Lee, Seoung RakSchalk, FelixSchwitalla, Jan W.Guo, HuijuanYu, Jae SikSong, MoonyongJung, Won HeeDe Beer, Z. WilhelmBeemelmanns, ChristineKim, Ki Hyun2023-05-102023-05-102022-06Lee, S.R., Schalk, F., Schwitalla, J.W. et al. 2022, 'GNPS - guided discovery of Madurastatin siderophores from the termite-associated actinomadura sp. RB99', Chemistry—A European Journal, vol. 28, no. 36, art. e202200612, pp. 1-9, doi : 10.1002/chem.202200612.0947-6539 (print)1521-3765 (online)10.1002/chem.202200612http://hdl.handle.net/2263/90623In this study, we analyzed if Actinomadura sp. RB99 produces siderophores that that could be responsible for the antimicrobial activity observed in co-cultivation studies. Dereplication of high-resolution tandem mass spectrometry (HRMS/MS) and global natural product social molecular networking platform (GNPS) analysis of fungus-bacterium cocultures resulted in the identification of five madurastatin derivatives (A1, A2, E1, F, and G1), of which were four new derivatives. Chemical structures were unambiguously confirmed by HR-ESI-MS, 1D and 2D NMR experiments, as well as MS/MS data and their absolute structures were elucidated based on Marfey’s analysis, DP4+ probability calculation and total synthesis. Structure analysis revealed that madurastatin E1 (2) contained a rare 4-imidazolidinone cyclic moiety and madurastatin A1 (5) was characterized as a Ga3+-complex. The function of madurastatins as siderophores was evaluated using the fungal pathogen Cryptococcus neoformans as model organism. Based on homology models, we identified the putative NRPS-based gene cluster region of the siderophores in Actinomadura sp. RB99.en© 2022 The Authors. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial License.MetabolomicsMicrobial communicationNatural productsSiderophoresHigh-resolution tandem mass spectrometry (HRMS/MS)Article