Phytochemical investigation of the polar extracts of the aerial parts of Origanum dictamnus afforded 15 secondary metabolites. One new depside was isolated, to which the trivial name salvianolic acid P (1) was given, in addition to the known depsides rosmarinic acid (2) and rosmarinic acid methyl ester (3), as well as two monoterpenes, thymoquinone (4) and thymoquinol 2-O-beta-glucopyranoside (5); two simple phenolic acids, oresbiusin A (6) and E-caffeic acid (7); six flavonoids, namely, apigenin (8), kaempferol (9), quercetin (10), eriodictyol (11), taxifolin (12), naringenin (13); and two alicyclic derivatives, that is, 12-hydroxyjasmonic acid (14) and its 12-O-beta-d-glucoside (15). The structures of all isolated compounds were established by spectroscopic methods, mainly 1D and 2D NMR, as well as HPLC-DAD-MS and HR-MS spectrometric analyses. The absolute configuration of compound 1 was determined by CD measurements as 7'R, 7''S, 8''S. Compound 1 is interesting as it contains a benzodioxane ring, which is unusual in natural products. Moreover, it has been proved to be active against the Gram-negative clinical strains Acinetobacter hemolyticus , Empedobacter brevis , Pseudomonas aeruginosa , and Klebsiella pneumoniae .