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

Abstract

Three new lavandulylated flavonoids, (2<i>S</i>,2''<i>S</i>)-6-lavandulyl-7,4'-dimethoxy-5,2'-dihydroxylflavanone (<b>1</b>), (2<i>S</i>,2''<i>S</i>)-6-lavandulyl-5,7,2',4'-tetrahydroxylflavanone (<b>2</b>), and (2''<i>S</i>)-5'-lavandulyl-2'-methoxy-2,4,4',6'-tetrahydroxylchalcone (<b>3</b>), along with seven known compounds <b>4</b><b>-</b><b>10</b> were isolated from culture broth of <i>Streptomyce</i>s 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 <b>1</b><b>-</b><b>3</b> were resolved by comparison of their experimental and calculated electronic circular dichroism spectra. Compounds <b>1</b><b>-</b><b>3</b> exhibited remarkable antimicrobial activity. Whereas, two known compounds <b>4</b> and <b>5</b> exhibited inhibitory activity against <i>Mycobacterium tuberculosis</i> H37Rv with minimum inhibitory concentration (MIC) values of 6.0 µg/mL and 11.1 µg/mL, respectively.