Total Synthesis of Kehokorins A–E, Cytotoxic <i>p</i>‑Terphenyls

This paper describes a general method for the synthesis of kehokorins A–E, novel cytotoxic <i>p</i>-terphenyls. 2,4,6-Trihydroxybenzaldehyde served as a common building block for preparation of the central aromatic ring. Construction of their <i>p</i>-terphenyl skeletons was achieved by a stepwise Suzuki–Miyaura coupling, whereas the phenyldibenzofuran moiety was built up by an intramolecular Ullmann reaction. Introduction of an l-rhamnose residue into partly protected kehokorin B was performed by the trichloroacetimidate method

Synthesis of 3-phenyldibenzo[<i>b,d</i>]furan-type bioprobes utilizing vialinin B as a structural motif

<p>Vialinin B is a natural 3-phenyldibenzo[<i>b,d</i>]furan product with a powerful inhibitory activity against tumor necrosis factor (TNF)–α production. This article describes the synthesis of three types of biotinylated <i>p</i>-terphenyls designed for clarifying the target molecule of vialinin B. Construction of the carbon backbone of the core was accomplished by stepwise Suzuki–Miyaura coupling while the phenyl dibenzofuran moiety was built up by the Ullmann reaction. The biotinyl unit was attached through click chemistry.</p

Total Synthesis of the Proposed Structure for Aromin and Its Structural Revision

This paper describes the first total synthesis of the proposed structure for aromin, an annonaceous acetogenin possessing an unusual bis-THF ring system, and its 4<i>S</i>,7<i>R</i>-isomer. The key steps involve an oxidative cyclization of a couple of terminal-diene alcohols and an intermolecular metathesis of an alkenyl tetrahydrofuran with an enone carrying a tetrahydrofuranyl lactone. The spectral data of both samples did not match those of aromin. Re-examination of the NMR data using the CAST/CNMR Structure Elucidator and chemical derivations suggested that the real structure of aromin should be revised to be a tetrahydropyran acetogenin, montanacin D. Cytotoxicities in human solid tumor cell lines for synthetic samples were also evaluated

Synthesis and Structural Revision of a Brominated Sesquiterpenoid, Aldingenin C

This paper describes a short step synthesis of the proposed structure for aldingenin C from <i>trans</i>-limonene oxide. The tetrahydropyran-fused 2-oxabicyclo[3.2.2]­nonane skeleton as the structural feature was constructed by an intramolecular epoxide-opening reaction and a brominative cyclization. The spectral data of the synthetic compound did not match those of the natural product reported. Re-examination of the reported NMR data using new CAST/CNMR Structure Elucidator suggests that the structure of aldingenin C should be revised to that of known caespitol

Total Synthesis of the Proposed Structure for Aromin and Its Structural Revision

This paper describes the first total synthesis of the proposed structure for aromin, an annonaceous acetogenin possessing an unusual bis-THF ring system, and its 4<i>S</i>,7<i>R</i>-isomer. The key steps involve an oxidative cyclization of a couple of terminal-diene alcohols and an intermolecular metathesis of an alkenyl tetrahydrofuran with an enone carrying a tetrahydrofuranyl lactone. The spectral data of both samples did not match those of aromin. Re-examination of the NMR data using the CAST/CNMR Structure Elucidator and chemical derivations suggested that the real structure of aromin should be revised to be a tetrahydropyran acetogenin, montanacin D. Cytotoxicities in human solid tumor cell lines for synthetic samples were also evaluated

Isolation of Coralmycins A and B, Potent Anti-Gram Negative Compounds from the Myxobacteria <i>Corallococcus coralloides</i> M23

Two new potent anti-Gram negative compounds, coralmycins A (<b>1</b>) and B (<b>2</b>), were isolated from cultures of the myxobacteria <i>Corallococcus coralloides</i> M23, together with another derivative (<b>3</b>) that was identified as the very recently reported cystobactamid 919-2. Their structures including the relative stereochemistry were elucidated by interpretation of spectroscopic, optical rotation, and CD data. The relative stereochemistry of <b>3</b> was revised to “<i>S*R*</i>” by NMR analysis. The antibacterial activity of <b>1</b> was most potent against Gram-negative pathogens, including <i>Escherichia coli</i>, <i>Pseudomonas aeruginosa</i>, <i>Acinetobacter baumanii</i>, and <i>Klebsiella pneumoniae</i>, with MICs of 0.1–4 μg/mL; these MICs were 4–10 and 40–100 times stronger than the antibacterial activities of <b>3</b> and <b>2</b>, respectively. Thus, these data indicated that the β-methoxyasparagine unit and the hydroxy group of the benzoic acid unit were critical for antibacterial activity

Ca²⁺-Signal Transduction Inhibitors, Kujiol A and Kujigamberol B, Isolated from Kuji Amber Using a Mutant Yeast

A podocarpatriene and a labdatriene derivative, named kujiol A [13-methyl-8,11,13-podocarpatrien-19-ol (<b>1</b>)] and kujigamberol B [15,20-dinor-5,7,9-labdatrien-13-ol (<b>2</b>)], respectively, were isolated from Kuji amber through detection with the aid of their growth-restoring activity against a mutant yeast strain (<i>zds1</i>Δ <i>erg3</i>Δ <i>pdr1</i>Δ <i>pdr3</i>Δ), which is known to be hypersensitive with respect to Ca²⁺-signal transduction. The structures were elucidated by spectroscopic data analysis. Compounds <b>1</b> and <b>2</b> are rare organic compounds from Late Cretaceous amber, and the mutant yeast used seems useful for elucidating a variety of new compounds from Kuji amber specimens, produced before the K–Pg boundary

Antiapoptotic activity of the F7 fraction in H₂O₂-treated cells.

<p>J774A.1 cells were preincubated with the F7 lipid fraction for 12 h. H₂O₂ was then added to the cells (112.5 μM). After 12 h, the TUNEL-positive cells were quantified and the results expressed as the mean ± standard deviation of triplicate experiments. (A) TUNEL staining of J774A.1 cells treated with the F7 lipid fraction. (B) Frequency of apoptosis. (*) According to Student’s <i>t</i> test, the difference between the lipid-treated cells and untreated cells (control) was significant (<i>P</i> < 0.05).</p

Viability of J774A.1 cells treated with LPC or Lyso-PAF.

<p>J774A.1 cells were preincubated with LPC or Lyso-PAF for 12 h, and H₂O₂ was then added to the cells (25 μM). After 12 h, cell viability was measured and is expressed as the mean viability ± standard deviation of triplicate experiments. (A) F7 lipid fraction. (B) Lipid mixture containing Lyso-PAF C18:0 (44%), Lyso-PAF (9<i>Z</i>)-C18:1 (44%), and LPC C18:0 (12%). (C) Lyso-PAF C18:0. (D) Lyso-PAF (9<i>Z</i>)-C18:1. (E) LPC. (*) Significant (<i>P</i> < 0.05) according to ANOVA followed by Tukey’s multiple comparisons.</p

ORAC assay.

<p>Antioxidant capacities of the F7 lipid fraction and a lipid mixture containing Lyso-PAF C18:0 (44%), Lyso-PAF (9<i>Z</i>)-C18:1 (44%), and LPC C18:0 (12%). Lyso-PAF C18:0, Lyso-PAF (9<i>Z</i>)-C18:1, and LPC are expressed in μmol Trolox equivalents (TE)/g, calculated from a Trolox standard curve.</p