Antimicrobial Lavandulylated Flavonoids from a Sponge-Derived Streptomyces sp. G248 in East Vietnam Sea

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 mu g/mL and 11.1 mu g/mL, respectively.