Activated production of silent metabolites from marine-derived fungus Penicillium citrinum.

As an attempt to utilize of rare earth elements as a novel method to activate the silent genes in fungus, the marine-derived fungus Penicillium citrinum was cultured under ordinary laboratory fermentation conditions in the presence of scandium chloride (ScCl ₃ , 50 μM), and chemical investigation led to the isolation and characterization of three new peptide derivatives (1-3), along with four known pyrrolidine alkaloids (4-7). Those structures were elucidated by spectroscopic data interpretation, as well as chemical reactions. Comparative metabolic profiling of the culture extracts (with/without scandium chloride) indicated that compounds 1-3 scarcely detected in the absence of ScCl ₃ . In addition, the antibacterial and cytotoxic activities of all isolated products were evaluated.
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