ABSTRACT
Analysis of an antimicrobial culture broth extract of the sponge-derived actinomycete Streptomyces sp. (strain G246) led to the isolation of two new lavandulylated flavonoids, 6-lavandulyl-7-methoxy-5,2',4'-trihydroxylflavanone (1) and 5'-lavandulyl-4'-methoxy-2,4,2',6'-tetrahydroxylchalcone (2), along with eight known compounds 3-10. Their structures were established by spectral data analysis, including MS, 1D, 2D-NMR and CD. The absolute configurations of 1 and 2 were suggested by comparison of their experimental and calculated electronic circular dichroism spectra. All the isolated compounds were evaluated for their antimicrobial activity against a panel of clinically significant microorganisms. Compounds 1 and 2 had a broad-spectrum of antimicrobial activity. Additionally, except the strain Escherichia coli, compound 2 exhibited remarkable inhibitory activity against Pseudomonas aeruginosa, Salmonella enterica, Enterococcus faecalis, Staphylococcus aureus, Bacillus cereus, and Candida albicans strains.
Subject(s)
Anti-Infective Agents/isolation & purification , Flavonoids/isolation & purification , Porifera/microbiology , Streptomyces/chemistry , Actinomycetales/chemistry , Animals , Anti-Infective Agents/chemistry , Anti-Infective Agents/pharmacology , Bacillus cereus/drug effects , Candida albicans/drug effects , Enterococcus faecalis/drug effects , Escherichia coli/drug effects , Flavonoids/chemistry , Flavonoids/pharmacology , Microbial Sensitivity Tests , Pseudomonas aeruginosa/drug effects , Staphylococcus aureus/drug effectsABSTRACT
Three new lavandulylated flavonoids, (2S,2''S)-6-lavandulyl-7,4'-dimethoxy-5,2'-dihydroxylflavanone (1), (2S,2''S)-6-lavandulyl-5,7,2',4'-tetrahydroxylflavanone (2), and (2''S)-5'-lavandulyl-2'-methoxy-2,4,4',6'-tetrahydroxylchalcone (3), along with seven known compounds 4-10 were isolated from culture broth of Streptomyces sp. G248. Their structures were established by spectroscopic data analysis, including 1D and 2D nuclear magnetic resonance (NMR), and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). The absolute configurations of 1-3 were resolved by comparison of their experimental and calculated electronic circular dichroism spectra. Compounds 1-3 exhibited remarkable antimicrobial activity. Whereas, two known compounds 4 and 5 exhibited inhibitory activity against Mycobacterium tuberculosis H37Rv with minimum inhibitory concentration (MIC) values of 6.0 µg/mL and 11.1 µg/mL, respectively.