Shizuko Eguchi

Denticulatolide, an ichthyotoxic peroxide-containing cembranolide from the soft coral Lobophytum denticulatum

Abstract Denticulatolide, an ichthyotoxic cembranoid diterpene bearing acetoxy, α-methylene γ-lactone, and cyclic peroxide functions, has been isolated from the soft coral Lobophytum denticulatum. The structure (1) has been determined by spectral and chemical evidence and X-ray crystallographic method.

Labdane diterpene glycosides with 6-deoxy-L-idose from Aster spathulifolius Maxim.

Abstract Three labdane type diterpene glycosides ( 1 , 2 and 3 ) with 6-deoxy-L-idose have been isolated from Aster spathulifolius Maxim. and their structures have been determined on the basis of chemical and spectral data.

Mass Spectra of Halkendin and Its Derivatives

The mass spectra of 4-methoxy (6), 3, 4-dimethoxy (halkendin) (1), 4-ethoxy-3-methoxy (12) furo(3, 2: 6, 7)coumarin, and their 2, 3 dihydrocompounds (7, 8, 13) are recorded in Figs.1, 3, 4, 6 and 7. The fragmentation is discussed on the basis of high resolution data, metastable ion evidences, and deuterium labelling studies (Tables ltv8 and Figs.2, 5, 9 and 10).The spectrum of halkendin (Z) shows a major breakdown pathway involving initial loss of a methyl radical from Cs methoxy group followed by expulsion of CQ, then successive loss of CO, CH3(C4), and CO(Fig.5).4-Ethoxycoumarin 12 shows Ioss of ethylene om C, side chain giving an ion m/e 232 whose further fragmentation is very similar to that of 4-hydroxycoumarin derivatives (Fig.10). op.It is shown that significant structural information can be obtained from the mass spectra of 3, 4-dialkoxyfurocoumarins.