The structures of two new bitter triterpenes, ganoderic acid A and B. isolated from a mushroom Ganoderma lucidum (FR.) Karst. (Polyporaceae) were determined as 1 and 2 on the basis of spectral data. Ganoderic acid A is a novel highly oxidized triterpene bearing a boat‐shaped A‐ring of lanostane.

Two novel A-seco limonoids, dumnin and dumsenin, were isolated from the methanolic extract of Croton jatrophoides by bioassay-guided fractionation, and the structures were determined by nuclear magnetic resonance, circular dichroism, and mass spectrometry experiments. These compounds showed potent antifeedant activity (PC(50)

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A novel A-seco limonoid was isolated from methanolic extract of Croton jatrophoides and designated as zumsin. This compound showed potent antifeedant activity against two lepidopteran larvae, pink bollworm, Pectinophora gossypiella (PC(50) = 1 microg/cm(2), PC(95) = 8 microg/cm(2)), and fall armyworm, Spodoptera frugiperda (PC(50) = 2 microg/cm(2), PC(95) = 16 microg/cm(2)). The structure of zumsin was determined as 1 using a variety of spectroscopic methods including nuclear magnetic resonance, mass spectrometry, and circular dichroism. The structure consists of an A'-B trans-fused ring while dumsin (2), a constituent of the same source, maintains an A'-B cis-fused ring, and suggests two unique biosynthetic processes after A ring oxidative expansion.

Three new A-seco limonoids, zumketol (1), zumsenin (2), and zumsenol (3), were isolated from a methanol extract of Croton jatrophoides by bioassay-guided fractionation, and their structures were determined by NMR analysis. The alpha-ketol 1 may be biosynthesized via the intramolecular acyloin condensation of a dicarboxylate intermediate.

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A large amount of 20-hydroxyecdysone was orally administered to larvae of the tobacco budworm,Heliothis virescens, in order to investigate its detoxification mechanisms. Four major relatively nonpolar metabolites were isolated from their frass. These compounds were identified as the 22-linoleate, 22-palmitate, 22-oleate, and 22-stearate of 20-hydroxyecdysone using various forms of spectroscopy, including NMR. This is the first report of this type of metabolite from an insect.

SummaryThe structures of two new bitter triterpenes, ganoderic acid A and B, isolated from a mushroom Ganoderma lucidum (FR.) KARST. (Polyporaceae) were determined as 1 and 2 on the basis of spectral data. Ganoderic acid A is a novel highly oxidized triterpene bearing a boat-shaped A-ring of lanostane.