Construction of 3D models of the CYP11B family as a tool to predict ligand binding characteristics

Aldosterone is synthesised by aldosterone synthase (CYP11B2). CYP11B2 has a highly homologous isoform, steroid 11β-hydroxylase (CYP11B1), which is responsible for the biosynthesis of aldosterone precursors and glucocorticoids. To investigate aldosterone biosynthesis and facilitate the search for selective CYP11B2 inhibitors, we constructed three-dimensional models for CYP11B1 and CYP11B2 for both human and rat. The models were constructed based on the crystal structure of Pseudomonas Putida CYP101 and Oryctolagus Cuniculus CYP2C5. Small steric active site differences between the isoforms were found to be the most important determinants for the regioselective steroid synthesis. A possible explanation for these steric differences for the selective synthesis of aldosterone by CYP11B2 is presented. The activities of the known CYP11B inhibitors metyrapone, R-etomidate, R-fadrazole and S-fadrazole were determined using assays of V79MZ cells that express human CYP11B1 and CYP11B2, respectively. By investigating the inhibitors in the human CYP11B models using molecular docking and molecular dynamics simulations we were able to predict a similar trend in potency for the inhibitors as found in the in vitro assays. Importantly, based on the docking and dynamics simulations it is possible to understand the enantioselectivity of the human enzymes for the inhibitor fadrazole, the R-enantiomer being selective for CYP11B2 and the S-enantiomer being selective for CYP11B1

Photo-substitution reactions of perylene red dyes

Irradiation of Lumogen Red 305 (3) in ethyl acetate with intense blue LED light led to very slow bleaching, showing a high photochemical stability. However, irradiation in ethanol led to the formation of a low yield product in which one of the phenoxy groups is substituted by an acetoxy group, the oxidized form of an ethoxy group. This reaction product was only formed in the presence of blue light and oxygen. Adding a small amount of acetic acid to the solutions resulted in a much higher yield of the product, indicating a possible photo oxidation of ethanol to acetic acid during the process in this solvent. A similar dye (5) containing less phenoxy side groups than Lumogen Red 305 showed the same reaction although the product formed showed lower chemical stability. The photo-substitution of phenoxy groups by acetoxy groups is a new reaction. The results are used to discuss the structural effects on the stability of these type of fluorescent dyes under irradiation conditions, potential reaction mechanisms and the possibility of using the photochemical transformations for preparative purposes

Photo-substitution reactions of perylene red dyes

\u3cp\u3eIrradiation of Lumogen Red 305 (3) in ethyl acetate with intense blue LED light led to very slow bleaching, showing a high photochemical stability. However, irradiation in ethanol led to the formation of a low yield product in which one of the phenoxy groups is substituted by an acetoxy group, the oxidized form of an ethoxy group. This reaction product was only formed in the presence of blue light and oxygen. Adding a small amount of acetic acid to the solutions resulted in a much higher yield of the product, indicating a possible photo oxidation of ethanol to acetic acid during the process in this solvent. A similar dye (5) containing less phenoxy side groups than Lumogen Red 305 showed the same reaction although the product formed showed lower chemical stability. The photo-substitution of phenoxy groups by acetoxy groups is a new reaction. The results are used to discuss the structural effects on the stability of these type of fluorescent dyes under irradiation conditions, potential reaction mechanisms and the possibility of using the photochemical transformations for preparative purposes.\u3c/p\u3

Automated synthesis of [18F]gefitinib on a modular system

In recent years, [18F]gefitinib PET has successfully been employed for a number of applications ranging from oncology to in vivo studies of drug transporter proteins. We here report a reliable, automated procedure for routine synthesis of this radiotracer on an Eckert and Ziegler modular system. The 3-step radiosynthesis followed by preparative HPLC-purification provided [18F]gefitinib in 17.2±3.3% (n=22) overall decay-corrected radiochemical yield with radiochemical purity >99% in a total synthesis time of about 2.5h

Lipid bilayer carrier for drugs or imaging agents

\u3cp\u3eDisclosed are carriers for drugs and/or MR imaging agents having a lipid bilayer shell comprising a phospholipid having two terminal alkyl chains, one being a short chain having a chain length of at most seven carbon atoms, the other being a long chain having a chain length of at least fifteen carbon atoms. The mixed long/short chain phospholipids serve to tune the release properties of the carrier. Preferred phospholipids are phosphatidylcholines.\u3c/p\u3

Chelating amphiphilic polymers

\u3cp\u3eDescribed are amphiphilic polymers that are provided with chelating moieties. The amphiphilic polymers are block copolymers comprising a hydrophilic block and a hydrophobic block, with the chelating moieties linked to the end-group of the hydrophilic block. The disclosed polymers are capable of self-assembly into structures such as micelles and polymersomes. With suitable metals present in the form of coordination complexes with 5 the chelating moieties, the chelating amphiphilic polymers of the invention are suitable for use in various imaging techniques requiring metal labeling, such as MRI (T 1 /T 2 weighted contrast agents or CEST contrast agents) SPECT, PET or Spectral CT.\u3c/p\u3

Chelating amphiphilic polymers

\u3cp\u3eDescribed are amphiphilic polymers that are provided with chelating moieties. The amphiphilic polymers are block copolymers comprising a hydrophilic block and a hydrophobic block, with the chelating moieties linked to the end-group of the hydrophilic block. The disclosed polymers are capable of self-assembly into structures such as micelles and polymersomes. With suitable metals present in the form of coordination complexes with 5 the chelating moieties, the chelating amphiphilic polymers of the invention are suitable for use in various imaging techniques requiring metal labeling, such as MRI (T 1/T 2 weighted contrast agents or CEST contrast agents) SPECT, PET or Spectral CT.\u3c/p\u3

Lipid bilayer carrier for drugs or imaging agents

\u3cp\u3eDisclosed are carriers for drugs and/or MR imaging agents having a lipid bilayer shell comprising a phospholipid having two terminal alkyl chains, one being a short chain having a chain length of at most seven carbon atoms, the other being a long chain having a chain length of at least fifteen carbon atoms. The mixed long/short chain phospholipids serve to tune the release properties of the carrier. Preferred phospholipids are phosphatidylcholines.\u3c/p\u3

Block-copolymer-stabilized iodinated emulsions for use as CT contrast agents

The objective of this study was to develop radiopaque iodinated emulsions for use as CT blood pool contrast agents. Three hydrophobic iodinated oils were synthesized based on the 2,3,5-triiodobenzoate moiety and formulated into emulsions using either phospholipids or amphiphilic polymers, i.e. Pluronic F68 and poly(butadiene)-b-poly(ethylene glycol) (PBD-PEO), as emulsifiers. The size, stability and cell viability was investigated for all stabilized emulsions. Three emulsions stabilized with either lipids or PBD-PEO were subsequently tested in vivo as a CT blood pool contrast agent in mice. While the lipid-stabilized emulsions turned out unstable in vivo, polymer-stabilized emulsions performed well in vivo. In blood, a contrast enhancement of 220 Hounsfield Units (HU) was measured directly after intravenous administration of 520 mg I/kg. The blood circulation half-life of a PBD-PEO stabilized emulsion was approximately 3 h and no noticeable in vivo toxicity was observed. These results show the potential of above emulsions for use as blood pool agents in contrast enhanced CT imaging

Evaluation of Iron Oxide Nanoparticle Micelles for Magnetic Particle Imaging (MPI) of Thrombosis

Magnetic particle imaging (MPI) is an emerging medical imaging modality that directly visualizes magnetic particles in a hot-spot like fashion. We recently developed an iron oxide nanoparticle-micelle (ION-Micelle) platform that allows highly sensitive MPI. The goal of this study was to assess the potential of the ION-Micelles for MPI-based detection of thrombi. To this aim, an in vivo carotid artery thrombosis mouse model was employed and ex vivo magnetic particle spectrometer (MPS) measurements of the carotid arteries were performed. In addition, we studied the effect of functionalization of the ION-Micelle nanoplatform with fibrin-binding peptides (FibPeps) with respect to nanoparticle thrombus uptake and hence thrombus detection. In vivo quantitative MR imaging pre- and post-ION-Micelle injection was performed as reference for visualization of ION-micelle uptake. ION-Micelles significantly decreased T2 values in the thrombi with respect to pre-injection T2 values (p < 0.01) and significantly increased ex vivo MPS thrombus signal with respect to the noninjured, contralateral carotid (p < 0.01). Functionalization of the ION-Micelles with the FibPep peptides did not result in an increased MPS thrombus signal with respect to the non-fibrin binding ION-Micelles. The lack of a significant increased thrombus uptake for the FibPep-ION-Micelles indicates that (non-fibrin-specific) entrapment of nanoparticles in the mesh-like thrombi is the key contributor to thrombus nanoparticle uptake. Therefore, (nontargeted) ION-Micelles might be of value for noninvasive MPI-based diagnosis, characterization and treatment monitoring of thrombosis