Aldgamycins J–O, 16-Membered Macrolides with a Branched Octose Unit from Streptomycetes sp. and Their Antibacterial Activities

Abstract

Six new 16-membered macrolides with a rare branched octose unit, aldgamycins J-O (1-6), along with two known compounds, swalpamycin B (7) and chalcomycin (8), were isolated from Streptomyces sp. HK-2006-1. Their structures were determined by detailed spectroscopic and X-ray crystallographic analysis. Natural products containing branched sugar units are rare. Aldgaropyranose and decarboxylated aldgaropyranose are branched octoses, specifically aldgarose-type branched octose. Until now, only 11 compounds have been reported to contain an aldgarose-type branched octose. The discovery of aldgamycins J-O (1-6) adds new members of this type of natural product. All the compounds (1-8) herein were tested for antimicrobial activities against Gram-positive Staphylococcus aureus 209P, Gram-negative Escherichia coli ATCC0111, and two fungi, Candida albicans FIM709 and Aspergillus niger R330. Most of these compounds showed antibacterial activity against S. aureus. Their preliminary structure-activity relationships are proposed.

Chalcomycins from Marine-Derived Streptomyces sp. and Their Antimicrobial Activities

“…Compounds 1 and 2 were established as dihydrochalcomycin and chalcomycin respectively by precisely comparing the nuclear magnetic resonance (NMR) data with literature values [11,24,28]. The single-crystal X-ray crystallographic analysis of dihydrochalcomycin ( 1 ) was reported for the first time (Figure 2).…”

“…Chalcomycin ( 2 ) was also obtained and identified in our previous study on the strain of Streptomyces sp. HK-2006-1 [11]. …”

“…The mycinose and chalcose units in the isolated macrolides from the strain of Streptomycetes sp. HK-2006-1 also had D configurations [11]. Therefore, the absolute configurations of the mycinose and chalcose units in 3 were assumed to be D. The relative configurations of the two units were established as β from the coupling constants of the anomeric protons (H-1′ and H-1′′).…”

“…Among our recent discoveries [11,12,13,14,15,16,17,18,19,20,21], we recently reported that a strain of Streptomyces sp. HK-2006-1 produced both aldgamycins and chalcomycins, which are 16-membered macrolides [11,21]. Chalcomycin and seven aldgamycins were isolated from this strain, and chalcomycin showed more potent antibacteria activity against Staphylococcus aureus than aldgamycins [11].…”

“…HK-2006-1 produced both aldgamycins and chalcomycins, which are 16-membered macrolides [11,21]. Chalcomycin and seven aldgamycins were isolated from this strain, and chalcomycin showed more potent antibacteria activity against Staphylococcus aureus than aldgamycins [11]. Chalcomycin, the first member of chalcomycins, was reported with its activity against bacteria as early as 1962 [22].…”