A new isomaneonene derivative from the red alga <i>Laurencia</i> cf. <i>mariannensis</i>

Determining the structures of new natural products from marine species not only enriches our understanding of the diverse chemistry of these species, but can also lead to the discovery of compounds with novel and/or important biological activities. Herein, we describe the isolation of isomaneonene C (1), a new halogenated C15 acetogenin, and three known compounds, α-snyderol (2), cis-maneonene D (3), and isomaneonene B (4), from the organic extract obtained from the red alga Laurencia cf. mariannensis collected from Iheya Island, Okinawa, Japan. The structures of these secondary metabolites were elucidated spectroscopically. All compounds were inactive at 30 μg/disc against methicillin-resistant Staphylococcus aureus (MRSA) in combination treatment with a β-lactam drug, meropenem. </p

Herquline A, produced by <i>Penicillium herquei</i> FKI-7215, exhibits anti-influenza virus properties

<p>In the course of screening for new anti-influenza virus antibiotics, we isolated herquline A from a culture broth of the fungus, <i>Penicillium herquei</i> FKI-7215. Herquline A inhibited replication of influenza virus A/PR/8/34 strain in a dose-dependent manner without exhibiting cytotoxicity against several human cell lines. It did not inhibit the viral neuraminidase.</p

Total Synthesis of Fusaramin, Enabling Stereochemical Elucidation, Structure–Activity Relationship, and Uncovering the Hidden Antimicrobial Activity against Plant Pathogenic Fungi

Fusaramin (1) was isolated as a mitochondrial inhibitor. However, the fungal producer stops producing 1, which necessitates us to supply 1 by total synthesis. We proposed the complete stereochemical structure based on the biosynthetic pathway of sambutoxin. We have established concise and robust total synthesis of 1, enabling us to determine the complete stereochemical structure and to elucidate the structure–activity relationship, and uncover the hidden antiplant pathogenic fungal activity

Simplifungin and Valsafungins, Antifungal Antibiotics of Fungal Origin

The targets of antifungal antibiotics in clinical use are more limited than those of antibacterial antibiotics. Therefore, new antifungal antibiotics with different mechanisms of action are desired. In the course of our screening for antifungal antibiotics of microbial origins, new antifungal antibiotics, simplifungin (<b>1</b>) and valsafungins A (<b>2</b>) and B (<b>3</b>), were isolated from cultures of the fungal strains <i>Simplicillium minatense</i> FKI-4981 and <i>Valsaceae</i> sp. FKH-53, respectively. The structures of <b>1</b> to <b>3</b> including their absolute stereochemistries were elucidated using various spectral analyses including NMR and collision-induced dissociation (CID)-MS/MS as well as chemical approaches including modifications to the Mosher’s method. They were structurally related to myriocin. They inhibited the growth of yeast-like and zygomycetous fungi with MICs ranging between 0.125 and 8.0 μg/mL. An examination of their mechanisms of action by the newly established assay using LC–MS revealed that <b>1</b> and <b>2</b> inhibited serine palmitoyltransferase activity, which is involved in sphingolipid biosynthesis, with IC₅₀ values of 224 and 24 nM, respectively

Aogacillins A and B Produced by <i>Simplicillium</i> sp. FKI-5985: New Circumventors of Arbekacin Resistance in MRSA

Aogacillins A and B, capable of overcoming arbekacin resistance in methicillin-resistant <i>Staphylococcus aureus</i> (MRSA), were isolated from a culture broth of <i>Simplicillium</i> sp. FKI-5985. Their structures were elucidated by NMR spectroscopic studies and ECD analyses. The aogacillins possessed a novel carbon skeleton, including a β-keto-γ-methyliden-δ-lactone ring connected to a 2-ethyl-6-methylcyclohexane ring by spiro conjugation