Integrated workflows using metabolomics, genome mining, and biological evaluation reveal oxepine‑sulfur-containing anti-cryptococcal diketopiperazine produced by the endophyte Penicillium setosum.

Cryptococcosis is a fungal infection for which treatment relies on old antifungal agents usually leading to drawbacks such as high toxicity and mainly low efficiency since drug resistance of microorganisms is strongly widespread. The discovery of new antifungal agents is urgent and investigations about underexplored Natural Product (NP) can yield the necessary outcomes to guide the discovery of new prototypes to anti-cryptococcal molecules development. In this scenario, an integrated strategy involving metabolomic data analysis, biological assessement and genome mining of P. setosum CMLD 18, revealed the biosynthesis of bis(methyl-sulfanyl) oxepine-containing diketopiperazine derivative, the bisdethiobis(methylthio)acetylaranotine (1) by the endophyte. The molecule showed a minimum inhibitory concentration (MIC) value of 0.125 mM when tested against C. neoformans. Evidence about the corresponding biosynthetic gene cluster (BGC) responsible for the biosynthesis of (1) in P. setosum were found. Moreover, other putative analogues of (1) were also detected, suggesting this microorganism may represent an important source of likely anti-cryptococcal molecules to be further investigated.