Masayori Hagimori

Synthesis, solid-state fluorescence properties, and computational analysis of novel 2-aminobenzo[4,5]thieno[3,2-d]pyrimidine 5,5-dioxides

Summary New fluorescent compounds, benzo[4,5]thieno[3,2-d]pyrimidine 5,5-dioxides (3a–g), 2-amino-4-methylsulfanylbenzo[4,5]thieno[3,2-d]pyrimidine (6), and 2-amino-4-methylsulfanyl-7-methoxybenzo[4,5]furo[3,2-d]pyrimidine (7), were synthesized in good yields from heterocyclic ketene dithioacetals (1a–c) and guanidine carbonate (2a) or (S)-methylisothiourea sulfate (2b) in pyridine under reflux. Among the fused pyrimidine derivatives, compound 3c, which has an amino group at the 2-position and a benzylamino group at the 4-position of the pyrimidine ring, showed the strongest solid-state fluorescence. The absorption and emission properties of the compounds were quantitatively reproduced by a series of ab initio quantum-chemical calculations.

Ligand peptide-grafted PEGylated liposomes using HER2 targeted peptide-lipid derivatives for targeted delivery in breast cancer cells: The effect of serine-glycine repeated peptides as a spacer

Ligand peptide-grafted PEGylated liposomes have been widely studied for targeted drug delivery systems. Because ligand peptides are commonly grafted using PEG as a spacer on the surface of PEGylated liposomes, the interaction between ligand peptides and their corresponding receptors can be interrupted by steric hindrance of the PEG layer. Therefore, we aimed to develop ligand peptide-lipid derivatives to enhance the targeting efficiency of ligand peptide-grafted PEGylated liposomes, and designed a new ligand peptide-lipid derivatives having serine-glycine repeats (SG)n as a spacer based on the peptide length calculated by PyMol (v0.99). We selected KCCYSL (KCC) as the ligand peptide for binding to human epidermal growth factor receptor-2 (HER2). We synthesized new KCC-(SG)n-lipid derivatives (n=3, 5, 7) and evaluated their cellular association in breast cancer cells. KCC-(SG)n/PEGylated liposomes dramatically increased cellular association on HER2-positive breast cancer cells. The results suggest that KCC can be grafted on the surface of KCC-(SG)n/PEGylated liposomes prepared from KCC-(SG)n-lipid derivatives (n=3, 5, 7). In summary, we succeeded in developing KCC-(SG)n-lipid derivatives for the preparation of ligand peptide-grafted PEGylated liposomes.

Effective intraperitoneal gene transfection system using nanobubbles and ultrasound irradiation

Abstract In this study, we demonstrate the low toxicity and highly efficient and spatially improved transfection of plasmid DNA (pDNA) with liposomal nanobubbles (bubble liposomes [BLs]) using ultrasound (US) irradiation in mice. Naked pDNA with BLs was intraperitoneally injected, followed by US irradiation. The injection volume, the duration of US irradiation, and the dose of BLs were optimized. Both BLs and US irradiation were essential to achieve high transgene expression from naked pDNA. We observed transgene expression in the entire peritoneal tissues, including the peritoneal wall, liver, spleen, stomach and small and large intestines. The area of transfection could be controlled with focused US irradiation. There were few changes in the morphology of the peritoneum, the peritoneal function or serum alanine aminotransferase levels, suggesting the safety of BLs with US irradiation. Using a tissue-clearing method, the spatial distribution of transgene expression was evaluated. BLs with US irradiation delivered pDNA to the submesothelial layer in the peritoneal wall, whereas transgene expression was restricted to the surface layer in the liver and stomach. Therefore, BLs with US irradiation could be an effective and safe method of gene transfection to the peritoneum.

Peptide-Based Cancer-Targeted DDS and Molecular Imaging

Targeting cancer cell-surface receptors is an attractive approach for cancer treatment and diagnosis. Peptides having high binding affinities to receptors overexpressed in cancer cells are useful because of their simple structure, low immunogenicity, and easy, cost-effective chemical synthesis. A number of peptide ligands have been developed for cancer cell-surface receptors and applied to nanoparticles with anticancer drugs, genes, small interfering RNAs (siRNAs), and molecular imaging agents. In particular, recent findings have revealed that peptide-modified PEGylated liposome-encapsulated drugs are effective in cancer-targeted therapy and cancer cell-specific imaging. This review discusses peptide-modified nanoparticles for drug delivery systems (DDS) and molecular imaging, focusing on peptide ligands for somatostatin receptors, integrin, transferrin receptor, human epidermal growth factor 2 (HER2), etc. In addition, methods to improve binding affinity or endosomal escape with spacer peptides and stimuli (internal and external) are discussed.

Synthesis of Quinolizino[3,2-a]quinolizine Derivatives and Their Fluorescence

Polycyclic quinolizine derivatives, quinolizino[3,2-a]quinolizines (4a-c), were synthesized in moderate yields by a one-pot method using ketene dithioacetal, methyl bis(methylsulfanyl)methylene-cyanoacetate (2), alkyl 2-pyridylacetates (1a, b), and 2-pyridylacetonitrile (1c). Compounds 4a, b exhibited red fluorescence (Em max: 576 nm) in solid state.

One-Pot Synthesis of 6-Substituted Amino-2,4-diaminopyrimidine Derivatives Using Ketene Dithioacetals with Amines and Guanidine Carbonate

6-Substituted amino-2,4-diaminopyrimidine derivatives were prepared by one-pot synthesis using ketene dithioacetals, amine compounds, and guanidine carbonate in pyridine. These pyrimidine products displayed blue fluorescence in the solid state.

An Activatable Fluorescent γ-Polyglutamic Acid Complex for Sentinel Lymph Node Imaging

Sentinel lymph nodes (SLN) are the first lymph nodes (LN) where cancer cells metastasize from the primary tumor. We designed fluorophore-quencher-based activatable nanoparticles for SLN imaging. We selected TAMRA as a fluorophore and BHQ2 or QSY7 as a quencher. Ternary anionic complexes were constructed with generation 4th polyamidoamine dendrimer (G4) modified with TAMRA and p-SCN-Bn-DTPA (DTPA), polyethyleneimine (PEI) modified with BHQ2 or QSY7, and γ-polyglutamic acid (γ-PGA) by the electrostatic self-assembly system. TAMRA-G4-DTPA/PEI-BHQ2/γ-PGA and TAMRA-G4-DTPA/PEI-QSY7/γ-PGA complexes had a particle size of about 40 nm and a ζ-potential of -50 mV, and showed fluorescence resonance energy transfer (FRET) quenching. Fluorescence microscopy studies demonstrated that TAMRA-G4-DTPA/PEI-QSY7/γ-PGA complex produced intracellular fluorescent signals in the lysosome. During in vivo fluorescent imaging, TAMRA-G4-DTPA/PEI-QSY7/γ-PGA complex enabled the detection of mouse popliteal LN. The fluorophore-quencher conjugated γ-PGA complex based on FRET quenching would be useful for fluorescence-based optical imaging of SLN.

Effect of pH and Additives on the Compatibility between Vancomycin and Furosemide Injections

　The physicochemical compatibility between injections of different agents is very important. An injection of the antibiotic vancomycin (VCM) is acidic and its standard pH range is 2.5-4.5. In clinical treatments, VCM injections are often used with Lasix® (furosemide) injections. The Lasix® injection is alkaline and its standard pH range is 8.6-9.6. Therefore, mixing VCM injections with Lasix® injections may cause compatibility problems. We evaluated the effect of pH on the compatibility between VCM (original and two generic) and Lasix® injections. Compatibility was not observed in non-pH-adjusted VCM with Lasix® injections, but white crystals appeared when VCM injections adjusted to pH 2.5 experimentally were mixed with a Lasix® injection, suggesting that the acidic condition of VCM injections cause compatibility. However, the residual rates of VCM did not change after 24 h in all mixtures. We analyzed the crystals by mass spectrometry and 1H-NMR, and identified them to comprise furosemide.

Development of High-Functionality and -Quality Lipids with RGD Peptide Ligands: Application for PEGylated Liposomes and Analysis of Intratumoral Distribution in a Murine Colon Cancer Model

High-functionality and -quality (HFQ) lipids have a discrete molecular weight and good water dispersibility and can be produced by solid-phase peptide synthesis. Therefore, HFQ lipids are a promising material for the preparation of ligand-grafted PEGylated liposomes. Recently, we have reported serine-glycine repeated peptides ((SG) n) as a spacer of HFQ lipids and to substitute a conventional PEG spacer. We demonstrated the advantage of using (SG) n spacers for peptide ligand presentation on the liposomal surface in vitro; however, the use of (SG) n spacers in ligand-grafted PEGylated liposomes in vivo has not been validated. The aim of this study was to validate the in vivo targeting ability of HFQ lipid-grafted PEGylated liposomes. We synthesized lipids containing GRGDS (RGD-(SG) n-lipid) to target integrin αvβ3 and prepared RGD-(SG) n/PEGylated liposomes. Subsequently, their cellular uptake characteristics in murine colon carcinoma (Colon-26) cells were evaluated. Two-color imaging of liposomes and tumor blood vessels following tissue clearing was performed to examine the spatial intratumoral distribution of liposomes. RGD-(SG)5/PEGylated liposomes were selectively associated with the cells in vitro. In vivo analysis of intratumoral distribution following tissue clearing revealed the superior targeting ability of RGD-(SG)5/PEGylated liposomes compared with that of conventional RGD-PEG2000/PEGylated liposomes for both tumor tissues and tumor blood vessels. We successfully synthesized RGD-HFQ lipids to prepare RGD-grafted PEGylated liposomes for the efficient targeting of integrin αvβ3-expressing cells. To the best of our knowledge, this is the first report of the intratumoral distribution of ligand-grafted PEGylated liposomes by two-color imaging following tissue clearing.

Efficient gene transfection to the brain with ultrasound irradiation in mice using stabilized bubble lipopolyplexes prepared by the surface charge regulation method

Introduction We previously developed anionic ternary bubble lipopolyplexes, an ultrasound-responsive carrier, expecting safe and efficient gene transfection. However, bubble lipopolyplexes have a low capacity for echo gas (C3F8) encapsulation (EGE) in nonionic solution such as 5% glucose. On the other hand, we were able to prepare bubble lipopolyplexes by inserting phosphate-buffered saline before C3F8 encapsulation. Surface charge regulation (SCR) by electrolytes stabilizes liposome/plasmid DNA (pDNA) complexes by accelerated membrane fusion. Considering these facts, we hypothesized that SCR by electrolytes such as NaCl would promote C3F8 encapsulation in bubble lipopolyplexes mediated by accelerated membrane fusion. We defined this hypothesis as SCR-based EGE (SCR-EGE). Bubble lipopolyplexes prepared by the SCR-EGE method (SCR-EGE bubble lipopolyplexes) are expected to facilitate the gene transfection because of the high amount of C3F8. Therefore, we applied these methods for gene delivery to the brain and evaluated the characteristics of transgene expression in the brain. Methods First, we measured the encapsulation efficiency of C3F8 in SCR-EGE bubble lipopolyplexes. Next, we applied these bubble lipopolyplexes to the mouse brain; then, we evaluated the transfection efficiency. Furthermore, three-dimensional transgene distribution was observed using multicolor deep imaging. Results SCR-EGE bubble lipopolyplexes had a higher C3F8 content than conventional bubble lipopolyplexes. In terms of safety, SCR-EGE bubble lipopolyplexes possessed an anionic potential and showed no aggregation with erythrocytes. After applying SCR-EGE bubble lipopolyplexes to the brain, high transgene expression was observed by combining with ultrasound irradiation. As a result, transgene expression mediated by SCR-EGE bubble lipopolyplexes was observed mainly on blood vessels and partially outside of blood vessels. Conclusion The SCR-EGE method may promote C3F8 encapsulation in bubble lipopolyplexes, and SCR-EGE bubble lipopolyplexes may be potent carriers for efficient and safe gene transfection in the brain, especially to the blood vessels.