| 31747558 |
Structure-activity relationship studies of Longicalcynin A analogues, as anticancer cyclopeptides |
10.1016/j.cbi.2019.108902. |
Chem Biol Interact |
Structure-activity relationship studies of Longicalcynin A analogues, as anticancer cyclopeptides
Abstract
- Cancer has emerged as the main cause of the highest rate of mortality in the world. Drugs used in cancer, although, show some beneficial effects on cancerous organs, demonstrate side effects on other normal tissues. On the other hand, anticancer peptides, being effective on target tissues, should be safe and less harmful on healthy organs, since peptides have several advantages, i.e., high activity, specificity, affinity, being less immunogenic and not accumulate in the body. In the present work, analogues of Longicalcynin A, a naturally occurring anticancer cyclopeptide, were synthesized and evaluated their cytotoxicity in order to gain information from structure-activity relationships of the such cyclopeptides which may lead to find novel and safer anticancer peptide compound(s) to be used in clinic. Peptides were prepared by the solid-phase peptide synthesis method using trityl-resin. Peptide cyclization was performed in liquid phase. To study anticancer activity of the peptide analogues of Longicalycinin A, several methods including MTT, flow cytometry analysis and Lysosomal membrane integrity assay were employed using two cell lines HepG2 and HT-29. Fibroblast cells were used to control the safety of the synthesized cyclopeptides on normal cells. Two cyclopeptides 11 and 17 with the sequences of cyclo-(Thr-Val-Pro-Phe-Ala) and cyclo-(Phe-Ser-Pro-Phe-Ala), respectively were cytotoxic against the colon as well as hepatic cancer cells with safety profile against fibroblast cells, probably with the mechanism of apoptosis as lysosomal membrane integrity damaged. These cyclopeptides showed to be more favorable compounds better than Longicalycinin A and good candidates to develop cyclopeptides as anticancer agents.
|
| 31763045 |
Rezafungin treatment in mouse models of invasive candidiasis and aspergillosis: Insights on the PK/PD pharmacometrics of rezafungin efficacy |
10.1002/prp2.546. |
Pharmacol Res Perspect |
Rezafungin treatment in mouse models of invasive candidiasis and aspergillosis: Insights on the PK/PD pharmacometrics of rezafungin efficacy
Abstract
- Rezafungin acetate is a novel echinocandin in clinical development for prevention and treatment of invasive fungal infections. Rezafungin is differentiated by a pharmacokinetic/pharmacodynamic (PK/PD) profile that includes a long half-life allowing once-weekly administration, front-loaded plasma drug exposures associated with antifungal efficacy, and penetration into deep-seated infections, such as intra-abdominal abscesses. In this series of in vivo studies, rezafungin demonstrated efficacy in the treatment of neutropenic mouse models of disseminated candidiasis, including infection caused by azole-resistant , and aspergillosis. These results contribute to a growing body of evidence demonstrating the antifungal efficacy and potential utility of rezafungin in the treatment of invasive fungal infections.
|
| 31935054 |
Tutuilamides A-C: Vinyl-Chloride-Containing Cyclodepsipeptides from Marine Cyanobacteria with Potent Elastase Inhibitory Properties |
10.1021/acschembio.9b00992. |
ACS Chem Biol |
Tutuilamides A-C: Vinyl-Chloride-Containing Cyclodepsipeptides from Marine Cyanobacteria with Potent Elastase Inhibitory Properties
Abstract
- Marine cyanobacteria (blue-green algae) have been shown to possess an enormous capacity to produce structurally diverse natural products that exhibit a broad spectrum of potent biological activities, including cytotoxic, antifungal, antiparasitic, antiviral, and antibacterial activities. Using mass-spectrometry-guided fractionation together with molecular networking, cyanobacterial field collections from American Samoa and Palmyra Atoll yielded three new cyclic peptides, tutuilamides A-C. Their structures were established by spectroscopic techniques including 1D and 2D NMR, HR-MS, and chemical derivatization. Structure elucidation was facilitated by employing advanced NMR techniques including nonuniform sampling in combination with the 1,1-ADEQUATE experiment. These cyclic peptides are characterized by the presence of several unusual residues including 3-amino-6-hydroxy-2-piperidone and 2-amino-2-butenoic acid, together with a novel vinyl chloride-containing residue. Tutuilamides A-C show potent elastase inhibitory activity together with moderate potency in H-460 lung cancer cell cytotoxicity assays. The binding mode to elastase was analyzed by X-ray crystallography revealing a reversible binding mode similar to the natural product lyngbyastatin 7. The presence of an additional hydrogen bond with the amino acid backbone of the flexible side chain of tutuilamide A, compared to lyngbyastatin 7, facilitates its stabilization in the elastase binding pocket and possibly explains its enhanced inhibitory potency.
|
| 31940927 |
Isolation and Characterization of Antimicrobial Peptides with Unusual Disulfide Connectivity from the Colonial Ascidian |
10.3390/md18010051. |
Mar Drugs |
Isolation and Characterization of Antimicrobial Peptides with Unusual Disulfide Connectivity from the Colonial Ascidian
Abstract
- This study reports the isolation of two novel cysteine-rich antibacterial peptides, turgencin A and turgencin B, along with their oxidized derivatives, from the Arctic marine colonial ascidian . The peptides are post-translationally modified, containing six cysteines with an unusual disulfide connectivity of Cys-Cys, Cys-Cys, and Cys-Cys and an amidated C-terminus. Furthermore, the peptides contain methionine residues resulting in the isolation of peptides with different degrees of oxidation. The most potent peptide, turgencin A with one oxidized methionine, displayed antimicrobial activity against both Gram-negative and Gram-positive bacteria with a minimum inhibitory concentration (MIC) as low as 0.4 µM against selected bacterial strains. In addition, the peptide inhibited the growth of the melanoma cancer cell line A2058 (IC = 1.4 µM) and the human fibroblast cell line MRC-5 (IC = 4.8 µM). The results from this study show that natural peptides isolated from marine tunicates have the potential to be promising drug leads.
|
| 32002605 |
The roles of genes associated with regulation, transportation, and macrocyclization in desotamide biosynthesis in Streptomyces scopuliridis SCSIO ZJ46 |
10.1007/s00253-020-10414-4. |
Appl Microbiol Biotechnol |
The roles of genes associated with regulation, transportation, and macrocyclization in desotamide biosynthesis in Streptomyces scopuliridis SCSIO ZJ46
Abstract
- The deep-sea-derived microbe Streptomyces scopuliridis SCSIO ZJ46 produces desotamides A-D. Notably, desotamides A and B display antibacterial activities against pathogenic Gram-positive Streptococcus pneumoniae NCTC 7466, Staphylococcus aureus ATCC 29213, and the methicillin-resistant clinical isolate Staphylococcus epidermidis (MRSE) shhs-E1. The 39-kb desotamide biosynthetic gene cluster (dsa) has previously been identified and heterologously expressed in S. coelicolor M1152 for the purposes of assigning dsa gene functions. In this work, we identified seven genes in the dsa cluster including three regulatory genes (dsaA, dsaM, and dsaN), two transporter genes (dsaK and dsaL), and two other genes, dsaB (annotated as a phosphate synthase) and dsaJ (a PBP-type thioesterase). The DsaA and DsaN were unambiguously shown to be positive regulators of desotamide biosynthesis, and consistent with these roles, inactivation of either gene completely abolished desotamide production. Moreover, overexpression of dsaA or dsaN (independent of each other) was shown to improve desotamide titers. Production of desotamides in M1152/07-6H::dsaA strain was 2.4-fold greater than that in the heterologous dsa expression strain M1152/07-6H whereas desotamide titers from the M1152/07-6H::dsaN strain were about twice that of M1152/07-6H. In addition, inactivation of dsaB and dsaJ (independent of each other) completely abolished desotamide production, indicating their indispensability for desotamide assembly. These studies provide new insights into the functions and combinatorial biosynthetic potentials of seven key genes within the dsa biosynthetic gene cluster. Findings reported here are likely to facilitate further efforts aimed at assessing and developing the desotamides and related analogs for future applications.
|
| 32083462 |
Acyldepsipeptide Antibiotics and a Bioactive Fragment Thereof Differentially Perturb ClpXP1P2 Activity |
10.1021/acschembio.9b00454. |
ACS Chem Biol |
Acyldepsipeptide Antibiotics and a Bioactive Fragment Thereof Differentially Perturb ClpXP1P2 Activity
Abstract
- Proteolytic complexes in (), the deadliest bacterial pathogen, are major foci in tuberculosis drug development programs. The Clp proteases, which are essential for viability, are high-priority targets. These proteases function through the collaboration of ClpP1P2, a barrel-shaped heteromeric peptidase, with associated ATP-dependent chaperones like ClpX and ClpC1 that recognize and unfold specific substrates in an ATP-dependent fashion. The critical interaction of the peptidase and its unfoldase partners is blocked by the competitive binding of acyldepsipeptide antibiotics (ADEPs) to the interfaces of the ClpP2 subunits. The resulting inhibition of Clp protease activity is lethal to . Here, we report the surprising discovery that a fragment of the ADEPs retains anti- activity yet stimulates rather than inhibits the ClpXP1P2-catalyzed degradation of proteins. Our data further suggest that the fragment stabilizes the ClpXP1P2 complex and binds ClpP1P2 in a fashion distinct from that of the intact ADEPs. A structure-activity relationship study of the bioactive fragment defines the pharmacophore and points the way toward the development of new drug leads for the treatment of tuberculosis.
|
| 32085719 |
Evaluation of in vitro antileishmanial efficacy of cyclosporin A and its non-immunosuppressive derivative, dihydrocyclosporin A |
10.1186/s13071-020-3958-x. |
Parasit Vectors |
Evaluation of in vitro antileishmanial efficacy of cyclosporin A and its non-immunosuppressive derivative, dihydrocyclosporin A
Abstract
- New therapeutic drugs are urgently needed against visceral leishmaniasis because current drugs, such as pentavalent antimonials and miltefosine, produce severe side effects and development of resistance. Whether cyclosporine A (CsA) and its derivatives can be used as therapeutic drugs for visceral leishmaniasis has been controversial for many years.
In this study, we evaluated the efficacy of CsA and its derivative, dihydrocyclosporin A (DHCsA-d), against promastigotes and intracellular amastigotes of Leishmania donovani. Sodium stibogluconate (SSG) was used as a positive control.
Our results showed that DHCsA-d was able to inhibit the proliferation of L. donovani promastigotes (IC: 21.24 μM and 12.14 μM at 24 h and 48 h, respectively) and intracellular amastigotes (IC: 5.23 μM and 4.84 μM at 24 and 48 h, respectively) in vitro, but CsA treatment increased the number of amastigotes in host cells. Both DHCsA-d and CsA caused several alterations in the morphology and ultrastructure of L. donovani, especially in the mitochondria. However, DHCsA-d showed high cytotoxicity towards cells of the mouse macrophage cell line RAW264.7, with CC50 values of 7.98 μM (24 h) and 6.65 μM (48 h). Moreover, DHCsA-d could increase IL-12, TNF-α and IFN-γ production and decrease the levels of IL-10, IL-4, NO and HO in infected macrophages. On the contrary, CsA decreased IL-12, TNF-α, and IFN-γ production and increased the levels of IL-10, IL-4, NO and HO in infected macrophages. The expression of L. donovani cyclophilin A (LdCyPA) in promastigotes and intracellular amastigotes and the expression of cyclophilin A (CyPA) in RAW 264.7 cells were found to be significantly downregulated in the CsA-treated group compared to those in the untreated group. However, no significant changes in LdCyPA and CyPA levels were found after DHCsA-d or SSG treatment.
Our findings initially resolved the dispute regarding the efficacy of CsA and DHCsA-d for visceral leishmaniasis treatment. CsA showed no significant inhibitory effect on intracellular amastigotes. DHCsA-d significantly inhibited promastigotes and intracellular amastigotes, but it was highly cytotoxic. Therefore, CsA and DHCsA-d are not recommended as antileishmanial drugs.
|
| 32101438 |
Dimerization of α-Conotoxins as a Strategy to Enhance the Inhibition of the Human α7 and α9α10 Nicotinic Acetylcholine Receptors |
10.1021/acs.jmedchem.9b01536. |
J Med Chem |
Dimerization of α-Conotoxins as a Strategy to Enhance the Inhibition of the Human α7 and α9α10 Nicotinic Acetylcholine Receptors
Abstract
- The affinity of α-conotoxins, a class of nicotinic acetylcholine receptor (nAChR) peptide inhibitors, can be enhanced by dendrimerization. It has been hypothesized that this improvement arose from simultaneous binding of the α-conotoxins to several spatially adjacent sites. We here engineered several α-conotoxin dimers using a linker length compatible between neighboring binding sites on the same receptor. Remarkably, the dimer of α-conotoxin PeIA compared to the monomer displayed an increase in potency by 11-fold (IC = 1.9 nM) for the human α9α10 nAChR. The dimerization of α-conotoxin RgIA# resulted in a dual inhibitor that targets both α9α10 and α7 nAChR subtypes with an IC = ∼50 nM. The RgIA# dimer is therapeutically interesting because it is the first dual inhibitor that potently and selectively inhibits these two nAChR subtypes, which are both involved in the etiology of several cancers. We propose that the dimerization of α-conotoxins is a simpler and efficient alternative strategy to dendrimers for enhancing the activity of α-conotoxins.
|
| 32163654 |
Landornamides: Antiviral Ornithine-Containing Ribosomal Peptides Discovered through Genome Mining |
10.1002/anie.201916321. |
Angew Chem Int Ed Engl |
Landornamides: Antiviral Ornithine-Containing Ribosomal Peptides Discovered through Genome Mining
Abstract
- Proteusins are a family of bacterial ribosomal peptides that largely remain hypothetical genome-predicted metabolites. The only known members are the polytheonamide-type cytotoxins, which have complex structures due to numerous unusual posttranslational modifications (PTMs). Cyanobacteria contain large numbers of putative proteusin loci. To investigate their chemical and pharmacological potential beyond polytheonamide-type compounds, we characterized landornamide A, the product of the silent osp gene cluster from Kamptonema sp. PCC 6506. Pathway reconstruction in E. coli revealed a peptide combining lanthionines, d-residues, and, unusually, two ornithines introduced by the arginase-like enzyme OspR. Landornamide A inhibited lymphocytic choriomeningitis virus infection in mouse cells, thus making it one of the few known anti-arenaviral compounds. These data support proteusins as a rich resource of chemical scaffolds, new maturation enzymes, and bioactivities.
|
| 32203656 |
Circular Permutation of the Native Enzyme-Mediated Cyclization Position in Cyclotides |
10.1021/acschembio.9b00996. |
ACS Chem Biol |
Circular Permutation of the Native Enzyme-Mediated Cyclization Position in Cyclotides
Abstract
- Cyclotides are a class of cyclic disulfide-rich peptides found in plants that have been adopted as a molecular scaffold for pharmaceutical applications due to their inherent stability and ability to penetrate cell membranes. For research purposes, they are usually produced and cyclized synthetically, but there are concerns around the cost and environmental impact of large-scale chemical synthesis. One strategy to improve this is to combine a recombinant production system with native enzyme-mediated cyclization. Asparaginyl endopeptidases (AEPs) are enzymes that can act as peptide ligases in certain plants to facilitate cyclotide maturation. One of these ligases, OaAEP1b, originates from the cyclotide-producing plant, , and can be produced recombinantly for use as an alternative to chemical cyclization of recombinant substrates. However, not all engineered cyclotides are compatible with AEP-mediated cyclization because new pharmaceutical epitopes often replace the most flexible region of the peptide, where the native cyclization site is located. Here we redesign a popular cyclotide grafting scaffold, MCoTI-II, to incorporate an AEP cyclization site located away from the usual grafting region. We demonstrate the incorporation of a bioactive peptide sequence in the most flexible region of MCoTI-II while maintaining AEP compatibility, where the two were previously mutually exclusive. We anticipate that our AEP-compatible scaffold, based on the most popular cyclotide for pharmaceutical applications, will be useful in designing bioactive cyclotides that are compatible with AEP-mediated cyclization and will therefore open up the possibility of larger scale enzyme-mediated production of recombinant or synthetic cyclotides alike.
|
| 32216308 |
Novel Stapling by Lysine Tethering Provides Stable and Low Hemolytic Cationic Antimicrobial Peptides |
10.1021/acs.jmedchem.9b02025. |
J Med Chem |
Novel Stapling by Lysine Tethering Provides Stable and Low Hemolytic Cationic Antimicrobial Peptides
Abstract
- Cationic antimicrobial peptides (CAMPs) are potent therapeutics for drug-resistant bacterial infections. However, the clinical application of CAMPs is hampered by its poor proteolytic stability and hemolytic activity toward eukaryotic cells. Great efforts have been made to design and generate derivatives of CAMPs with improved pharmacological properties. Here, we report a novel stapling protocol, which tethers two ε-amino groups of the lysine residue by the N-alkylation reaction on the hydrophilic face of amphiphilic antimicrobial peptides. A series of lysine-tethered stapled CAMPs were synthesized, employing the antimicrobial peptide OH-CM6 as a model. Biological screening of the stapled CAMPs provided an analogue with strong antimicrobial activity, high proteolytic stability, and low hemolytic activity. This novel stapling approach offers an important chemical tool for developing CAMP-based antibiotics.
|
| 32221295 |
A bifunctional asparaginyl endopeptidase efficiently catalyzes both cleavage and cyclization of cyclic trypsin inhibitors |
10.1038/s41467-020-15418-2. |
Nat Commun |
A bifunctional asparaginyl endopeptidase efficiently catalyzes both cleavage and cyclization of cyclic trypsin inhibitors
Abstract
- Asparaginyl endopeptidases (AEPs) catalyze the key backbone cyclization step during the biosynthesis of plant-derived cyclic peptides. Here, we report the identification of two AEPs from Momordica cochinchinensis and biochemically characterize MCoAEP2 that catalyzes the maturation of trypsin inhibitor cyclotides. Recombinantly produced MCoAEP2 catalyzes the backbone cyclization of a linear cyclotide precursor (MCoTI-II-NAL) with a k/K of 620 mM s, making it one of the fastest cyclases reported to date. We show that MCoAEP2 can mediate both the N-terminal excision and C-terminal cyclization of cyclotide precursors in vitro. The rate of cyclization/hydrolysis is primarily influenced by varying pH, which could potentially control the succession of AEP-mediated processing events in vivo. Furthermore, MCoAEP2 efficiently catalyzes the backbone cyclization of an engineered MCoTI-II analog with anti-angiogenic activity. MCoAEP2 provides enhanced synthetic access to structures previously inaccessible by direct chemistry approaches and enables the wider application of trypsin inhibitor cyclotides in biotechnology applications.
|
| 32235388 |
Effects of Cyclization on Activity and Stability of α-Conotoxin TxIB |
10.3390/md18040180. |
Mar Drugs |
Effects of Cyclization on Activity and Stability of α-Conotoxin TxIB
Abstract
- α-Conotoxin TxIB specifically blocked α6/α3β2β3 acetylcholine receptors (nAChRs), and it could be a potential probe for studying addiction and other diseases related to α6/α3β2β3 nAChRs. However, as a peptide, TxIB may suffer from low stability, short half-life, and poor bioavailability. In this study, cyclization of TxIB was used to improve its stability. Four cyclic mutants of TxIB (cTxIB) were synthesized, and the inhibition of these analogues on α6/α3β2β3 nAChRs as well as their stability in human serum were measured. All cyclized analogues had similar activity compared to wild-type TxIB, which indicated that backbone cyclization of TxIB had no significant effect on its activity. Cyclization of TxIB with a seven-residue linker improved its stability significantly in human serum. Besides this, the results showed that cyclization maintained the activity of α-conotoxin TxIB, which is conducive to its future application.
|
| 32239926 |
Cyclic Peptides in Seed of Are Ribosomally Synthesized |
10.1021/acs.jnatprod.9b01209. |
J Nat Prod |
Cyclic Peptides in Seed of Are Ribosomally Synthesized
Abstract
- Small, cyclic peptides are reported to have many bioactivities. In bacteria and fungi, they can be made by nonribosomal peptide synthetases, but in plants they are exclusively ribosomal. Cyclic peptides from the genus possess cytotoxic and anti-inflammatory activities, but their biosynthesis is unknown. The medicinal soursop plant, , contains annomuricatins A (cyclo-PGFVSA) and B (cyclo-PNAWLGT). Here, using transcriptomics and tandem mass spectrometry, we identify a suite of short transcripts for precursor proteins for 10 validated annomuricatins, 9 of which are novel. In their precursors, annomuricatins are preceded by an absolutely conserved Glu and each peptide sequence has a conserved proto-C-terminal Pro, revealing parallels with the segetalin orbitides from the seed of , which are processed through ligation by a prolyl oligopeptidase in a transpeptidation reaction.
|
| 32347293 |
Brevinin-1GHd: a novel Hylarana guentheri skin secretion-derived Brevinin-1 type peptide with antimicrobial and anticancer therapeutic potential |
10.1042/BSR20200019. |
Biosci Rep |
Brevinin-1GHd: a novel Hylarana guentheri skin secretion-derived Brevinin-1 type peptide with antimicrobial and anticancer therapeutic potential
Abstract
- Host-defense antimicrobial peptides (AMPs) from amphibians are usually considered as one of the most promising next-generation antibiotics because of their excellent antimicrobial properties and low cytotoxicity. In the present study, one novel Brevinin-1 type peptide, Brevinin-1GHd, was isolated and characterized from the skin secretion of the frog, Hylarana guentheri. Brevinin-1GHd was found to possess a wide range of antimicrobial activity through penetrating the bacterial membrane within a short time while showing low hemolysis at bactericidal concentrations, even against the resistant strains. It also inhibited and eradicated biofilms that are thought to be closely related to the rise in resistance. Meanwhile, Brevinin-1GHd exhibited wide-spectrum anti-proliferation activity toward human cancer lines. Taken together, these results indicate that Brevinin-1GHd with its excellent antimicrobial and anticancer activities is a promising candidate for a novel antibiotic agent, and study of its structure-activity relationships also provided a rational template for further research and peptide analog design.
|
