Pigmentosins from Gibellula sp. as antibiofilm agents and a new glycosylated asperfuran from Cordyceps javanica

In the course of our exploration of the Thai invertebrate-pathogenic fungi for biologically active metabolites, pigmentosin A ( 1 ) and a new bis(naphtho-α-pyrone) derivative, pigmentosin B ( 2 ), were isolated from the spider-associated fungus Gibellula sp. Furthermore, a new glycosylated asperfuran 3 , together with one new ( 6 ) and two known ( 4 and 5 ) cyclodepsipeptides, was isolated from Cordyceps javanica . The pigmentosins 1 and 2 showed to be active against biofilm formation of Staphylococcus aureus DSM1104. The lack of toxicity toward the studied microorganism and cell lines of pigmentosin B ( 2 ), as well as the antimicrobial effect of pigmentosin A ( 1 ), made them good candidates for further development for use in combination therapy of infections involving biofilm-forming S. aureus . The structure elucidation and determination of the absolute configuration were accomplished using a combination of spectroscopy, including 1D and 2D NMR, HRMS, Mosher ester analysis, and comparison of calculated/experimental ECD spectra. A chemotaxonomic investigation of the secondary metabolite profiles using analytical HPLC coupled with diode array detection and mass spectrometry (HPLC–DAD–MS) revealed that the production of pigmentosin B ( 2 ) was apparently specific for Gibellula sp., while the glycoasperfuran 3 was specific for C. javanica .