Abstract
Two new α-pyrone derivatives, violapyrones H (1) and I (2), along with known violapyrones B (3) and C (4) were isolated from the fermentation broth of a marine actinomycete Streptomyces sp. The strain was derived from a crown-of-thorns starfish, Acanthaster planci, collected from Chuuk, Federated States of Micronesia. The structures of violapyrones were elucidated by the analysis of 1D and 2D NMR and HR-ESIMS data. Violapyrones (1–4) exhibited cytotoxicity against 10 human cancer cell lines with GI50 values of 1.10–26.12 μg/mL when tested using sulforhodamine B (SRB) assay. This is the first report on the cytotoxicity of violapyrones against cancer cell lines and the absolute configuration of violapyrone C.
Highlights
Marine actinomycetes, isolated from the surface of marine algae and invertebrates, have received increased attention as a potential source because they produce a variety of new bioactive secondary metabolites compared to terrestrial microorganisms [1,2]
The bacterial strain 112CH148 was isolated from the crown-of-thorns starfish, Acanthaster planci, collected from Chuuk, Federated States of Micronesia and identified as Streptomyces sp. by 16S rRNA
Thereafter, two new violapyrones (1,2) and two known violapyrones (3,4) were isolated from the EtOAc extract by stepwise gradient open column chromatography followed by reversed-phase High performance liquid chromatography (HPLC) separations
Summary
Marine actinomycetes, isolated from the surface of marine algae and invertebrates, have received increased attention as a potential source because they produce a variety of new bioactive secondary metabolites compared to terrestrial microorganisms [1,2]. As a part of our ongoing research for the discovery of bioactive metabolites from marine bacteria, we isolated a marine actinomycete. A. planci has a long history in the scientific literature but only few studies have been done on its microbial symbionts [3,4,5]. We tried to isolate bioactive strains from the starfish and found that among the isolates, the strain. We report the isolation, structure determination of the new 3,4,6-trisubstituted α-pyrone derivatives, violapyrones H (1) and I (2), and the cytotoxicity of violapyrones (1–4) (Figure 1)
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