Establishing the Secondary Metabolite Profile of the Marine Fungus: Tolypocladium geodes sp. MF458 and Subsequent Optimisation of Bioactive Secondary Metabolite Production.

Bethlehem Kebede,Antje Labes,Johannes Imhoff,Bernhard Ellinger,Anjali Prashar,Janina Rahlff,Stephen Wrigley,Markus Wolf,Philip Gribbon,Jeanette Reinshagen,Johanna Silber

doi:10.3390/md15040084

Abstract

As part of an international research project, the marine fungal strain collection of the Helmholtz Centre for Ocean Research (GEOMAR) research centre was analysed for secondary metabolite profiles associated with anticancer activity. Strain MF458 was identified as Tolypocladium geodes, by internal transcribed spacer region (ITS) sequence similarity and its natural product production profile. By using five different media in two conditions and two time points, we were able to identify eight natural products produced by MF458. As well as cyclosporin A (1), efrapeptin D (2), pyridoxatin (3), terricolin A (4), malettinins B and E (5 and 6), and tolypocladenols A1/A2 (8), we identified a new secondary metabolite which we termed tolypocladenol C (7). All compounds were analysed for their anticancer potential using a selection of the NCI60 cancer cell line panel, with malettinins B and E (5 and 6) being the most promising candidates. In order to obtain sufficient quantities of these compounds to start preclinical development, their production was transferred from a static flask culture to a stirred tank reactor, and fermentation medium development resulted in a nearly eight-fold increase in compound production. The strain MF458 is therefore a producer of a number of interesting and new secondary metabolites and their production levels can be readily improved to achieve higher yields.

Highlights

The urgent need for novel substances for the treatment of severe human diseases such as cancer, combined with the recognition that marine organisms provide a rich potential source of such substances, support the intensive exploration of new substances from marine organisms [1]
Survive in, the marine ecosystem, characterized by very special conditions that differ from those found in other habitats, marine microorganisms sometimes produce structurally unique bioactive secondary metabolites not found in terrestrial organisms [6]
Due to its structural similarity to the tolypocladenols from another Tolypocladium species, T. cylindrosporum, we propose to assign this molecule to this family and name it tolypocladenol C

Summary

Introduction

The urgent need for novel substances for the treatment of severe human diseases such as cancer, combined with the recognition that marine organisms provide a rich potential source of such substances, support the intensive exploration of new substances from marine organisms [1]. Mar. Drugs 2017, 15, 84 are sources of a large group of structurally unique natural products that are mainly accumulated in marine macroorganisms such as invertebrates (e.g., sponges, soft corals, tunicates) and algae. Drugs 2017, 15, 84 are sources of a large group of structurally unique natural products that are mainly accumulated in marine macroorganisms such as invertebrates (e.g., sponges, soft corals, tunicates) and algae Several of these secondary metabolites have pronounced pharmacological activities [2]. Microorganisms such as fungi and bacteria are truly prolific producers of bioactive molecules and an increasing number of studies support the hypothesis that many compounds originally thought to be produced by macroorganisms come from associated microbes [3,4,5]. Survive in, the marine ecosystem, characterized by very special conditions that differ from those found in other habitats, marine microorganisms sometimes produce structurally unique bioactive secondary metabolites not found in terrestrial organisms [6]

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