Isolation and conversion of penicillic acid to 6-<i>iodo</i>-α-pyran-2,5-dione: A key intermediate for the synthesis of pectinolide F

<p>Penicillic acid was isolated from <i>Aspergillus sclerotiorum</i> and converted into 6-<i>iodo</i>-α-pyran-2,5-diones using iodolactonization, a key intermediate for the synthesis of pectinolide F. Structures of penicillic acid and its iodolactonized product were confirmed by using NMR experiments.</p

Establishment of LCMS Based Platform for Discovery of Quorum Sensing Inhibitors: Signal Detection in <i>Pseudomonas aeruginosa</i> PAO1

Targeting the main three networking systems, <i>viz.</i> Las, RhI, and PQS, <i>via</i> natural quenchers is a new ray of hope for combating the persistent behavior of <i>Pseudomonas aeruginosa</i>. In the bacterial chemical vocabulary pyocyanin, N-AHLs and rhamnolipids are the main keywords, which are responsible for the social and nomadic behavior of <i>P. aeruginosa</i>. In the present work, LC-MS based real-time qualitative and quantitative analysis of pyocyanin, green phenazine, N-AHLs, and rhamnolipids were performed on <i>P. aeruginosa</i> PAO1. The quantitative analysis indicates that the production of pyocyanin and NHSLs increases with time while the production of rhamnolipids discontinued after 16 h. This indicates the emergence of persisters in the medium instead of planktonic cells. Rhamnolipids acting as a surfactant enhances the motility of the bacterial cells, whereas the pyocyanin is responsible for the biofilm formation. In a microtiter plate based assay, an effect of capsaicin and 6-gingerol was recorded. In the presence of capsaicin and 6-gingerol, a substantial decrease in the production of rhamnolipids, phenazine, quinolone, and N-AHLs was observed. Most interestingly, the 6-gingerol treatment led to a drastic decrease of rhamnolipids, phenazine, quinolone, and N-AHLs versus capsaicin. These studies demonstrate the effectiveness of the capsaicin and 6-gingerol on Las, PQS, and Rhl circuits in a bacterium in order to understand the persistent and social behavior. Here, we are reporting LC-MS/MS based qualitative and quantitative analysis of QS molecules by taking a low volume of culture (up to 200 μL). This method can be used as a platform to screen the new antivirulence agents for fighting the resistant behavior of <i>P. aeruginosa</i> during biofilm formation