Michel Kaisin

Terpenoids—LXXI: Chemical studies of marine invertebrates—XIV. Four representatives of a novel sesquiterpene class—the capnellane skeleton

Abstract The isolation and complete structure determination of four marine sesquiterpenoids: Δ 9(12) -capnellene-8β,10α-diol ( 1 ), Δ 9(12) -capnellene-3β,8β,10α-triol ( 3 ), Δ 9(12) -capnellene-5α,8β,10α-triol ( 5 ), Δ 9(12) -capnellene-2ξ,8β,10α-triol ( 7 ) from the soft coral Capnella imbricata is described. These alcohols are the first members of a fundamentally new sesquiterpene class consisting of three 5-membered fused rings which we have named capnellane (A).

Ichthyotoxic sesterterpenoids from the neo guinean sponge carteriospongia foliascens

Abstract Six 20,24-dimethylscalarane derivatives ( 5 , 12 , 15 , 17 , 19 , and 21 ) have been isolated from the Neo Guinean sponge Carteriospongia foliascens. Compound 12 is identical with a C27 tetracyclic terpene previously isolated from an Australian specimen of the same sponge. The five other derivatives are new and their structures have been established on the basis of their spectral data. The structure of 5 was confirmed by single-crystal X-ray diffraction and that of 15 by chemical correlation with 12 . The configuration at C-4 for all these compounds has been determined through 13C NMR data. Evidence leading to reverse the configuration at this centre in previously reported C27 tetracyclic terpenes is discussed. An ecological function is suggested for these molecules.

Novel acetoxycapnellenes from the alcyonacean Capnella imbricata

Abstract The isolation of eight novel acetylated capnellenes (2,4,6,9,10,16,21 and 22) by acetone extraction of fresh colonies of C. imbricata is described. They are the major sesquiterpenes present in the living animal. The previously reported capnellene polyols, isolated by CH2Cl2 or hexane extraction of sun-dried colonies, are shown to be artifacts, produced by (a) substrate-specific hydrolase(s) present in the soft coral. The hydrolase containing fraction is also able to catalyze the transfer of acetyl groups from several alkyl acetates to the capnellene polyols.

Study of complex marine sterol mixtures by mass-analyzed ion kinetic energy spectrometry.

Mass-analyzed ion kinetic energy spectrometry (MIKE) is shown to be an efficient and rapid method for the analysis of complex sterol mixtures. The method has been applied to the study of the free sterol fractions of five marine and one freshwater invertebrates.

Host plant influence on the composition of the defensive secretion of Chrysomela vigintipunctata larvae (Coleoptera: Chrysomelidae)

Abstract Phenolic glucosides from willow leaves are used by Chrysomela vigintipunctata larvae as precursors of salicylaldehyde produced in the defensive secretion. When these larvae were fed on different Salix species with high to moderate phenolic glucoside content (S. purpurea, S. myrsinifolia, S. fragilis), their defensive secretion mainly contained salicylaldehyde and only traces of other constituents (benzaldehyde and phenylethanol). The volume of secretions was reduced in larvae fed on host plant with low to very low phenolic glucoside content (S. caprea). Salicylaldehyde remained the predominant constituent in most secretions, but in some, (Z)-3-hexen-1-ol, benzaldehyde and phenylethanol, appeared as major constituents besides salicylaldehyde. Quantitative assessments demonstrate that these compounds did not compensate for the reduction in salicylaldehyde as compared with the amount produced when fed on Salix with high phenolic glucoside content. The results are discussed in terms of sequestration ability, defence, and host range observed in nature.

Chemical defense in the three European species ofCrematogaster ants

The composition of the Dufour gland of the antC. scutellaris has been reinvestigated by gas chromatography/mass spectrometry. The major components of the gland are (2E,5E,12Z)-4-oxoheneicosa-2,5,12-trien-1-ol acetate (1a) itsΔ 14 andΔ 16 double bond isomers (1b and1c), and the corresponding (Z,Z)-dienes5a and5b, all containing an acetylated C21 chain. The previously proposed structures1d, 1e, and5c, which are based on an homologous acetylated C23 chain, correspond to minor derivatives present in the gland. Traces of acetylated C19 homologs, tentatively identified as1g-1i, have also been found. The Dufour gland contents of the two other EuropeanCrematogaster species have also been studied.C. auberti is very similar toC. scutellaris in producing mainly1a, 1b and1c, together with the same higher and lower homologs, but it lacks the dienic derivatives5, whereasC. sordidula contains essentially the acetylated C19 compounds1g, 1h, and1i, accompanied by acetylated C17 homologs.

Steroids from starfish

Abstract Starfish Linckia multifora, Protoreaster nodosus, Protoreaster lincki, Culcita schmideliana, Nardoa variolata and Acanthaster planci were examined for sterols and sapogenins. All asteroids contained cholestanol in addition to C 27 to C 30 mono and diunsaturated sterols. A planci contained largest amounts of 5α-cholesta-9(11), 20(22)-diene-3β, 6α-diol-23-one and 5α-pregn-9(11)-ene-3β,6α-diol-20-one whereas P. nodosus, P. lincki and C. schmideliana contained only small amounts. Neither pregnane nor cholestane genins were detected in L. Multifora and N. variolata .

Chemical studies of marine invertebrates. XVI.: Structure and absolute configuration of lobosterol, a novel polyoxygenated sterol from the alcyonacean Lobophytum pauciflorum (coelenterata, octocorallia)☆

Lobosterol [(24S)-24-methylcholestane-3beta,4beta,5beta,25-tetrol-6-one 25 monoacetate] has been isolated from the Alcyonacean Lobophytum pauciflorum. The structural elucidation of this novel polyoxygenated sterol was achieved by chemical and spectroscopic evidence, and by X-ray diffraction analysis.

Study of the mass spectral fragmentation processes in dinitroquinoxalines using tandem methodologies

Following electron ionization, the fragmentations of isomeric dinitroquinoxalines have been investigated making use of tandem mass spectrometry methodologies such as collisional activation (CA), various linked-scanning (LS) experiments, and mass-analyzed ion kinetic energy (MIKE) spectrometry. It was shown that, for the two ortho-dinitroquinoxalines 1 and 2, the most abundant fragment ion at m/z 116 is generated for 1 by successive losses of NO2•, CO, and NO•, whereas for 2, it is the result of two main competing fragmentation routes. The fragmentation of the meta-dinitroquinoxaline 3 differs significantly as an abundant and quite characteristic ion at m/z 127 is the result of consecutive eliminations of NO2• and HNO2. Substitution of the pyrazine ring (for example, compounds 4 and 5) or of the benzene ring (for example, compounds 6 and 7) strongly modifies the reactivity.