Isolation of cyclohumulanoids from Daedaleopsis tricolor and their biosynthesis based on in silico simulations

Abstract

Two protoilludanes tricoprotoilludanone (1) and tricoilludanlactone (2), a cerapicane tricocerapicanol D (3), an illudane tricoilludin D (4), and a ceratopicane tricoceratopicanone A (5) were isolated from Daedaleopsis tricolor along with a spiroaxane tricospiroaxane (6). Density functional theory (DFT)-based 1H and 13C NMR chemical shift studies verified the hypothesized structures. The absolute configurations of 2, 3, 5, and 6 were established by the ECD spectral comparisons with those based on DFT calculations. Although the absolute configurations of 1 and 4 were not directly discussed with the ECD spectra, structural resemblance to other compounds suggested the (11R)-configuration for 1 and 4. The authors hypothesized that protonated a 6,7-α-epoxyprotoilludene biosynthesizes a variety of illudane, cerapicane, and ceratopicane frameworks. These were successfully simulated in silico.