Two New Members of Streptothricin Class Antibiotics from Streptomyces qinlingensis sp. nov

Abstract

Four streptothricin-group antibiotics (1ϳ4) were isolated from the fermentation broth of Streptomyces qinlingensis sp. nov. Along with the known antibiotics streptothricins F (1) and D (3), two new members of this class (2, 4) were identified as 12-carbamoyl derivatives of 1 and 3, respectively, mainly by analysis of the IR, HR-MS and NMR spectral data. The antibacterial activities of 1ϳ4 against Escherichia coli (MICs 3.1, 25.0, 3.1 and 12.5 m g/ml), Bacillus subtilis (MICs 6.3, 25.0, 3.1 and 50 m g/ml), Staphylococcus aureus (MICs 12.5, Ͼ100.0, 6.3, Ͼ100.0 mg/ml), Bacillus cereus (MICs 25.0, 50.0, 25.0 and 50.0 mg/ml) and Pseudomonas aeruginosa (MICs 50.0, Ͼ100.0, 50.0, Ͼ100.0mg/ml) were assayed by micro-broth dilution. The results based on MIC data indicated that 2 and 4 exhibited significantly less potent antibacterial activities when compared to that of 1 and 3.

Synthesis of 1-isopropyl-3-acyl-5-methyl-benzimidazolone Derivatives and Their Antimicrobial Activity

“…MICs of the title compounds against five strains of bacteria were evaluated by the micro-broth dilution method in 96-well plates [21]. The inoculum was prepared by suspending several colonies from an overnight culture of tested bacteria from 0.5% sheep blood agar media in Müller-Hinton broth and adjusting to a 0.5 McFarland standard (approximately 1.5 × 10 8 colony-forming units per mL).…”

Isolation, structure elucidation and antibacterial activities of streptothricin acids

“…To our best knowledge, only four 12-carbamoylstreptothricins, 12-carbamoylstreptothricin F, D, C and B, have been reported; so compound 3 is a novel 12-carbamoylstreptothricin antibiotic ( Figure 1). 9,11 Compound 4 was obtained as a colorless amorphous powder. The molecular formula C 31 H 60 N 12 O 11 was determined by HR-ESI-MS at m/z 777.4576 [M+H] + (calcd for C 31 H 61 N 12 O 11 , 777.4577).…”

“…ST-F, ST-D and two other novel compounds, 12-carbamoyl-ST-F and 12-carbamoyl-ST-D, have been isolated from its fermentation broth in our laboratory. 9 In subsequent research, a facile LC-MS/MS method based on RP-HPLC coupled with electrospray ionization tandem mass spectrometry was used for the analysis of STs in the fermentation broth of S. qinlingensis. 10 A total of 19 ST-like compounds were identified or tentatively characterized on the basis of their mass spectral data; among them, 12 were ST acids.…”

Identification of Streptothricin Class Antibiotics in the Earlystage of Antibiotics Screening by Electrospray Ionization Mass Spectrometry

“…More recently, other members of the family, which are chemically closely related to streptothricin, have been described in references [11,12] and our laboratory [13]. Ando reported the structure elucidation of N-acetylstreptothricins by application of NMR and fast atom bombardment mass spectrometry (FAB-MS), in which the fragmentation ions were used to determine the position of the acetyl group [14].…”