<jats:p> Four new dinorsesterterpenoids, designated as trinulactones A–D (1–4), were isolated from the Streptomyces sp. S006 strain. All the compounds contained a tricyclic skeleton, which was attached to a highly oxygenated unsaturated γ-lactone. Their structures were determined by analysis of their spectroscopic data, mainly 1D, 2D NMR and HR-ESIMS data. In particular, compounds 3a/3b and 4a/4b were identified individually as atropisomers.