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1.  Benzylidene Acylhydrazides Inhibit Chlamydial Growth in a Type III Secretion- and Iron Chelation-Independent Manner 
Journal of Bacteriology  2014;196(16):2989-3001.
Chlamydiae are widespread Gram-negative pathogens of humans and animals. Salicylidene acylhydrazides, developed as inhibitors of type III secretion system (T3SS) in Yersinia spp., have an inhibitory effect on chlamydial infection. However, these inhibitors also have the capacity to chelate iron, and it is possible that their antichlamydial effects are caused by iron starvation. Therefore, we have explored the modification of salicylidene acylhydrazides with the goal to uncouple the antichlamydial effect from iron starvation. We discovered that benzylidene acylhydrazides, which cannot chelate iron, inhibit chlamydial growth. Biochemical and genetic analyses suggest that the derivative compounds inhibit chlamydiae through a T3SS-independent mechanism. Four single nucleotide polymorphisms were identified in a Chlamydia muridarum variant resistant to benzylidene acylhydrazides, but it may be necessary to segregate the mutations to differentiate their roles in the resistance phenotype. Benzylidene acylhydrazides are well tolerated by host cells and probiotic vaginal Lactobacillus species and are therefore of potential therapeutic value.
doi:10.1128/JB.01677-14
PMCID: PMC4135636  PMID: 24914180
2.  Screening for Inhibition of Vibrio cholerae VipA-VipB Interaction Identifies Small-Molecule Compounds Active against Type VI Secretion 
The type VI secretion system (T6SS) is the most prevalent bacterial secretion system and an important virulence mechanism utilized by Gram-negative bacteria, either to target eukaryotic cells or to combat other microbes. The components show much variability, but some appear essential for the function, and two homologues, denoted VipA and VipB in Vibrio cholerae, have been identified in all T6SSs described so far. Secretion is dependent on binding of an α-helical region of VipA to VipB, and in the absence of this binding, both components are degraded within minutes and secretion is ceased. The aim of the study was to investigate if this interaction could be blocked, and we hypothesized that such inhibition would lead to abrogation of T6S. A library of 9,600 small-molecule compounds was screened for their ability to block the binding of VipA-VipB in a bacterial two-hybrid system (B2H). After excluding compounds that showed cytotoxicity toward eukaryotic cells, that inhibited growth of Vibrio, or that inhibited an unrelated B2H interaction, 34 compounds were further investigated for effects on the T6SS-dependent secretion of hemolysin-coregulated protein (Hcp) or of phospholipase A1 activity. Two compounds, KS100 and KS200, showed intermediate or strong effects in both assays. Analogues were obtained, and compounds with potent inhibitory effects in the assays and desirable physicochemical properties as predicted by in silico analysis were identified. Since the compounds specifically target a virulence mechanism without affecting bacterial replication, they have the potential to mitigate the virulence with minimal risk for development of resistance.
doi:10.1128/AAC.02819-13
PMCID: PMC4068513  PMID: 24798289
3.  Inhibitory Activity of the Isoflavone Biochanin A on Intracellular Bacteria of Genus Chlamydia and Initial Development of a Buccal Formulation 
PLoS ONE  2014;9(12):e115115.
Given the established role of Chlamydia spp. as causative agents of both acute and chronic diseases, search for new antimicrobial agents against these intracellular bacteria is required to promote human health. Isoflavones are naturally occurring phytoestrogens, antioxidants and efflux pump inhibitors, but their therapeutic use is limited by poor water-solubility and intense first-pass metabolism. Here, we report on effects of isoflavones against C. pneumoniae and C. trachomatis and describe buccal permeability and initial formulation development for biochanin A. Biochanin A was the most potent Chlamydia growth inhibitor among the studied isoflavones, with an IC50 = 12 µM on C. pneumoniae inclusion counts and 6.5 µM on infectious progeny production, both determined by immunofluorescent staining of infected epithelial cell cultures. Encouraged by the permeation of biochanin A across porcine buccal mucosa without detectable metabolism, oromucosal film formulations were designed and prepared by a solvent casting method. The film formulations showed improved dissolution rate of biochanin A compared to powder or a physical mixture, presumably due to the solubilizing effect of hydrophilic additives and presence of biochanin A in amorphous state. In summary, biochanin A is a potent inhibitor of Chlamydia spp., and the in vitro dissolution results support the use of a buccal formulation to potentially improve its bioavailability in antichlamydial or other pharmaceutical applications.
doi:10.1371/journal.pone.0115115
PMCID: PMC4267780  PMID: 25514140
4.  N-Acylated Derivatives of Sulfamethoxazole and Sulfafurazole Inhibit Intracellular Growth of Chlamydia trachomatis 
Antibacterial compounds with novel modes of action are needed for management of bacterial infections. Here we describe a high-content screen of 9,800 compounds identifying acylated sulfonamides as novel growth inhibitors of the sexually transmitted pathogen Chlamydia trachomatis. The effect was bactericidal and distinct from that of sulfonamide antibiotics, as para-aminobenzoic acid did not reduce efficacy. Chemical inhibitors play an important role in Chlamydia research as probes of potential targets and as drug development starting points.
doi:10.1128/AAC.02015-13
PMCID: PMC3993265  PMID: 24566180
5.  Isolation and Characterization of Anti-Adenoviral Secondary Metabolites from Marine Actinobacteria 
Marine Drugs  2014;12(2):799-821.
Adenovirus infections in immunocompromised patients are associated with high mortality rates. Currently, there are no effective anti-adenoviral therapies available. It is well known that actinobacteria can produce secondary metabolites that are attractive in drug discovery due to their structural diversity and their evolved interaction with biomolecules. Here, we have established an extract library derived from actinobacteria isolated from Vestfjorden, Norway, and performed a screening campaign to discover anti-adenoviral compounds. One extract with anti-adenoviral activity was found to contain a diastereomeric 1:1 mixture of the butenolide secondary alcohols 1a and 1b. By further cultivation and analysis, we could isolate 1a and 1b in different diastereomeric ratio. In addition, three more anti-adenoviral butenolides 2, 3 and 4 with differences in their side-chains were isolated. In this study, the anti-adenoviral activity of these compounds was characterized and substantial differences in the cytotoxic potential between the butenolide analogs were observed. The most potent butenolide analog 3 displayed an EC50 value of 91 μM and no prominent cytotoxicity at 2 mM. Furthermore, we propose a biosynthetic pathway for these compounds based on their relative time of appearance and structure.
doi:10.3390/md12020799
PMCID: PMC3944516  PMID: 24477283
adenovirus; antiviral; natural products; secondary metabolites; marine actinobacteria; extract screening; butenolides
6.  The Resveratrol Tetramer (-)-Hopeaphenol Inhibits Type III Secretion in the Gram-Negative Pathogens Yersinia pseudotuberculosis and Pseudomonas aeruginosa 
PLoS ONE  2013;8(12):e81969.
Society faces huge challenges, as a large number of bacteria have developed resistance towards many or all of the antibiotics currently available. Novel strategies that can help solve this problem are urgently needed. One such strategy is to target bacterial virulence, the ability to cause disease e.g., by inhibition of type III secretion systems (T3SSs) utilized by many clinically relevant gram-negative pathogens. Many of the antibiotics used today originate from natural sources. In contrast, most virulence-blocking compounds towards the T3SS identified so far are small organic molecules. A recent high-throughput screening of a prefractionated natural product library identified the resveratrol tetramer (-)-hopeaphenol as an inhibitor of the T3SS in Yersinia pseudotuberculosis. In this study we have investigated the virulence blocking properties of (-)-hopeaphenol in three different gram-negative bacteria. (-)-Hopeaphenol was found to have micromolar activity towards the T3SSs in Yersinia pseudotuberculosis and Pseudomonas aeruginosa in cell-based infection models. In addition (-)-hopeaphenol reduced cell entry and subsequent intracellular growth of Chlamydia trachomatis.
doi:10.1371/journal.pone.0081969
PMCID: PMC3853165  PMID: 24324737
7.  Mutations in hemG Mediate Resistance to Salicylidene Acylhydrazides, Demonstrating a Novel Link between Protoporphyrinogen Oxidase (HemG) and Chlamydia trachomatis Infectivity 
Journal of Bacteriology  2013;195(18):4221-4230.
Salicylidene acylhydrazides (SAHs) inhibit the type III secretion system (T3S) of Yersinia and other Gram-negative bacteria. In addition, SAHs restrict the growth and development of Chlamydia species. However, since the inhibition of Chlamydia growth by SAH is suppressed by the addition of excess iron and since SAHs have an iron-chelating capacity, their role as specific T3S inhibitors is unclear. We investigated here whether SAHs exhibit a function on C. trachomatis that goes beyond iron chelation. We found that the iron-saturated SAH INP0341 (IS-INP0341) specifically affects C. trachomatis infectivity with reduced generation of infectious elementary body (EB) progeny. Selection and isolation of spontaneous SAH-resistant mutant strains revealed that mutations in hemG suppressed the reduced infectivity caused by IS-INP0341 treatment. Structural modeling of C. trachomatis HemG predicts that the acquired mutations are located in the active site of the enzyme, suggesting that IS-INP0341 inhibits this domain of HemG and that protoporphyrinogen oxidase (HemG) and heme metabolism are important for C. trachomatis infectivity.
doi:10.1128/JB.00506-13
PMCID: PMC3754756  PMID: 23852872
8.  2-[4,5-Difluoro-2-(2-Fluorobenzoylamino)-Benzoylamino]Benzoic Acid, an Antiviral Compound with Activity against Acyclovir-Resistant Isolates of Herpes Simplex Virus Types 1 and 2 
Antimicrobial Agents and Chemotherapy  2012;56(11):5735-5743.
Herpes simplex viruses 1 and 2 (HSV-1 and HSV-2) are responsible for lifelong latent infections in humans, with periods of viral reactivation associated with recurring ulcerations in the orofacial and genital tracts. In immunosuppressed patients and neonates, HSV infections are associated with severe morbidity and, in some cases, even mortality. Today, acyclovir is the standard therapy for the management of HSV infections. However, the need for novel antiviral agents is apparent, since HSV isolates resistant to acyclovir therapy are frequently isolated in immunosuppressed patients. In this study, we assessed the anti-HSV activity of the antiadenoviral compounds 2-[2-(2-benzoylamino)-benzoylamino]benzoic acid (benzavir-1) and 2-[4,5-difluoro-2-(2-fluorobenzoylamino)-benzoylamino]benzoic acid (benzavir-2) on HSV-1 and HSV-2. Both compounds were active against both viruses. Importantly, benzavir-2 had potency similar to that of acyclovir against both HSV types, and it was active against clinical acyclovir-resistant HSV isolates.
doi:10.1128/AAC.01072-12
PMCID: PMC3486576  PMID: 22908173
9.  Expression, purification, crystallization and initial X-ray diffraction analysis of thiol peroxidase from Yersinia pseudotuberculosis  
Recombinant thiol peroxidase from Y. pseudotuberculosis has been purified and crystallized in three crystal forms.
Thiol peroxidase is an atypical 2-Cys peroxiredoxin that reduces alkyl hydroperoxides. Wild-type and C61S mutant protein have been recombinantly expressed in Escherichia coli and purified using nickel-affinity chromatography. Initial crystallization trials yielded three crystal forms in three different space groups (P21, P64 and P212121) both in the presence and the absence of DTT.
doi:10.1107/S1744309110039679
PMCID: PMC2998365  PMID: 21139206
Yersinia pseudotuberculosis; thiol peroxidases; Tpx; peroxiredoxins
10.  Protection of Mice From a Chlamydia trachomatis Vaginal Infection Using a Salicylidene Acylhydrazide, a Potential Microbicide 
The Journal of Infectious Diseases  2011;204(9):1313-1320.
The salicylidene acylhydrazide INP0341 inhibits growth of Chlamydia in HeLa cells, has negligible cell toxicity, and does not inhibit the growth of lactobacilli. The antichlamydial activity of INP0341 was retained when tested in vaginal and semen simulants. Vaginal tissue from INP0341-treated mice appeared similar to control sham-treated mice. To determine whether INP0341 can protect mice from a vaginal challenge, C3H/HeJ mice were either sham or INP0341 treated intravaginally pre- and postinoculation with 5 × 102 inclusion-forming units (IFUs) of Chlamydia trachomatis serovar D. Vaginal cultures taken over a month-long period showed a significant difference in the number of control mice that were culture positive versus the number in the INP0341-treated group, 100% (25/25) and 31% (8/26), respectively (P < .05). The quantity of IFUs shed and antibody titers to Chlamydia were significantly higher for the control group (P < .05). In summary, INP0341 is a promising compound to be considered for formulation as a vaginal microbicide.
doi:10.1093/infdis/jir552
PMCID: PMC3182314  PMID: 21933873
11.  In vitro anti-HIV-1 activity of salicylidene acylhydrazide compounds 
Introduction
Salicylidene acylhydrazide compounds have been shown to inhibit bacterial pathogens, including Chlamydia and Neisseria gonorrhoeae. If such compounds could also target HIV-1, their potential use as topical microbicides to prevent sexually transmitted infections would be considerable. We determined the in vitro anti-HIV-1 activity, cytotoxicity and mechanism of action of several salicylidene acylhydrazides.
Methods
Inhibitory activity was assessed using TZMbl cells and primary peripheral blood mononuclear cells (PBMCs) as targets for HIV-1 infection. Anti-viral activity was measured against cell-free and cell-associated virus and in vaginal fluid and semen simulants. Since the anti-bacterial activity of salicylidene acylhydrazides is reversible by Fe2+, we determined whether Fe2+ and other cations could reverse the anti-HIV-1 activity of the compounds. We also employed real-time PCR to determine the stage affected in the HIV-1 replication cycle.
Results
We identified four compounds with 50% HIV-1 inhibitory concentrations of 1 to 7 μM. In vitro toxicity varied but was generally limited. Activity was similar against three R5 clade B primary isolates and whether targets for virus replication were TZMbl cells or PBMCs. Compounds inhibited cell-free and cell-associated virus and were active in vaginal fluid and semen simulants. Fe2+, but not other cations, reversed the anti-HIV-1 effect. Finally, inhibitory effect of the compounds occurred at a post-integration step.
Conclusions
We identified salicylidene acylhydrazides with in vitro anti-HIV-1 activity in the μM range. The activity of these compounds against other sexually transmitted pathogens makes them potential candidates to formulate for use as a broad-spectrum topical genital microbicide.
doi:10.1016/j.ijantimicag.2012.05.023
PMCID: PMC3438335  PMID: 22819150
Salicylidene acylhydrazides; HIV; microbicide; iron chelation
12.  Structural Characterisation of Tpx from Yersinia pseudotuberculosis Reveals Insights into the Binding of Salicylidene Acylhydrazide Compounds 
PLoS ONE  2012;7(2):e32217.
Thiol peroxidase, Tpx, has been shown to be a target protein of the salicylidene acylhydrazide class of antivirulence compounds. In this study we present the crystal structures of Tpx from Y. pseudotuberculosis (ypTpx) in the oxidised and reduced states, together with the structure of the C61S mutant. The structures solved are consistent with previously solved atypical 2-Cys thiol peroxidases, including that for “forced” reduced states using the C61S mutant. In addition, by investigating the solution structure of ypTpx using small angle X-ray scattering (SAXS), we have confirmed that reduced state ypTpx in solution is a homodimer. The solution structure also reveals flexibility around the dimer interface. Notably, the conformational changes observed between the redox states at the catalytic triad and at the dimer interface have implications for substrate and inhibitor binding. The structural data were used to model the binding of two salicylidene acylhydrazide compounds to the oxidised structure of ypTpx. Overall, the study provides insights into the binding of the salicylidene acylhydrazides to ypTpx, aiding our long-term strategy to understand the mode of action of this class of compounds.
doi:10.1371/journal.pone.0032217
PMCID: PMC3288085  PMID: 22384182
13.  Candidate vaginal microbicides with activity against Chlamydia trachomatis and Neisseria gonorrhoeae 
Vaginal microbicides with activity towards organisms that cause sexually transmitted infections have been proposed as a strategy to reduce transmission. Small-molecule inhibitors of Chlamydia trachomatis serovar D belonging to the class of salicylidene acylhydrazides (INPs) have been shown to work through a mechanism that involves iron restriction. Expanding on this work, ten INPs were tested against a lymphogranuloma venereum strain of C. trachomatis serovar L2, Neisseria gonorrhoeae, and hydrogen peroxide-producing Lactobacillus crispatus and Lactobacillus jensenii. Seven INPs had minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations of <50 µM towards C. trachomatis L2. Three INPs had an MIC <12.5 µM against N. gonorrhoeae. Inhibition by was reversed by iron, holo-transferrin and holo-lactoferrin but not by the iron-poor forms of these compounds. The compounds exhibited no bactericidal activity toward Lactobacillus. The INPs were not cytotoxic to HeLa 229 cells. When INP 0341 was tested in a mouse model of a Chlamydia vaginal infection there was a significant reduction in the number of mice shedding C. trachomatis up to 4 days after infection (P < 0.01). In summary, select INPs are promising vaginal microbicide candidates as they inhibit the growth of two common sexually transmitted organisms in vitro, are active in a mouse model against C. trachomatis, are not cytotoxic and do not inhibit organisms that compose the normal vaginal flora.
doi:10.1016/j.ijantimicag.2010.03.018
PMCID: PMC2902681  PMID: 20605703
Vaginal microbicide; Sexually transmitted infections; Chlamydia trachomatis; LGV; Neisseria gonorrhoeae
14.  Identification of Bacterial Target Proteins for the Salicylidene Acylhydrazide Class of Virulence-blocking Compounds* 
The Journal of Biological Chemistry  2011;286(34):29922-29931.
A class of anti-virulence compounds, the salicylidene acylhydrazides, has been widely reported to block the function of the type three secretion system of several Gram-negative pathogens by a previously unknown mechanism. In this work we provide the first identification of bacterial proteins that are targeted by this group of compounds. We provide evidence that their mode of action is likely to result from a synergistic effect arising from a perturbation of the function of several conserved proteins. We also examine the contribution of selected target proteins to the pathogenicity of Yersinia pseudotuberculosis and to expression of virulence genes in Escherichia coli O157.
doi:10.1074/jbc.M111.233858
PMCID: PMC3191033  PMID: 21724850
Bacteria; Bacterial Genetics; Gene Regulation; Protein Drug Interactions; Protein Secretion; Protein Targeting; Transcription
15.  Small-Molecule Screening Using a Whole-Cell Viral Replication Reporter Gene Assay Identifies 2-{[2-(Benzoylamino)Benzoyl]Amino}-Benzoic Acid as a Novel Antiadenoviral Compound▿  
Adenovirus infections are widespread in society and are occasionally associated with severe, but rarely with life-threatening, disease in otherwise healthy individuals. In contrast, adenovirus infections present a real threat to immunocompromised individuals and can result in disseminated and fatal disease. The number of patients undergoing immunosuppressive therapy for solid organ or hematopoietic stem cell transplantation is steadily increasing, as is the number of AIDS patients, and this makes the problem of adenovirus infections even more urgent to solve. There is no formally approved treatment of adenovirus infections today, and existing antiviral agents evaluated for their antiadenoviral effect give inconsistent results. We have developed a whole cell-based assay for high-throughput screening of potential antiadenoviral compounds. The assay is unique in that it is based on a replication-competent adenovirus type 11p green fluorescent protein (GFP)-expressing vector (RCAd11pGFP). This allows measurement of fluorescence changes as a direct result of RCAd11pGFP genome expression. Using this assay, we have screened 9,800 commercially available small organic compounds. Initially, we observed approximately 400 compounds that inhibited adenovirus expression in vitro by ≥80%, but only 24 were later confirmed as dose-dependent inhibitors of adenovirus. One compound in particular, 2-{[2-(benzoylamino)benzoyl]amino}-benzoic acid, turned out to be a potent inhibitor of adenovirus replication.
doi:10.1128/AAC.00203-10
PMCID: PMC2935025  PMID: 20585112
16.  Characterization of the Effects of Salicylidene Acylhydrazide Compounds on Type III Secretion in Escherichia coli O157:H7 ▿ †  
Infection and Immunity  2009;77(10):4209-4220.
Recent work has highlighted a number of compounds that target bacterial virulence by affecting gene regulation. In this work, we show that small-molecule inhibitors affect the expression of the type III secretion system (T3SS) of Escherichia coli O157:H7 in liquid culture and when this bacterium is attached to bovine epithelial cells. Inhibition of T3SS expression resulted in a reduction in the capacity of the bacteria to form attaching and effacing lesions. Our results show that there is marked variation in the abilities of four structurally related compounds to inhibit the T3SS of a panel of isolates. Using transcriptomics, we performed a comprehensive analysis of the conserved and inhibitor-specific transcriptional responses to these four compounds. These analyses of gene expression show that numerous virulence genes, located on horizontally acquired DNA elements, are affected by the compounds, but the number of genes significantly affected varied markedly for the different compounds. Overall, we highlight the importance of assessing the effect of such “antivirulence” agents on a range of isolates and discuss the possible mechanisms which may lead to the coordinate downregulation of horizontally acquired virulence genes.
doi:10.1128/IAI.00562-09
PMCID: PMC2747932  PMID: 19635828
17.  Characterization of a Novel Mammalian Phosphatase Having Sequence Similarity to Schizosaccharomyces pombe PHO2 and Saccharomyces cereVisiae PHO13† 
Biochemistry  2002;41(24):7841-7848.
p34, a specific p-nitrophenyl phosphatase (pNPPase) was identified and purified from the murine cell line EL4 in a screen for the intracellular molecular targets of the antiinflammatory natural product parthenolide. A BLAST search analysis revealed that it has a high degree of sequence similarity to two yeast alkaline phosphatases. We have cloned, sequenced, and expressed p34 as a GST-tagged fusion protein in Escherichia coli and an EE-epitope-tagged fusion protein in mammalian cells. Using p-nitrophenyl phosphate (pNPP) as a substrate, p34 is optimally active at pH 7.6 with a Km of 1.36 mM and Kcat of 0.052 min−1. Addition of 1 mM Mg2+ to the reaction mixture increases its activity by 14-fold. Other divalent metal ions such as Co2+ and Mn2+ also stimulated the activity of the enzyme, while Zn2+, Fe2+, and Cu2+ had no effect. Furthermore, both NaCl and KCl enhanced the activity of the enzyme, having maximal effect at 50 and 75 mM, respectively. The enzyme is inhibited by sodium orthovanadate but not by sodium fluoride or okadaic acid. Mutational analysis data suggest that p34 belongs to the group of phosphatases characterized by the sequence motif DXDX(T/V).
PMCID: PMC2556553  PMID: 12056916
18.  Salicylidene Acylhydrazides That Affect Type III Protein Secretion in Salmonella enterica Serovar Typhimurium▿  
A collection of nine salicylidene acylhydrazide compounds were tested for their ability to inhibit the activity of virulence-associated type III secretion systems (T3SSs) in Salmonella enterica serovar Typhimurium. The compounds strongly affected Salmonella pathogenicity island 1 (SPI1) T3SS-mediated invasion of epithelial cells and in vitro secretion of SPI1 invasion-associated effector proteins. The use of a SPI1 effector β-lactamase fusion protein implicated intracellular entrapment of the protein construct upon application of a salicylidene acylhydrazide, whereas the use of chromosomal transcriptional gene fusions revealed a compound-mediated transcriptional silencing of SPI1. Salicylidene acylhydrazides also affected intracellular bacterial replication in murine macrophage-like cells and blocked the transport of an epitope-tagged SPI2 effector protein. Two of the compounds significantly inhibited bacterial motility and expression of extracellular flagellin. We conclude that salicylidene acylhydrazides affect bacterial T3SS activity in S. enterica and hence could be used as lead substances when designing specific inhibitors of bacterial T3SSs in order to pharmaceutically intervene with bacterial virulence.
doi:10.1128/AAC.00223-07
PMCID: PMC1932493  PMID: 17548496
19.  Inhibition of Type III Secretion in Salmonella enterica Serovar Typhimurium by Small-Molecule Inhibitors▿  
Type III secretion systems (T3SS) are conserved in many pathogenic gram-negative bacteria. Small molecules that specifically target T3SS in Yersinia and Chlamydia spp. have recently been identified. Here we show that two such compounds inhibit Salmonella T3SS-1, preventing secretion of T3SS-1 effectors, invasion of cultured epithelial cells, and enteritis in vivo.
doi:10.1128/AAC.01492-06
PMCID: PMC1913257  PMID: 17502403
20.  Reversal of the Antichlamydial Activity of Putative Type III Secretion Inhibitors by Iron▿  
Infection and Immunity  2007;75(7):3478-3489.
INPs, which are chemically synthesized compounds belonging to a class of acylated hydrazones of salicylaldehydes, can inhibit the growth of Chlamydiaceae. Evidence has been presented that in Yersinia and Chlamydia INPs may affect the type III secretion (T3S) system. In the present study 25 INPs were screened for antichlamydial activity at a concentration of 50 μM, and 14 were able to completely inhibit the growth of Chlamydia trachomatis serovar D in McCoy and HeLa 229 cells. The antichlamydial activities of two of these INPs, INPs 0341 and 0400, were further characterized due to their low cytotoxicity. These compounds were found to inhibit C. trachomatis in a dose-dependent manner; were not toxic to elementary bodies; were cidal at a concentration of ≥20 μM; inhibited all Chlamydiaceae tested; and could inhibit the development of C. trachomatis as determined by the yield of progeny when they were added up to 24 h postinfection. INP 0341 was able to affect the expression of several T3S genes. Compared to the expression in control cultures, lcrH-1, copB, and incA, all middle- to late-expressed T3S genes, were not expressed in the INP 0341-treated cultures 24 to 36 h postinfection. Iron, supplied as ferrous sulfate, as ferric chloride, or as holo-transferrin, was able to negate the antichlamydial properties of the INPs. In contrast, apo-transferrin and other divalent metal ions tested were not able to reverse the inhibitory effect of the INPs. In conclusion, the potent antichlamydial activity of INPs is directly or indirectly linked with iron, and this inhibition of Chlamydia has an effect on the T3S system of this intracellular pathogen.
doi:10.1128/IAI.00023-07
PMCID: PMC1932962  PMID: 17470544
21.  A Potent Trivalent Sialic Acid Inhibitor of Adenovirus Type 37 Infection of Human Corneal Cells** 
doi:10.1002/anie.201101559
PMCID: PMC3210828  PMID: 21648036
adenoviruses; antiviral agents; crystal-structure elucidation; sialic acids; surface plasmon resonance
22.  Pre-clinical pharmacokinetics and anti-chlamydial activity of salicylidene acylhydrazide inhibitors of bacterial type III secretion 
The Journal of Antibiotics  2012;65(8):397-404.
Salicylidene acylhydrazides belong to a class of compounds shown to inhibit bacterial type III secretion (T3S) in pathogenic Gram-negative bacteria. This class of compounds also inhibits growth and replication of Chlamydiae, strict intracellular bacteria that possess a T3S system. In this study a library of 58 salicylidene acylhydrazides was screened to identify inhibitors of Chlamydia growth. Compounds inhibiting growth of both Chlamydia trachomatis and Chlamydophila pneumoniae were tested for cell toxicity and seven compounds were selected for preliminary pharmacokinetic analysis in mice using cassette dosing. Two compounds, ME0177 and ME0192, were further investigated by individual pharmacokinetic analysis. Compound ME0177 had a relatively high peak plasma concentration (Cmax) and area under curve and therefore may be considered for systemic treatment of Chlamydia infections. The other compound, ME0192, had poor pharmacokinetic properties but the highest anti-chlamydial activity in vitro and therefore was tested for topical treatment in a mouse vaginal infection model. ME0192 administered vaginally significantly reduced the infectious burden of C. trachomatis and the number of infected mice.
doi:10.1038/ja.2012.43
PMCID: PMC3428607  PMID: 22669447
Chlamydophila pneumoniae; Chlamydia trachomatis; pre-clinical pharmacokinetics; type III secretion inhibitor; vaginal microbicide; virulence inhibitor

Results 1-22 (22)