Carbazole and Quinazolinone Derivatives from a Fluoride-Tolerant Streptomyces Strain OUCMDZ-5511

Abstract

Six new 9H-carbazole derivatives (1−6) and nine previously reported compounds (7−15) were isolated from a fermented solid medium of the Thailand mangrove-derived Streptomyces strain, OUCMDZ-5511, under fluoride stress. Compounds 2−5, 12, and 15 were exclusively present in the fluoride-supplemented fermentation medium, while compounds 7−9, 13, and 14 were newly discovered natural products. The molecular structures of the compounds were identified by a spectroscopic analysis. The new compound 2 displayed antiquorum sensing activity against Chromobacterium violaceum ATCC 12472 by reducing the violacein production and inhibiting the biofilm formation in a concentration-dependent manner. The study revealed that compound 2 could be a novel potential inhibitor of quorum sensing.

Bromine/Sulfur-Substituted 9H-Carbazoles Produced by the Marine-Derived Streptomyces sp. OUCMDZ-5511 upon NaBr Exposure

“…The molecular formula was thus established as C 13 H 10 BrNO, corresponding to seven degrees of unsaturation. The UV (Figure S6) and NMR spectra, including both 1 H and 13 C (Figures S7 and S8, Table ), were similar to those of 1-chloro-4-methoxy-9 H -carbazole, identifying compound 1 as a carbazole analogue. The distinction lies in the disubstituted carbazole’s benzene ring, evidenced by the chemical shifts’ change and the HMBC correlations (Figures and S11) from methoxy protons (δ H 3.89) to C-3 (δ C 148.9), one of the two ortho -coupled protons (δ H 7.48, H-1) to C-3 and C-4a (δ C 121.7), and another (δ H 7.26, H-2) to C-4 (δ C 104.3) and C-9a (δ C 135.8).…”

“…The actinobacterial strain OUCMDZ-5511 was isolated from Thai mangrove soil and identified as Streptomyces sp. by 16S rRNA gene sequence and morphological characteristics …”

“…To further investigate the influence of halide salt stress on microbial secondary metabolites, − the halotolerant strain Streptomyces sp. OUCMDZ-5511, originally isolated from mangrove sediments and known for metabolizing chlorinated carbazole derivatives with anti-quorum sensing (QS) activity under NaF stress, was cultured in media containing NaBr. Ethyl acetate (EtOAc) extracts of the fermentation media were tested for anti-inflammatory properties using a CuSO 4 -induced zebrafish model .…”