The coordinates of proteins PfFabZ, PfFabG, PfFabI, SaFabI, EcFabI and MtFabI targets for molecular docking (PDB entries 1z6b, 2c07, 1v35, 3gr6, 1c14 and 1p45, respectively), were imported into the Maestro (Maestro, version 9.2, Schr?dinger, LLC, New York, NY, 2011) and processed using Protein Preparation Wizard workflow to remove water molecules, collection atom types, put hydrogen atoms for proteins at pH 7.4 and deal GW1929 with the problems with protein constructions. prophylaxis and prevention by halting the initiation of BS, ii) to prevent transmission in support of eradication attempts, iii) to reduce the risk of resistance development due to low parasite weight, long residence time and solitary replication cycle, and iv) to target hypnozoites of and causing relapses.3,4 Primaquine, the only approved drug active against LS parasites and hypnozoites suffers from poor compliance, risk of haemolysis and high toxicity,5 hence new medicines are needed. Recent efforts possess led to the finding of synthetic compounds,6 and a few natural products of flower or microbial source with LS inhibitory activity.7C11 Several metabolic pathways, such as haem detoxification or nucleic acid metabolism, are involved in the BS action of antimalarial medicines. Many compounds with anti-LS activity inhibit related metabolic pathways in BS parasites such as dihydrofolate reductase and cyctochrome bc1 complex.6 Interestingly, the transcriptome and proteome expression levels of malaria parasites reveal that a large number of genes and proteins are indicated only in LS and hence represent stage-specific drug targets.12,13 The type II fatty acid biosynthesis pathway (FAS-II) GW1929 has recently been shown to be crucial for survival of LS parasites but dispensable in BS parasites, thus appears to be the 1st target for solely prophylactic medicines.14,15 The FAS-II system involves a set of individual monofunctional enzymes, which is fundamentally different to the mammalian type I system (FAS-I) consisting of a dimer of a large multifunctional polypeptide. The sequence similarity between the enzymes of FAS-II and the related GW1929 domains of FAS-I are fragile, although the individual methods in biosynthesis are basically the same.16 A few synthetic compounds have been characterised with activity against LS and FAS-II enzymes; enoyl-ACP reductase (FabI) inhibitor triclosan,17 beta-ketoacyl-ACP reductase (FabG) inhibitor hexachlorophene,12,18 and 2-hexadecynoic acid (2-HDA), which inhibits three GW1929 enzymes, FabI, FabG and FabZ (beta-hydroxyacyl-ACP dehydratase).19 Lichens are symbiotic associations between an exhabitant fungus and one or more inhabitant photosynthetic partners (algae or cyanobacteria). Several studies Rabbit Polyclonal to COX5A revealed a broad range of biological activities of lichen metabolites, including inhibition of gram-positive bacteria and mycobacteria.20,21 However, their mechanism of action offers often remained unidentified. Lichens are traditionally utilized for a variety of purposes, as antibiotics, laxatives, antifebrile providers or against coughing (including that associated with tuberculosis).22,23 varieties are used for malaria and fever in Kenya24 and the in vitro activity of (+)-usnic acid (4) against BS parasites has been confirmed.25 Derivatives of 4 have recently been shown to inhibit LS parasites, 26 however to our knowledge, no study has yet reported the prophylactic potential of 4 or the other lichen compounds. The aim of this study was to assess the malaria prophylactic and chemotherapeutic potential of four selected lichen metabolites, evernic, vulpic, psoromic and (+)-usnic acids (1-4) towards LS and BS parasites. To investigate the FAS-II enzymes as potential target for LS activity, inhibitory effects of the compounds were assessed against three FAS-II elongation enzymes, i.e. (((LS parasites by assessment of infections after compound exposure with quantitative actual time-PCR (qRT-PCR). All compounds showed activity with (+)-usnic acid (4) exhibiting the highest inhibitory effect with an IC50 value of 2.3 K1 strain, 3 exhibited the best BS potential (IC50 29.2 parasites 48 h post-infection. Images shown depict liver stage parasites recognized by an antibody against parasite protein HSP70 (FITC, green) and stained with Hoechst nuclear stain (blue) at 40X objective magnification. a) Infected cultures cultivated in the presence of positive control Atovaquone (Ato) at three independent concentrations and GW1929 0.1% DMSO control. b) Infected cultures cultivated in the presence of four lichen metabolites in the concentration of 10 ((((MIC 15.1 (IC50 > 64 (MIC 32 elongation enzymes, was inactive against all bacterial/mycobacterial FabI analogues. Compounds 1-4 were docked to the analogue enzymes LS.