Five secondary metabolites including three flavonoids, 6-lavandulyl-5,7,2′,4′-tetrahydroxyflavanone (1), 5′-lavandulyl-2′-methoxy-2,4,4′,6′-tetrahydroxychalcone (2), 6-lavandulyl-7-methoxy-5,2′,4′-trihydroxyflavanone (3), and two alkaloids, tryptoline (4), and norharman (5) were isolated from the culture broth of Streptomyces sp. C011. Their structures were determined by spectral data analysis, including MS, 2D NMR, and CD spectrum. All the separated compounds were evaluated for their antimicrobial activities. Compounds 1, 2, 3 and 5 exhibited antimicrobial activity. © 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim