Antimicrobial lavandulylated flavonoids from a sponge-derived actinomycete.

Analysis of an antimicrobial culture broth extract of the sponge-derived actinomycete sp. (strain G246) led to the isolation of two new lavandulylated flavonoids, 6-lavandulyl-7-methoxy-5,2',4'-trihydroxylflavanone () and 5'-lavandulyl-4'-methoxy-2,4,2',6'-tetrahydroxylchalcone (), along with eight known compounds -. Their structures were established by spectral data analysis, including MS, 1D, 2D-NMR and CD. The absolute configurations of and 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 and had a broad-spectrum of antimicrobial activity. Additionally, except the strain , compound exhibited remarkable inhibitory activity against , , , , , and strains.