Top PDF Solid Phase Synthesis of Modular Peptide-based Targeted Molecular Imaging Agents

Solid Phase Synthesis of Modular Peptide-based Targeted Molecular Imaging Agents

Solid Phase Synthesis of Modular Peptide-based Targeted Molecular Imaging Agents

The peptide was successfully synthesized by using the methodology developed as described in Chapter 3. Each step was carefully monitored by cleaving a tiny amount of the resin with 1 % TFA and assaying the trace residue by LC-MS. The recipe works well and each coupling and each deprotection step proceeded perfectly as shown by LC-MS, described in Chapters 2c, 3e and 8 and shown in the LC-MS data in Appendix I. In most cases the acid-sensitive protecting groups were removed but in some cases a mixture of protected and deprotected intermediates were observed. The Mtt on d-lysine is removed rapidly, but t-butyl on tyrosine and t-butyl on glutamic acid are partially removed. The Boc group on tryptophan is difficult to remove and requires harsher conditions. In work carried on in the lab, unprotected tryptophan is being used.
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A convenient and efficient total solid-phase synthesis of DOTA-functionalized tumor-targeting peptides for PET imaging of cancer

A convenient and efficient total solid-phase synthesis of DOTA-functionalized tumor-targeting peptides for PET imaging of cancer

There is an ongoing interest in the development of new methods for facile and cost-effective synthesis of metal chelating agents, their conjugation to peptides, and ul- timate use of these radiometal complexes in imaging and targeted therapy to accelerate the research and clinical translation of emerging molecular imaging agents [4, 5]. As stated earlier, DOTA is one of the most widely used macrocyclic bifunctional ligands for the de- velopment of new metal-based imaging and therapeutic agents [2, 6, 21]. DO3A-tri-t-butyl ester (1,4,7,10-tetraa- zacyclododecane-1,4,7-tris (t-butyl acetate)) is an im- portant starting material for the preparation of macrocyclic chelating agents and magnetic resonance imaging contrast agents [5, 8]. Commercially available DOTA-tris-(t-Bu ester) is not an optimal ligand as it contains impurities and is costly [8]. In order to make DOTA-coupled compounds more readily available, we describe herein a simple and cost-efficient three-step solid-phase synthetic route of DOTA-linked peptide preparation starting from the condensation reaction of bromoacetylated peptides with cyclen followed by the al- kylation of cyclen-peptide with ter-butylbromoacetate. We chose BN peptides as our model tumor-targeting peptides because of the overexpression of BN/gastrin-re- leasing peptide (BN/GRP) receptors on various human
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Gastrin-releasing peptide receptor-targeted gadolinium oxide-based multifunctional nanoparticles for dual magnetic resonance/fluorescent molecular imaging of prostate cancer

Gastrin-releasing peptide receptor-targeted gadolinium oxide-based multifunctional nanoparticles for dual magnetic resonance/fluorescent molecular imaging of prostate cancer

Gadolinium(III) acetate, dimethyl sulfoxide (DMSO), tetram- ethylammonium hydroxide (TMAH), anhydrous EtOH, FI, dichloromethane (DCM), α -carboxyl, ω -hydroxy PEG (PEG- 2000), N-hydroxysuccinimide and 1-[3-(dimethylamino) propyl]-3-ethylcarbodiimide hydrochloride (EDC ⋅ HCl) were purchased from Adamas Chemical Reagents Co, Ltd (Shanghai, People’s Republic of China). BBN, CGGG- QWAVGHLM-NH2(7–14), was synthesized using standard fluorenylmethoxycarbonyl (fmoc) chemistry solid phase peptide synthesis method by Boxin Biotechnology (Xiamen, People’s Republic of China). All other chemicals were used without further purification.
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Modular Synthesis of Targeted Molecular Imaging Agents for MRI, PET, and PET-MRI of Cancer

Modular Synthesis of Targeted Molecular Imaging Agents for MRI, PET, and PET-MRI of Cancer

was dissolved in NMP (3mL) and to this solution was added triethylamine (39.8mg, 0.393mmol) and a solution of TSTU (118.3mg, 0.393mmol) in NMP (3mL). This reaction stirred under argon 1hr and was monitored by HPLC-MS after treating a sample with 0.1% aqueous butylamine. Upon completion of this portion of the reaction, crude intermediate product was precipitated by the addition of EtOAc and diethyl ether, and after centrifugation the organic layer was decanted and the crude solid dried briefly under argon. Compound (4) (44.5mg, 6.48x10-2mmol) was dissolved in 2mL DMSO. To this solution was added triethylamine (39.8mg, 0.393mmol), followed by the previously isolated crude product which had been reconstituted in NMP (3mL). This reaction ran 1hr. Crude product was precipitated by the addition of ethyl ether, and the organic layer was decanted after centrifugation. Pure product was obtained by preparatory HPLC (ACN/0.1% acetic acid aqueous, 30-60%). Fractions containing pure product were collected, concentrated by rotary evaporation, and freeze dried. Yield: 16.2mg, 26.5%. MS (HR, ESI) calc. for C 59 H 85 GdLaN 13 O 18 780.22212
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Triple-Modal Imaging of Magnetically-Targeted Nanocapsules in Solid Tumours In Vivo

Triple-Modal Imaging of Magnetically-Targeted Nanocapsules in Solid Tumours In Vivo

In this work, we developed a novel approach using polymeric nanocapsule to engineer a tri- ple-modal fluorescence/MR/SPECT imaging system and investigated their passive and magnetic targeting properties for cancer imaging. To our knowledge, this is the first report to examine the magnetic tumour targeting of magnetic nanocarrier using tri- ple-imaging technique. In this study, SPION and a near-infrared dye, indocyanine green (ICG), were physically incorporated in the magnetic nanocapsules as a negative MR contrast agent and fluorescence imaging probe, respectively. Furthermore, a chelating agent, diethylene triamine pentaacetic acid (DTPA), was chemically conjugated to the PEGylated PLGA polymer for radio-isotope chelation and therefore facilitated nuclear imaging. In vivo studies were per- formed to characterise the organ biodistribution pro- file and magnetic targeting of the magnetic nanocap- sules using triple-modal imaging technique.
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<p>Current Molecular Targeted Agents for Advanced Gastric Cancer</p>

<p>Current Molecular Targeted Agents for Advanced Gastric Cancer</p>

Approximately 15 – 45% of GC patients have a overexpression of EGFR and HER2 tyrosine kinases, and lapatinib is a dual inhibitor that blocks autophosphorylation and downstream signaling. 62 More importantly, HER2 status might be affected by different stages of the disease, host immune status, conco- mitant genomic alterations and prior fi rst-line chemotherapy with or without trastuzumab. The TyTAN trial showed a prolonged median OS of 2.1 months with lapatinib plus paclitaxel as second-line therapy in Asian patients with HER2- ampli fi ed AGC. 63 Although the median OS and PFS were increased in lapatinib recipients, the change was not statisti- cally signi fi cant. However, the ORR was signi fi cantly improved in the experimental group. Subgroup analyses showed clinically relevant OS and PFS gains in Chinese patients with HER2 overexpression (FISH positive and IHC 3+). The TRIO-013/LOGiC phase III trial also demonstrated that lapatinib combined with CapeOx did not improve OS for HER2-ampli fi ed GC. 64 Nevertheless, a subgroup analysis based on age showed that patients < 60 years of age had signi fi cant improvement (HR = 0.69; 95% CI, 0.51 – 0.94), but older patients had an unfortunate outcome (HR = 1.08; 95% CI, 0.81 – 1.45). 64 Since many factors, such as race, region, age, and sex, may in fl uence drug effects, further studies need to be performed to choose an appropriate intent-to-treat popula- tion that could obtain a favorable prognosis from lapatinib therapy. Lapatinib could be an option for second-line therapy for AGC patients younger than 60 with HER2 overexpression (FISH positive and IHC 3+).
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Peptide-Mediated Targeting of Angiogenesis for Molecular Imaging and Treatment of Cancer

Peptide-Mediated Targeting of Angiogenesis for Molecular Imaging and Treatment of Cancer

addition, proteins displayed on cellular surface, or proteins that formed complexes with other cell surface proteins may have several unexposed epitopes, allowing only certain sites of the protein to be available for targeting. These limitations highlight the attractiveness of using cell-based assays to screen OBOC libraries (as reviewed in (6)). Several studies have demonstrated much success in using whole cell binding assays to screen OBOC libraries to isolate ligands specific to cell surface receptors of numerous human cancer cell lines (23), ie. Jurkat T-leukemia cells (24), T-lymphoma cell (25), and breast cancer cells (26). Nonetheless, conventional methods for isolating few positive hits from billions of OBOC library beads through manual techniques remain impractical and challenging. The COPAS (Complex Object Parametric Analyzer and Sorter) large particle biosorter (purchased from Union Biometrica) carries great potential for high-throughput and rapid isolation of surface binding ligands from a random OBOC library. However, the biggest challenge associated with this strategy is the dissociation of cells from the beads upon flowing them through the tubes of the instrument. Currently, there have been no studies to combine on-bead cell-based screening approaches `with automated sorting.
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The Development of Organometallic OBOC Peptide Libraries for use in Molecular Imaging

The Development of Organometallic OBOC Peptide Libraries for use in Molecular Imaging

than small molecules in targeting enzymes or receptors which exhibit protein-protein interactions. This because some protein-protein interactions occur over a wide surface area with no obvious binding pockets. 14 These properties make peptides more promising imaging agents for these particular targets due to their ability to interact in a similar fashion. Peptides are also a very diverse class of compounds, with the potential to use a large number of natural and unnatural amino acids, alter the chain length, utilize both L and D-amino acids and are easily modified. When compared to antibodies, although peptides generally have lower affinity to targets, peptides rarely produce side effects 15 and have more favourable pharmacokinetic properties 16, 17 resulting in higher quality images. Also, peptides are more stable to the harsh chemical modification and radiolabelling conditions such as elevated temperatures or organic solvents. 18 The beneficial properties of peptide-based imaging agents can be shown by the widespread use of Octreotide, an 111 In-peptide imaging agent acting on the somatostatin receptor (Figure 1.3). 19 Because of these advantages, peptides as targeting entities have become important in the development of novel molecular imaging agents.
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Microwave Assisted Solid Phase Synthesis of Trisubstituted

Microwave Assisted Solid Phase Synthesis of Trisubstituted

mixture, methanol and DCM and dried. 250 mg of the resulted resin 2 was treated with ethanolic solution of 2-(1-ethoxyethylidene)malononitrile (488.52 mg, 4 mmol) under microwave irradiation for 20 min in presence of triethylamine (0.4 mL). The resulted resin 3 was filtered, washed with methanol and DCM and dried. In the final step 250 mg of the resin 3 was mixed with 15 mL TFA/DCM mixture (1:9) and stirred for 10 min under microwave irradiation. The resulted resin was filtered, washed with DCM and methanol. The filtrate was collected and evaporated to get a solid product. The solid product was then recrystallised from methanol to get pure 2,4-diaminopyrimidine-5-carbonitrile with an yield of 90%.
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Solid phase synthesis of recyclable diphosphine ligands

Solid phase synthesis of recyclable diphosphine ligands

General Experimental ........................................................................................................................... S-2 General Procedure for the Preparation of Lithium Phosphides ............................................................ S-2 General Procedure for the Synthesis of Resin-Bound Phosphine-Boranes ........................................ S-3 General Procedure for the Synthesis of Resin-Bound Phosphine-Borane Sulfates ............................ S-4 General Procedure for the Synthesis of Resin-Bound Diphosphines .................................................. S-5 General Procedure for the Synthesis of Cyclic Sulfates ...................................................................... S-6 General Procedure for Asymmetric Hydrogenation Experiments ........................................................ S-8 General Procedure for Catalyst Recycling Experiments ...................................................................... S-8 In-Situ Complexation Study .................................................................................................................. S-8
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Imaging heterogeneity of peptide delivery and binding in solid tumors using SPECT imaging and MRI

Imaging heterogeneity of peptide delivery and binding in solid tumors using SPECT imaging and MRI

However, heterogeneity of cancer is often present and a well-known negative prognostic factor for therapy out- come [1, 2]. Heterogeneous tumors tend to be more re- sistant to therapy and more likely to have an aggressive phenotype. Next to the routine study of morphologic tis- sue appearance, it is also crucial to study functional tissue properties, as heterogeneity in functional characteristics, e.g., vasculature, are also prognostic markers. Current clinical studies that use tumor-targeting radiolabeled pep- tides are unable to explain potential variable responses to be caused by the degree of homogenous or heterogeneous intra-tumoral distribution of radiopeptides in patients as nuclear imaging techniques do not have sufficient spatial resolution [3, 4]. The influence of intra-tumoral peptide heterogeneity on therapeutic efficacy has as yet not been studied due to these spatial restrictions and remains an important issue to investigate. Multi-modal imaging pro- vides the opportunity to address this challenge.
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Actively-targeted LTVSPWY peptide-modified magnetic nanoparticles for tumor imaging

Actively-targeted LTVSPWY peptide-modified magnetic nanoparticles for tumor imaging

100 µ L of serum-free RMPI 1640 medium into the flank of male BALB/C + nu/F1 nude mice. The mice were then subjected to imaging studies when their tumors had reached an acceptable size. After tail vein injection of DiR-loaded magnetic nanoparticles (with Fe 3 O 4 , oleic acid, mono- stearin, chitosan, and DiR concentrations of 50, 50, 350, 50, and 200 µ g/mL, respectively), the mice were anesthetized and imaged at multiple time points (1, 3, 6, 12, 24, 48, 72, and 96 hours) using Maestro in vivo imaging system (CRI Inc, Woburn, MA). The tunable filter was automatically stepped up in 10 nm increments from 580 nm to 700 nm while the camera captured images at each wavelength with constant exposure. Overall acquisition time was about 0.4 seconds. For ex vivo imaging, the tissues were subjected to fluorescence imaging using the Spectral system immediately after the tumors and organs were harvested.
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Solid phase synthesis of oxetane modified peptides

Solid phase synthesis of oxetane modified peptides

Despite resurgent interest in the use of peptides as drugs, 1 their development is often hampered by their poor oral bioavailabil- ity and short plasma half-lives. As a consequence, there is intense interest in the design, synthesis and study of pep- tidomimetics that mimic the structure and biological function of native peptides yet possess better drug-like properties. 2-4 Independently, Shipman 5 and Carreira 6 introduced a new type of peptide bond isostere in which the heterocyclic 3- aminooxetane unit was used as a replacement for one of the amide bonds (Figure 1). 7 Several features of these oxetane modified peptides (OMPs) make them of particular interest as peptidomimetics. Firstly, deletion of one of the amide bonds can improve peptide half-lives through increased stability to proteases whilst retaining bioactivity. 6b Secondly, oxetanes are known to make excellent bioisosteric replacements for C=O bonds, and are commonly used in conventional, small mole- cule drug discovery. 8 Thirdly, the 3-aminooxetane unit can act as both a H-bond donor and acceptor, supporting the types of non-covalent interactions available to peptides. Finally, con- formational changes arising from removal of the double bond character of the peptide bond change the conformational bias of OMPs, 5a opening up new areas of peptide structural space to explore.
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Disclosing the CXCR4 Expression in Lymphoproliferative Diseases by Targeted Molecular Imaging

Disclosing the CXCR4 Expression in Lymphoproliferative Diseases by Targeted Molecular Imaging

research. Initially, the major focus was directed to- wards their evaluation as effective anti-HIV agents and safe agents for the mobilization of HSPC for au- tologous transplantation in patients with hematolog- ical malignancies such as lymphoma and multiple myeloma. Plerixafor (AMD3100, Mozobil) is the only approved drug for this application so far [5], but other candidates such as the 14-mer peptidic antagonist BKT140 [80] also showed excellent results in patients with multiple myeloma and is now evaluated in clin- ical trials [81]. However, triggered by the recognition of the important role of CXCR4 in tumor growth and metastasis, the focus in the clinical evaluation of these compounds has shifted towards an additional as- sessment of their suitability and efficacy as anti-cancer and anti-metastatic drugs, both for their use in mon- otherapy as well as in combination therapy. Fur- thermore, other novel therapeutics such as the fully human IgG 4 Mab BMS-936564/MDX-1338 have en-
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Multimodality Imaging of Angiogenesis in a Rabbit Atherosclerotic Model by GEBP11 Peptide Targeted Nanoparticles

Multimodality Imaging of Angiogenesis in a Rabbit Atherosclerotic Model by GEBP11 Peptide Targeted Nanoparticles

The toxicity of magnetic nanoparticles is one of the most important issues that needs further investigation. Emerging studies suggest that DMSA-MNPs have good biocompatibility for MR imaging both in vitro and in vivo [41-45]. In spite of the greater uptake of nanoparticles mediated by GEBP11 peptide, rare detectable cytotoxic effect was observed in cells and tissues assays. Furthermore, biochemical analysis (AST, ALT and CREA) verified that NGD-MNPs had little effect on these important biological functions of normal rats and showed good biocompatibility for further biomedical application. Immunogenicity is another significant concern for biologic drugs as it can affect both safety and efficacy [46]. In this study, we found that NGD-NPs did not strongly stimulate T-cell proliferative response in mice. The immune response might depend not only on the chemical structure of GEBP11 peptide on the nanoparticle surface, but also on extrinsic factors, such as MNP dose and the MNPs coating modification.
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Cyanopivaloyl Ester in the Automated Solid-Phase Synthesis of Oligorhamnans

Cyanopivaloyl Ester in the Automated Solid-Phase Synthesis of Oligorhamnans

solvent system using a Vydac C4 HPLC column; Grace, 250 × 10 mm, 5 μ m). High-resolution mass spectra were recorded by direct injection (2 μL of a 2 μM solution in water/acetonitrile; 50/50; v/v and 0.1% formic acid) on a mass spectrometer (Thermo Finnigan LTQ Orbitrap) equipped with an electrospray ion source in positive mode (source voltage 3.5 kV, sheath gas flow 10, capillary temperature 250 °C) with resolution R = 60000 at m/z 400 (mass range m/z = 150−2000) and dioctyl phthalate (m/z = 391.2842) as a “lock mass”. The high-resolution mass spectrometer was calibrated prior to measurements with a calibration mixture (Thermo Finnigan). MALDI spectra were recorded on an Ultra fl extreme MALDI-TOF (Bruker Daltonics), equipped with Smartbeam-II laser, to measure the samples in re fl ectron positive ion mode. The MALDI-TOF was calibrated using a peptide calibration standard prior to measurement. One microliter of 2,5-dihydroxybenzoic acid (Bruker Daltonics) matrix (20 mg/mL in ACN/water; 50:50 (v/v)) was applied on a 384-MTP target plate (Bruker Daltonics, Bremen, Germany) and air-dried. Subsequently, 1 μL of compound water solution was spotted on the plate, and the spots were left to dry prior to MALDI-TOF analysis.
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Optimization of solid phase synthesis of quinazolin 4 ones

Optimization of solid phase synthesis of quinazolin 4 ones

Optimization of microwave assisted solid phase synthesis of quinazolin-4-ones was discussed in this paper. Two step synthesis yielded in 2-methyl-4H-3,1-beznoxazin-4-one and quinazolin-4- one was optimized in microwave conditions. Different solid supports as well as reaction time, amount of support and temperature were optimized by means of design of experiment approach. We were able to obtain the product with 80% overall yield and with good purity above 95% Resulted terms of synthesis were applied in synthesis of biologically active styrylquinazolines. Keywords: Solid phase; microwave synthesis; quinazolinones.
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Solid-phase synthesis of C-terminally modified peptides

Solid-phase synthesis of C-terminally modified peptides

In order to investigate the scope of this C-terminal modification method, the steric hindrance of the amines was increased by employing amine-functional polystyrene (2.5 kg/mol, polydispersity index (PDI) = 1.12, degree of polymerization (DP) 20) and an amine- functional crown ether in the coupling procedure (Figure 1). The reductive amination still proceeded smoothly using the same protocol and the first amino acid was coupled in high yield to the crown-ether modified resin (entry 28). The coupling of the first amino acid to the polystyrene-modified resin was more difficult and resulted in a lower yield (entry 27). The next seven amino acids in the GANPNAAG sequence were efficiently coupled to both resins, and the N-termini were modified either with a polystyrene chain (3.8 kg/mol, PDI = 1.04, DP 35) or another crown ether, forming a giant bio- hybrid amphiphile [3] or a peptide switch, respectively. Both the peptides were characterized with NMR and MALDI-TOF. From the results it is clear that sterically demanding primary amines can be coupled successfully to the aldehyde resin using a single protocol and one peptide coupling strategy.
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Developing Peptide Based Capture Agents for Diagnostics and Therapeutics

Developing Peptide Based Capture Agents for Diagnostics and Therapeutics

In this work we evaluate the effect of branching a linear peptide ligand starting with the same weak binding monoligand peptide arm. Two approaches are described. One involves replacing an amino acid in the isolated linear biligand with an amino acid of similar hydrophobicity, to make the biligand branched. The protein, in presence of this branched biligand searches for a third linear peptide arm. The resulting triligands developed are branched. The developed triligands ligands 45, 46 and 47 have either similar or lower limits of detection than the linear triligand previously developed. The other strategy involves using an OBOC peptide library with random number and position of the branching amino acid azidolysine to find the natural preference of the protein binding in presence of the weak monoligand peptide. Using focused libraries, this pattern is further resolved as wX(Az4)xw or vX(Az4)Xw. The protein in presence of this branched biligand anchor is screened against a linear peptide library to find triligand binders. Of the four ligands isolated though the screens, two triligand arms are found to have a pattern of hdtXX. However despite the high homology of the triligand sequences, their limit of detection are higher than the other branched triligands using the semi quantitative dot blot method. The ligands are also used as capture agents in an ELISA platform. The ELISA assays show the same trend as the dot blots, with branched triligands 46 and 47 having ~3 times higher affinity than the linear triligand 44.
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Molecular Docking and Synthesis of Some Substituted Sulphonylurea/Pyrrolidine  Based Derivatives as Hypoglycemic Agents

Molecular Docking and Synthesis of Some Substituted Sulphonylurea/Pyrrolidine Based Derivatives as Hypoglycemic Agents

The 4th position of derivatives substituted with F and NO2, which was shown better result compare to unsubstituted or substituted with other derivatives. Subsequently, in vivo biological evaluation compound 5B (F), 5G (NO2)and 5I (F) containing electron withdrawing groups which give more % reduction of blood sugar level with compare to glibenclamide. Finally, it was concluded that results obtained from in vitro docking analysis and in vivo biological activity on rat are significantly same and the compound 5B, 5G and 5I can be used as lead molecule for further development of more potent sulphonylureas /guanidine based derivatives as oral hypoglycemic agents.
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