| 27818338 |
Antimicrobial and host cell-directed activities of Gly/Ser-rich peptides from salmonid cathelicidins |
10.1016/j.fsi.2016.11.004. |
Fish Shellfish Immunol |
Antimicrobial and host cell-directed activities of Gly/Ser-rich peptides from salmonid cathelicidins
Abstract
- Cathelicidins, a major family of vertebrate antimicrobial peptides (AMPs), have a recognized role in the first line of defense against infections. They have been identified in several salmonid species, where the putative mature peptides are unusually long and rich in serine and glycine residues, often arranged in short multiple repeats (RLGGGS/RPGGGS) intercalated by hydrophobic motifs. Fragments of 24-40 residues, spanning specific motifs and conserved sequences in grayling or brown, rainbow and brook trout, were chemically synthesized and examined for antimicrobial activity against relevant Gram-positive and Gram-negative salmonid pathogens, as well as laboratory reference strains. They were not active in complete medium, but showed varying potency and activity spectra in diluted media. Bacterial membrane permeabilization also occurred only under these conditions and was indicated by rapid propidium iodide uptake in peptide-treated bacteria. However, circular dichroism analyses indicated that they did not significantly adopt ordered conformations in membrane-like environments. The peptides were not hemolytic or cytotoxic to trout cells, including freshly purified head kidney leukocytes (HKL) and the fibroblastic RTG-2 cell line. Notably, when exposed to them, HKL showed increased metabolic activity, while a growth-promoting effect was observed on RTG-2 cells, suggesting a functional interaction of salmonid cathelicidins with host cells similar to that shown by mammalian ones. The three most active peptides produced a dose-dependent increase in phagocytic uptake by HKL simultaneously stimulated with bacterial particles. The peptide STF(1-37), selected for further analyses, also enhanced phagocytic uptake in the presence of autologous serum, and increased intracellular killing of live E. coli. Furthermore, when tested on HKL in combination with the immunostimulant β-glucan, it synergistically potentiated both phagocytic uptake and the respiratory burst response, activities that play a key role in fish immunity. Collectively, these data point to a role of salmonid cathelicidins as modulators of fish microbicidal mechanisms beyond a salt-sensitive antimicrobial activity, and encourage further studies also in view of potential applications in aquaculture.
|
| 27864109 |
Selective cytotoxicity of microcystins LR, LW and LF in rat astrocytes |
10.1016/j.toxlet.2016.11.008. |
Toxicol Lett |
Selective cytotoxicity of microcystins LR, LW and LF in rat astrocytes
Abstract
- Microcystins (MCs) comprise a group of cyanobacterial toxins with hepatotoxic, nephrotoxic and, possibly, neurotoxic activity in mammals. In order to understand the development of their neurotoxicity we investigated the toxic effects of MC variants, MC-LR, MC-LW and MC-LF, in astrocytes that play a central role in maintaining brain homeostasis. 24h exposure of cultured rat cortical astrocytes to MCs revealed dose-dependent toxicity of MC-LF and MC-LW, but not of MC-LR, observed by significant reduction in cell number, declined viability monitored by MTT test and an increased percentage of apoptotic cells, confirmed by Annexin-V labelling. The cultured astrocytes expressed organic anion-transporting polypeptides (Oatp) Oatp1a4, Oatp1c1 and Oatp1a5, but not Oatp1b2. Intracellular localisation of MC-LF and MC-LW, proven by anti-Adda primary antibody, demonstrated transport of tested MCs into cultured astrocytes. Acute MC-LW and MC-LF intoxication induced cytoskeletal disruption as seen by the degradation of glial fibrillary acid protein (GFAP), actin and the tubulin network. In this in vitro study, MC-LF and MC-LW, but not MC-LR, are shown to cause the dysfunction of astrocytic homeostatic capabilities, already at low concentrations, suggesting that astrocyte atrophy, with loss of function, could be expected in the brain response to the toxic insult.
|
| 27873246 |
Structure Elucidation of Antibiotics by Nmr Spectroscopy |
10.1007/978-1-4939-6634-9_4. |
Methods Mol Biol |
Structure Elucidation of Antibiotics by Nmr Spectroscopy
Abstract
- Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for the structure elucidation of antibiotics in solution. Over the past 30 years there have been numerous publications describing the use of NMR to characterize naturally derived or synthetic antibiotics. A large number of one-dimensional (1D) and two-dimensional (2D) NMR methods are available today and the list continues to expand. In this chapter, we will consider the key NMR experiments that provide useful information for compound structure elucidation.
|
| 27875306 |
Family-wide Structural Characterization and Genomic Comparisons Decode the Diversity-oriented Biosynthesis of Thalassospiramides by Marine Proteobacteria |
10.1074/jbc.M116.756858. |
J Biol Chem |
Family-wide Structural Characterization and Genomic Comparisons Decode the Diversity-oriented Biosynthesis of Thalassospiramides by Marine Proteobacteria
Abstract
- The thalassospiramide lipopeptides have great potential for therapeutic applications; however, their structural and functional diversity and biosynthesis are poorly understood. Here, by cultivating 130 Rhodospirillaceae strains sampled from oceans worldwide, we discovered 21 new thalassospiramide analogues and demonstrated their neuroprotective effects. To investigate the diversity of biosynthetic gene cluster (BGC) architectures, we sequenced the draft genomes of 28 Rhodospirillaceae strains. Our family-wide genomic analysis revealed three types of dysfunctional BGCs and four functional BGCs whose architectures correspond to four production patterns. This correlation allowed us to reassess the "diversity-oriented biosynthesis" proposed for the microbial production of thalassospiramides, which involves iteration of several key modules. Preliminary evolutionary investigation suggested that the functional BGCs could have arisen through module/domain loss, whereas the dysfunctional BGCs arose through horizontal gene transfer. Further comparative genomics indicated that thalassospiramide production is likely to be attendant on particular genes/pathways for amino acid metabolism, signaling transduction, and compound efflux. Our findings provide a systematic understanding of thalassospiramide production and new insights into the underlying mechanism.
|
| 27905482 |
Pharmacologic modulation of RORγt translates to efficacy in preclinical and translational models of psoriasis and inflammatory arthritis |
10.1038/srep37977. |
Sci Rep |
Pharmacologic modulation of RORγt translates to efficacy in preclinical and translational models of psoriasis and inflammatory arthritis
Abstract
- The IL-23/IL-17 pathway is implicated in autoimmune diseases, particularly psoriasis, where biologics targeting IL-23 and IL-17 have shown significant clinical efficacy. Retinoid-related orphan nuclear receptor gamma t (RORγt) is required for Th17 differentiation and IL-17 production in adaptive and innate immune cells. We identified JNJ-54271074, a potent and highly-selective RORγt inverse agonist, which dose-dependently inhibited RORγt-driven transcription, decreased co-activator binding and promoted interaction with co-repressor protein. This compound selectively blocked Th17 differentiation, significantly reduced IL-17A production from memory T cells, and decreased IL-17A- and IL-22-producing human and murine γδ and NKT cells. In a murine collagen-induced arthritis model, JNJ-54271074 dose-dependently suppressed joint inflammation. Furthermore, JNJ-54271074 suppressed IL-17A production in human PBMC from rheumatoid arthritis patients. RORγt-deficient mice showed decreased IL-23-induced psoriasis-like skin inflammation and cytokine gene expression, consistent with dose-dependent inhibition in wild-type mice through oral dosing of JNJ-54271074. In a translational model of human psoriatic epidermal cells and skin-homing T cells, JNJ-54271074 selectively inhibited streptococcus extract-induced IL-17A and IL-17F. JNJ-54271074 is thus a potent, selective RORγt modulator with therapeutic potential in IL-23/IL-17 mediated autoimmune diseases.
|
| 27995363 |
Unacylated ghrelin analog prevents myocardial reperfusion injury independently of permeability transition pore |
10.1007/s00395-016-0595-9. |
Basic Res Cardiol |
Unacylated ghrelin analog prevents myocardial reperfusion injury independently of permeability transition pore
Abstract
- Reperfusion injury is responsible for an important part of myocardial infarct establishment due notably to triggering cardiomyocytes death at the first minutes of reperfusion. AZP-531 is an optimized analog of unacylated ghrelin currently in clinical development in several metabolic diseases. We investigated a potential cardioprotective effect of AZP-531 in ischemia/reperfusion (IR) and the molecular underlying mechanism(s) involved in this protection. In vivo postconditioning with AZP-531 in C57BL6 mouse IR model decreased infarct size. Western blot analysis on areas at risk from the different mouse groups showed that AZP-531 activates Akt, ERK1-2 as well as S6 and 4EBP1, mTORC1 effectors. We also showed an inhibition of caspase 3 cleavage and Bax translocation to the mitochondria. AZP-531 also stimulated the expression of antioxidants and was capable of decreasing mitochondrial HO production, contributing to the reduction of ROS accumulation. AZP-531 exhibits cardioprotective effect when administrated for postconditioning in C57BL6 mouse IR model. Treatment with AZP-531 rescued the myocardium from cell death at early reperfusion by stimulating protein synthesis, inhibiting Bax/caspase 3-induced apoptosis as well as ROS accumulation and oxidative stress-induced necrosis. AZP-531 may prove useful in the treatment of IR injury.
|
| 28006906 |
Isolation and Characterization of Cyclotides from Brazilian Psychotria: Significance in Plant Defense and Co-occurrence with Antioxidant Alkaloids |
10.1021/acs.jnatprod.6b00492. |
J Nat Prod |
Isolation and Characterization of Cyclotides from Brazilian Psychotria: Significance in Plant Defense and Co-occurrence with Antioxidant Alkaloids
Abstract
- Plants from the genus Psychotria include species bearing cyclotides and/or alkaloids. The elucidation of factors affecting the metabolism of these molecules as well as their activities may help to understand their ecological function. In the present study, high concentrations of antioxidant indole alkaloids were found to co-occur with cyclotides in Psychotria leiocarpa and P. brachyceras. The concentrations of the major cyclotides and alkaloids in P. leiocarpa and P. brachyceras were monitored following herbivore- and pathogen-associated challenges, revealing a constitutive, phytoanticipin-like accumulation pattern. Psyleio A, the most abundant cyclotide found in the leaves of P. leiocarpa, and also found in P. brachyceras leaves, exhibited insecticidal activity against Helicoverpa armigera larvae. Addition of ethanol in the vehicle for peptide solubilization in larval feeding trials proved deleterious to insecticidal activity and resulted in increased rates of larval survival in treatments containing indole alkaloids. This suggests that plant alkaloids ingested by larvae might contribute to herbivore oxidative stress detoxification, corroborating, in a heterologous system with artificial oxidative stress stimulation, the antioxidant efficiency of Psychotria alkaloids previously observed in planta. Overall, the present study reports data for eight novel cyclotides, the identification of P. leiocarpa as a cyclotide-bearing species, and the absence of these peptides in P. umbellata.
|
| 28045232 |
Corrigendum: A Unique Tryptophan C-Prenyltransferase from the Kawaguchipeptin Biosynthetic Pathway |
10.1002/anie.201609949. |
Angew Chem Int Ed Engl |
Corrigendum: A Unique Tryptophan C-Prenyltransferase from the Kawaguchipeptin Biosynthetic Pathway
Abstract
|
| 28049490 |
Mobilization of hematopoietic stem cells with the novel CXCR4 antagonist POL6326 (balixafortide) in healthy volunteers-results of a dose escalation trial |
10.1186/s12967-016-1107-2. |
J Transl Med |
Mobilization of hematopoietic stem cells with the novel CXCR4 antagonist POL6326 (balixafortide) in healthy volunteers-results of a dose escalation trial
Abstract
- Certain disadvantages of the standard hematopoietic stem and progenitor cell (HSPC) mobilizing agent G-CSF fuel the quest for alternatives. We herein report results of a Phase I dose escalation trial comparing mobilization with a peptidic CXCR4 antagonist POL6326 (balixafortide) vs. G-CSF.
Healthy male volunteer donors with a documented average mobilization response to G-CSF received, following ≥6 weeks wash-out, a 1-2 h infusion of 500-2500 µg/kg of balixafortide. Safety, tolerability, pharmacokinetics and pharmacodynamics were assessed.
Balixafortide was well tolerated and rated favorably over G-CSF by subjects. At all doses tested balixafortide mobilized HSPC. In the dose range between 1500 and 2500 µg/kg mobilization was similar, reaching 38.2 ± 2.8 CD34 + cells/µL (mean ± SEM). Balixafortide caused mixed leukocytosis in the mid-20 K/µL range. B-lymphocytosis was more pronounced, whereas neutrophilia and monocytosis were markedly less accentuated with balixafortide compared to G-CSF. At the 24 h time point, leukocytes had largely normalized.
Balixafortide is safe, well tolerated, and induces efficient mobilization of HSPCs in healthy male volunteers. Based on experience with current apheresis technology, the observed mobilization at doses ≥1500 µg/kg of balixafortide is predicted to yield in a single apheresis a standard dose of 4× 10E6 CD34+ cells/kg from most individuals donating for an approximately weight-matched recipient. Exploration of alternative dosing regimens may provide even higher mobilization responses. Trial Registration European Medicines Agency (EudraCT-Nr. 2011-003316-23) and clinicaltrials.gov ().
|
| 28055207 |
Octaminomycins A and B, Cyclic Octadepsipeptides Active against Plasmodium falciparum |
10.1021/acs.jnatprod.6b00758. |
J Nat Prod |
Octaminomycins A and B, Cyclic Octadepsipeptides Active against Plasmodium falciparum
Abstract
- Two new cyclic octadepsipeptides, octaminomycins A (1) and B (2), were isolated from a microbial metabolite fraction library of Streptomyces sp. RK85-270 based on Natural Products Plot screening. Their structures were elucidated on the basis of HRESIMS, 1D and 2D NMR spectroscopic data, and MS/MS experiments for sequence analysis. The absolute configurations of the constituent amino acid residues were determined by a combination of single-crystal X-ray diffraction and Marfey's methodology. Notably, octaminomycins A (1) and B (2) showed good in vitro antiplasmodial activity against chloroquine-sensitive as well as chloroquine-resistant strains with no cytotoxicity up to 30 μM.
|
| 28055219 |
Integrating Molecular Networking and Biological Assays To Target the Isolation of a Cytotoxic Cyclic Octapeptide, Samoamide A, from an American Samoan Marine Cyanobacterium |
10.1021/acs.jnatprod.6b00907. |
J Nat Prod |
Integrating Molecular Networking and Biological Assays To Target the Isolation of a Cytotoxic Cyclic Octapeptide, Samoamide A, from an American Samoan Marine Cyanobacterium
Abstract
- Integrating LC-MS/MS molecular networking and bioassay-guided fractionation enabled the targeted isolation of a new and bioactive cyclic octapeptide, samoamide A (1), from a sample of cf. Symploca sp. collected in American Samoa. The structure of 1 was established by detailed 1D and 2D NMR experiments, HRESIMS data, and chemical degradation/chromatographic (e.g., Marfey's analysis) studies. Pure compound 1 was shown to have in vitro cytotoxic activity against several human cancer cell lines in both traditional cell culture and zone inhibition bioassays. Although there was no particular selectivity between the cell lines tested for samoamide A, the most potent activity was observed against H460 human non-small-cell lung cancer cells (IC = 1.1 μM). Molecular modeling studies suggested that one possible mechanism of action for 1 is the inhibition of the enzyme dipeptidyl peptidase (CD26, DPP4) at a reported allosteric binding site, which could lead to many downstream pharmacological effects. However, this interaction was moderate when tested in vitro at up to 10 μM and only resulted in about 16% peptidase inhibition. Combining bioassay screening with the cheminformatics strategy of LC-MS/MS molecular networking as a discovery tool expedited the targeted isolation of a natural product possessing both a novel chemical structure and a desired biological activity.
|
| 28073163 |
Hydrocarbon-stapled lipopeptides exhibit selective antimicrobial activity |
10.1002/bip.23006. |
Biopolymers |
Hydrocarbon-stapled lipopeptides exhibit selective antimicrobial activity
Abstract
- Antimicrobial peptides (AMPs) occur widely in nature and have been studied for their therapeutic potential. AMPs are of interest due to the large number of possible chemical structural combinations using natural and unnatural amino acids, with varying effects on their biological activities. Using physicochemical properties from known naturally occurring amphipathic cationic AMPs, several hydrocarbon-stapled lipopeptides (HSLPs) were designed, synthesized, and tested for antimicrobial properties. Peptides were chemically modified by N-terminal acylation, C-terminal amidation, and some were hydrocarbon stapled by intramolecular olefin metathesis. The effects of peptide length, amphipathic character, and stapling on antimicrobial activity were tested against Escherichia coli, three species of Gram-positive bacteria (Staphylococcus aureus, Bacillus megaterium, and Enterococcus faecalis), and two strains of Candida albicans. Peptides were shown to disrupt liposomes of different phospholipid composition, as measured by leakage of a fluorescent compound from vesicles. Peptides with (S)-2-(4'-pentenyl)-alanine substituted for l-alanine in a reference peptide showed a marked increase in antimicrobial activity, hemolysis, and membrane disruption. Stapled peptides exhibited slightly higher antimicrobial potency; those with greatest hydrophobic character showed the greatest hemolysis and liposome leakage, but lower antimicrobial activity. The results support a model of HSLPs as membrane-disruptive AMPs with potent antimicrobial activity and relatively low hemolytic potential at biologically active peptide concentrations.
|
| 28091879 |
New medical therapies on the horizon: oral octreotide |
10.1007/s11102-016-0785-3. |
Pituitary |
New medical therapies on the horizon: oral octreotide
Abstract
- Somatostatin analog treatment is first line medical treatment in patients with acromegaly. This drug is currently mainly administered by monthly depot preparations of octreotide and lanreotide. With the innovative transient permeability enhancer, a technology enabling the absorption of drug molecules via transient opening of the tight junctions of the gut epithelium, it is possible to achieve therapeutic octreotide levels after oral ingestion. The present review summarized the preclinical work and the recently reported phase I and III study on oral octreotide capsules in patients with acromegaly. Maintenance of control in 155 participating patients was achieved in 65% at the end of core period. Once controlled on oral octreotide, the response was maintained to the end of the extension phase in 85%. Side effects were comparable to currently available preparations. There was a profound suppression of growth hormone levels, and significant symptom reduction. Currently available parental somatostatin analogs are generally well tolerated and are able to achieve longstanding biochemical control in patients with somatostatin sensitive tumors. Potential advantages of an oral alternative is the lack injection-related side effects, but there will be an ongoing need for a very strict compliance with the 2 daily dose regimen and fasting around drug administrations. A second phase III study is currently being conducted. The potential place in the treatment of acromegaly is discussed.
|
| 28135874 |
New cytotoxic furan from the marine sediment-derived fungi Aspergillus niger |
10.1080/14786419.2017.1283499. |
Nat Prod Res |
New cytotoxic furan from the marine sediment-derived fungi Aspergillus niger
Abstract
- A fungal strain of Aspergillus niger was recovered from sediments collected in the Northeast coast of Brazil (Pecém's offshore port terminal). Cultivation in different growth media yielded a new ester furan derivative, 1, along with malformin A1, malformin C, cyclo (trans-4-hydroxy-L-Pro-L-Leu), cyclo (trans-4-hydroxy-L-Pro-L-Phe), cyclo (L-Pro-L-Leu), cyclo (L-Pro-L-Phe), pseurotin D, pseurotin A, chlovalicin, cyclo (L-Pro-L-Tyr) and cyclo (L-Pro-L-Val). Compound 1 was cytotoxic against HCT-116 cell line, showing IC = 2.9 μg/mL (CI 95% from 1.8 to 4.7 μg/mL).
|
| 28142234 |
Plasma Protein Binding Structure-Activity Relationships Related to the N-Terminus of Daptomycin |
10.1021/acsinfecdis.7b00015. |
ACS Infect Dis |
Plasma Protein Binding Structure-Activity Relationships Related to the N-Terminus of Daptomycin
Abstract
- Daptomycin is a lipopeptide antibiotic that is highly bound to plasma proteins. To date, the plasma components and structure-activity relationships responsible for the plasma protein binding profile of daptomycin remain uncharacterized. In the present study we have employed a surface plasmon resonance assay together with molecular docking techniques to investigate the plasma protein binding structure-activity relationships related to the N-terminal fatty acyl of daptomycin. Three compounds were investigated: (1) native daptomycin, which displays an N-terminal n-decanoyl fatty acid side chain, and two analogues with modifications to the N-terminal fatty acyl chain; (2) des-acyl daptomycin; and (3) acetyl-daptomycin. The surface plasmon resonance (SPR) data showed that the binding profile of native daptomycin was in the rank order human serum albumin (HSA) ≫ α-1-antitrypsin > low-density lipoprotein ≥ hemoglobin > sex hormone binding globulin > α-1-acid-glycoprotein (AGP) > hemopexin > fibrinogen > α-2-macroglobulin > β2-microglobulin > high-density lipoprotein > fibronectin > haptoglobulin > transferrin > immunoglobulin G. Notably, binding to fatty acid free HSA was greater than binding to nondelipidated HSA. SPR and ultrafiltration studies also indicated that physiological concentrations of calcium increase binding of daptomycin and acetyl-daptomycin to HSA and AGP. A molecular model of the daptomycin-human serum albumin A complex is presented that illustrates the pivotal role of the N-terminal fatty acyl chain of daptomycin for binding to drug site 1 of HSA. In proof-of-concept, the capacity of physiological cocktails of the identified plasma proteins to inhibit the antibacterial activity of daptomycin was assessed with in vitro microbiological assays. We show that HSA, α-1-antitrypsin, low-density lipoprotein, sex hormone binding globulin, α-1-acid-glycoprotein, and hemopexin are responsible for the majority of the sequestering activity in human plasma. The findings are relevant to medicinal chemistry programs focused on the development of next-generation daptomycin lipopeptides. Tailored modifications to the N-terminal fatty acyl domain of the daptomycin molecule should yield novel daptomycin lipopeptides with more ideal plasma protein binding profiles to increase the levels of active (free) drug in plasma and improved in vivo activity.
|
