Bases de Dados de Compostos Químicos , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/toxicidade , Ácido Glutâmico/química , Glutamina/química , Guanidinas/síntese química , Guanidinas/toxicidade , Humanos , Peróxido de Hidrogênio/química , Cinética , Lactoperoxidase/antagonistas & inibidores , Lipoproteínas LDL/química , Modelos Químicos , Simulação de Acoplamento Molecular , Neutrófilos/efeitos dos fármacos , Neutrófilos/metabolismo , Oxirredução , Quinazolinas/síntese química , Quinazolinas/toxicidade , EstereoisomerismoRESUMO
Cordia gilletii De Wild (Boraginaceae), a medicinal plant used against infectious diseases in the Democratic Republic of Congo, was investigated for direct and indirect antimicrobial properties. On one hand, the methanol extract is active against many pathogenic bacteria, including resistant strains. Its bio-guided fractionation led to the isolation of ferulaldehyde; this compound showed antimicrobial and antioxidant properties that may support the activity we observed for the methanol extract and some of the traditional uses of C. gilletii. On the other hand, the n-hexane extract of root barks possesses indirect antimicrobial properties, enhancing the activity of antibiotics against methicillin-resistant Staphylococcus aureus (MRSA). The fractionation of this extract led to the isolation of lupeol, which decreases the minimum inhibitory concentration of several antibiotics (4 to 8 fold) against MRSA and contributes to the effects observed for the raw n-hexane extract.