A chemical investigation of Streptomyces sp. Hu186 afforded two known quinone antibiotics, sarubicin A (1) and sarubicin B (2), together with three unusual variants, sarubicinols A−C (3−5), and two new 1,4naphthoquinone metabolites, sarubicin B 1 (6) and sarubicin B 2 (7). Compounds 3−5 possess a rare 2-oxabicyclo [2.2.2] substructure and a benzoxazole ring system. Their structures were elucidated using 1D and 2D nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry data. The absolute configurations of the side-chain moieties in 4 and 5 were solved by electronic circular dichroism calculations. Compounds 1−7 showed moderate cytotoxic activity against four tumor cell lines.
Bioinformatics analysis of a whole genome sequence coupled with HPLC-DAD analysis revealed that Streptomyces sp. Hu103 has the capacity to produce skyllamycin analogues. A subsequent chemical investigation of this strain yielded four new cinnamoyl-containing cyclopeptides, anulamycins A−D (1−4), two new cinnamoyl-containing linear peptides, anulamycins E and F (5 and 6), and two known cyclopeptides, skyllamycins A (7) and B (8). Their structures including absolute configurations were elucidated by detailed analysis of NMR and HRESIMS/ MS spectroscopic data and the advanced Marfey's method. Compounds 1−4 exhibited antibacterial activity comparable to those of skyllamycins A and B.
Two actinomycete strains, NEAU-C11 and NEAU-C8, isolated from rhizosphere soil and wheat root, respectively, collected from Langfang, Hebei Province, China. A polyphasic study was carried out to establish the taxonomic position of the two strains. Morphological and chemotaxonomic characteristics of the isolates coincided with the genus Glycomyces. Sequences analysis of the 16S rRNA gene also showed that the organisms belong to the genus Glycomyces and Glycomyces algeriensis is the highest sequence match for both strains. Furthermore, a combination of DNA-DNA hybridization results and some differential physiological and biochemical properties indicated that they were distinguishable from the phylogenetically closest relatives. Therefore, the two strains represent a novel species, for which the name Glycomycesrhizosphaerae sp. nov. is proposed. The type strain is NEAU-C11 (=CGMCC 4.7396=DSM 104646).
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