Planta Medica International Open 2017; 4(S 01): S1-S202
DOI: 10.1055/s-0037-1608336
Lecture Session – Analytical Studies & Natural Products Chemistry II
Georg Thieme Verlag KG Stuttgart · New York

Molecular Networking for Identification of Enhanced Chemical Inventories of Baltic Marine Fungi

D Parrot
1   GEOMAR Centre for Marine Biotechnology, Research Unit Marine Natural Product Chemistry, GEOMAR Helmholtz Centre for Ocean Research Kiel, Am Kiel-Kanal 44, Kiel, Germany
,
E Oppong-Danquah
1   GEOMAR Centre for Marine Biotechnology, Research Unit Marine Natural Product Chemistry, GEOMAR Helmholtz Centre for Ocean Research Kiel, Am Kiel-Kanal 44, Kiel, Germany
,
B Fan
1   GEOMAR Centre for Marine Biotechnology, Research Unit Marine Natural Product Chemistry, GEOMAR Helmholtz Centre for Ocean Research Kiel, Am Kiel-Kanal 44, Kiel, Germany
,
D Tasdemir
1   GEOMAR Centre for Marine Biotechnology, Research Unit Marine Natural Product Chemistry, GEOMAR Helmholtz Centre for Ocean Research Kiel, Am Kiel-Kanal 44, Kiel, Germany
› Author Affiliations
Further Information

Publication History

Publication Date:
24 October 2017 (online)

 

Molecular networking (MN) has revitalized natural product dereplication and metabolomics studies. By organizing the MS/MS spectra based on their fragment similarity, MN efficiently annotates the unknown derivatives of known compound clusters and reveal putative new molecular families [1]. In this study, over 220 fungi from Baltic Sea environment have been isolated and identified by 18S and ITS sequencing. In order to activate biosynthetic gene clusters (BGCs) that often remain silent under artificial culture conditions, we used OSMAC (One-Strain-MAny-Compounds, changing culture conditions) and direct co-cultivation (against a competitive microorganism on the same Petri dish) techniques. The EtOAc extracts of the fungi (mono- and co-cultures) were tested against a large panel of phytopathogens and cancer cell lines. We comparatively profiled the secondary metabolome of the most active extracts by UPLC-QTOF-MS/MS-based MN, employing the open source GNPS database and XCMS statistical methods. Co-cultures of an Aspergillus species and the phytopathogen Botrytis cinerea showed increased cluster sizes of quinolones and echinulin-type indole alkaloids with a number of putative unknown analogues. Additionally, three putatively unknown clusters were identified. The seaweed-associated fungus Cadophora malorum was cultivated in four different media. Only the Potato Dextrose Broth (PDB) medium extract demonstrated activity against HepG2 liver cancer cell line (IC50 value 11 µg/ml). The MN analysis showed this strain to be dominated by an enniatin-type cyclohexadepsipeptide cluster, plus two unknown molecular families. MN provided a visible and analyzable platform for quick identification and comparison of enhanced chemical inventories of large marine fungal extract libraries. In combination with bioactivity, it enabled us prioritizing the most promising extracts for subsequent bioassay-guided isolation studies. Hence, MN has great potential for accelerating the discovery of new, bioactive fungal metabolites.

[1] Quinn RA, Nothias LF, Vining O, Meehan M, Esquenazi E, Dorrestein PC. Trends Pharmacol Sci 2017; 38: 143 – 154