Biomembranes are important targets in molecular design. Our laboratory has been exploring the design of functional peptides that modulate membrane barrier function, lipid packing, and structure. Evaluation of the results obtained and analyses of cellular mechanisms have yielded peptides with more refined designs and functions. This review highlights the progress made in our laboratory towards the development of unique peptides that modulate membrane properties.

The coumarin skeleton has been a focus of attention for many years, and its fluorescence properties vary depending on the substituents. Fluorescent coumarin derivatives are useful tools for many strategies have been developed for their synthesis. Although 7-diethylaminocoumarin has excellent fluorescence properties, it is unstable. We have developed a facile strategy for the synthesis of 7-diethylaminocoumarin derivatives by increasing the electrophilicity of the ynone moiety to promote nucleophilic addition reactions and cyclization. The reaction tolerates a variety of substitutions at the 4-position.

Preservatives in eye drops have always been the focus of people’s attention. Benzalkonium chloride (BAC) is one of the most frequently used bacteriostatic agents in eye drops, which has broad-spectrum and efficient bactericidal ability. However, the inappropriate dosage of BAC may lead to high cytotoxicity. Therefore, adding low-toxic hydroxypropyltrimethyl ammonium chloride chitosan (HACC) can not only achieve antimicrobial effect, but also have the advantages of moisturizing and biocompatibility. In this paper, the minimum inhibitory concentrations (MICs) of HACC and BAC were evaluated against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Diphtheroid bacillus and Candida albicans. Based on the MIC of each antimicrobial agent, an antimicrobial assay was performed to investigate the antimicrobial ability of disinfectant solution. Besides, cytotoxicity had also been assessed. When the HACC/BAC solution at weight ratio of 150/1 showed a highest antimicrobial efficiency and the cell proliferation rates were the highest in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Furthermore, the cell leakage was examined by UV absorption, indicating the great synergistic antimicrobial effect between HACC and BAC. What is more, the results of micromorphology research suggested that as the result of repulsive force between the two molecules, the average particle size of HACC would decrease. Finally, the impedance experiment showed that with the addition of BAC, current density would increase significantly, suggesting that more positive charge group was exposed to aqueous solution, leading the the increase of antimicrobial ability. Based on these results, HACC–BAC combination solution might be a promising novel antimicrobial group for biomedical applications.

Poly(ADP-ribose)polymerase (PARP) is a significant therapeutic target for the treatment of numerous human diseases. Olaparib has been approved as a PARP inhibitor. In this paper, a series of new compounds were designed and synthesized with Olaparib as the lead compound. In order to evaluate the inhibitory activities against PARP1 of the synthesized compounds, in vitro PARP1 inhibition assay and intracellular PARylation assay were conducted. The results showed that the inhibitory activities of the derivatives were related to the type of substituent and the length of alkyl chain connecting the aromatic ring. 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT)-based assay also proved that these compounds demonstrating strong inhibition to PARP1 also have high anti-proliferative activities against BRCA2-deficient cell line (Capan-1). Analysis of the entire results suggest that compound 23 with desirable inhibitory efficiency may hold promise for further in vivo exploration of PARP inhibition.

Recently, quantitative NMR (qNMR), especially ¹H-qNMR, has been widely used to determine the absolute quantitative value of organic molecules. We previously reported an optimal and reproducible sample preparation method for ¹H-qNMR. In the present study, we focused on a ³¹P-qNMR absolute determination method. An organophosphorus compound, cyclophosphamide hydrate (CP), listed in the Japanese Pharmacopeia 17th edition was selected as the target compound, and the ³¹P-qNMR and ¹H-qNMR results were compared under three conditions with potassium dihydrogen phosphate (KH₂PO₄) or O-phosphorylethanolamine (PEA) as the reference standard for ³¹P-qNMR and sodium 4,4-dimethyl-4-silapentanesulfonate-d₆ (DSS-d₆) as the standard for ¹H-qNMR. Condition 1: separate sample containing CP and KH₂PO₄ for ³¹P-qNMR or CP and DSS-d₆ for ¹H-qNMR. Condition 2: mixed sample containing CP, DSS-d₆, and KH₂PO₄. Condition 3: mixed sample containing CP, DSS-d₆, and PEA. As conditions 1 and 3 provided good results, validation studies at multiple laboratories were further conducted. The purities of CP determined under condition 1 by ¹H-qNMR at 11 laboratories and ³¹P-qNMR at 10 laboratories were 99.76 ± 0.43 and 99.75 ± 0.53%, respectively, and those determined under condition 3 at five laboratories were 99.66 ± 0.08 and 99.61 ± 0.53%, respectively. These data suggested that the CP purities determined by ³¹P-qNMR are in good agreement with those determined by the established ¹H-qNMR method. Since the ³¹P-qNMR signals are less complicated than the ¹H-qNMR signals, ³¹P-qNMR would be useful for the absolute quantification of compounds that do not have a simple and separate ¹H-qNMR signal, such as a singlet or doublet, although further investigation with other compounds is needed.

The purpose of the present study was to evaluate whether iontophoresis (IP) accelerates the intradermal migration rate of medium molecular weight drugs. Sodium polystyrene sulfonate (PSA) and fluorescein isothiocyanate-dextran (FD) were used as model medium molecular weight acidic and non-electrolyte drugs, respectively. Low molecular weight acid and non-electrolyte drugs were also used for comparison. Drug-loaded excised split-layered skin (SL skin) was used in the experiment. SL skin was prepared using (i) whole skin was split once, (ii) the drug solution was applied on the lower skin, and (iii) the upper skin was layered onto the lower skin containing the drug solution as in the original skin. The effect of constant-current cathodal or anodal IP was applied to the SL skin, and the time course of the cumulative amount of drug migration from the SL skin through the dermis to the receiver was followed. In cases without IP and with anodal IP, the intradermal migration rates of medium molecular weight drugs were much lower than those of small molecules. The driving force for drug migration was thought to be simple diffusion through the skin layer. In contrast, cathodal IP significantly increased the intradermal migration rate of PSA not but of FD or low molecular weight drugs. This IP-facilitated migration of PSA was probably due to electrorepulsion. These results suggest that IP can be used to increase the intradermal migration of medium molecular weight charged drugs.

With the aim of studying the pharmacokinetics of letermovir, which is a newly developed antiviral agent for human cytomegalovirus, a rapid and simple ultra-performance liquid chromatography coupled with mass spectrometry (UPLC/MS) method was developed and validated for the quantification of letermovir in human plasma. Separation was performed in reverse phase mode using an ACQUITY UPLC BEH C18 column (130 Å, 1.7 µm, 2.1 × 50 mm) at a flow rate of 0.3 mL/min, 10 mM ammonium acetate–0.1% formic acid solution as mobile phase A, and acetonitrile as mobile phase B with a gradient elution. The method was validated over a linear range of 10–1000 ng/mL with a coefficient of determination (R²) >0.99 using weighted linear regression analysis. The intra- and inter-assay accuracy (nominal%) and precision (relative standard deviation%) were within ±15 and ≤15%, respectively. The specificity, recovery, matrix effect, stability, and dilution integrity of this method were also within acceptable limits. This method could be useful in studying the pharmacokinetics and pharmacodynamics, as well as performing the therapeutic drug monitoring of letermovir.

The hydrocarbon-chain packing structure of intercellular lipids in the stratum corneum (SC) is critical to the skin’s barrier function. We previously found that formation of V-shaped ceramide reduces the barrier function of skin. There are few agents, apart from ceramides and fatty acids that can improve the orthorhombic packing (Orth) ratio of the intercellular lipid packing structure. In this study, we investigated agents that directly increase the Orth ratio. We selected an intercellular lipid model consisting of ceramide, cholesterol, and palmitic acid and performed differential scanning calorimetry. We focused on natural moisturizing factor components in the SC, and therefore investigated amino acids and their derivatives. The results of our intercellular lipid model-based study indicate that N-acetyl-L-hydroxyproline (AHYP), remarkably, maintains the lamellar structure. We verified the effect of AHYP on the lamellar structure and hydrocarbon chain packing structure of intercellular lipids using time-resolved X-ray diffraction measurements of human SC. We also determined the direct physicochemical effects of AHYP on the Orth ratio of the hydrocarbon-chain packing structure. Hence, the results of our human SC study suggest that AHYP preserves skin barrier function by maintaining the hydrocarbon-chain packing structure of intercellular lipids via electrostatic repulsion. These findings will facilitate the development of skincare formulation that can maintain the skin’s barrier function.

In this study, based on our previous study, derivatives of naphtho[2,3-b]furan-4,9-diones were synthesized and their antimicrobial activities were evaluated. The screening of these naphthoquinones revealed that the fluorine-containing NQ008 compound exhibited potent and broad antimicrobial activities against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA), Gram-negative bacteria, and fungi. The results of the ratio of the minimum bactericidal concentration (MBC) to the minimum inhibitory concentrations (MICs) and time–kill assays suggest that the mode of action of NQ008 is bactericidal. Additionally, the results of a drug resistance study revealed that NQ008 exhibited potent antibacterial activity and may delay the development of bacteria resistance. Furthermore, NQ008 exhibited preliminary antiviral activity against the swine influenza virus and Feline calicivirus.

Quality by design (QbD) is an essential concept for modern manufacturing processes of pharmaceutical products. Understanding the science behind manufacturing processes is crucial; however, the complexity of the manufacturing processes makes implementing QbD challenging. In this study, structural equation modeling (SEM) was applied to understand the causal relationships between variables such as process parameters, material attributes, and quality attributes. Based on SEM analysis, we identified a model composed of the above-mentioned variables and their latent factors without including observational data. Difficulties in fitting the observed data to the proposed model are often encountered in SEM analysis. To address this issue, we adopted Bayesian estimation with Markov chain Monte Carlo simulation. The tableting process involving the wet-granulation process for acetaminophen was employed as a model case for the manufacturing process. The results indicate that SEM analysis could be useful for implementing QbD for the manufacturing processes of pharmaceutical products.

Protein–protein interactions (PPIs) are often mediated by helical, strand and/or coil secondary structures at the interface regions. We previously showed that non-naturally occurring, stable helical trimers of bicyclic β-amino acids (Abh) with all-trans amide bonds can block the p53–MDM2/MDMX α-helix–helix interaction, which plays a role in regulating p53 function. Here, we conducted docking and molecular dynamics calculations to guide the structural optimization of our reported compounds, focusing on modifications of the C-terminal/N-terminal residues. We confirmed that the modified peptides directly bind to MDM2 by means of thermal shift assay, isothermal titration calorimetry, and enzyme-linked immunosorbent assay (ELISA) experiments. Biological activity assay in human osteosarcoma cell line SJSA-1, which has wild-type p53 and amplification of the Mdm2 gene, indicated that these peptides are membrane-permeable p53–MDM2/MDMX interaction antagonists that can rescue p53 function in the cells.

One-step mid- and far-Fourier-transform (FT)-IR spectroscopy is a facile and powerful tool that provides various information regarding chemical and crystal states. However, its potentially high applicability has not been sufficiently demonstrated. In the present study, ibuprofen (IB)-loaded MgO samples are prepared via different methods, and they are evaluated using scanning electron microscopy (SEM), thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction analysis (XRD), N₂ adsorption-desorption measurement, CO₂ temperature-programmed desorption technique (CO₂-TPD), and FT-IR spectroscopy. The obtained results indicate that IB becomes ionized, amorphous, and/or dispersed by using MgO. Since the CO₂-TPD result shows that MgO possesses basic surfaces, it is considerable that acid–base interactions cause the above different chemical states. Furthermore, the FT-IR spectra in mid- and far-IR regions also suggest that the above physical and chemical properties of IB-loaded MgO changes through the interactions. Therefore, the characterization results suggest that one-step mid- and far-FT-IR measurements can provide valuable information regarding the chemical and crystal states.

By employing a silica-coated magnetite as a catalyst, a silica-catalyzed carboxylative cyclization of propargylic amines with carbon dioxide (CO₂) proceeded to afford the corresponding 2-oxazolidinones. Moreover, after the reaction, the silica-coated magnetic catalyst was readily recovered by use of an external magnet and could be reused up to six times without deactivation.

A new brominated pyrrolactam stylissaol A (1) together with four known analogues, 2-bromoaldisine, aldisine, spongiacidin D, and Z-hymenialdisine, were isolated from the EtOAc extract of marine sponge Stylissa massa collected in Myanmar. The absolute configuration at C-10 of 1 was determined as R by the electronic circular dichroism (ECD) data. Among the isolated compounds, 2-bromoaldisine showed anti-Viral Protein R (Vpr) activity against TREx-HeLa-Vpr cells with an effective dose of 10 µM and its potency was comparable to that of positive control damnacanthal.