GA 2017

In the search for new anticancer agents of natural origin, plant-associated endophytes could be a good source for bioactive secondary metabolites. The endophytic fungus Chaetomium subaffine was obtained from the plant Anthemis palestina and cultured in liquid and rice media for different time periods to optimize its growth and production of compounds employing both NMR and mass spectrometry-based metabolomics. Culturing the fungus on rice gave better yield and more chemically diverse extract. Therefore, this type of medium was chosen for scaling-up purposes. The scaled-up extract was subjected to partitioning between lipophilic and hydrophilic phases. The lipophilic phase which is mainly composed of fatty acids was discarded while the hydrophilic phase was fractioned using a flash-chromatography system and yielded 12 fractions. These fractions were tested in-vitro against both ZR75 and A549 cell lines and analyzed using both proton nuclear magnetic resonance (NMR) and liquid chromatography-high resolution Fourier transform mass spectrometry (LC-HRFTMS). The HRFTMS data was processed with MZmine then subjected to Partial Least Square-Discriminant Analysis (PLS-DA). The PLS-DA results pinpointed the biologically active secondary metabolites. Metabolomic-guided isolation work targeted the bioactive secondary metabolites. Six compounds were isolated and elucidated by employing 1D and 2D NMR. Stereochemistry was determined by Mosher’s method. These compounds included four new orsillides as well as the already known compounds acremonisol A and cochliodinol.