New Antifungal Metabolites from the Mariana Trench Sediment-Associated Actinomycete Streptomyces sp. SY1965.

Wenwen Yi,Le Qin,Zhizhen Zhang,Xiao-Yuan Lian

doi:10.3390/md18080385

Abstract

New streptothiazolidine A (1), streptodiketopiperazines A (2) and B (3), and (S)-1-(3-ethylphenyl)-1,2-ethanediol (4), together with eight known compounds (5–12), were isolated from the Mariana Trench sediment-associated actinomycete Streptomyces sp. SY1965. The racemic mixtures of (±)-streptodiketopiperazine (2 and 3) and (±)-1-(3-ethylphenyl)-1,2-ethanediol (4 and 5) were separated on a chiral high-performance liquid chromatography (HPLC) column. Structures of the new compounds were elucidated by their high-resolution electrospray ionization mass spectroscopy (HRESIMS) data and extensive nuclear magnetic resonance (NMR) spectroscopic analyses. Streptothiazolidine A is a novel salicylamide analogue with a unique thiazolidine-contained side chain and its absolute configuration was established by a combination of nuclear Overhauser effect spectroscopy (NOESY) experiment, electronic circular dichroism (ECD) and 13C NMR calculations. New streptothiazolidine A (1) and streptodiketopiperazines A (2) and B (3) showed antifungal activity against Candida albicans with MIC values of 47, 42, and 42 g/mL, respectively.

Highlights

The deep-sea organisms under extreme conditions have had to make significant biochemical and physiological adaptations for survival, which result in the modification of both gene regulation and metabolic pathways to produce metabolites with unique structures and bioactivities that differ from those produced by shallow-water organisms [1,2,3]
SY1965, according to its 16S rDNA sequence (1416 bp, Figure S2), which was over 99.6%
SY1965, according to its 16S rDNA sequence (1416 bp, Figure S2), which was over match to those of several Streptomyces strains (Table S1)

Summary

Introduction

The deep-sea organisms under extreme conditions have had to make significant biochemical and physiological adaptations for survival, which result in the modification of both gene regulation and metabolic pathways to produce metabolites with unique structures and bioactivities that differ from those produced by shallow-water organisms [1,2,3]. The well-known example is salinosporamide A, which was isolated from a marine obligate actinomycete Salinospora tropica strain CNB-392 [4]. The marine obligate Salinospora actinomycetes were found in tropical and subtropical marine sediments at depths of up to 1100 m [7,8], and most of the secondary metabolites reported to date from the genus Salinospora are novel structural molecules [9]. The Mariana Trench is the deepest known site in the Earth’s oceans, reaching a depth of about 11,000 m at the Challenger Deep. Recent studies revealed that Mariana Trench sediments are enriched in microorganisms [10,11,12], the structures and bioactivities of their secondary metabolites are poorly known. During the course of our ongoing research program for the discovery

Methods

Results

Conclusion