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Structural transformation changes the activity of biological reactions. Neurotransmitter aralkylamines, such as phenethylamine, tyramine, dopamine, tryptamine, serotonin, and histamine, absorb aerial CO₂, and heteronuclear multiple bond connectivity (HMBC) correlations between the carbon derived from CO₂ and the α-hydrogen of the several amines were confirmed in the D₂O solution. The isolation of methyl carbamate from phenethylamine and CO₂ in water with TMSCHN₂ also supported the formation of covalently bound carbamic acid in the amine aqueous solution containing CO₂. Therefore, it is suggested that CO₂ produced in the body would react with neurotransmitter amines to form covalently bound carbamic acid, which might affect biological reactions.

Efficient cytosolic delivery of functional proteins such as therapeutic antibodies remains a major challenge in drug development. In this study, we sought to optimize the cytosolic delivery peptide Mel-V8G12, a melittin derivative, through structure-guided design and functional screening of its amino acid substitutions. Among seven derivatives, VG-6, featuring A10L, T11E, and S18K substitutions demonstrated superior cytosolic delivery efficiency compared with the parental Mel-V8G12, while maintaining low cytotoxicity. Notably, VG-6 exhibited enhanced membrane-lytic activity toward neutral lipid membranes, yet did not increase cellular toxicity, suggesting a delivery mechanism distinct from conventional pH-responsive endosomolytic peptides. Mechanistic studies revealed that, in contrast to Mel-V8G12 which predominantly utilizes actin-mediated endocytosis, VG-6 additionally engages caveolae-mediated endocytosis, contributing to its enhanced cytosolic delivery. Furthermore, VG-6 enabled successful cytosolic delivery of functional Cre recombinase and immunoglobulin G (IgG), facilitating biological activity and subcellular targeting. These findings suggest that VG-6 is a promising tool for intracellular delivery of protein therapeutics via a unique membrane-interacting and endocytic pathway.

The phytochemical investigation of the rainforest plant Croton argyratus (Euphorbiaceae) led to the isolation of two halimane-type diterpenes, crotargyolides A (1) and B (2), with an uncommon γ-lactone ring at C-5 and C-9, together with a crotofolane-type diterpene, 3-hydroxylated crotofolin C (3, crokocrotogenoid A), and the known clerodane diterpenes, junceic acid (4) and epoxyjunceic acid (5). The structures of the newly isolated compounds were elucidated by various NMR techniques, high resolution (HR)MS analysis, and electronic circular dichroism (ECD) spectroscopy. The proposed biosynthetic pathway of 1 from 4 was discussed. Crotargyolide A (1) and known compounds 4 and 5 were evaluated for antiproliferative activity and displayed no growth inhibitory effect toward all tested tumor cell lines.

5'-O-Triethylsilyl-2'-deoxy-5-azacytidine (5'-O-TesDAC) is a prodrug developed to counteract deamination by cytidine deaminase and spontaneous hydrolytic cleavage of the triazine ring. In this study, we have evaluated the physical properties of the crystal forms to determine the optimal crystal form for solid pharmaceutical development. Therefore, the crystalline morphology of 5'-O-TesDAC was assessed using terahertz spectroscopy, in addition to conventional methods (thermal analysis, powder X-ray diffraction, IR absorption spectroscopy and dynamic vapor sorption). Terahertz spectroscopy has the feature of being able to sensitively capture structural changes between lattices and molecules because the absorptions of the terahertz region correspond to those of skeletal vibrations, intermolecular vibrations, and/or lattice vibrations. For this reason, in the evaluation of crystal polymorphism, terahertz spectroscopy was considered to complement methods that have conventionally been used. Furthermore, the metastable state evaluated in this study rapidly transitions to hemihydrate at relative humidity (RH) above 10%, so it could not be measured using attenuated total reflectance-Fourier transform IR (ATR-FTIR), which is performed under atmosphere, whereas terahertz spectroscopy allowed measurements with the sample chamber exposed to dry air easily. The chemical stability was evaluated through a stability test that measured the amount of the main degradation product of each crystalline form using HPLC. As a result, four crystalline forms of 5'-O-TesDAC were identified. The characterization of 5'-O-TesDAC in this study provides valuable information for optimizing the manufacturing parameters of the formulation and selecting appropriate packaging materials for pharmaceutical development.

Silica powder is an essential pharmaceutical ingredient, which in some combinations with drugs, causes chemical instability of the drug adsorbed on it. NMR measurements have been used to determine the drug adsorption state; however, the relationship between drug chemical stability and NMR relaxation, one of the NMR processes, is yet to be thoroughly studied. This work investigated the relationship between the chemical stability of itraconazole (ITZ)-adsorbed silica and its NMR relaxation. NMR can specifically observe ¹H nuclei, and this feature was exploited to study only the T₁ relaxation of these nuclei in the drug, excluding the silica signal composed of Si and O. ITZ, a poorly water-soluble model drug, was physically adsorbed on nonporous silica (Aerosil 200, AER), and mesoporous silica (Sylysia 320), and the ¹H T₁ relaxation was measured before storage using the time domain (TD)-NMR technique. The amount of ITZ degradant adsorbed in the silicas was also measured after storage at humidified conditions. Then, the relationship between the degradant amount of ITZ-adsorbed silica after storage and the T₁ relaxation rate (1/T₁) before storage was investigated. The ITZ-adsorbed silicas showed a positive correlation between the degradant amount and the 1/T₁ value. ITZ-adsorbed AER showed a strong positive correlation (R² = 0.751). Thus, the 1/T₁ value may be an efficient parameter to determine the chemical stability of ITZ adsorbed on nonporous silica. The 1/T₁ value measurement by TD-NMR could provide new insight for evaluating the chemical stability of solid dosage forms containing silica.

N-Glycosylated RNA (glycoRNA) has been identified on the cell surface, and 3-(3-amino-3-carboxypropyl)uridine has been reported as a conjugation site of N-glycans on RNA. Although the association of glycoRNAs with various diseases has been reported, their biosynthetic mechanisms and biological roles remain unexplored. Here, we report the preparation of two species of N-glycan-conjugated 3-(3-amino-3-carboxypropyl)uridine as the minimal units of glycoRNA. Our synthesized glycoRNA unit would contribute to future biochemical research on glycoRNAs.

Veratridine is a neurotoxic compound classified into the cevanine group of the Veratrum alkaloids and is characterized by its highly functionalized hexacyclic structure. Here, we report the synthesis of the ABC-ring system of veratridine from a known cis-decalin. The cis-decalin was synthesized from 1,5-pentanediol by modification of a literature method. A site-selective acylation of the C3-hydroxy group with 3,4-dimethoxybenzoyl chloride, a chemo- and stereoselective (allyl)₂Zn-mediated C9-allylation, and ring closing metathesis were employed as key transformations to construct the ABC-ring system of veratridine.

Several approaches for synthesizing [1-¹³C]2-oxoglutaric acid were attempted, and the synthesis was successfully achieved in 4 steps from trimethylsilyl ¹³C-cyanide. The ¹³C-breath tests on rats were conducted by orally administering the newly synthesized [1-¹³C]2-oxoglutaric acid, the previously prepared [1'-¹³C]citric acid, and [1-¹³C]acetic acid as a control drug, and the results were compared. The results indicate that [1-¹³C]2-oxoglutaric acid and [1'-¹³C]citric acid may serve as potential substrates for assessing the TCA cycle flux.

Lipids, including fatty acids and phospholipids, play crucial roles in biological systems and are widely utilized in pharmaceutical and biomedical applications. However, their inherent hydrophobicity poses significant challenges for formulation and administration. In this study, we aimed to enhance the aqueous solubility of lipidic compounds by leveraging light-responsive molecular design. We synthesized azo-lipids by incorporating azobenzene units into a fatty acid and phosphatidylcholine, hypothesizing that light-induced trans-cis isomerization would improve solubility. The synthesized compounds exhibited reversible photoisomerization upon alternating UV (365 nm) and visible light irradiation, as confirmed by UV-vis spectroscopy and reverse-phase HPLC. The solubilization of these azo-lipids was quantified under UV-unirradiated and irradiated conditions. Azobenzene-incorporated phosphatidylcholine 2 exhibited a drastic increase in solubilization from 2.030 to 1008 µM (496-fold) after UV irradiation. This significant improvement was attributed to efficient photoisomerization and molecular bending in the cis, cis conformation, reducing intermolecular interactions. Our findings suggest that this on-demand aqueous solubilization strategy offers a novel approach for improving the handling, storage, and potential therapeutic administration of lipid-based compounds.

Despite the great strides in biopharmaceuticals and monoclonal antibodies today, natural products remain highly attractive as drug candidates. Therefore, building a library of natural products through total synthesis is critically important for drug discovery. This perspective article details the collective total synthesis of polycyclic natural products using "bioinspired reactions" that mimic natural product biosynthesis. It discusses the total syntheses of 20 natural products, including dimeric diketopiperazine alkaloids, monoterpenoid indole alkaloids, and iridoid glycosides, each achieved in fewer than 14 steps starting from commercially available materials.