4-Chloroisocoumarins as Chlamydial Protease Inhibitors and Anti-Chlamydial Agents.

4-Chloroisocoumarin compounds have broad inhibitory properties against serine proteases. Here, we show that selected 3-alkoxy-4-chloroisocoumarins preferentially inhibit the activity of the conserved serine protease High-temperature requirement A of Chlamydia trachomatis. The synthesis of a new series of isocoumarin-based scaffolds has been developed, and their anti-chlamydial properties were investigated. The structure of the alkoxy substituent was found to influence the potency of the compounds against High-temperature requirement A, and modifications to the C-7 position of the 3-alkoxy-4-chloroisocoumarin structure attenuate anti-chlamydial properties.

Alternative strategies for Chlamydia treatment: Promising non-antibiotic approaches.

Chlamydia is an obligate intracellular bacterium where most species are pathogenic and infectious, causing various infectious diseases and complications in humans and animals. Antibiotics are often recommended for the clinical treatment of chlamydial infections. However, extensive research has shown that antibiotics may not be sufficient to eliminate or inhibit infection entirely and have some potential risks, including antibiotic resistance. The impact of chlamydial infection and antibiotic misuse should not be underestimated in public health. This study explores the possibility of new therapeutic techniques, including a review of recent studies on preventing and suppressing chlamydial infection by non-antibiotic compounds.

Jatrolignans C and D: New Neolignan Epimers from Jatropha curcas.

Two new neolignans jatrolignans, C (1) and D (2), a pair of epimers, were isolated from the whole plants of Jatropha curcas L. (Euphorbiaceae). Their structures were determined with HRESIMS, IR, and NMR data analysis, and electronic circular dichroism (ECD) experiments via a comparison of the experimental and the calculated ECD spectra. Their antichlamydial activity was evaluated in Chlamydia abortus. They both showed dose-dependent antichlamydial effects. Significant growth inhibitory effects were observed at a minimum concentration of 40 µM.

Synthesis of 1-substituted phenazines as novel antichlamydial agents.

A novel series of 1-substituted phenazines 4a-4l were designed and synthesized via Palladium-catalyzed reactions from 1-phenazine trifluoromethanesulfonate. These phenazines showed antichlamydial activity with IC50 values from 1 to 10 µM. Among them, compounds 4c and 4i exhibited the best antichlamydial activity with IC50 values from 2.06 to 2.74 µM without apparent cytotoxicity to host cells.

In vitro inhibitory effect of Hydrocotyle bonariensis Lam. extracts over Chlamydia trachomatis and Chlamydia pneumoniae on different stages of the chlamydial life cycle.

Chlamydial infections in humans are widely distributed and are responsible for a variety of acute and chronic diseases. Both Chlamydia trachomatis and Chlamydia pneumoniae can lead to chronic conditions that have been linked to complications and sequelae. This study aimed to develop a culture method in order to detect in vitro antichlamydial activity of different extracts obtained from native Argentinian plants used as antimicrobials in local ethnomedicine and to evaluate their inhibitory activity over Chlamydia trachomatis and Chlamydia pneumoniae growth. The inhibitory activity over different stages of the chlamydial life cycle on cell culture was assessed: the entry, the inclusion developing after entry, and the exponential growth stage. Also, the capability of rendering the cell refractory to chlamydial infection by pre-incubation with the extracts was assayed. Inhibitory activity of water-based and organic-based extracts obtained from Hydrocotyle bonariensis Lam. (Araliaceae), Lithraea molleoides (Vell.) Engl. (Anacardiaceae) and Hybanthus parviflorus (Mutis ex L.f.) Baill. (Violaceae) were tested against five strains of Chlamydia trachomatis (L2/434/BU and four clinical isolates form both neonatal conjunctivitis and adult genital infections, genotypes D, E, and K) and against Chlamydia pneumoniae AR39. The Hydrocotyle bonariensis dichloromethane extract showed a broad inhibitory activity over the exponential growth stage of Chlamydia trachomatis and Chlamydia pneumoniae independently from the chlamydial strain and the cell line. These results suggest a high inhibitory potential on both Chlamydiae species. In order to characterize the Hydrocotyle bonariensis dichloromethane active extract, an 1H-NMR was performed. The 1H-NMR characterization showed a spectrum with characteristic signals of the fatty acid moiety of lipids or cerebrosides, volatile phenolics, phytosterols, methyl triterpenes signals, and glucose moiety of the cerebrosides.

Ambroxol Treatment Suppresses the Proliferation of Chlamydia pneumoniae in Murine Lungs.

Ambroxol (Ax) is used as a mucolytics in the treatment of respiratory tract infections. Ax, at a general dose for humans, does not alter Chlamydia pneumoniae growth in mice. Therefore, we aimed to investigate the potential anti-chlamydial effect of Ax at a concentration four timed higher than that used in human medicine. Mice were infected with C. pneumoniae and 5-mg/kg Ax was administered orally. The number of recoverable C. pneumoniae inclusion-forming units (IFUs) in Ax-treated mice was significantly lower than that in untreated mice. mRNA expression levels of several cytokines, including interleukin 12 (IL-12), IL-23, IL-17F, interferon gamma (IFN-γ), and surfactant protein (SP)-A, increased in infected mice treated with Ax. The IFN-γ protein expression levels were also significantly higher in infected and Ax-treated mice. Furthermore, the in vitro results suggested that the ERK 1/2 activity was decreased, which is essential for the C. pneumoniae replication. SP-A and SP-D treatments significantly decreased the number of viable C. pneumoniae IFUs and significantly increased the attachment of C. pneumoniae to macrophage cells. Based on our results, a dose of 5 mg/kg of Ax exhibited an anti-chlamydial effect in mice, probably an immunomodulating effect, and may be used as supporting drug in respiratory infections caused by C. pneumoniae.

The antichlamydial activity of 1, 2-disubstituted pyrrole derivatives in vitro / 中国药理学通报

Aim To evaluate the antichlamydial activity of our previously synthesized sixteen 1, 2-disubstituted pyrroles in vitro, providing candidate for the development of novel agents against Chlamydia. Methods Firstly, the inhibitory effect of compounds on the generation of infectious progeny EBs at different concentrations was analyzed for Chlamydia trachomatis L2 (Ct L2), C. muridarum (Nigg II strain, known as MoPn) and C. pneumonia (Cpn AR39). The IC

Synthesis and Assessment of 3-Substituted Phenazines as Novel Antichlamydial Agents.

BACKGROUND: In the past century, many phenazines were isolated from the marine microorganism, and some of these phenazines possessed potent antibacterial activities. We found that a few of the synthesized 4-substituted phenazines could block the infectivity of chlamydiae without host cell toxicity. OBJECTIVE: The aim of this study was to design and synthesize two series of novel 3-substituted phenazines to find novel antichlamydial agents. METHODS: The 3-substituted phenazines were synthesized via Buchwald-Hartwig cross coupling reaction and Suzuki reaction from 3-bromo-1-methoxyphenazine. The antichlamydial activity of these synthesized compounds was evaluated by determining their effect on the yield of infectious progeny EBs. Cytotoxicity of these compounds on host cells was assessed by the treatment of uninfected HeLa cells using WST-1 method. RESULTS: Most of the 3-substituted phenazines possessed potent antichlamydial activity with IC50 values from 0.15 to 12.08 µM against Chlamydia trachomatis L2, C. muridarum MoPn and C. pneumoniae AR39. Among them, 7d and 9a exhibited better antichlamydial activity with IC50 values from 0.20 to 1.01 µM while they have no apparent cytotoxicity to host cells. Biological assay disclosed that both 7d and 9a inhibited chlamydial infection by reducing elementary body infectivity and disturbing chlamydial growth during the whole chlamydial developmental cycle. CONCLUSION: Our findings suggested that 3-substituted phenazine derivatives might be a promising class of therapeutic agents for chlamydial infections. More effective phenazines with low toxicity could be acquired through further chemical modification on C-3 position rather than C-4 position of phenazine.

Tratamientos alternativos de medicina tradicional para Chlamydia trachomatis, agente causal de una infección asintomática / Alternative Treatments of Traditional Medicine for Chlamydia trachomatis, Causal Agent of an Asympomatic Infection

Resumen En la actualidad, Chlamydia trachomatis (CT) es una de las causas más frecuentes de infecciones de transmisión sexual (ITS) y morbilidad reproductiva en el mundo, Incluye tanto países desarrollados como en vía de desarrollo, con un reporte alrededor de 92 millones de casos anuales. CT es una bacteria intracelular obligada cuyo inicio de la infección es asintomático, causa infección crónica, puede generar infección persistente y complicaciones como cáncer de ovario. Las infecciones por CT son asintomáticas en el 70% de las mujeres y el 40% de los hombres, lo que dificulta el diagnóstico en las fases tempranas de la infección y el tratamiento oportuno, lo que conlleva a un aumento en los contagios en la población. De acuerdo con la Organización Mundial de la Salud (OMS), el tratamiento para CT incluye la utilización de antibióticos tipo tetraciclinas, macrólidos y fluoroquinolonas. Sin embargo, a pesar de su alta tasa de eficacia, cada vez son más recurrentes las infecciones. Reportes recientes han demostrado resistencia por parte de los cuerpos elementales y se ha podido determinar que los antibióticos disminuyen la población de lactobacillus vaginales beneficiosos, causando mayores complicaciones en los pacientes. Basados en estos hallazgos, las investigaciones actuales se han centrado en terapias alternativas que reduzcan la actividad antichlamydial y que sean de libre acceso, generando el menor daño posible en los pacientes.

Abstract Currently, Chlamydia trachomatis (CT) is one of the most frequent causes of sexually transmitted infections (STIs) and reproductive morbidity in the world, including both developed and developing countries, with a report of around 92 million annual cases. CT is an obligate intracellular bacterium whose onset's infection is asymptomatic, causes chronic infection, can generate persistent infection and complications such as ovarian cancer. CT infections are asymptomatic in 70% of women and 40% of men, which makes diagnosis difficult in the early stages of infection and timely treatment, which leads to an increase in infections in the population. According to the World Health Organization (WHO), treatment for TC includes the use of antibiotics such as tetracyclines, macrolides and fluoroquinolones. However, despite their high efficacy rate, infections are becoming more frequent. Recent reports have shown resistance on the part of elementary bodies and it has been determined that antibiotics decrease the beneficial vaginal lactobacillus population, causing greater complications in patients. Based on these findings, current research has focused on alternative therapies that reduce antichlamydial activity and that are freely accessible, generating the least possible harm to patients.

Pyocyanin Inhibits Chlamydia Infection by Disabling Infectivity of the Elementary Body and Disrupting Intracellular Growth.

The obligate intracellular bacterium Chlamydia is a widespread human pathogen that causes serious problems, including (but not limited to) infertility and blindness. Our search for novel antichlamydial metabolites from marine-derived microorganisms led to the isolation of pyocyanin, a small compound from Pseudomonas aeruginosa Pyocyanin is an effective antichlamydial for all three Chlamydia spp. tested. It has a 50% inhibitory concentration (IC50) of 0.019 to 0.028 µM, which is comparable to the IC50 of tetracycline. At concentrations as low as 0.0039 µM, pyocyanin disables infectivity of the chlamydial elementary body (EB). At 0.5 µM or higher concentrations, the continuous presence of pyocyanin also inhibits chlamydial growth in the inclusion during later stages of the developmental cycle. Oxidative stress, a major known antimicrobial mechanism of pyocyanin, appears to be responsible only for the inhibition of bacterial growth and not for the disinfection of EBs. Pyocyanin is well-tolerated by probiotic vaginal Lactobacillus spp. Our findings suggest that pyocyanin is of therapeutic value for chlamydial infections and can serve as a valuable chemical probe for studying chlamydial biology.

In vitro Antichlamydial Activity of 1,2,3,5-Tetrasubstituted Pyrrole Derivatives.

BACKGROUND: Chlamydia is a group of bacterial pathogens distributed worldwide that can lead to serious reproductive and other health problems. The rise of antibiotic-resistant pathogens promotes the development of novel antichlamydial agents. The aim of this study is to assess in vitro antichlamydial activity of our previously synthesized 1,2,3,5- tetrasubstituted pyrroles. METHODS: The derivatives were screened for their antichlamydial activity against three Chlamydia strains by calculating IC50 values using concentration-response inhibition data between 1 and 32 µM. The action of the compounds on Chlamydia elementary body (EB) infectivity and the impact of the chemicals' administration time on their antichlamydial effect were evaluated to reveal the inhibitory mechanism. RESULTS: Some of the compounds moderately inhibited the Chlamydia strains. Compound 10 exhibited the strongest inhibitory activity, with IC50 values from 4.34 to 5.83 µM. These pyrrole derivatives inhibited Chlamydia infection by reducing EB infectivity during the early stage and disturbing Chlamydia growth by targeting the early-to-middle stage prior to 12 h of the chlamydial life cycle. CONCLUSION: Our findings highlight the potential of 1,2,3,5-tetrasubstituted pyrrole derivatives as promising lead molecules for the development of antichlamydial agents.

Red Fluorescent Chlamydia trachomatis Applied to Live Cell Imaging and Screening for Antibacterial Agents.

In this study, we describe the application of a transformed Chlamydia trachomatis strain constitutively expressing the red fluorescent protein mCherry, to allow real-time monitoring of the infection cycle and screening for agents that block replication of C. trachomatis. The red fluorescent C. trachomatis strain was detected autonomously without antibody staining and was equally susceptible to doxycycline as the wild type strain. A high-throughput screening assay was developed using the transformed strain and automated fluorescence microscopy. The assay was used in a pilot screen of a 349 compound library containing natural products from Australian flora and fauna. Compounds with anti-chlamydial activity were tested for dose response and toxicity to host cells and two non-toxic compounds had 50% effective concentration (EC50) values in the low micromolar range. Natural products are valuable sources for drug discovery and the identified Chlamydia growth inhibition may be starting points for future drug development. Live cell imaging was used to visualize growth of the red fluorescent C. trachomatis strain over time. The screening assay reduced workload and reagents compared to an assay requiring immunostaining and could further be used to monitor the development of Chlamydia inclusions and anti-chlamydial effect in real time.

Lead Discovery Strategies for Identification of Chlamydia pneumoniae Inhibitors.

Throughout its known history, the gram-negative bacterium Chlamydia pneumoniae has remained a challenging target for antibacterial chemotherapy and drug discovery. Owing to its well-known propensity for persistence and recent reports on antimicrobial resistence within closely related species, new approaches for targeting this ubiquitous human pathogen are urgently needed. In this review, we describe the strategies that have been successfully applied for the identification of nonconventional antichlamydial agents, including target-based and ligand-based virtual screening, ethnopharmacological approach and pharmacophore-based design of antimicrobial peptide-mimicking compounds. Among the antichlamydial agents identified via these strategies, most translational work has been carried out with plant phenolics. Thus, currently available data on their properties as antichlamydial agents are described, highlighting their potential mechanisms of action. In this context, the role of mitogen-activated protein kinase activation in the intracellular growth and survival of C. pneumoniae is discussed. Owing to the complex and often complementary pathways applied by C. pneumoniae in the different stages of its life cycle, multitargeted therapy approaches are expected to provide better tools for antichlamydial therapy than agents with a single molecular target.

Neutralizing antichlamydial activity of complement by chlamydia-secreted protease CPAF.

Ascending infection by sexually transmitted Chlamydia trachomatis is required for chlamydial induction of tubal pathology. To achieve ascension, the C. trachomatis organisms may have to spread from cell to cell, which inevitably exposes the organisms to extracellular mucosal effectors such as complement factors that are known to possess strong antichlamydial activities. Here, we report that the chlamydia-secreted protease CPAF efficiently neutralized complement factor C3-dependent antichlamydial activity. The neutralization was dependent on the proteolytic activity of CPAF and correlated with the CPAF-mediated degradation of complement factor C3 and factor B. As a result, CPAF preferentially inhibited the alternative complement activation pathway. The significance and limitation of these observations were discussed.

Chlamydia-host cell interaction not only from a bird's eye view: some lessons from Chlamydia psittaci.

Chlamydia psittaci causes psittacosis/ornithosis in birds and is an economically important pathogen for poultry farming. It also infects nonavian domestic animals as well as rodents, and is a zoonotic human pathogen responsible for atypical pneumonia. The bacterium efficiently disseminates in host organisms causing pulmonary and systemic disease. Its rapid entry, fast replication cycle, and tight control of intracellular transport routes contribute to the host-to-host transmission and efficient growth observed with C. psittaci. Recent studies have revealed that the pathogen copes better than other chlamydial strains with proinflammatory effectors produced during the early immune reaction of infected hosts. These features likely contribute to successful infections and might explain the potent adaptation and evasion characteristics of the agent. Current findings on cell-autonomous, innate, and adaptive defenses against C. psittaci provide novel insights into the concerted immune mechanisms involved in the clearance of the pathogen. Further in-depth studies on C. psittaci and other related agents in cellular as well as animal models are needed to develop more efficient antichlamydial therapies and vaccination strategies.

Association of the Serum Anti-chlamydial Antibodies with Tubal Infertility.

BACKGROUND: Infertility is increasingly becoming a significant health problem in many areas of the world. The infection which is caused by Chlamydia trachomatis is a major cause of tubal factor infertility secondary to salpingitis. However, the data which pertains to infertility attributed to the C. trachomatis infection is limited in India. AIMS: To evaluate the chlamydial infection in women who suffered from infertility and to investigate the possible role of the chlamydia serology as a screening test for tubal infertility. METHOD: This study was aimed at evaluating the chlamydial infection in fifty women with primary infertility and at investigating the possible role of the chlamydial serology as a screening test for tubal infertility, by the detection of the anti-chlamydial IgM antibodies by using E.L.I.S.A. SETTING AND DESIGN: The present prospective study was carried out at a tertiary care hospital in north India. RESULTS: In this study, a high seropositivity (60%) for the antichlamydial antibody was observed. 52% females showed bilateral tubal blockage, while the most common site of the blockage was the ampullary portion (36%). CONCLUSION: These findings highlighted a strong correlation between the tubal factor infertility and the antichlamydial antibodies. It also stressed on the need of the screening of infertile women for C. trachomatis with laboratory investigations, which could provide a rapid and specific diagnosis so that early therapeutic interventions could be instituted.