Isolation and Characterization of Two Novel Antibacterial Cyclic Hexapeptides from Streptomyces alboflavus 313

Abstract

Two novel cyclic hexapeptides, designated NW-G08 (1) and NW-G09 (2), were isolated from the fermentation broth of Streptomyces alboflavus 313. Their structures were elucidated on the basis of extensive spectroscopic analysis, MS experiments, and chemical analysis. Their antibacterial activities against several strains of bacteria were evaluated by micro-broth dilution method. NW-G08 (1) and NW-G09 (2) were highly antibacterial against Gram-positive but not active against Gram-negative bactaria. The minimum inhibitory concentrations (MICs) of 1 against Bacillus cereus, Bacillus subtilis, and Staphylococcus aureus were 6.25, 6.25, and 1.56 μg/ml, respectively. It is worth noting that 1 and 2 exhibited much higher activities against methicillin-resistant Staphylococcus aureus (MRSA) than ampicillin, which implies that they might be potential candidates for the development of novel drugs against resistant pathogenic bacteria.

Synthesis of 3a‐hydroxyhexahydropyrrolo[2,3‐B]Indole‐2‐carboxamide, an oxidation product of tryptophan present in natural products

“…Pseudo‐monomers of himastatin ( 13 ) and chloptosin ( 14 ) were also identified in fungi. For example, the NW‐G family was isolated from Streptomyces alboflavus 313 . The NW‐G family encompasses at least nine members.…”

Antibacterial Activity and Composition of the Fermentation Broth of Streptomyces Parvus 33

“…More than 60% of the nearly 6000 antibiotics of microbial origin are produced by Streptomyces spp. including both antibacterial and antifungal agents beside a considerable number of other bioactive compounds (5)(6)(7)(8)(9)(10)(11). Microorganisms represent a potentially valuable source of biologically significant compounds that should be explored for their potential agrochemical use (12).…”

Identification of pyrroloindoline-containing cyclic hexapeptides in the metabolites of Streptomyces alboflavus 313 by HPLC-DAD-ESI-MS/MS

“…1 In our previous investigation of natural products from microorganisms for drug discovery, nine pyrroloindoline-containing cyclic hexapeptides, NW-G01, NW-G03 and NW-G05-NW-G11, were discovered in the fermentation broth of Streptomyces alboflavus 313. [2][3][4][5][6][7] They are structurally related to himastatin and chloptosin ( Figure 1), two cyclic hexapeptides antibiotics produced by strains of Streptomyces. They all contain the common rare amino acids, piperazine-3-carboxylic acid and pyrroloindoline derivative, especially for chloptosin, it has the identical Trp-Val-PA 3 -PA 2 moiety in its structure with that of NW-series cyclic hexapeptides.…”