Secondary metabolites isolated from <i>Penicillium christenseniae</i> SD.84 and their antimicrobial resistance effects

A pair of new quinolone alkaloid enantiomers, (Ra)-(-)-viridicatol (1) and (Sa)-(+)-viridicatol (4), and seven known compounds, namely, 2, 3 and 5–9, were isolated from Penicillium christenseniae SD.84. The structures of 1 and 4 were determined using NMR and HRESIMS data. Theoretical calculations through CD and ECD confirmed 1 and 4 as a pair of enantiomers. The MIC values of 4 against Staphylococcus aureus and methicillin-resistant S. aureus were 12.4 and 24.7 μM, respectively, compound 1 had no inhibitory activity. Antimicrobial assays of 2, 3, and 5–7 showed a moderate activity against S. aureus and methicillin-resistant S. aureus. This study demonstrated the remarkable potential of Penicillium sp. to produce new drug-resistant leading compounds, thereby advancing the mining for new sources of antimicrobial agents.</p

The Plackett-Burman design for screening variables for C₁₅-surfactin production.

<p>R² = 96.25%, R² (adj)  = 86.25%.</p>*<p>Coef: coefficient.</p

Design and results of CCD.

<p>Design and results of CCD.</p

ANOVA of regression model.

<p>Determination of coefficient R² = 0.9611; adjusted determination coefficient Adj R² = 0.9262.</p>1<p>DF, Degree of freedom;</p>2<p>SS, sum of squares;</p>3<p>MS, mean square.</p

Caesanines A–D, New Cassane Diterpenes with Unprecedented N Bridge from <i>Caesalpinia sappan</i>

Serial antibacterial furanoditerpenes caesanines A–D (<b>1</b>–<b>4</b>), possessing a cassane-type diterpenoid skeleton with an unusual N bridge between C-19/C-20, were identified from a Chinese herb <i>Caesalpinia sappan</i> Linn. In addition, caesanine D (<b>4</b>) showed the first class of dicassane diterpenoid ethers. Their structures were determined by different spectroscopic methods and ECD calculation. Caesanines A and B exhibited strong activities against MRSA suggesting a promising entry point for the development of anti-infective drugs

Regression coefficients and their significance for response surface model.

a<p><i>X₁, X₂ and X₃</i> represent Sucrose, NH₄NO₃ and NaH₂PO₄•2H₂O, respectively.</p

Effects of nitrogen source on the production of C₁₅-surfactin from <i>B. amyloliquefaciens</i> MB199 with sucrose as the carbon source.

<p>Effects of nitrogen source on the production of C₁₅-surfactin from <i>B. amyloliquefaciens</i> MB199 with sucrose as the carbon source.</p

Effects of carbon source on the production of C₁₅-surfactin from <i>B. amyloliquefaciens</i> MB199.

<p>Effects of carbon source on the production of C₁₅-surfactin from <i>B. amyloliquefaciens</i> MB199.</p

Neighbour-joining phylogenetic tree of <i>B. amyloliquefaciens</i> MB199 constructed by Mega 4.0.

<p>Numbers at nodes indicate levels of bootstrap support (%) based on a neighbour-joining analysis of 1000 resampled datasets; only values >50% are given. NCBI accession numbers are given in parentheses. Bar, 0.005 nucleotide substitutions per site.</p

Response surface plot for C₁₅-surfactin production by <i>B. amyloliquefaciens</i> MB199.

<p>Response surface plot for C₁₅-surfactin production by <i>B. amyloliquefaciens</i> MB199.</p