The structure of gephyrotoxin (GTX) 223AB

Summary The structure 3-butyl-5-propylindolizidine (2), tentatively assigned to a minor alkaloid in skin extracts from a number of poison frogs of the Neotropical genusDendrobates, has been confirmed and its stereochemistry determined as 5E, 9E (2d) by comparison on GC and GC-MS with the four synthetic diastereomers2a-2d.     

Enzymatic oxidation of xanthobilirubic acid

Summary Xanthobilirubic acid (XBR) undergoes enzymatic oxidation in the presence of horseradish peroxidase and tertbutyl hydroperoxide to give cleanly methylethylmaleimide (1) and 5-formyl-2,4-dimethyl-1H-pyrrole-3-propanoic acid (2).The authors wish to thank the National Science Foundation (NSF CHE 79-10133) and the National Institute of Child Health (HD 09026) for generous support of this work.     

Annonacin,a novel,biologically active polyketide fromAnnona densicoma

Summary A new linear polyketide, Annonacin (I), has been isolated from active extracts of the stembark ofAnnona densicoma Mart. Annonacin (I) is highly cytotoxic and is active in an assay designed to detect antimitotic agents. The structure of (I) was determined by analysis of spectroscopic data.25 September 1986     

Observations on the toxicity and metabolic relationships of polygodial,the chemical defense of the nudibranchDendrodoris limbata

Summary Polygodial (1), the defense metabolite stored in the skin of the nudibranchDendrodoris limbata, is toxic for the mollusc itself when injected into the hepatopancreas. Biosynthetic experiments using labeled mevalonic acid were devised to investigate a possible metabolic relationship between1 and the mixture of sesquiterpenoidic esters2, stored in the hepatopancreas. The results suggest that1 and2 are biosynthesized by independent pathways.Thanks are due to G. Villani for supplyingDendrodoris limbata and to A. Trabucco for technical assistance.     

Über die Oxydation ungesättigter Fettsäuren durch Pflanzensäfte

Summary Extracts from various parts, including root nodules, of different leguminous plants, and extracts from leaves of several other plants (belonging toSolanaceae andLabiatae) are able to accelerate efficiently the oxidation of unsaturated fatty acids.     

Anthraquinone pigments from a conidiating mutant ofTrichoderma viride

Summary Two pigments responsible for the yellow-orange color of a brown conidiating mutant of the deuteromyceteTrichoderma viride were isolated and spectroscopically identified as 1,3,6,8-tetrahydroxyanthraquinone (I) and 1-acetyl-2,4,5,7-tetrahydroxy-9,10-anthracenedione (II). Both compounds are known substances but were not yet reported as metabolites of this fungal species. Their relationship to other anthraquinones produced byT. viride is discussed.Dedicated to Dr Z. Vanek, on the occasion of his 60th birthday.Upper case letters denote multiplicity arising from the directly bonded protons, lower case letters that from the geminal and vicinal couplings.     

Guggulsterol-like steroids from the Mediterranean gorgonianLeptogorgia sarmentosa

Summary Several polyoxygenated steroids (1, 2, 3) have been isolated from the marine gorgonianLeptogorgia sarmentosa. One of these (1) is the known guggulsterol III, previously found in the pharmacologically active resin from the treeCommiphora mukul; the others,2 and3, have not been found before in nature, and are closely related to1. During the structural work apparent anomalies in the CMR-spectra of1 were observed.The authors are grateful to Prof. Sukh Dev for the PMR-spectra of guggulsterol III. Thanks are also due to Zoological Station (Naples), for the collection of the gorgonian, to Centro Metodologie Chimico-Fisiche, Università di Napoli, for recording PMR-spectra on WH-270 Superconducting Spectrometer-Bruker, to Mr C. Di Pinto for the CMR-spectra and to Mr A. Milone for the MS spectral measurements.     

Goniothalamicin and annonacin: Bioactive acetogenins fromGoniothalamus giganteus (Annonaceae)

Summary Using brine shrimp lethality for activity-directed fractionation, goniothalamicin (I), a new tetrahydroxy-mono-tetrahydrofuran fatty acid -lactone (acetogenin), has been isolated from ethanolic extracts of the stem bark ofGoniothalamus giganteus Hook. f., Thomas (Annonaceae). This novel compound was found to be cytotoxic and insecticidal and inhibited the formation of crown gall tumors on potato discs. Annonacin (II), the only other reported mono-tetrahydrofuran acetogenin, was also isolated; the previously reported 9ASK (astrocytoma reversal) activity ofII was confirmed, andII is now also found to be weakly active against 3PS murine leukemia.     

The antifertility action ofa-chlorohydrin: Enzyme inhibition bya-chlorohydrin phosphate

Summary Preparations of the enzymes glyceraldehyde-3-phosphate dehydrogenase and triosephosphate isomerase are shown to be inhibited bya-chlorohydrin phosphate (II) in a competitive and non-competitive manner, respectively.a-Chlorohydrin (I), glycidol and epi-chlorohydrin have no inhibitory activities suggesting that their antifertility actions are due to their metabolism in vivo toa-chlorohydrin phosphate.     

Glycogen contents in the rat uterus: Response toHibiscus rosa-sinensis Linn. extracts

Summary Ethanolic extracts (50%), as well the benzene extracts, ofH. rosa-sinensis Linn. have reduced significantly the glycogen contents in the uterus of adult rat. Both the extracts exhibit a clear-cut dose-response relation. The inhibition in glycogen contents increases as the dose is increased. Of the 2, benzene extract seems to be more potent. The results are due to antiestrogenic nature of the extracts.This investigation was supported by a grant from Council of Scientific & Industrial Research, New Delhi.     

Biotransformation of the flavonoid tiliroside to 7-methylether tiliroside: bioactivity of this metabolite and of its acetylated derivative

Incubation of kaempferol-3-O-β-D-(6"-E-p-coumaroyl)-glucopyranoside (tiliroside) (1) with Aspergillus nidulans gives the 7-methyl ether of tiliroside (2) which is a new compound. Its structure is determined by spectroscopic methods. Cytotoxic studies of 2 and of its acetylated derivative 2a were carried out in vitro against fourteen human leukemic cell lines. Results clearly show that compound 2 is ineffective against all leukemic cell lines tested. On the contrary, compound 2a exhibited cytotoxic activity against four of the cell lines (HL60, DAUDI, HUT78 and MOLT3) and additionally, a dose- and time-dependent effect on DNA synthesis. Received 18 February 1997; received after revision 8 April 1997; accepted 6 May 1997     

Research Articles¶Naturally occurring 2′-O-methylpurine nucleosides with hypotensive properties

2′-O-Methylinosine (1) has been isolated for the first time and shown to be an intrinsic hypotensive principle. Its probable in vivo precursor, 2′-O-methyladenosine (3), showed stronger and even orally potent hypotensive activity. Resistance of the methyladenosine (3) against adenosine deaminase is thought to contribute to its long-lasting activity. The effect of both nucleosides (1 and 3) was not accompanied with any significant change in heart rate, which is often observed with adenosine. Received 2 October 1997; accepted 28 October 1997     

Antimutagenic unusual amino acids from plants

Summary Five unusual amino acids were identified as antimutagens against spontaneous mutation ofSalmonella typhimurium TA100: L-azetidine-2-carboxylic acid (1) from Liliaceae plants, -(methylenecyclopropyl)glycine (2) fromLitchi chinensis seeds, and 2-amino-4-methylhex-5-ynoic acid (3), hypoglycin A (4), and (2S, 4R)-2-amino-4-hydroxyhept-6-ynoic acid (5) fromEuphoria longana seeds. The absolute stereochemistry of5 was determined by its chiral synthesis from L-allylglycine, proving that5 is the C-4 epimer of the amino acid previously isolated from dried longan seeds.This work was partly supported by a Grant-in-Aid form the Ministry of Education, Science, and Culture, Japan, No. 57740283 (to HK).     

The status of blue-green bile pigments of butterflies,and their phototransformations

Summary Blue-green bile pigments are found in adults or larvae of many species of butterfly. They are reviewed here. In contrast to the presence of biliverdin IX 1 in some insect species, many Lepidoptera contain pterobilin2 (biliverdin IX ), phorcabilin3, and sarpedobilin4, derived from2 by cyclization. Pigments3 and4 are members of a new natural family of heterocyclic systems which can also be obtainedin vitro from2, by irradiation under visible light. This review presents the information so far available about the chemistry and biochemistry of these pigments, together with a discussion about the possible biological significance of their photosensitivity.Acknowledgments. Thanks are due to Prof. D.H.R. Barton, E. Lederer and J. Bergerard, for their interest and for discussions.     

Structure of two biologically active sesquiterpenoid amino-quinones from the marine spongeDysidea avara

Summary The structures of 2 minor constituents of the marine spongeDysidea avara, which induce developmental aberrations in sea-urchin eggs, are described. The structures were confirmed also by a simple synthesis from avarol (1).Acknowledgments. The authors wish to thank Mr A. Crispino for his skillfull laboratory technical assistance. Thanks are also due to Mr C. Di Pinto (NMR) and Mr A. Milone (MS).     

Zur Stereochemie der Propandioldehydrase-Reaktion

Summary Propanedioldehydrase is shown to convert both (+)-(S)-2-²H-propanediol,3, and (–)-(R)-1-²H₂-propanediol,5, to specimens of deuterated propion-aldehyde, for which the (S)-configuration has been established. Thus, in the propanedioldehydrase reaction migration of hydrogen atoms from C–1 to C–2 always occurs with inversion of configuration.     

Über die Aktivität der Tyrosinase in Tabaksamen

Summary Water or buffered extracts from tobacco seeds (Mont Calme brun) showed both cresolase and catecholase activity of tyrosinase, which was inhibited by 10^–2 M thiourea. No difference of activity could be observed in extracts from old and fresh seeds. Unexpectedly, chlorogenic acid is not oxidized by this tyrosinase.     

On the synthesis of serine and homoserine samples asymmetrically labelled with tritium and deuterium in the hydroxymethylene group

Summary (1 R) [1-³H,²H₁] 3-Phenylpropanol, the key intermediate in the synthesis of (4 R) [4-³H,²H₁] D, L-homoserine and of the (4 S)-isomer, is obtained from (1 S) [1-²H₁] 3-phenylpropanol and (1 RS) [1-³H] ethanol upon incubation with yeast alcohol dehydrogenase and NAD⁺; under similar conditions 2-phenylethanol undergoes very small exchange with [1-²H₂] ethanol.     

6,10,14-Trimethylpentadecan-2-one and 6,10,14-trimethyl-5-trans, 9-trans, 13-pentadecatrien-2-one from the androgenic glands of the male crab Carcinus maenas

Summary 2 C₁₈ isoprenoid ketones, hexahydrofarnesylacetone (1) and farnesylacetone (2) have been identified for the first time in lipid extracts from the androgenic glands of the male crab Carcinus maenas, using coupled gas chromatography-mass spectrometry. The 2 compounds prepared by synthesis, are biologically active, inhibiting the incorporation of³H-leucine in Crustaceans ovaries subcultures.We wish to thank Professors H. Charniaux-Cotton and E. Lederer for their permanent interest in this work.     

Cortinarins inCortinarius speciosissimus? A critical revision

Summary Fluorescent cyclic decapeptides, the so-called cortinarins, have been claimed to cause the toxicity of the deadly poisonous mushroomCortinarius speciosissimus. As the structure elucidation described in the literature is doubtful in decisive parts, the proposed structures must be disputed. The present study demonstrates that the fluorescence is mainly due to ergosta-4,6,8 (14),22-tetraen-3-one (8) and to photodecomposition products of the nephrotoxin orellanine (1). Moreover, we were not able to reproduce the isolation of fluorescent or any other cyclic peptides related to cortinarins fromC. speciosissimus, by various methods.