Shubin Niu

Isoprenylated chromone derivatives from the plant endophytic fungus Pestalotiopsis fici.

Pestaloficiols F-L (1-7), new isoprenylated chromone derivatives including one heterodimer (7), have been isolated from a scale-up fermentation extract of the plant endophytic fungus Pestalotiopsis fici. The structures of these compounds were elucidated primarily by NMR and MS methods. The absolute configurations of 1 and 4 were assigned using the modified Mosher method. Compounds 1-3, 5, and 6 displayed inhibitory effects on HIV-1 replication in C8166 cells, whereas 4-7 showed cytotoxic activity against the human tumor cell lines HeLa and MCF7.

Polyketides from the Ascomycete Fungus Leptosphaeria sp.

The new polyketides leptosphaerins A-G (1-7) and the known compounds monodictysin B (8), 2-(2,6-dihydroxybenzoyl)-3-hydroxy-5-methylbenzoic acid (9), and 2-(2,6-dihydroxy-4-methylbenzoyl)-6-hydroxybenzoic acid (10) have been isolated from solid cultures of the ascomycete fungus Leptosphaeria sp. The absolute configurations of compounds 1, 2, and 6 were assigned using the modified Mosher method, whereas that of C-2 in 3 was determined via the circular dichroism data of the [Rh(2)(OCOCF(3))(4)] complex. Compound 7 showed antifungal activity against Aspergillus flavus.

A thiopyranchromenone and other chromone derivatives from an Endolichenic fungus, Preussia africana.

The first example of a naturally occurring thiopyranchromenone, preussochromone A (1), and five other new chromone derivatives, preussochromones B-F (2-6), were isolated from solid cultures of an endolichenic fungus, Preussia africana. The structures of 1-6 were established primarily by NMR experiments, and 2 and 4 were further confirmed by X-ray crystallography. The absolute configurations of 1 and 2 were determined by the application of electronic circular dichroism (ECD), whereas those of C-5 in 3, C-6 in 4, and the 6,7-diol in 5 were deduced via the CD data of the in situ formed [Rh₂(OCOCF₃)₄] complex, the modified Mosher method, and Snatzkes method, respectively. Compounds 1 and 3 showed significant cytotoxicity against A549 cells.

The first naturally occurring thiepinols and thienol from an endolichenic fungus Coniochaeta sp.

Coniothiepinols A (1) and B (2) and coniothienol A (3), the first naturally occurring thiepinols (1 and 2) and thienol (3), have been isolated from the crude extract of an endolichenic fungus Coniochaeta sp. 1 possesses a unique 8-oxa-2-thia-bicyclo[3.2.1]octane skeleton, and its structure was assigned by NMR spectroscopy and X-ray crystallography. 1 showed significant activity against the gram-positive bacteria, Enterococcus faecium and Enterococcus faecalis.

Pyrrolidinones from the Ascomycete Fungus Albonectria rigidiuscula

The new pyrrolidinones, rigidiusculamides A-D (1-4), have been isolated from the crude extract of the ascomycete fungus Albonectria rigidiuscula. The structures of these compounds were elucidated primarily by NMR experiments. The absolute configuration of the 3,4-diol moieties in 1 and 4 was assigned using Snatzkes method. Compounds 1 and 2 showed modest cytotoxicity against the human tumor cell lines HeLa and MCF-7.

Verrucamides A―D, Antibacterial Cyclopeptides from Myrothecium verrucaria

Four new cyclic tetradecapeptides, verrucamides A-D (1-4), have been isolated from the solid-substrate fermentation culture of the ascomycete fungus Myrothecium verrucaria. The structures of these compounds, each featuring six N-methylated amino acid residues, were elucidated primarily by NMR and MS methods. The absolute configurations of 1-4 were assigned by application of Marfeys method on their acid hydrolysates. Compounds 1-4 showed antimicrobial activity against the Gram-positive bacterium Staphylococcus aureus.

Naphthalenones from a Perenniporia sp. Inhabiting the Larva of a Phytophagous Weevil, Euops chinesis

The new naphthalenone derivatives perenniporides A-D (1-4) were isolated from solid cultures of a fungus Perenniporia sp. inhabiting the larva of Euops chinesis, a phytophagous weevil with high host specificity to the medicinal plant Fallopia japonica. The structures of 1-4 were elucidated primarily by NMR experiments, and 1 was confirmed by X-ray crystallography. The absolute configuration of 1 and 2 was assigned by electronic circular dichroism (ECD) calculations, whereas that of the C-10 tertiary alcohol in 3 was deduced via the CD data of the in situ formed [Rh(2)(OCOCF(3))(4)] complex and supported by the ECD data. Compound 1 showed antifungal activity against five plant pathogens.

Dioxatricyclic and oxabicyclic polyketides from Trichocladium opacum.

Five new polyketides, trichocladinols D-H (1-5) with dioxatricyclic (1-3) and oxabicyclic (4 and 5) skeletons, and the known massarilactone C (6) were isolated from the solid-substrate fermentation cultures of the ascomycete fungus Trichocladium opacum. The structures of 1-5 were determined mainly by NMR experiments, and 1, 3, and 4 were confirmed by X-ray crystallography. The absolute configurations of 1 and 3 were assigned by X-ray crystallography using Cu Kα radiation, whereas that of C-5 in 2 and 4 was deduced via the circular dichroism (CD) data. Compounds 2-4 showed weak cytotoxicity against the human tumor cell lines A549, HCT116, and SW480.

Guanacastane Diterpenoids from the Plant Endophytic Fungus Cercospora sp.

Cercosporenes A-F (1-6, respectively), six new guanacastane diterpenes, including a homodimer (5) and a heterodimer (6), were isolated from the crude extract of the fungus Cercospora sp., endophytic to the medicinal plant Fallopia japonica. The structures of 1-6 were elucidated by nuclear magnetic resonance experiments, and 4 and 5 were further confirmed by X-ray crystallography. The absolute configuration of 1 and 3 was assigned by electronic circular dichroism calculations, whereas that of 6 was deduced by the application of the circular dichroism exciton chirality method. In addition to its cytotoxicity against a panel of five human tumor cell lines, HeLa, A549, MCF-7, HCT116, and T24, heterodimer 6 also induced autophagy in HCT116 cells.

Cytotoxic Cleistanthane and Cassane Diterpenoids from the Entomogenous Fungus Paraconiothyrium hawaiiense

Hawaiinolides A-D (1-4), four new secondary metabolites including three cleistanthane (1, 3, and 4) and one cassane (2) type of diterpene lactones, were isolated from the crude extract of Paraconiothyrium hawaiiense, a fungus entomogenous to the Septobasidium-infected insect Diaspidiotus sp. The structures of 1-4 were elucidated by nuclear magnetic resonance experiments, and 1 and 3 were further confirmed by X-ray crystallography. The absolute configuration of 1 was assigned via single-crystal X-ray diffraction analysis using Cu Kα radiation, whereas that of 2-4 was deduced via the circular dichroism data. Compound 1 showed significant cytotoxicity against a small panel of five human tumor cell lines, A549, T24, HeLa, HCT116, and MCF-7.