A new cyclic hexapeptide and a new isocoumarin derivative from the marine sponge-associated fungus Aspergillus similanensis KUFA 0013.

Chadaporn Prompanya,Sara Cravo,Carla Fernandes,Madalena M M Pinto,Artur M S Silva,Tida Dethoup,Anake Kijjoa

doi:10.3390/md13031432

A new cyclic hexapeptide and a new isocoumarin derivative from the marine sponge-associated fungus Aspergillus similanensis KUFA 0013.

Chadaporn Prompanya, Sara Cravo + Show 5 more

Open Access

https://doi.org/10.3390/md13031432

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Abstract

A new isocoumarin derivative, similanpyrone C (1), a new cyclohexapeptide, similanamide (2), and a new pyripyropene derivative, named pyripyropene T (3) were isolated from the ethyl acetate extract of the culture of the marine sponge-associated fungus Aspergillus similanensis KUFA 0013. The structures of the compounds were established based on 1D and 2D NMR spectral analysis, and in the case of compound 2 the stereochemistry of its amino acid constituents was determined by chiral HPLC analysis of the hydrolysate by co-injection with the d and l amino acids standards. Compounds 2 and 3 were evaluated for their in vitro growth inhibitory activity against MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer) and A373 (melanoma) cell lines, as well as antibacterial activity against reference strains and the environmental multidrug-resistant isolates (MRS and VRE). Only compound 2 exhibited weak activity against the three cancer cell lines, and neither of them showed antibacterial activity.

Highlights

In recent years, there has been an increasing interest in marine-derived fungi as a target source of bioactive marine natural products because many consider them among the world’s greatest untapped resources for new biodiversity as well as chemodiversity [1,2,3]
Several cyclopeptides have been reported from many fungi of the genus Aspergillus, this is the first report of isolation of cyclohexapeptide from the marine-derived fungus
The fact that these new cyclohexapeptide and pyripyropene analog did not exhibit relevant antibacterial and the in vitro growth inhibitory activities on human cancer cell lines does not mean that they are void of other interesting biological activities

Summary

Introduction

There has been an increasing interest in marine-derived fungi as a target source of bioactive marine natural products because many consider them among the world’s greatest untapped resources for new biodiversity as well as chemodiversity [1,2,3]. In our ongoing search for new natural products with antibacterial and anticancer activities produced by the marine-derived fungi of the genera Neosartorya and Aspergillus, we have recently reported the isolation of new isocoumarins similanpyrones A and B, a new chevalone (chevalone E), and a new natural product pyripyrone S; besides the previously reported chevalone B and C, a meroterpenoid. Compounds 2 and 3 were evaluated for their antibacterial activity as well their cytotoxicity against three human cancer cell lines

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