New asymmetrical bispyrrolidinoindoline diketopiperazines from the marine fungus <i>Aspergillus</i> sp. DX4H

<p>Known diketopiperazine WIN 64821 and its asymmetric stereoisomers (<b>1</b>–<b>3</b>) had been isolated from the culture broth of a marine gut fungus <i>Aspergillus</i> sp. DX4H. The planar and stereochemistry for new compounds were determined by a suite of techniques including mass, NMR and CD spectra together with Marfey’s method. Their inhibitory activity against PC3 cell line had been tested.</p

Novel Stemphol Derivatives from a marine fungus <i>Pleospora</i> sp

<p>Four novel stemphol derivatives, pleosporols A–D (<b>1</b>, <b>2</b> and mixture of <b>3</b> and <b>4</b>) together with known compounds stemfolones (mixture of <b>5</b> and <b>6</b>), stemphol (<b>7</b>) were isolated from a marine fungus <i>Pleospora</i> sp. (PO4) derived from the gut of marine isopod <i>Ligia oceanica</i>. The planar structures of novel compounds were elucidated on the basis of mass and NMR spectral analysis. The stereo-chemistries of <b>1–2</b> were determined by CD spectra, NOESY data, coupling constants analysis and modified Mosher’s method while the absolute configurations of <b>3–6</b> were not clear. Novel compounds contained <i>α</i>, <i>β</i>-unsaturated cyclohexanone ring and possibly derived from the oxidation of stemphol. All novel ones showed strong antimicrobial activity against <i>Staphylococcus epidermidis</i> CMCC26069 with MIC values less than 10 μg/mL.</p

Fatty acid compositions in plasma membrane and ergosterol content of strains Z5 and SZ3-1 cultivated in different conditions.

<p>Data are the mean values and standard deviation of three dependent experiments.</p>a<p>Fatty acids are denoted by the number of carbon atoms: number of unsaturated linkeages.</p>b<p>Unsaturation Index(Δ/mol) was calculated as: Δ/mol = [1×(% monoene)+2×(% diene)+3×(% triene)]/100.</p

The fermentation performance of strains Z5, Z5Δ<i>GPD2</i> and SZ3-1.

<p>The ethanol yield (A), glucose consumption (B), glycerol (filled symbols) and acetate (open symbols) production (C), and cell survival rate (D) of control strains Z5 (squares), Z5Δ<i>GPD2</i> (circles), and shuffled strain SZ3-1 (triangles) during fermentation were monitored and compared.</p

Determination of ethanol stress tolerance of strains Z5, Z5Δ<i>GPD2</i> and SZ3-1.

<p>(A) Growth of strains Z5, Z5Δ<i>GPD2</i> and SZ3-1 on different concentration of ethanol. Cells were grown in the YPD liquid medium at 30°C overnight and 10-fold serial dilutions of each sample were spotted onto the YPD medium and the YPD medium containing 10%, 15%, 20% (v/v) ethanol. Stress tolerance was calculated as the percentage of biomass formation or viable cells in stressed culture compared with that in control culture. (B) Time course of extracellular nucleotide concentration in cell suspension of strains Z5 (filled symbols) and SZ3-1 (open symbols). Yeast cells were suspended in aqueous solution with 0% (triangles), 10% (squares), 15% (diamonds), and 20% (circles) (v/v) ethanol and incubated at 30°C. Concentration of nucleotide that leaked into the supernatant was measured every few hours.</p

Trehalose concentrations and related enzymatic activity of stains Z5 and SZ3-1.

<p>Yeast strains were harvested at the stationary phase and exposed to ethanol stress. Trehalose concentration (A) of strains Z5 (light gray) and SZ3-1 (gray) subjected to different ethanol stress (0%, 5%, 10%, and 15% (v/v) ethanol) was measured. Finally, we determined related enzymatic activities, namely, trehalose-P-synthase (B), acid trehalase (C), and neutral trehalase (D) under 0% ethanol and 10% ethanol conditions.</p

Relative expression level of six genes related to trehalose metabolism.

<p>Strains Z5 and SZ3-1 were grown in the absence (0%) or presence (10%) of ethanol. Gene expression of four cases were compared: strain Z5 grown in the presence and absence of ethanol (Z5 (10%)/Z5 (0%)); strain SZ3-1 grown in the presence and absence of ethanol (SZ3-1 (10%)/SZ3-1 (0%)); strain SZ3-1 and Z5 grown in absence of ethanol (SZ3-1(0%)/Z5(0%)); and strain SZ3-1 and Z5 grown in the presence of ethanol (SZ3-1 (10%)/Z5 (10%)).</p

Karyotype profiles of strains Z5 and SZ3-1 obtained by PFGE.

<p>Lanes M, Z5 and SZ3-1 respectively represent the chromosomal profiles of strains BY4743, Z5 and SZ3-1. Numbers corresponding to each band are designated in the left.</p