RESUMO
The prokaryotic ATP-dependent ClpP protease, localized in the relict plastid of malaria parasite, represents a potential drug target. In the present study, we utilized in silico structure-based screening and medicinal chemistry approaches to identify a novel pyrimidine series of compounds inhibiting P. falciparum ClpP protease activity and evaluated their antiparasitic activities. Structure-activity relationship indicated that morpholine moiety at C2, an aromatic substitution at N3 and a 4-oxo moiety on the pyrimidine are important for potent inhibition of ClpP enzyme along with antiparasiticidal activity. Compound 33 exhibited potent antiparasitic activity (EC50 9.0±0.2µM), a 9-fold improvement over the antiparasitic activity of the hit molecule 6. Treatment of blood stage P. falciparum cultures with compound 33 caused morphological and developmental abnormalities in the parasites; further, compound 33 treatment hindered apicoplast development indicating the targeting of apicoplast.
Assuntos
Antimaláricos/síntese química , Endopeptidase Clp/antagonistas & inibidores , Plasmodium/efeitos dos fármacos , Plasmodium/enzimologia , Antimaláricos/química , Antimaláricos/farmacologia , Apicoplastos/efeitos dos fármacos , Domínio Catalítico , Humanos , Concentração Inibidora 50 , Estrutura Molecular , Inibidores de Proteases/síntese química , Inibidores de Proteases/química , Inibidores de Proteases/farmacologia , Relação Estrutura-AtividadeRESUMO
Falcipain-2 is a papain family cysteine protease and an emerging antimalarial drug target. A pseudo-tripeptide scaffold I was designed using in silico screening tools and the three dimensional structures of falcipain-2, falcipain-3, and papain. This scaffold was investigated at four positions, T1, T2, T3, and T3', with various targeted substitutions to understand the structure-activity relationships. Inhibitor synthesis was accomplished by first obtaining the appropriate dipeptide precursors with common structural components. The pyrrolidine moiety introduced interesting rotamers in a number of synthesized molecules, which was confirmed using high-temperature (1)H NMR spectroscopy. Among the synthesized compounds, 61, 62, and 66 inhibited falcipain-2 activity with inhibition constants (Ki) of 1.8 ± 1.1, 0.2 ± 0.1 and 7.0 ± 2.3 µM, respectively. A group of molecules with a pyrrolidine moiety at the T2 position (68, 70, 71, 72, and 73) also potently inhibited falcipain-2 activity (Ki=0.4 ± 0.1, 2.5 ± 0.5, 3.3 ± 1.1, 7.5 ± 1.9, and 4.6 ± 0.7 µM, respectively). Overall, compound 74 exhibited potent anti-parasitic activity (IC50=0.9 ± 0.1 µM), corresponding with its inhibitory activity against falcipain-2, with a Ki of 1.1 ± 0.1 µM. Compounds 62 and 67 inhibited the growth of the drug resistant parasite Dd2 with better efficacy, and compound 74 exhibited a 7- to 12-fold higher potency against Dd2 and MCamp isolates, than the laboratory strain (3D7). These data suggest that this novel series of compounds should be further investigated as potential antimalarial agents.
Assuntos
Antimaláricos/farmacologia , Cisteína Endopeptidases/metabolismo , Inibidores de Cisteína Proteinase/classificação , Inibidores de Cisteína Proteinase/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/enzimologia , Animais , Antimaláricos/síntese química , Antimaláricos/química , Células CHO , Proliferação de Células/efeitos dos fármacos , Cricetulus , Inibidores de Cisteína Proteinase/síntese química , Inibidores de Cisteína Proteinase/química , Relação Dose-Resposta a Droga , Desenho de Fármacos , Resistência a Medicamentos/efeitos dos fármacos , Modelos Moleculares , Estrutura Molecular , Testes de Sensibilidade Parasitária , Plasmodium falciparum/crescimento & desenvolvimento , Relação Estrutura-AtividadeRESUMO
Employing a ligand-based approach, 3-methoxyquinoxalin-2-carboxamides were designed as serotonin type-3 (5-HT(3) ) receptor antagonists and synthesized from the starting material o-phenylenediamine in a sequence of reactions. The structures of the synthesized compounds were confirmed by spectral data. These carboxamides were investigated for their 5-HT(3) receptor antagonisms in longitudinal muscle myenteric plexus preparations from guinea-pig ileum against a standard 5-HT(3) agonist, 2-methy-5-HT, and their antagonism activities are expressed as pA(2) values. Compounds 6a (pA(2) : 7.2), 6e (pA(2) : 7.0), 6f (pA(2) : 7.5), 6g (pA(2) : 7.5), 6n (pA(2) : 7.0), and 6o (pA(2) : 7.2) exhibited antagonism greater than that of the standard 5-HT(3) antagonist, ondansetron (pA(2) : 6.9).
Assuntos
Desenho de Fármacos , Quinoxalinas/síntese química , Antagonistas do Receptor 5-HT3 de Serotonina/síntese química , Animais , Cobaias , Íleo/efeitos dos fármacos , Íleo/inervação , Íleo/metabolismo , Técnicas In Vitro , Ligantes , Masculino , Estrutura Molecular , Músculo Liso/efeitos dos fármacos , Músculo Liso/inervação , Músculo Liso/metabolismo , Plexo Mientérico/efeitos dos fármacos , Plexo Mientérico/metabolismo , Quinoxalinas/química , Quinoxalinas/farmacologia , Agonistas do Receptor 5-HT3 de Serotonina/farmacologia , Antagonistas do Receptor 5-HT3 de Serotonina/química , Antagonistas do Receptor 5-HT3 de Serotonina/farmacologia , Relação Estrutura-AtividadeRESUMO
ODCase is a highly proficient enzyme responsible for the decarboxylation of orotidine monophosphate to generate uridine monophosphate. ODCase has attracted early attention due to its interesting mechanism of catalysis. In order to exploit therapeutic advantages due to the inhibition of ODCase, one must have selective inhibitors of this enzyme from the pathogen, or a dysregulated molecular mechanism involving ODCase. ODCase inhibitors have potential applications as anticancer agents, antiviral agents, antimalarial agents and potentially act against other parasitic diseases. A variety of C6-substituted uridine monophosphate derivatives have shown excellent inhibition of ODCase. 6-iodouridine is a potent inhibitor of the malaria parasite, and its monophosphate form covalently inhibits ODCase. A variety of inhibitors of ODCase with potential applications as therapeutic agents are discussed in this review.