Synthesis of syn-4,6-dimethyldodecanal, the male sex pheromone and trail-following pheromone of two species of the termite Zootermopsis.

Recently, we reported that syn-4,6-dimethyldodecanal is the male sex pheromone and the trail-following pheromone of the Termopsidae Zootermopsis nevadensis and Zootermopsis angusticollis. In this article, we describe the syntheses of the mixture of the four stereoisomers of 4,6-dimethyldodecanal using a synthetic pathway where the key step is a Wittig reaction between methyl 4-methyl-5-oxo-pentanoate and 1-methylheptyl-triphenylphosphonium iodide, and of (±)-syn-4,6-dimethyldodecanal starting from 3,5-dimethyl-2-cyclohexen-1-one. Direct GC-MS comparison of these synthetic samples with the natural pheromone allowed its unambiguous identification.

New calamenene sesquiterpenes from Tarenna madagascariensis.

Four calamenene sequiterpenes, (+)-(7R,10S)-15-hydroxycalamenene (3), (+)-(7R,10S)-2,15-dihydroxycalamenene (4), (+)-(7R,10S)-2-hydroxy-15-calamenal (5), (+)-(7R,10S)-15-calamenal (6), along with the amorphane sesquiterpene (+)-(1S,6R,7R,10S)-1-hydroxy-3-oxo-amorph-4-ene (16), have been isolated from the Madagascan shrub Tarenna madagascariensis (Rubiaceae) and their structures determined by spectroscopic methods and chemical correlations. Furthermore, five known related sesquiterpenes [(+)-(7R,10S)-2-hydroxycalamenene (1), (+)-(7R,10S)-3-hydroxycalamenene (2), (-)-alpha-cadinol (13), cadinenal (14), 6-epicadinenal (15)], and three known lignans [(-)-hinokinin, (-)-dihydrocubebin, (-)-cubebin] were also isolated from the same plant. This is the first report of compounds 3, 4, 5, 6, and 16 from a natural source.

New terpenoids from two Indonesian marine sponges.

A C16 norsesterterpenoid (euplectellodiol, 1) and a norditerpenoid (2) have been isolated from the marine sponges Mycale euplectelloides and Diacarnus megaspinorhabdosa, respectively. Their structures have been determined by spectroscopic methods. Compounds 1 and 2 are new natural products.

Trinervitene diterpenes from soldiers of two Nasutitermes species from French Guyana.

Methanolic extracts of soldiers of Nasutitermes guayanae and N. surinamensis have been shown to contain complex mixtures of diterpenes and monoterpenes. Eighteen diterpenes have been isolated and identified; twelve of them are previously known nasute termite diterpenes, while six are new trinervitene diterpenes. 2alpha,9beta-Dihydroxy-3beta,8beta-oxido-1(15)-trinervitene has been isolated from N. guayanae, while 3alpha,14alpha-diacetoxy-2beta-hydroxy-1(15),8(19),9-trinervitatriene, 14alpha-acetoxy-2beta,3alpha-dihydroxy-1(15),8(19),9-trinervitatriene, 2beta,3alpha-diacetoxy-11beta,14alpha-dihydroxy-1(15),8(19)-trinervitadiene, 9alpha,14alpha-diacetoxy-2beta,3alpha-dihydroxy-1(15),8(19)-trinervitadiene, and 2beta,9alpha,14alpha-triacetoxy-3alpha-hydroxy-1(15),8(19)-trinervitadiene have been isolated from N. surinamensis. Their structures were determined on the basis of their spectroscopic properties.

A new C-20 polyacetylene from the sponge Callyspongia pseudoreticulata.

The Indonesian marine sponge Callyspongia pseudoreticulata was found to contain (3S,18S,4E,16E)-eicosa-1,19-diyne-3,18-diol-4,16-diene (1), the structure of which was determined by detailed spectroscopic analysis. Its absolute configuration was established using the modified Mosher's method after esterification of the secondary alcohols with Mosher's reagent.

Cytotoxic pentacyclic triterpenes from Combretum nigricans.

A new pentacyclic triterpene, 11alpha-acetoxy-20,24-epoxy-25-hydroxy-dammar-3-one (1), has been isolated from the African tree Combretum nigricans, together with the known corresponding diol, 20,24-epoxy-11alpha, 25-dihydroxy-dammar-3-one (2). They are responsible, at least in part, for the cytotoxic activity of the methanolic extract of the plant.

Cellular location of (2R, 3R, 7Z)-2-aminotetradec-7-ene-1, 3-diol, a potent antimicrobial metabolite produced by the Caribbean sponge Haliclona vansoesti.

The Caribbean sponge Haliclona vansoesti has been found to contain large amounts of a new sphingosine derivative, (2R, 3R, 7Z)-2-aminotetradec-7-ene-1, 3-diol (compound 1). To determine the localization of this compound within the organism, cell distribution and quantitative determination of the aminodiol content of cell fractions obtained by differential centrifugation have been performed. Results show that choanocytes and archaeocytes are the major sponge cell types and that H. vansoesti harbour small photosynthetic symbionts (cyanobacteria) and few heterotrophic bacteria. Reverse-phase HPLC analyses of the cell fractions reveal that the aminodiol 1 is not associated with the prokaryotic endobionts but with the sponge cells, in particular the archaeocytes. This is clearly established by the positive significant correlation existing between the numbers of archaeocytes and the amounts of aminodiol 1. The mean aminodiol concentration is estimated to be 2 microg/10(5) archaeocytes. The aminodiol 1 is also found in substantial amounts in primary cell cultures, so that cell culture can be envisaged as an option for its production. Sponge cell suspensions display potent antibacterial and antiyeast activities, in correlation with their aminodiol content, indicating that this compound is at least in part responsible for these activities in the sponge. The release of the aminodiol I into the external medium suggests that this substance may be involved in the defence mechanisms of the sponge.

Absolute configuration of anabasine from Messor and Aphaenogaster ants.

A method has been developed to assign the absolute configuration and enantiomeric excess of anabasine based on small amounts of material (in the microgram range), by derivatization with (+)-menthylchloroformate followed by capillary GC analysis of the resulting carbamate(s). This method was applied to three samples of anabasine isolated from Messor and Aphaenogaster ants. In Messor sanctus, only (2'S)-anabasine was present, whereas in Aphaenogaster subterranea and A. miamiana (2'S)-anabasine was determined to have an ee of 78 and 24%, respectively.

Triterpene saponins, quaternary ammonium compounds, phosphatidyl cholines, and amino acids in the pronotal and elytral secretions of Platyphora opima and Desmogramma subtropica.

Secretions of the pronotal and elytral glands of adults of the chrysomelid beetle Platyphora opima from Panama have been shown to contain two oleanane triterpene saponins: the known 3-O-beta-D-glucopyranosyl-(1-->3)-beta-D-glucuronopyranosyl-oleano lic acid-28-O-beta-D-glucopyranoside and compound 1, whose structure was established as 3-O-beta-D-glucopyranosyl-(1-->3)-beta-D-glucuronopyranosyl-29- hydrox yoleanolic acid-28-O-beta-D-glucopyranoside by a combination of 1D and 2D NMR methods (COSY, HMQC, HMBC, and TOCSY) and FABMS. The secretions also contained N,N,N-trimethylcadaverine and its 1, 2-dehydro derivative 3, as well as the nicotinamide derivative 4. Secretions of Desmogramma subtropica, also from Panama, contained as sole triterpene derivative 3-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucuronopyranosyl-24- hydrox yoleanolic acid (2), together with glutamic acid, glutamine, pyroglutamic acid, and arginine. A mixture of phosphatidylcholines was also present in the secretions of both species.

(2R,3R,7Z)-2-Aminotetradec-7-ene-1,3-diol, a new amino alcohol from the caribbean sponge Haliclona vansoesti.

The Caribbean marine sponge Haliclona vansoesti was found to contain a high amount (5% dry wt) of a new analogue of 4-sphingenine, (2R,3R, 7Z)-2-aminotetradec-7-ene-1,3-diol (1). Its structure was determined by detailed spectroscopic analysis. The relative configuration was deduced from the NMR data of the corresponding acetonide 5, while the absolute configuration was secured via protection of the primary alcohol and amino groups, and esterification of the secondary alcohol with Mosher's reagent.

Triterpene saponins in the defensive secretion of a chrysomelid beetle, Platyphora ligata.

The secretion of the defensive glands of adults of the chrysomelid beetle Platyphora ligata from Panama has been shown to contain, besides chlorogenic acid (1) and a mixture of phosphatidylcholines, two new oleanane triterpene saponins, named ligatosides A and B. Their structures were established as 3-O-beta-D-glucuronopyranosyl-16alpha,23-dihydroxyoleanol ic acid-28-O-2-(3,4-dimethoxybenzoyl)-beta-D-glucopyranoside (2) and 3-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucuronopyranosyl-16a lpha, 23-dihydroxyoleanolic acid-28-O-2-(3, 4-dimethoxybenzoyl)-beta-D-glucopyranoside (3), respectively, by a combination of extensive 1D and 2D NMR methods (COSY, HMQC, HMBC, and TOCSY) and FABMS. This is the first report of triterpene saponins in the defensive secretion of an insect.

New sesquiterpene/quinones from two sponges of the genus Hyrtios.

Two sponges of the genus Hyrtios have been found to contain new sesquiterpene/quinones identified by detailed spectroscopic analysis. Four new compounds with a 4,9-friedodrim-3-ene skeleton [hyrtiophenol (2), 5-epihyrtiophenol (3), 18-hydroxy-5-epihyrtiophenol (4), and 18-hydroxyhyrtiophenol (5)] were isolated from Hyrtios sp. (Seychelles Islands) along with isospongiaquinone (1). Moreover, the new compound 21-hydroxy-19-methoxyarenarone (8), which bears the 4, 9-friedodrim-4(15)-ene skeleton, was isolated from Hyrtios tubulatus (Curaçao) along with arenarol (6) and 5-epiilimaquinone (7). Assignment of the (13)C NMR signals of four types of 4, 9-friedodrimene skeletons found in sponges is presented.

Novel polycyclic guanidine alkaloids from two marine sponges of the genus Monanchora.

Two marine sponges of the genus Monanchora (Poecilosclerida, Crambeidae) have been found to contain new polycyclic guanidine alkaloids bearing the (5,6,8b)-triazaperhydroacenaphthylene skeleton. Their structures have been determined by detailed spectroscopic analysis. Dehydrobatzelladine C (1) has been isolated from M. arbuscula and crambescidins 359 (2) and 431 (3) from M. unguiculata. The chemotaxonomic implications of these findings are discussed.

First report on the identification of microcystin in a water bloom collected in Belgium.

A toxic cyanobacterial bloom dominated by Microcystis aeruginosa occurred in 1995 in three adjacent ponds near Liège (Belgium) where at the same time conspicuous bird deaths were observed. The toxicity assay using primary rat hepatocytes indicated a high hepatoxicity. A 4 h incubation yielded a LD50 of 0.23 mg bloom material (dry weight)/ml cell culture medium. Toxicity was due to hepatotoxins of the microcystin class, microcystin-LR and-RR being the major microcystins present as determined by RP-HPLC absorption spectra, 1H NMR, and ESMS spectra. Additionally, the bloom sample contained small amounts of microcystin-YR. The microcystin content of the dry bloom biomass was 870 micrograms/g (on the basis of the hepatotoxicity assay) and 556 micrograms/g (on the basis of the RP-HPLC peak area). A higher yield of microcystins was obtained by acetic acid extraction instead of methanol extraction, whereas different extraction temperatures (20 degrees C, 40 degrees C) had no effect on the yield.

New polyketides from the sponge Plakortis sp.

Fractionation of the MeOH extract of the sponge Plakortis sp. collected around the Amirantes Islands yielded four novel polyketides (4-7). The structures have been established by a detailed highfield 2D NMR study.

The Na+-I- cotransporter of the thyroid: characterisation of new inhibitors.

New inhibitors of the Na+-I- cotransporter of the thyroid in bovine thyroid slices and in bovine plasma membrane vesicles have been investigated. They include: (1) econazole; (2) 5-(N,N-hexamethylene)amiloride (HMA); and (3) dysidenin. In both systems, the kinetics of iodide transport yielded apparent Km values of 39 and 14 microM respectively. The possible interaction of each of these inhibitors with the iodide site of the Na+-I- cotransporter was tested by performing detailed transport kinetics analysis at varying iodide concentrations and at 150 mM NaCl. Econazole induced a non-competitive inhibition while dysidenin and HMA gave a mixed type of inhibition. The Ki values for dysidenin and econazole, computed from Dixon plots, were 5 and 2 microM respectively while the Ki value for HMA could not be determined. Each inhibition was reversible, indicating the absence of covalent binding of the inhibitor to the Na+-I- cotransporter.

Biosynthesis and metabolism of 2-iodohexadecanal in cultured dog thyroid cells.

2-Iodohexadecanal (2-IHDA) is a major thyroid iodolipid. It mimics the main regulatory effects of iodide on thyroid metabolism: inhibition of H2O2 production and of adenylyl cyclase. The biosynthesis of 2-IHDA and its metabolism have been investigated in cultured dog thyroid cells maintained in a differentiated state by forskolin. Incubation of these cells with [9,10-3H]hexadecan-1-ol or [9,10-3H]palmitic acid labeled several phospholipids, but [9, 10-3H]hexadecan-1-ol was selectively incorporated into plasmenylethanolamine. In the presence of an exogenous H2O2 generating system (glucose oxidase), iodide induced the production of [9,10-3H]2-IHDA from [9,10-3H]hexadecan-1-ol-labeled cells but not from [9,10-3H]palmitic acid-labeled cells. 2-IHDA was also generated during the lactoperoxidase-catalyzed iodination of brain and heart plasmalogens, and of ethyl hexadec-1-enyl ether, a synthetic vinyl ether-containing compound. Taken together, these results show that thyroid 2-IHDA is derived from plasmenylethanolamine via an attack of reactive iodine on the vinyl ether group. 2-Iodohexadecan-1-ol (2-IHDO) was also detected in these studies; it was formed later than 2-IHDA, and thyroid cells converted exogenous 2-IHDA into 2-IHDO in a time-dependent way. The ratio of 2-IHDO/2-IHDA increased with H2O2 production and decreased as a function of iodide concentration. An aldehyde-reducing activity was detected in subcellular fractions of the horse thyroid. No formation of 2-iodohexadecanoic acid could be detected. Reduction into the biologically inactive 2-IHDO is thus a major metabolic pathway of 2-IHDA in dog thyrocytes.

Inhibition of human thyroid adenylyl cyclase by 2-iodoaldehydes.

2-Iodohexadecanal (IHDA), which can be formed upon addition of iodine to the vinyl ether group of plasmalogens, has been identified as a major thyroid iodolipid (Pereira et al. (1990) J. Biol. Chem. 265, 17018-17025). In this study, we have investigated the possibility that it would be a mediator of the inhibitory effect of iodide on thyroid adenylyl cyclase. In human thyroid membranes, IHDA inhibited the adenylyl cyclase activity stimulated by thyrotropin (TSH), GTP-gamma-S or forskolin (FSK), whereas it did not decrease the specific binding of TSH to its receptors. The inhibitory effect on the cyclase reached a maximum after a 1-h-pre-incubation of the membranes with IHDA at 30 degrees C and was poorly reversible. It was also observed following a 4-h incubation with IHDA at 4 degrees C, a condition in which adenylyl cyclase is protected against heat inactivation. IHDA decreased the Vmax of adenylyl cyclase, but had no effect on the Km for ATPMg2-.IHDA also inhibited the FSK-stimulated adenylyl cyclase activity in liver and kidney cortex membranes, but had no effect on the Mg(2+)-ATPase activity of thyroid membranes. The inhibitory effect of IHDA has also been demonstrated in intact cells. As in membranes, IHDA decreased the rise in cAMP induced by TSH in cultured dog thyroid cells and this inhibition was maintained following pretreatment of the cells with pertussis toxin. In order to evaluate the specificity of the IHDA action, various analogs have been synthesized. This study has permitted the identification of two major structural features required for the inhibition of human thyroid adenylyl cyclase; the terminal aldehyde function and an iodine atom at C2, other halogens being ineffective. In conclusion, we have shown that IHDA exerts a direct inhibitory effect at or near adenylyl cyclase; all the properties of this effect characterized so far are identical to those of the adenylyl cyclase inhibition obtained following the exposure of thyroid tissue to iodide.

Inhibition of H2O2 production by iodoaldehydes in cultured dog thyroid cells.

2-Iodohexadecanal (IHDA) has been identified as a major thyroid iodolipid which can be formed upon addition of iodine to the vinyl ether group of plasmalogens (Pereira et al., 1990). In order to test whether IHDA plays a role in the thyroid autoregulation by iodide, we have investigated its effects on the production of H2O2 by cultured dog thyroid cells. IHDA inhibited the formation of H2O2 in dog thyroid cells stimulated by carbamylcholine (CCHOL). In the presence of BSA, which potentiated its action, the effect of IHDA was maximal after 2 h and had an IC50 around 5 microM. The effect of IHDA was not decreased by methimazole, which abolished the inhibition by iodide. IHDA also inhibited the stimulatory effect of bradykinin, but had only a marginal effect on the production of H2O2 induced by ionomycin or phorbol 12-myristate 13-acetate (PMA). The accumulation of inositol phosphates in CCHOL-stimulated thyroid cells was decreased by IHDA. As evaluated by measurements of 51Cr release and [3H]thymidine incorporation into DNA, IHDA had no adverse effect on thyroid cell viability. Several analogs of IHDA, of which the synthesis is described, have been tested for their inhibitory activity. This allowed the identification of two major structural features required for the biological activity: the carbonyl group at C1 and an halogen atom at C2, with iodine conferring a greater activity than bromine, while chlorine and fluorine were inactive. In conclusion, IHDA inhibits the production of H2O2 in CCHOL-stimulated dog thyroid cells by decreasing the phospholipase C cascade activity. This effect involves both the aldehyde function and the iodine atom. These results suggest that IHDA might be the mediator of some of the regulatory actions of iodide on the thyroid gland.