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