Chemical & pharmaceutical bulletin最新文献

Four teleocidin analogs were isolated from Streptomyces eurocidicus, along with teleocidin B3. A combination of MS and NMR analyses elucidated their structures, revealing teleocidin A2 acetate and teleocidin B3 acetate as newly isolated metabolites. Teleocidins A2 and B3, known metabolites, exhibited weak antibacterial activities against Kocuria rhizophila and Bacillus subtilis. Notably, membrane vesicles of Burkholderia multivorans modulated the production levels of teleocidin analogs in S. eurocidicus, upregulating teleocidin biosynthesis but downregulating the subsequent acetylation step.

Site-selective conjugation on aryl azides is hampered by a fundamental trade-off: electron-withdrawing groups that promote the reaction often preclude further functionalization, while versatile electron-donating groups suppress reactivity. We report a strategy that resolves this by using an ortho-amido group to activate an electron-rich aryl azide via an intramolecular hydrogen bond. This non-covalent interaction renders the ortho-amidoaryl azide significantly more reactive than its para-isomer and even activated alkyl azides, although competition experiments revealed that steric hindrance presents a counteracting effect. The principle was successfully applied to achieve excellent site-selectivity in a diazide molecule, favoring reaction at the aryl position. Its utility was further demonstrated in a highly selective classical Staudinger-Bertozzi ligation. This work establishes the ortho-amido group as a powerful controlling element, offering a new click conjugation platform that enables ready functionalization.

Three new acylated glycosidic acid methyl esters and one known compound were isolated by treating the crude resin glycoside fraction derived from the seeds of Ipomoea lacunosa with indium(III) chloride in methanol, and their structures were elucidated using spectroscopic methods. The new compounds contained methyl 3S,11S-dihydroxytetradecanoate as the aglycone. Two were hexaglycosides and one was a nonaglycoside, with saccharide cores partially acylated by a glycosidic acid, 7S-hydroxydecanoic acid 7-O-β-d-quinovopyranoside (quamoclinic acid B), and/or organic acids, including isobutyric and 2S-methylbutyric acids. Furthermore, the cytotoxic activities of the isolated compounds against HL-60 human promyelocytic leukemia cells were evaluated, and they exhibited moderate activities.

We designed and synthesized an oligonucleotide acetylating reagent (Ac-probe) that selectively acetylates the 2'-OH groups of RNA upon forming a duplex with the target RNA. The Ac-probe can be readily prepared via a post-synthetic modification method using an oligodeoxynucleotide probe containing 4-thio-dT. During the acetylation reaction, 4-thio-dT is regenerated as the reaction proceeds. Notably, an efficient modification was observed when the complementary base of RNA to 4-thio-dT was cytosine or uracil, indicating the selectivity for the pyrimidine base.

Two new glycosides, named 3-methoxy-5-methylphenol-6-O-β-glucopyranosyl-(1→6)-β-glucopyranoside (compound 1) and 1-O-feruloyl-α-arabinofuranosyl-(1→6)-β-glucopyranoside (compound 2), were isolated from Asiasarum root, together with eight known compounds. Asiasarum root (crude drug name in Latin: ASIASARI RADIX) is well known for its anti-inflammation and antitussive properties and is commonly found in Kampo formula in Japan. The structures of new compounds 1 and 2 were characterized using one- and two-dimensional (1D and 2D) NMR spectroscopy and MS. In addition, the anti-glycation activity of the isolates was evaluated. Glycation is particularly advanced in patients with diabetes and is suspected to be associated with diabetic complications such as nephropathy, osteoporosis, and Alzheimer's disease. The inhibition of this reaction is thought to be linked to the prevention and treatment of these diseases. Compounds 2 (79.4%), 4 (82.4%), 5 (79.8%), 6 (86.5%), 7 (90.1%), 9 (61.4%), and 10 (82.2%) showed activities comparable to that of aminoguanidine (45.3%) used as a positive control.

Conventional peptide synthesis involves multiple protection and deprotection steps, and typically relies on stoichiometric amounts of coupling reagents and additives. This makes the process cumbersome, and results in poor atom economy and hazardous waste generation. Therefore, direct peptide bond formation using unprotected amino acids is a promising alternative. However, this approach presents some challenges: 1) Solubility of unprotected amino acids in organic solvents; 2) Control of undesired side reactions; 3) Chemo-selective activation of the carboxylic acid group in the presence of an amine functionality; and 4) Epimerization. To address these challenges, we developed tris(2,2,2-trifluoroethoxy)silane [H-Si(OCH₂CF₃)₃], a cost-effective and accessible coupling reagent. This single reagent efficiently synthesizes N-terminal free peptides from unprotected amino acids and amino acid tert-butyl esters, without the need for any additives. H-Si(OCH₂CF₃)₃ enhances amino acid solubility through coordinating with both termini and plays a dual role, serving as a transient amine-protecting group and as a carboxylic acid activating or promoting reagent for peptide bond formation. This method is operationally simple and versatile, enabling the efficient synthesis of N-terminal free peptides from unprotected amino acids and amino acid tert-butyl esters, with good yields, high optical purity, and broad side-chain compatibility.

This study evaluated the cadmium (Cd) adsorption characteristics of sugarcane bagasse (BG) calcined at different temperatures (200-1000°C). The point of zero charge (pH_pzc) of the BGs ranged from 4.3 to 6.5. The amount of Cd adsorbed was higher at pH 4-8 than at pH 2. These results indicate that the negative charge on the BG surface and the presence of Cd(II) cations are important for Cd adsorption. Meanwhile, the amount of Cd adsorbed and the specific surface area (SSA) of BG increased with increasing calcination temperature of BG. Furthermore, a partial correlation analysis revealed that acidic surface functional groups (SFGs) were also significantly associated with Cd adsorption, independently of SSA. These results suggest that both SSA and acidic SFGs jointly contribute to Cd adsorption.

Antibody-based therapeutics have shown remarkable success in targeting extracellular molecules, yet their application to intracellular targets remains largely unexplored due to the absence of efficient delivery systems. The large molecular weight and hydrophilicity of immunoglobulin G (IgG) make cytosolic delivery particularly challenging. Previously, we developed a cytosolic delivery peptide, E3MPH16, based on a modified Mastoparan X sequence, which enabled efficient delivery of macromolecules such as dextran with minimal cytotoxicity. However, effective intracellular delivery of antibodies required high concentrations, limiting its practical utility. In this study, we aimed to enhance delivery efficiency while preserving low toxicity by introducing d-amino acid substitutions into E3MPH16. The resulting peptide, e3MPH16, incorporates d-glutamic acid residues at the N-terminus to improve serum stability and protease resistance. Functional analyses demonstrated that e3MPH16 significantly improves cytosolic delivery of Cre recombinase and antibodies compared with the original E3MPH16, without increasing membrane-lytic activity or cytotoxicity. These results underscore the potential of d-amino acid-substituted peptides such as e3MPH16 as a promising platform for the intracellular delivery of unmodified functional antibodies.

The pandemic of coronavirus disease 2019, caused by the new coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a serious concern worldwide. Although some effective vaccines have been developed, only a few anti-SARS-CoV-2 drugs have been approved for their clinical use. In this study, we designed and synthesized new anti-SARS-CoV-2 drugs based on the chemical structure of amodiaquine, which is known as an antimalarial drug. Consequently, we have identified amodiaquine analogs functionalized with dialkylamino-pendant aminophenol moieties that possess a high level of anti-SARS-CoV-2 activity with a low level of toxicity.

A squaramide organocatalyst was employed to efficiently promote asymmetric oxidative lactonization to construct spiro-fused 2-oxindoles in moderate-to-good yield and enantioselectivity (up to 81% enantiomeric excess (ee)). Herein, we report the first study accomplishing stereoselective oxidative cyclization from indole propionic acid using an organocatalyst, N-iodosuccinimide (NIS), and hydrogen peroxide under metal-free and mild reaction conditions.