Daphnane Diterpenes from Daphne genkwa Activate Nurr1 and Have a Neuroprotective Effect in an Animal Model of Parkinson's Disease.

Nurr1 is an orphan nuclear receptor that is essential for the differentiation and maintenance of dopaminergic neurons in the brain, and it is a therapeutic target for Parkinson's disease (PD). During the screening for Nurr1 activators from natural sources using cell-based assay systems, a methanol extract of the combined stems and roots of Daphne genkwa was found to activate the transcriptional function of Nurr1 at a concentration of 3 µg/mL. The active components were isolated and identified as genkwanine N (1) and yuanhuacin (2). Both compounds 1 and 2 significantly enhanced the function of Nurr1 at 0.3 µM. Nurr1-specific siRNA abolished the activity of 1 and 2, strongly suggesting that transcriptional activation by 1 and 2 occurred through the modulation of Nurr1 function. Additionally, treatment with 1 and 2 inhibited 6-hydroxydopamine (6-OHDA)-induced neuronal cell death and lipopolysaccharide (LPS)-induced neuroinflammation. Moreover, in a 6-OHDA-lesioned rat model of PD, intraperitoneal administration of 2 (0.5 mg/kg/day) for 2 weeks significantly improved behavioral deficits and reduced tyrosine hydroxylase (TH)-positive dopaminergic neuron death induced by 6-OHDA injection and had a beneficial effect on the inflammatory response in the brain. Accordingly, compounds 1 and 2, the first reported Nurr1 activators of natural origin, are potential lead compounds for the treatment of PD.

The Lactone form of stachybotrydial: a new inhibitor of dihydrofolate reductase from stachybotrys sp. FN298.

Dihydrofolate reductase (DHFR) has been confirmed to be a novel target for antibacterial drug development. In this study, we determined that a fungal metabolite from Stachybotrys sp. FN298 can inhibit the DHFR of Staphylococcus aureus. Its structure was identified as a lactone form of stachybotrydial using mass spectrometry and nuclear magnetic resonance analysis. This compound inhibited S. aureus DHFR with a half-maximal inhibitory concentration of 41 µM. It also prevented the growth of S. aureus and methicillin-resistant S. aureus (MRSA) with a minimum inhibitory concentration of 32 µg·mL(-1). To our knowledge, this is the first description of a DHFR inhibitor of microbial origin. The inhibitory function of the lactone form of stachybotrydial highlights its potential for development into a new broad-spectrum antibacterial agent and as an agent against MRSA.

Verrulactone C with an unprecedented dispiro skeleton, a new inhibitor of Staphylococcus aureus enoyl-ACP reductase, from Penicillium verruculosum F375.

An highly quaternary and unprecedented dispiro compound, verrulactone C, with the known compound, altenuisol, were isolated from a culture broth of the fungal strain Penicillium verruculosum F375 and their structures were established by various spectral analysis. Verrulactone C and altenuisol showed FabI-selective inhibition. Especially altenuisol had the high correlation between FabI-inhibition and whole cell antibacterial activity against Staphylococcus aureus and MRSA with MICs of 8-32µg/mL.

Meleagrin, a new FabI inhibitor from Penicillium chryosogenum with at least one additional mode of action.

Bacterial enoyl-acyl carrier protein reductase (FabI) is a promising novel antibacterial target. We isolated a new class of FabI inhibitor from Penicillium chrysogenum, which produces various antibiotics, the mechanisms of some of them are unknown. The isolated FabI inhibitor was determined to be meleagrin by mass spectroscopy and nuclear magnetic resonance spectral analyses, and its more active and inactive derivatives were chemically prepared. Consistent with their selective inhibition of Staphylococcus aureus FabI, meleagrin and its more active derivatives directly bound to S. aureus FabI in a fluorescence quenching assay, inhibited intracellular fatty acid biosynthesis and growth of S. aureus, and increased the minimum inhibitory concentration for fabI-overexpressing S. aureus. The compounds that were not effective against the FabK isoform, however, inhibited the growth of Streptococcus pneumoniae that contained only the FabK isoform. Additionally no resistant mutant to the compounds was obtained. Importantly, fabK-overexpressing Escherichia coli was not resistant to these compounds, but was resistant to triclosan. These results demonstrate that the compounds inhibited another target in addition to FabI. Thus, meleagrin is a new class of FabI inhibitor with at least one additional mode of action that could have potential for treating multidrug-resistant bacteria.

Panosialins, inhibitors of enoyl-ACP reductase from Streptomyces sp. AN1761.

In the continued search for inhibitors of enoyl-acyl carrier protein (ACP) reductase, we found that four acylbenzenediol sulfate metabolites from Streptomyces sp. AN1761 potently inhibited bacterial enoyl-ACP reductases of Staphylococcus aureus, Streptococcus pneumoniae, and Mycobacterium tuberculosis. Their structures were identified as panosialins A, B, wA, and wB by MS and NMR data. They showed stronger inhibition against S. aureus FabI and S. pneumoniae FabK with IC50 of 3-5 microM than M. tuberculosis InhA with IC50 of 9-12 microM. They also exhibited a stronger antibacterial spectrum on S. aureus and S. pneumoniae than M. tuberculosis. In addition, the higher inhibitory activity of panosialin wB than panosialin B on fatty acid biosynthesis was consistent with that on bacterial growth, suggesting that they could exert their antibacterial activity by inhibiting fatty acid synthesis.

Chalcomoracin and moracin C, new inhibitors of Staphylococcus aureus enoyl-acyl carrier protein reductase from Morus alba.

Bacterial enoyl-acyl carrier protein (ACP) reductase has been confirmed as a novel target for antibacterial drug development. In the screening of inhibitors of Staphylococcus aureus enoyl-ACP reductase (FabI), we found that a methanol extract of leaves of Morus alba L. potently inhibited S. aureus FabI as well as growth of S. aureus. The active principles were identified as chalcomoracin and moracin C by MS and NMR analysis. Chalcomoracin and moracin C inhibited S. aureus FabI with IC(50) of 5.5 and 83.8 µM, respectively. They also prevented the growth of S. aureus with minimum inhibitory concentration (MIC) of 4 and 32 µg/mL, respectively. Consistent with their inhibition against FabI and bacterial growth, they prevented (14)C]acetate incorporation into fatty acid in S. aureus while didn't affect protein synthesis. In this study, we reported that chalcomoracin and moracin C, potent antibacterial compounds from Morus alba, inhibited FabI and fatty acid synthesis.

Verrulactones A and B, new inhibitors of Staphylococcus aureus enoyl-ACP reductase produced by Penicillium verruculosum F375.

New dimeric compounds of alternariol class, verrulactones A and B, were isolated from a culture broth of the fungal strain Penicillium verruculosum F375 and their structure were established by various spectral analysis. Verrulactones A and B strongly inhibited Staphylococcus aureus enoyl-ACP reductase with IC(50) of 0.92 and 1.41 µM, respectively, and also showed antibacterial activity against S. aureus and MRSA with MICs of 8 and 16 µg/mL, respectively.

Flavimycins A and B, dimeric 1,3-dihydroisobenzofurans with peptide deformylase inhibitory activity from Aspergillus flavipes.

Flavimycins A (1) and B (2), novel dimeric 1,3-dihydroisobenzofurans, were isolated as inhibitors of peptide deformylase from cultures of Aspergillus flavipes. Their chemical structures were established by NMR and MS data analysis. Compounds 1 and 2 exist as epimeric mixtures at C-1 through fast hemiacetal-aldehyde tautomerism. Compounds 1 and 2 inhibited Staphylococcus aureus peptide deformylase with IC50 values of 35.8 and 100.1 µM, respectively. Consistent with their PDF inhibition, 1 showed two times stronger antibacterial activity than 2 on S. aureus including MRSA, with MIC values of 32-64 µg/mL.

An autonomous CMOS hysteretic sensor for the detection of desorption-free DNA hybridization.

This paper describes a sensor for label-free, fully electrical detection of DNA hybridization based on capacitive changes in the electrode-electrolyte interface. The sensor measures capacitive changes in real time according to a charging-discharging principle that is limited by the hysteresis window. In addition, a novel autonomous searching technique, which exclusively monitors desorption-free hybridized electrodes among electrode arrays, enhances the performance of the sensor compared with conventional capacitive measurement. The sensor system achieves a detection range of 80 dB. The integrated circuit sensor is fabricated with a 0.35 µm CMOS process. The proposed sensor offers rapid, robust and inexpensive measurement of capacitance with highly integrated detection circuitry. It also facilitates quantitative evaluations of molecular densities on a chip with distinctive impedance variations by monitoring desorption-free hybridized electrodes. Our electrical biosensor has great potential for use with bio analytical tools and point-of-care diagnosis.

Phellinstatin, a new inhibitor of enoyl-ACP reductase produced by the medicinal fungus Phellinus linteus.

A new trimeric hispidin derivative, phellinstatin, was isolated from a culture broth of the medicinal fungus Phellinus linteus and its structure was established by various spectral analysis. Phellinstatin strongly inhibited Staphylococcus aureus enoyl-ACP reductase with an IC(50) of 6 µM and also showed antibacterial activity against S. aureus and MRSA.

An electronic DNA sensor chip using integrated capacitive read-out circuit.

This paper presents fully integrated label-free DNA recognition circuit based on capacitance measurement. A CMOS-based DNA sensor is implemented for the electrical detection of DNA hybridization. The proposed architecture detects the difference of capacitance through the integration of current mismatch of capacitance between reference electrodes functionalized with only single-stranded DNA and sensing electrodes bound with complementary DNA strands specifically. In addition, to minimize the effects of parallel resistance between electrodes and DNA layers, the compensation technique of leakage current through the use of constant current charging and discharging is implemented in the proposed detection circuit. The chip was fabricated in 0.35um 4-metal 2-poly CMOS process, and 16 × 8 sensing electrode arrays were fabricated by post-processing steps.

One-chip electronic detection of DNA hybridization using precision impedance-based CMOS array sensor.

This paper describes a label-free and fully electronic detection method of DNA hybridization, which is achieved through the use of a 16×8 microarray sensor in conjunction with a new type of impedance spectroscopy constructed with standard complementary metal-oxide-semiconductor (CMOS) technology. The impedance-based method is based on changes in the reactive capacitance and the charge-transfer resistance after hybridization with complementary DNA targets. In previously published label-free techniques, the measured capacitance presented unstable capacitive properties due to the parallel resistance that is not infinite and can cause a leakage by discharging the charge on the capacitor. This paper presents an impedance extraction method that uses excitation by triangular wave voltage, which enables a reliable measurement of both C and R producing a highly sensitive sensor with a stable operation independent of external variables. The system was fabricated in an industrial 0.35-µm 4-metal 2-poly CMOS process, integrating working electrodes and readout electronics into one chip. The integrated readout, which uses a parasitic insensitive integrator, achieves an enlarged detection range and improved noise performance. The maximum average relative variations of C and R are 31.5% and 68.6%, respectively, after hybridization with a 1 µM target DNA. The proposed sensor allows quantitative evaluation of the molecule densities on the chip with distinguishable variation in the impedance. This fully electronic microsystem has great potential for use with bioanalytical tools and point-of-care diagnosis.

Methyl-branched fatty acids, inhibitors of enoyl-ACP reductase with antibacterial activity from Streptomyces sp. A251.

Bacterial enoyl-ACP reductase (FabI) has been demonstrated to be a novel antibacterial target. In the course of our screening for FabI inhibitors we isolated two methyl-branched fatty acids from Streptomyces sp. A251. They were identified as 14-methyl-9(Z)-pentadecenoic acid and 15-methyl-9(Z)-hexadecenoic acid by MS and NMR spectral data. These compounds inhibited Staphylococcus aureus FabI with IC50 of 16.0 and 16.3mu M, respectively, while didn't affect FabK, an enoyl-ACP reductase of Streptococcus pneumonia, at 100muM. Consistent with their selective inhibition for FabI, they blocked intracellular fatty acid synthesis as well as the growth of S. aureus, while didn't inhibit the growth of S. pneumonia. Additionally, these compounds showed reduced antibacterial activity against fabI-overexpressing S. aureus compared to the wild-type strain. These results demonstrate that the methyl-branched fatty acids showed antibacterial activity by inhibiting FabI in vivo.

Vinaxanthone, a new FabI inhibitor from Penicillium sp.

OBJECTIVES: Bacterial enoyl-ACP reductase (FabI) has been validated as a novel antibacterial target for tackling infections caused by multidrug-resistant pathogens. A few FabI inhibitors, however, are known. This study isolated a new FabI inhibitor from Penicillium sp. METHODS: A screening programme led to the selection of a Penicillium sp. producing a strong FabI-inhibitory metabolite. The chemical structure of the isolated FabI inhibitor was elucidated by mass spectrometry and nuclear magnetic resonance spectral data. The antibacterial target of the inhibitor was validated by overexpression assays. RESULTS: The isolated FabI inhibitor was elucidated to be vinaxanthone. It selectively inhibited Staphylococcus aureus FabI with an IC(50) of 0.9 microM; it did not affect FabK, an enoyl-ACP reductase of Streptococcus pneumoniae. Consistent with its inhibition of FabI, the inhibitor prevented intracellular fatty acid synthesis while it did not affect protein biosynthesis. It also prevented the growth of S. aureus as well as methicillin-resistant S. aureus (MRSA) and quinolone-resistant S. aureus. Importantly, fabI-overexpressing S. aureus showed reduced susceptibility to the inhibitor compared with the wild-type strain, demonstrating that its antibacterial action is mediated by inhibition of FabI. CONCLUSIONS: Vinaxanthone is a new FabI-directed antibacterial of natural origin that could have potential for further development as a new anti-MRSA agent.

Olean-27-carboxylic acid-type triterpenes with potent antibacterial activity from Aceriphyllum rossii.

Aceriphyllum rossii Engler (Saxifragaceae) have been used as a nutritious food in Korea. We found that the methanol extract of the root portion of A. rossii potently inhibited the growth of Staphylococcus aureus , with a minimal inhibitory concentration (MIC) value of 8 microg/mL. Using mass spectrometry and nuclear magnetic resonance (NMR) studies, four active constituents were isolated and identified: aceriphyllic acid A, 3-oxoolean-12-en-27-oic acid, 3alpha-hydroxyolean-12-en-27-oic acid, and 3beta-hydroxyolean-12-en-27-oic acid. Aceriphyllic acid A and 3-oxoolean-12-en-27-oic acid showed a potent antibacterial activity against several strains of S. aureus , including methicillin-resistant S. aureus and quinolone-resistant S. aureus , with MIC values of 2-8 microg/mL, while 3alpha-hydroxyolean-12-en-27-oic acid and 3beta-hydroxyolean-12-en-27-oic acid exhibited a very weak activity, with MIC values of 128 microg/mL. The methyl ester derivative of aceriphyllic acid A lost its antibacterial activity. The time-kill study against S. aureus indicated that aceriphyllic acid A had rapid bactericidal activity. These results indicated that aceriphyllic acid A and 3-oxoolean-12-en-27-oic acid are the most active principles, and both the carboxylic group at C-27 and the hydroxyl group at C-24 in aceriphyllic acid A are critical for the rapid bactericidal activity.

Naturally acquired IgM antibody response to the C-terminal region of the merozoite surface protein 1 of Plasmodium vivax in Korea: use for serodiagnosis of vivax malaria.

The antibody levels against the C-terminal region of the merozoite surface protein 1 of Plasmodium vivax (PvMSP1c) were measured in 276 patients with P. vivax malaria (patient group), 320 malaria-naïve healthy individuals (control group 1), and 70 malaria-naïve individuals with various disorders (control group 2) using the immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (ELISA) and the direct sandwich ELISA. To evaluate the antibody response during relapse, 5 relapsed patients were tested using the IgM capture ELISA. The IgM antibodies were negative in 99.7% of control group 1 and in 100% of control group 2; they were positive in 90.6% of the patient group. The total antibody levels were positive in 88.4% of the patient group with the direct sandwich ELISA. The sera from the second malaria episode, i.e., relapsed patients, were 100% positive on the IgM capture ELISA. The results of this study suggest that the IgM capture ELISA may be a useful diagnostic method for P. vivax malaria for both primary infection and relapse.

Macrolactin S, a new antibacterial agent with FabG-inhibitory activity from Bacillus sp. AT28.

In the course of screening for FabG inhibitors from microbial sources, a new 24-membered ring lactone named macrolactin S, along with the known compound macrolactin B, has been isolated from the mycelium of liquid fermentation cultures of Bacillus sp. AT28. The structure of macrolactin S was determined on the basis of MS and NMR data. Macrolactin S showed a dose-dependent inhibition of Staphylococcus aureus FabG, not inhibiting S. aureus FabI. Also macrolactin S inhibited the growth of S. aureus, Bacillus subtilis, and Escherichia coli.