scholarly journals Novel solid-phase strategy for the synthesis of ligand-targeted fluorescent-labelled chelating peptide conjugates as a theranostic tool for cancer

2018 ◽  
Vol 14 ◽  
pp. 2665-2679 ◽  
Author(s):  
Sagnik Sengupta ◽  
Mena Asha Krishnan ◽  
Premansh Dudhe ◽  
Ramesh B Reddy ◽  
Bishnubasu Giri ◽  
...  
Keyword(s):  
Rhodamine B ◽  
Solid Phase ◽  
Inflammatory Diseases ◽  
Folate Receptor ◽  
Continuous Process ◽  
Solid Phase Peptide Synthesis ◽  
High Yield ◽  
Future Application ◽  
Fluorescent Tags

In this article, we have successfully designed and demonstrated a novel continuous process for assembling targeting ligands, peptidic spacers, fluorescent tags and a chelating core for the attachment of cytotoxic molecules, radiotracers, nanomaterials in a standard Fmoc solid-phase peptide synthesis in high yield and purity. The differentially protected Fmoc-Lys-(Tfa)-OH plays a vital role in attaching fluorescent tags while growing the peptide chain in an uninterrupted manner. The methodology is versatile for solid-phase resins that are sensitive to mild and strong acidic conditions when acid-sensitive side chain amino protecting groups such as Trt (chlorotrityl), Mtt (4-methyltrityl), Mmt (4-methoxytrityl) are employed to synthesise the ligand targeted fluorescent tagged bioconjugates. Using this methodology, DUPA rhodamine B conjugate (DUPA = 2-[3-(1,3-dicarboxypropyl)ureido]pentanedioic acid), targeting prostate specific membrane antigen (PSMA) expressed on prostate, breast, bladder and brain cancers and pteroate rhodamine B, targeting folate receptor positive cancers such as ovarian, lung, endometrium as well as inflammatory diseases have been synthesized. In vitro studies using LNCaP (PSMA +ve), PC-3 (PSMA −ve, FR −ve) and CHO-β (FR +ve) cell lines and their respective competition experiments demonstrate the specificity of the newly synthesized bioconstructs for future application in fluorescent guided intra-operative imaging.

scholarly journals Design of PSMA ligands with modifications at the inhibitor part: an approach to reduce the salivary gland uptake of radiolabeled PSMA inhibitors?

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Veronika Barbara Felber ◽  
Manuel Amando Valentin ◽  
Hans-Jürgen Wester
Keyword(s):  
Salivary Gland ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
In Vivo Studies ◽  
Tumor Xenograft ◽  
Tumor Uptake ◽  
Lncap Cells ◽  
High Affinity

Abstract Aim To investigate whether modifications of prostate-specific membrane antigen (PSMA)-targeted radiolabeled urea-based inhibitors could reduce salivary gland uptake and thus improve tumor-to-salivary gland ratios, several analogs of a high affinity PSMA ligand were synthesized and evaluated in in vitro and in vivo studies. Methods Binding motifs were synthesized ‘on-resin’ or, when not practicable, in solution. Peptide chain elongations were performed according to optimized standard protocols via solid-phase peptide synthesis. In vitro experiments were performed using PSMA+ LNCaP cells. In vivo studies as well as μSPECT/CT scans were conducted with male LNCaP tumor xenograft-bearing CB17-SCID mice. Results PSMA ligands with A) modifications within the central Zn2+-binding unit, B) proinhibitor motifs and C) substituents & bioisosteres of the P1′-γ-carboxylic acid were synthesized and evaluated. Modifications within the central Zn2+-binding unit of PSMA-10 (Glu-urea-Glu) provided three compounds. Thereof, only natLu-carbamate I (natLu-3) exhibited high affinity (IC50 = 7.1 ± 0.7 nM), but low tumor uptake (5.31 ± 0.94% ID/g, 1 h p.i. and 1.20 ± 0.55% ID/g, 24 h p.i.). All proinhibitor motif-based ligands (three in total) exhibited low binding affinities (> 1 μM), no notable internalization and very low tumor uptake (< 0.50% ID/g). In addition, four compounds with P1′-ɣ-carboxylate substituents were developed and evaluated. Thereof, only tetrazole derivative natLu-11 revealed high affinity (IC50 = 16.4 ± 3.8 nM), but also this inhibitor showed low tumor uptake (3.40 ± 0.63% ID/g, 1 h p.i. and 0.68 ± 0.16% ID/g, 24 h p.i.). Salivary gland uptake in mice remained at an equally low level for all compounds (between 0.02 ± 0.00% ID/g and 0.09 ± 0.03% ID/g), wherefore apparent tumor-to-submandibular gland and tumor-to-parotid gland ratios for the modified peptides were distinctly lower (factor 8–45) than for [177Lu]Lu-PSMA-10 at 24 h p.i. Conclusions The investigated compounds could not compete with the in vivo characteristics of the EuE-based PSMA inhibitor [177Lu]Lu-PSMA-10. Although two derivatives (3 and 11) were found to exhibit high affinities towards LNCaP cells, tumor uptake at 24 h p.i. was considerably low, while uptake in salivary glands remained unaffected. Optimization of the established animal model should be envisaged to enable a clear identification of PSMA-targeting radioligands with improved tumor-to-salivary gland ratios in future studies.

scholarly journals Model Amphipathic Peptide Coupled with Tacrine to Improve Its Antiproliferative Activity

2020 ◽  
Vol 22 (1) ◽  
pp. 242
Author(s):  
Sara Silva ◽  
Cláudia Alves ◽  
Diana Duarte ◽  
Ana Costa ◽  
Bruno Sarmento ◽  
...  
Keyword(s):  
Antiproliferative Activity ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Drug Repurposing ◽  
Parent Drug ◽  
Ache Inhibitor ◽  
Amphipathic Peptide ◽  
Reference Drug ◽  
Mcf 7

Drug repurposing and drug combination are two strategies that have been widely used to overcome the traditional development of new anticancer drugs. Several FDA-approved drugs for other indications have been tested and have demonstrated beneficial anticancer effects. In this connection, our research group recently reported that Tacrine, used to treat Alzheimer’s Disease, inhibits the growth of breast cancer MCF-7 cells both alone and in combination with a reference drug. In this view, we have now coupled Tacrine with the model amphipathic cell-penetrating peptide (CPP) MAP, to ascertain whether coupling of the CPP might enhance the drug’s antiproliferative properties. To this end, we synthesized MAP through solid-phase peptide synthesis, coupled it with Tacrine, and made a comparative evaluation of the parent drug, peptide, and the conjugate regarding their permeability across the blood-brain barrier (BBB), ability to inhibit acetylcholinesterase (AChE) in vitro, and antiproliferative activity on cancer cells. Both MAP and its Tacrine conjugate were highly toxic to MCF-7 and SH-SY5Y cells. In turn, BBB-permeability studies were inconclusive, and conjugation to the CPP led to a considerable loss of Tacrine function as an AChE inhibitor. Nonetheless, this work reinforces the potential of repurposing Tacrine for cancer and enhances the antiproliferative activity of this drug through its conjugation to a CPP.

scholarly journals Pyrrole-Mediated Peptide Cyclization Identified through Genetically Reprogrammed Peptide Synthesis

Biomedicines ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 99 ◽  
Author(s):  
Klaas Decoene ◽  
Willem Vannecke ◽  
Toby Passioura ◽  
Hiroaki Suga ◽  
Annemieke Madder
Keyword(s):  
Peptide Synthesis ◽  
Cyclic Peptide ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Screening Method ◽  
In Vitro Translation ◽  
Side Chain ◽  
One Pot ◽  
Depth Analysis

Flexible in vitro translation (FIT) was used as a screening method to uncover a new methodology for peptide constraining based on the attack of a nucleophilic side-chain functionality onto an oxidized furylalanine side chain. A set of template peptides, each containing furylalanine as furan-modified amino acid and a nucleophilic residue (Cys, His, Lys, Arg, Ser, or Tyr), was produced through FIT. The translation mixtures were treated with N-bromosuccinimide (NBS) to achieve selective furan oxidation and subsequent MALDI analysis demonstrated Lys and Ser as promising residues for cyclisation. Solid-phase peptide synthesis (SPPS) was used to synthesize suitable amounts of material for further in-depth analysis and characterisation. It was found that in the case of the peptide containing lysine next to a furylalanine residue, a one-pot oxidation and reduction reaction leads to the generation of a cyclic peptide featuring a pyrrole moiety as cyclisation motif, resulting from the attack of the lysine side chain onto the oxidized furylalanine side chain. Structural evidence was provided via NMR and the generality of the methodology was explored. We hereby expand the scope of our previously developed furan-based peptide labeling and crosslinking strategy.

A Comprehensive One-Pot Synthesis of Protected Cysteine and Selenocysteine SPPS Derivatives

2014 ◽  
Vol 21 (12) ◽  
pp. 1257-1264
Author(s):  
Stevenson Flemer
Keyword(s):  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Reduction Process ◽  
Building Blocks ◽  
High Yield ◽  
One Pot ◽  
Peptide Models ◽  
Direct Use ◽  
Proof Of Principle ◽  
Subsequent Incorporation

A proof-of-principle methodology is presented in which all commercially-available cysteine (Cys) and selenocysteine (Sec) solid phase peptide synthesis (SPPS) derivatives are synthesized in high yield from easily prepared protected dichalcogenide precursors. A Zn-mediated biphasic reduction process applied to a series of four bis-Nα-protected dichalcogenide compounds allows facile conversion to their corresponding thiol and selenol intermediates followed by insitu S- or Se-alkylation with various electrophiles to directly access twenty one known Cys and Sec SPPS derivatives. Most of these derivatives were able to be precipitated in crude form out of petroleum ether in sufficient purity for direct use as peptide building blocks. Subsequent incorporation of these derivatives into peptide models nicely illustrates their viability and applicability toward SPPS.

scholarly journals Small peptide-based GLP-1R ligands: an approach to reduce the kidney uptake of radiolabeled GLP-1R-targeting agents?

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Veronika Barbara Felber ◽  
Hans-Jürgen Wester
Keyword(s):  
Renal Excretion ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Cross Coupling ◽  
Solution Synthesis ◽  
Small Peptides ◽  
Small Peptide ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Abstract Aim Elevated kidney uptake in insulinoma patients remains a major limitation of radiometallated exendin-derived ligands of the glucagon-like peptide 1 receptor (GLP-1R). Based on the previously published potent GLP-1R-activating undecapeptide 1, short-chained GLP-1R ligands were developed to investigate whether kidney uptake can be reduced by means of direct 18F-labeling (nuclide-based accelerated renal excretion) or the reduction of the overall ligand charge (ligand-based reduced kidney uptake). Materials & methods GLP-1R ligands were prepared according to optimized standard protocols via solid-phase peptide synthesis (SPPS) or, when not practicable, via fragment coupling in solution. Synthesis of (2‘-Et, 4‘-OMe)4, 4’-L-biphenylalanine ((2′-Et, 4′-OMe)BIP), required for the preparation of 1, was accomplished by Suzuki-Miyaura cross-coupling. In vitro experiments were performed using stably transfected GLP-1R+ HEK293-hGLP-1R cells. Results In contrast to the three reference ligands glucagon-like peptide 1 (GLP-1, IC50 = 23.2 ± 12.2 nM), [Nle14, Tyr(3-I)40]exendin-4 (IC50 = 7.63 ± 2.78 nM) and [Nle14, Tyr40]exendin-4 (IC50 = 9.87 ± 1.82 nM), the investigated GLP-1R-targeting small peptides (9–15 amino acids), including lead peptide 1, exhibited only medium to low affinities (IC50 > 189 nM). Only SiFA-tagged undecapeptide 5 (IC50 = 189 ± 35 nM) revealed a higher affinity than 1 (IC50 = 669 ± 242 nM). Conclusion The investigated small peptides, including lead peptide 1, could not compete with favorable in vitro characteristics of glucagon-like peptide 1 (GLP-1), [Nle14, Tyr(3-I)40]exendin-4 and [Nle14, Tyr40]exendin-4. The auspicious EC50 values of 1 provided by the literature could not be transferred to competitive binding experiments. Therefore, the use of 1 as a basic scaffold for the design of further GLP-1R-targeting radioligands cannot be recommended. Further investigations might include the scaffold of 5, although substantial optimizations concerning affinity and lipophilicity would be required. In sum, GLP-1R-targeting radioligands with reduced kidney uptake could not be obtained in this work, which emphasizes the need for further ligands addressing this particular issue.

scholarly journals Stereorandomization as a Method to Probe Peptide Bioactivity

2020 ◽  
Author(s):  
Thissa N. Siriwardena ◽  
Bee-Ha Gan ◽  
Thilo Köhler ◽  
Christian van Delden ◽  
Sacha Javor ◽  
...  
Keyword(s):  
Cyclic Peptide ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Therapeutic Index ◽  
Building Blocks ◽  
Polymyxin B ◽  
High Yield ◽  
Peptide Antibiotic ◽  
Disruptive Effect ◽  
Peptide Dendrimers

<p>Solid-phase peptide synthesis (SPPS) is usually performed with optically pure building blocks to prepare peptides as single enantiomers. Herein we report that SPPS using racemic amino acids provides stereorandomized (<i>sr</i>) peptides, containing up to billions of different stereoisomers,<a> </a>as well-defined single HPLC peak, single mass products with high yield, which can be used to investigate peptide bioactivity. To exemplify our method, we show that stereorandomization abolishes the membrane disruptive effect of α-helical amphiphilic antimicrobial peptides but preserves their antibiofilm effect, implying different mechanisms involving folded versus disordered conformations. For antimicrobial peptide dendrimers by contrast, stereorandomization preserves antibacterial, membrane disruptive and anti-biofilm effects but reduces hemolysis and cytotoxicity, thereby increasing their therapeutic index. Finally, we identify partially stereorandomized analogs of the last resort cyclic peptide antibiotic polymyxin B with preserved antibacterial activity but lacking membrane disruptive and lipopolysaccharide neutralizing activity, pointing to the existence of additional targets.</p>

scholarly journals A microfluidic approach for sequential assembly of siRNA polyplexes with a defined structure-activity relationship

2019 ◽  
Vol 1 ◽  
pp. e1 ◽  
Author(s):  
Dominik M. Loy ◽  
Philipp M. Klein ◽  
Rafał Krzysztoń ◽  
Ulrich Lächelt ◽  
Joachim O. Rädler ◽  
...  
Keyword(s):  
Nucleic Acids ◽  
Hydrophobic Interactions ◽  
Solid Phase ◽  
Transfection Efficiency ◽  
Folate Receptor ◽  
Endosomal Escape ◽  
The Core ◽  
Functional Components ◽  
Lipid Anchor

Therapeutic nucleic acids provide versatile treatment options for hereditary or acquired diseases. Ionic complexes with basic polymers are frequently used to facilitate nucleic acid’s transport to intracellular target sites. Usually, these polyplexes are prepared manually by mixing two components: polyanionic nucleic acids and polycations. However, parameters such as internal structure, size, polydispersity and surface charge of the complexes sensitively affect pharmaceutical efficiency. Hence a controlled assembly is of paramount importance in order to ensure high product quality. In the current study, we present a microfluidic platform for controlled, sequential formulation of polyplexes. We use oligo-amidoamines (termed “oligomers”) with precise molecular weight and defined structure due to their solid phase supported synthesis. The assembly of the polyplexes was performed in a microfluidic chip in two steps employing a design of two successive Y junctions: first, siRNA and core oligomers were assembled into core polyplexes. These core oligomers possess compacting, stabilizing, and endosomal escape mediating motifs. Second, new functional motifs were mixed to the core particles and integrated into the core polyplex. The iterative assembly formed multi-component polyplexes in a highly controlled manner and enabled us to investigate structure-function relationships. We chose nanoparticle shielding polyethylene glycol (PEG) and cell targeting folic acid (termed “PEG-ligands”) as functional components. The PEG-ligands were coupled to lipid anchor oligomers via strain promoted azide—alkyne click chemistry. The lipid anchors feature four cholanic acids for inserting various PEG-ligands into the core polyplex by non-covalent hydrophobic interactions. These core—lipid anchor—PEG-ligand polyplexes containing folate as cell binding ligand were used to determine the optimal PEG-ligand length for transfecting folate receptor-expressing KB cells in vitro. We found that polyplexes with 20 mol % PEG-ligands (relative to ncore oligomer) showed optimal siRNA mediated gene knock-down when containing defined PEG domains of in sum 24 and 36 ethylene oxide repetitions, 12 EOs each from the lipid anchor and 12 or 24 EOs from the PEG-ligand, respectively. These results confirm that transfection efficiency depends on the linker length and stoichiometry and are consistent with previous findings using core—PEG-ligand polyplexes formed by click modification of azide-containing core polyplexes with aforementioned PEG-ligands. Hence, successive microfluidic assembly might be a potentially powerful route to create defined multi-component polyplexes with reduced batch-to-batch variability.

Synthesis and Characterization of Bradykinin Derivatives Based on a β-Cyclodextrin Core

2016 ◽  
Vol 69 (3) ◽  
pp. 328 ◽  
Author(s):  
Rachel J. Stephenson ◽  
Fran Wolber ◽  
Paul G. Plieger ◽  
David R. K. Harding
Keyword(s):  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Synthesis And Characterization ◽  
Structure Activity ◽  
Fmoc Spps ◽  
Model Drug ◽  
Sulfonamide Group ◽  
Important Structure

Mono-6A-fluorenylmethyloxycarbonylamino-mono-6X-succinyl-β-cyclodextrin (1), an amino acid-based bi-functionalized derivative of β-cyclodextrin (β-CD), has been functionalized with the bioactive peptide, bradykinin and/or sulfonamides using fluorenylmethyloxycarbonyl (Fmoc) solid phase peptide synthesis (SPPS). The all-in-one molecule contains a carrier (cyclodextrin), targeting agent (bradykinin), and/or model drug (sulfonamide). Varying combinations of these bradykinin-focussed molecules have been synthesized using Fmoc SPPS on Rink amide resin. The positioning of the sulfonamide group, the bradykinin peptide and the cyclodextrin carrier are essential for biological activity. The inclusion of spacers is also important. Structure–activity studies performed on three cancer cell lines in vitro support these conclusions.

scholarly journals Conjugation of proapoptotic peptides with folate and cyanine dyes for enhanced potency and selectivity towards tumor cell lines

2021 ◽  
Author(s):  
Davide Cardella ◽  
Louis Yu Pan Luk ◽  
Yu-Hsuan Tsai
Keyword(s):  
Tumor Cells ◽  
Cell Lines ◽  
Solid Phase ◽  
Folate Receptor ◽  
Solid Phase Peptide Synthesis ◽  
Cyanine Dyes ◽  
Cyanine Dye ◽  
Tumor Cell Lines ◽  
Mammalian Cell Lines ◽  
Proapoptotic Peptides

Despite continuous advances, anticancer therapy still faces several technical hurdles such as selectivity on cellular and subcellular targets of therapeutics. Toward addressing these limitations, we have combined the use of proapoptotic peptides, cyanine dyes and folate to target the mitochondria of tumor cells. Hence, a series of proapoptotic peptides and their conjugates with a cyanine dye and/or a folate were prepared via solid-phase peptide synthesis (SPPS) and their activity tested in different mammalian cell lines. Compounds bearing either a cyanine dye or folate were found to be more cytotoxic than the parent peptides or more selective towards cells overexpressing the folate receptor α, which is commonly found on the surface of tumor cells. Nevertheless, constructs containing both components showed diminished potency and selectivity.

scholarly journals A new Kunitz-type snake toxin family associated with an original mode of interaction with the vasopressin 2 receptor.

2021 ◽  
Author(s):  
Laura Droctové ◽  
Justyna CioleK ◽  
Christiane Mendre ◽  
Amélia Chorfa ◽  
Paola Huerta ◽  
...  
Keyword(s):  
Mode Of Action ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Screening Assay ◽  
Dendroaspis Angusticeps ◽  
Peptide Family ◽  
V2 Receptor ◽  
Kunitz Type ◽  
Molecular Mode

Background and purpose. Venomous animals express numerous Kunitz-type peptides. The mambaquaretin-1 (MQ1) recently identified from the Dendroaspis angusticeps venom is the most selective antagonist of the arginine-vasopressin V2 receptor (V2R) and the unique Kunitz-type peptide active on a GPCR. We aimed to exploit other mamba venoms to enlarge the V2R-Kunitz peptide family and get insight into the MQ1 molecular mode of action. Experimental approach. We used a bio-guided screening assay to identify novel MQs and placed them phylogenetically. Several newly identified MQs were produced by solid phase peptide synthesis. They were characterized in vitro by binding and functional tests andin vivo by diuresis measurement in rats. Key results. Eight additional MQs were identified with nanomolar affinities for the V2R, all antagonists. MQs form a new subgroup in the Kunitz family, close to the V2R non-active dendrotoxins and to 2 V2R active cobra toxins. Sequence comparison between active and non-active V2R Kunitz peptides highlighted 5 specific V2R positions. Four of them are involved in V2R activity and belong to the 2 large MQ1 loops. We finally determined that 8 positions, part of these 2 loops, interact with the V2R. The variant MQ1-K39A showed specificity for the human versus the rat V2R . Conclusions and implications. A third function and mode of action is now associated with the Kunitz-peptides. The number of MQ1 residues involved in V2R binding is large and may explain its absolute selectivity. MQ1-K39A represents the first step in the improvement of the MQ1 design for medicinal perspective.

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