Tenacibactins K-M, cytotoxic siderophores from a coral-associated gliding bacterium of the genus Tenacibaculum.

Yasuhiro Igarashi,Agus Trianto,Enjuro Harunari,Amit Raj Sharma,Naoya Oku,Yiwei Ge,Tao Zhou

doi:10.3762/bjoc.18.12

Abstract

HPLC/DAD-based chemical investigation of a coral-associated gliding bacterium of the genus Tenacibaculum yielded three desferrioxamine-class siderophores, designated tenacibactins K (1), L (2), and M (3). Their chemical structures, comprising repeated cadaverine–succinic acid motifs terminated by a hydroxamic acid functionality, were elucidated by NMR and negative MS/MS experiments. Compounds 1–3 were inactive against bacteria and a yeast but displayed cytotoxicity against 3Y1 rat embryonic fibroblasts and P388 murine leukemia cells at GI50 in submicromolar to micromolar ranges. Their iron-chelating activity was comparable to deferoxamine mesylate.

Highlights

Marine organisms continue to be a prolific resource of new bioactive natural products that are applicable to pharmaceutical purposes
The producing strain C16-1 was isolated from a scleractinian coral of the genus Favia and was identified as a member of the genus Tenacibaculum on the basis of 16S rRNA gene sequence similarity
Considering the productivity of siderophores to be an essential trait for the virulence of many microbial pathogens [37], compounds 1–3 could be involved in the pathogenesis of Tenacibaculum maritimum in fish, which is not well understood [38]

Summary

Introduction

Marine organisms continue to be a prolific resource of new bioactive natural products that are applicable to pharmaceutical purposes. In our continuing search for bioactive compounds from underexplored marine bacteria [19,20,21], a Tenacibaculum strain, isolated from a stony coral, was found to produce three metabolites, which turned out to be new cytotoxic hydroxamate-class siderophores, tenacibactins K–M (1–3, Figure 1).

Results

Conclusion