Two novel β-diketones, 2,6,9-trimethyl-8-decene-3,5-dione (A) and 3,7,10-trimethyl-9-undecene-4,6-dione (B), were identified from the renowned medicinal plant Hypericum perforatum L. The structures of β-diketones A and B were corroborated by syntheses (4 steps starting from methyl acetoacetate,
Investigation of the methanolic extract from the aerial parts of Hypericum yezoense resulted in the isolation of three new acylphloroglucinols, yezo'otogirins D-F (1-3), and two new meroterpenes, yezo'otogirins G (4) and H (5). The structures of 1-5 were assigned on the basis of spectroscopic data.