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This paper analyses the relation between individual migrations and the risk attitudes of other household members when migration is a household decision. We develop a simple model that implies that which members migrate depends on the distribution of risk attitudes among all household members, and that the risk diversification gain to other household members may induce migrations that would not take place in an individual framework. Using unique data for China on risk attitudes of internal (rural-urban) migrants and the families left behind, we empirically test three key implications of the model: (i) that conditional on migration gains, less risk averse individuals are more likely to migrate; (ii) that within households, the least risk averse individual is more likely to emigrate; and (iii) that across households, the most risk averse households are more likely to send migrants as long as they have at least one family member with sufficiently low risk aversion. Our results not only provide strong evidence that migration decisions are taken on a household level but also that the distribution of risk attitudes within the household affects whether a migration takes place and who will emigrate. JEL classification: J61, 015, R23, D81

This paper provides a comprehensive analysis of refugee migration, with emphasis on the current refugee crisis. After first reviewing the institutional framework laid out by the Geneva Convention for Refugees, we demonstrate that, despite numerous attempts at developing a common European asylum policy, EU countries continue to differ widely in interpretation and implementation. We then describe key features of the current refugee crisis and document the overall magnitudes and types of refugee movements, illegal border crossings and asylum applications to EU Member States. We next study the labour market integration of past refugee migrants to EU countries and draw conclusions for the current situation. Finally, we turn to the economics of refugee migrations, contrasting economic and refugee migrants, discussing the trade-offs between long-term asylum and temporary protection and highlighting the benefits of well-coordinated national asylum policies. We conclude with several policy recommendations. Luigi Minale gratefully acknowledges support from the Ministerio de Economía y Competitividad (Spain, Maria de Maeztu Grant) and Comunidad de Madrid (MadEco CM S2015/HUM 3444). Christian Dustmann acknowledges funding through the Norface WSF Programme and the DFG (DU1024/1 1) ERC Advanced Grant 323992 DMEA.

This article analyses the way households in rural China use rural-urban migration and off-farm work as a response to negative productivity shocks in agriculture. I employ various waves of a longitudinal survey to construct a panel of individual migration and labour supply histories, and match them to detailed weather information, which I use to instrument agricultural productivity. For identification, I exploit the year-by-county variation in growing season rainfalls to explain within-individual changes in labour allocation. Data on days of work supplied to each sector allow to study the responses to weather shocks along both the participation and the intensive margin. Results suggest that farming is reduced by 4.5% and migration increased by about 5% in response to a 1 standard deviation negative rainfall shock. Increase in rural-urban migration derives from both longer spells in the city and from increment in the likelihood to participate in the urban sector. I find interesting heterogeneous response across generations driven by age-specific productivities in the different sectors and migration costs. Finally, land tenure insecurity seems to partially prevent households from freely reallocating labour away from farming in bad times. I wish to gratefully acknowledge financial support from the Ministerio Economía y Competitividad (Spain), Maria de Maeztu grant (MDM 2014-0431), and the Comunidad de Madrid, MadEco-CM grant (S2015/HUM-3444).

In democracies, voters rely on media outlets to learn about politically salient issues. This raises an important question: how strongly can media affect public perceptions? This paper uses a natural experiment - the staggered introduction of the Digital TV signal in Italy - to measure the effect of media persuasion on the perceptions individuals hold. We focus on crime perceptions and, combining channel-specific viewership and content data, we show that the reduced exposure to channels characterized by high levels of crime reporting decreases individual concerns about crime. The effect is driven by individuals aged 50 and over, who turn out to be more exposed to television while using other sources of information less frequently. Finally, we provide evidence about the effect of the digital introduction on public policies closely related to crime perceptions and on voting behaviour Luigi Minale acknowledges support from the Ministerio Economía y Competitividad (Spain), María de Maeztu grant (MDM 2014-0431), Comunidad de Madrid, MadEco-CM (S2015/HUM-3444), and Fundación Ramón Areces.

In this paper, we study the labour market performance of refugees vis-A -vis comparable migrants across twenty European countries and over time. In the first part of our analysis, we document that labour market outcomes for refugees are consistently worse than those for other migrants. Refugees are 11.6 percent less likely to have a job and 22.1 percent more likely to be unemployed than migrants with similar characteristics. Moreover, their income, occupational quality and labour market participation are also relatively weaker. The refugee-migrant gap remains sizeable even after controlling for individual characteristics as well as for unobservables using a rich set of fixed effects and interactions between area of origin, entry cohort and destination country. These gaps persist until about 10-15 years after immigration. In the second part of our analysis, we investigate the role of economic and asylum policy conditions at the time of arrival in shaping integration paths of refugees versus migrants. First, we find that immigrating in a recession produces scarring effects for all migrants but no differential effect for forced migrants, leaving little role for this channel to explain observed refugee gaps. Second, we focus on the impact on refugees of being subject to spatial dispersal policies. Our estimates imply that dispersed refugees experience a persistent impact on their residential choices and substantial long run losses in their economic integration with respect to non-dispersed refugees.

This paper analyses the relation between individual migrations and the risk attitudes of other household members when migration is a household decision. We develop a simple model that implies that which member migrates depends on the distribution of risk attitudes among all household members, and that the risk diversification gain to other household members may induce migrations that would not take place in an individual framework. Using unique data for China on risk attitudes of internal (rural-urban) migrants and the families left behind, we empirically test three key implications of the model: (i) that conditional on migration gains, less risk averse individuals are more likely to migrate; (ii) that within households, the least risk averse individual is more likely to emigrate; and (iii) that across households, the most risk averse households are more likely to send migrants as long as they have at least one family member with sufficiently low risk aversion. Our results not only provide evidence that migration decisions are taken on a household level but also that the distribution of risk attitudes within the household affects whether a migration takes place and who will emigrate.

Three novel sulphated polyhydroxylated steroids, named asterasterols A-C (1-3), have been isolated from an Antarctic starfish of the family Asteriidae and their structures elucidated by spectroscopic studies. Steroid 1 has the seven-membered 5-oxalactone B-ring; 2 and 3 are the corresponding 6-oxo steroids. © 1997 Published by Elsevier Science Ltd. In connection with our systematic investigation of steroid constituents from echinoderms, we examined some Antarctic starfish species, t'2 These studies have led to the isolation of a series of sulfated polyhydroxysteroids and steroidal glycosides structurally very close, some identical, with those found in species collected in warm environments. 3 During the investigation of the polar extracts of an Antarctic starfish of the family Asteriidae, which is the subject of this report, we have isolated a structurally novel steroid exhibiting 7-membered 5- oxalactone B-ring, along with the corresponding 6-oxo steroids. The starfish, Asteriidae family, was collected in Tethis Bay during the Italian-Antarctic expedition in January 1990 at a depth of 50-100 mt. The starfish (500 g fresh) was extracted with water and then with acetone; from the aqueous extract the sulphated steroids and steroidal glycosides were recovered by passing it through a column of Amberlite, washing out salts with distilled water, and eluting the absorbed material with methanol. The acetone extracts were solvent partitioned between water and n-butanol. The combined methanol eluate and n-butanol soluble material, were separated by sequential application of gel permeation on Sephadex LH- 60, DCCC and HPLC, to give the sulphated steroids 1-3, in small amounts, ranging from 7.2 mg of 1 (major) to 3.4 mg of 3 (minor).

Two new sulphated polyhydroxylated steroid glucuronides. downeyoside A and B ( 1, 2 ), C-24 methyl epimers possessing an ethereal ring linking C-16 to C-22 of the steroid, were isolated from the starfish Henricia downeyae collected from the Gulf of Mexico. Their structures were determined by spectral analysis and the stereochemistry of the highly oxygenated steroid side chain was derived from NMR data combined with molecular dynamics calculation. Compounds 1 and 2 were tested against non-small-cell lung human carcinoma cells and found to be cytotoxic with IC50 of 60 μg/ml and 36 μg/ml, respectively.

Two novel polyoxygenated steroids, incrustasterol A ( 1 ) and B ( 2 ), have been isolated from the marine sponge Dysidea incrustans , collected in the Mediterranean sea along the coasts of Tunisia. The structures, which include a rare Δ 8(9) , 11-keto functionality along with other oxygenated functions on the rings A and B, were determined by interpretation of spectral data. These steroids were cytotoxic against human non-small-cell lung, renal and melanoma carcinoma cell lines.

Nine ophiuroid species from different geographical areas have been analyzed for their polar steroid content. Six new sulfated polyhydroxysteroids have been isolated, together with six known compounds of this type previously reported from brittle scars. The new steroids possess C-21 and 3 alpha- sulfate groups, which are distinctive features of the steroid sulfates of ophiuroids. Hydroxylation at C-2, C-4, and C-11 and the presence of double bonds at C-5 are further features of the new steroids. The structures of the new compounds were solved by spectroscopic analysis.

Following the characterization of anchinopeptolide A[1], three new congeneric dimeric peptide alkaloids, named anchinopeptolides B [2], C[3], and D[4], have been isolated from the Mediterranean sponge Anchinoe tenacior. A fourth compound, cycloanchinopeptolide C[5], which is related to anchinopeptolide C[3] by a head-to-head intramolecular [2+2] cyclo-addition reaction, has also been isolated. The structures of these peptide alkaloids have been elucidated on the basis of spectral evidence. Anchinopeptolides bind to the somatostatin, human B2 bradykinin, and neuropeptide Y receptors.

A highly cytotoxic macrolide, superstolide A (1), has been isolated from the deep water marine sponge Neosiphonia superstes, collected off New Caledonia. The gross structure was determined by extensive 2D NMR experiments on the lactone 1 and on its opened-ring-derived methyl esters 2 and 3. The relative stereochemistries of the decaline moiety and of the C22-C26 fragment were determined by a combination of NMR data and acetonide analysis on 2. Absolute stereostructure of the decaline portion of 1 has been determined on the basis of GLC-modified Horeau's methodology applied to 4, whereas the results of the application of the modified Mosher's method to 1 and 3 allowed us to propose for the C22-C26 fragment the 22R, 23R, 24R, 25S, 26R configuration. We also propose the solution conformations of superstolide A (1) based on molecular dynamics and mechanics calculations using NMR-derived constraints.

Four new sulfated asterosaponins, designated as cosmasterosides A [1], B [2], C [4], and D [5], have been isolated from the Atlantic starfish Cosmasterias lurida along with large amounts of the pentaglycoside ophidianoside F [3] and the minor component forbeside H [6], previously isolated from Ophidiaster ophidianus and Asterias forbesi, respectively. Cosmasteroside A [1] contains the same oligosaccharide chain as ophidianoside F [3] and a (20S)-5 alpha-cholesta-9(11),24-diene-3 beta,6 alpha,20-triol-3 beta-sulfated aglycone. Cosmasterosides B [2], C [4], and D [5] are based on the known aglycone, thornasterol A, and differ in the number and type of monosaccharide components of the carbohydrate chain. Cosmasteroside B [2] contains a novel oligosaccharide chain that differs from that of ophidianoside F [3] by the replacement of the quinovose unit attached to C-6 of the steroidal aglycone by glucose. The tetraglycosides cosmasterosides C [4] and D [5] are structurally related to ophidianoside F [3] and cosmasteroside B [2], respectively, by the loss of a terminal fucose unit.

Anchinopeptolide A ( 1 ), a dimeric peptide alkaloid of a completely new type, has been isolated from the marine sponge Anchinoe tenacior collected in the Mediterranean sea along the coasts of Tunisia. The structure elucidation of 1 , which include in each half a C-terminal trans 4-hydroxystirylamino residue linked to L-alanine, which in turn is attached to an arginine derived 5-guanidino-2-hydroxy-pentanoyl residue, is described.

A review, with 386 refs., on polyoxygenated steroids of marine origin, e.g. marine algae, Porifera, Coelenterata, Bryozoa, Mollusca, Echinodermata, Arthropoda, tunicates, and vertebrates (fish).

The phylum Echinodermata, which comprises about 6,000 living species distributed in all seas from the tropics to the antarctic zone, is divided into five classes: Crinoidea (sea lilies and feather stars), Holothuroidea (sea cucumbers or holothurians), Echinoidea (sea urchins), Asteroidea (sea stars or starfishes) and Ophiuroidea (brittle stars). Among the echinoderms, sea cucumbers and starfishes invariably contain saponins which are generally responsible for their toxicity. Saponins, complex water soluble compounds composed of a carbohydrate moiety attached to a steroid or triterpenoid aglycone, have been isolated from a great number of terrestrial plants, but are uncommon animal constituents. In the animal kingdom they are almost ubiquitous in sea cucumbers and starfishes (1), while found only rarely in alcyonarians (2), gorgonians (3-5), sponges (6-10) and as potent shark-repelling compounds in fishes (11). Chemically, saponins from sea cucumbers are triterpenoid glycosides whereas those from starfishes are steroidal glycosides.

Following the characterization of callipeltin A (1), two new cytotoxic peptides, callipeltin B (2) and C (3), were isolated from the New Caledonian sponge Callipelta sp.. Callipeltin B (2) possess the same cyclic depsipeptidal structure as in callipeltin A (1) and differs from 1 by having the N-terminal 2,3-dimethylpyroglutamic acid unit instead of the tripeptide chain with the N-terminus blocked by an hydroxyacid. Callipeltin C (3) is simply the acyclic callipeltin A. The structures 2–3 have been determined by NMR experiments, FAB mass spectrometry, evaluation of the aminoacids obtained by acid hydrolysis and by comparison of the data with those of callipeltin A (1). Following the characterization of callipeltin A (1), two new peptides, callipeltin B (2) and C (3), were isolated form Callipelta sp.. Callipeltin B (2) possess the same cyclic depsipeptidal structure as in callipeltin A (1) and differs from 1 by having the N-terminal 2,3-dimethylpyroglutamic acid unit instead of the tripeptide chain with the N-terminus blocked by an hydroxyacid. Callipeltin C (3) is the acyclic callipeltin A. Callipeltins have been found to be cytotoxic against various human carcinoma cells.

A new nonsymmetric dimeric steroid, crellastatin A (1), was isolated from the Vanuatu Island marine sponge Crella sp. Structural assignment was accomplished through extensive 2D NMR spectroscopy. The stereochemistry of 1 was established from an analysis of ROESY experiments and from molecular mechanics and dynamics calculations. Crellastatin A (1), which possesses an unprecedented connection through the side chains, exhibits in vitro cytotoxic activity against NSCLC-N6 cells (IC50 of 1.5 μg/mL).

This paper reports a complete steroid glycoside and polyhydroxysteroid analysis of the starfish Solaster borealis, collected at Mutsu Bay, Japan. The glycosides include a new pentaglycoside steroid sulfate ("asterosaponin"), designated solasteroside A [1], two new sulfated 24-O-diglycosides, both with the common 5 alpha-cholesta-3 beta,6 alpha,8,15 alpha, 24-pentaol aglycone, borealosides A [2] and B [3], two new 24-O-(3-O-methyl)xylosides, borealosides C [4] and D [5], having the same aglycone with an additional hydroxy group at 4 beta-position in 5, and the known amurensoside B, previously isolated from Asterias amurensis. Among the polyhydroxysteroid constituents, four (7-10) are new, and five (11-15) have previously been isolated from starfishes.

Three steroid constituents have been isolated from the starfish Tremaster novaecaledoniae (Jangoux 1982) collected at a depth of 530 m off New Caledonia. Compounds 1 – 3 , designated as tremasterol A – C, are characterized by the presence of 3β-O-sulphated, 6α-O-phosphated and 16β-O-acetylated groupings on a steroidal skeleton. In compound 1 the monophosphate residue is further linked to 1′-glucose (1′-glucose tetracetate in 2 and 1′-glucose-6′-acetate in 3 ).

The isolation and characterization of two novel triterpene glycosides from a sponge of the genus Erylus , collected at a depth of 500 m in the South of New Caledonia, are described. The structures are characterized by the presence of a branched oligosaccharide chain, composed of three ( 1 ) and four (2) D-galactopyranose units, respectively. Analysis of the oligosaccaride structures was achieved by { 1 H, 1 H} correlation spectroscopy, two-dimensional homonuclear Hartmann-Hahn, and 1 H-detected { 1 H, 13 C} one bond (HMQC) and multiple-bond (HMBC) shift correlation NMR experiments. The novel lanostane derived aglycone features a rare 14-carboxyl group and a 24-methylene, 25-methyl side chain.

Five new bioactive sesterterpenes (1-5) have been isolated from the New Caledonian marine sponge Petrosaspongia nigra Bergquist and named petrosaspongiolides M-R. Their chemical structures were determined from 1D and 2D NMR studies and MS data. All compounds inhibited different preparations of phospholipase A(2) (PLA(2)) by irreversibly blocking these enzymes (particularly human synovial and bee venom, see Table 3), with IC50 values in the micromolar range. Interestingly, these compounds displayed a much lower activity (or no activity at all) toward porcine pancreas and Naja naja venom PLA(2) enzymes. The most potent compound, 1 (IC50 1.6 and 0.6 mu M for human synovial and bee venom PLA(2) enzymes, respectively), was slightly more active than manoalide (6) (IC50 3.9 and 7.5 mu M) under our experimental conditions. Compound 3 is more selective, inhibiting-human synovial PLA(2) to a greater extent than bee venom PLA(2).

Along with two known cheilanthane sesterterpene lactones, 1 and 2, eight new related sesterterpenes (3–10) and two new nor-sesterterpenes (11 and 12) have been isolated from the New Caledonian marine sponge Petrosaspongia nigra Bergquist 1995 (new genus, new species). Their structures were determined from 1D and 2D NMR studies and mass spectral data. They exhibited cytoxicity against the NSCLC-N6 human bronchopulmunary non-small-cell-lung carcinoma cell lines.

Five new amino acid derivs. were isolated from the New Caledonian sponge Jaspis carteri, together with known bengamides A and B. The structures of the new compds. were detd. by interpretation of their spectral data and by comparison with spectral data of known bengamides. Bengamides G (I), and H, I, and J are simply the tridecanoate and pentadecanoate analogs of the original bengamides A and B, whereas bengamide K (II) is a caprolactam formamide deriv. of bengamide B.

A new nonsymmetric dimeric steroid, crellastatin A (1), was isolated from the Vanuatu Island marine sponge Crella sp. Structural assignment was accomplished through extensive 2D NMR spectroscopy. The stereochemistry of 1 was established from an analysis of ROESY experiments and from molecular mechanics and dynamics calculations. Crellastatin A (1), which possesses an unprecedented connection through the side chains, exhibits in vitro cytotoxic activity against NSCLC-N6 cells (IC(50) of 1.5mgr;g/mL).

A total of 19 steroids, of which 13 steroidal oligoglycosides (nine new and four known) and six polyhydroxylated steroids (four new and two known), has been isolated from the Antarctic starfish Acodontaster conspicuus. The mixture is dominated by glycosides composed of steroidal aglycons having the hydroxyl groups typically disposed on one side of the tetracyclic nucleus, i.e., 3 beta,4 beta,6 alpha,8,15 beta-, with some having a sulfate at C-6, and differing in the side chains and/or in the disaccharide moieties that are usually attached at C-26, with some at C-28 and C-29. Those compounds are accompanied by minute amounts of glycosides with a delta 8(14)-double bond in the steroid, which is a structural feature not previously found among polyhydroxysteroids derived from starfish. Small amounts of six related unglycosidated polyhydroxysteroids and three higher-molecular-weight asterosaponins complete the composition of the mixture. The structures of the new compounds were determined by interpretation of their spectral data and by comparison with spectral data of known compounds. Eighteen of these compounds were evaluated for their ability to inhibit growth in Antarctic marine bacteria isolated from either the water column or the surfaces of benthic marine invertebrates. Of these compounds, 50% were active against at least one Antarctic marine bacterium. This suggests that these compounds may play an important role in deterring microbial fouling.

Following the characterization of callipeltoside A (1), the first member of a novel class of marine glycoside macrolides, two more bioactive constituents, callipeltoside B (2) and C(3), were isolated from Callipelta sp. in very low amounts. The structures, assigned on the basis of spectral analysis, include the same 14-membered macrolide as in callipeltoside A (1) but differed in the saccharide moieties.

Thirteen new (1-13) and seven known (14-20) steroid glycosides were isolated from Henricia downeyae, collected from the offshore waters of the northern Gulf of Mexico. Ethanolic extracts of these starfish caused growth inhibition in bacteria and fungi, potent antifouling activity against barnacle and bryozoan larvae, and feeding deterrent activity against a marine fish. The known compounds are typical glycosides found in several species of the family Echinasteridae, i.e., Echinaster sp. and Henricia Laeviuscola. One of the new compounds belongs to this group, whereas the remaining 12 new compounds represent a novel series of steroid glycosides which have aglycons with structural similarities to the ''asterosaponins''. They possess a Delta(9(11)) 3 beta,6 alpha-dihydroxysteroidal aglycon with 23-oxo or 22,23-epoxy functionalities and often a 20-hydroxyl group in the side chain. The sulfate is located at C-6 and the saccharide moiety at C-3, in contrast with the asterosaponins which have the sulfate at C-3 and the oligosaccaride moiety at C-6. All the new compounds contain a glucuronic acid unit, which is uncommon among steroid glycosides from echinoderms. The structures of the new compounds, isolated in amounts ranging from 3.4 to 0.9 mg, were determined by interpretation of their spectral data and by comparison with spectral data of known compounds.

Following the characterization of callipeltin A (1), two new cytotoxic peptides, callipeltin B (2) and C (3), were isolated from the New Caledonian sponge Callipelta sp.. Callipeltin B (2) possess the same cyclic depsipeptidal structure as in callipeltin A (1) and differs from 1 by having the N-terminal 2,3-dimethylpyroglutamic acid unit instead of the tripeptide chain with the N-terminus blocked by an hydroxyacid. Callipeltin C (3) is simply the acyclic callipeltin A. The structures 2–3 have been determined by NMR experiments, FAB mass spectrometry, evaluation of the aminoacids obtained by acid hydrolysis and by comparison of the data with those of callipeltin A (1). Following the characterization of callipeltin A (1), two new peptides, callipeltin B (2) and C (3), were isolated form Callipelta sp.. Callipeltin B (2) possess the same cyclic depsipeptidal structure as in callipeltin A (1) and differs from 1 by having the N-terminal 2,3-dimethylpyroglutamic acid unit instead of the tripeptide chain with the N-terminus blocked by an hydroxyacid. Callipeltin C (3) is the acyclic callipeltin A. Callipeltins have been found to be cytotoxic against various human carcinoma cells.

Saponins have been considered for a long time typical metabolites of plant origin. It has been only in the last two decades that the world-wide investigation of marine organisms as sources of new bioactive metabolites disclosed the wide distribution of these molecules also among marine animals. Today saponins are recognized as the most common characteristic metabolites in two classes of the phylum Echinodermata (Holothuroidea and Asteroidea). Furthermore, several steroid and triterpenoid oligoglycosides have been isolated from different species of marine sponges, more rarely Anthozoans, and also from fishes of the genus Pardachirus, where they have been shown to act as shark repellents. This communication offers a general view of the distribution of steroid and triterpenoid oligoglycosides among marine organisms and focuses on a number of recent examples to discuss structural characteristics, biological activities, and methods of investigation.

Callipeltin A (1) is a cyclic depsidecapeptide from a shallow water sponge of the genus Callipelta (order Lithistida), collected in the waters off New Caledonia. The structure of callipeltin A (1), which possesses the N-terminus blocked with a β-hydroxy acid, and the C-terminus lactonized with a threonine residue, was determined by interpretation of spectral data, chemical degradation, and evaluation of the amino acids obtained by acid hydrolysis. Along with four common l-, one d-, and two N-methyl amino acids, it contains three new amino acid residues: β-methoxytyrosine (βOMeTyr), (2R,3R,4S)-4-amino-7-guanidino-2,3-dihydroxyheptanoic acid (AGDHE), and (3S,4R)-3,4-dimethyl-l-glutamine. Callipeltin A (1) has been found to protect cells infected by human immunodeficiency (HIV) virus.

The structure of two minor polyhydroxysteroids isolated from the deep water starfish Styracaster caroli were determined as (22E,24R,25R)-24-ethyl-5α-cholest-22-en-3β,5,6β,8,15α,25,26-heptol 26-sulf...

An investigation of the extracts from a starfish collected in the Antarctic Sea, Echinasteridae family, has led to the isolation of thirteen glycosides of polyhydroxysteroids (1–13), fourteen polyhydroxysteroids (14–27), which are the subject of this report, and seven asterosaponins (penta-and hexa-saccharides), described in a previous paper. Glycosides 1–13 are composed of the same 3β,4β,6α,8,15β,26-hexahydroxysteroidal aglycone with small variations in the side chains, and a carbohydrate portion made up of one or two monosaccharide units attached at C-26, except 11, which has a steroidal aglycone with a 24,28-dihydroxylated side chain and the monosaccharide unit attached at C-24. The structures of the polyhydroxysteroids (14–27) have the hydroxyl groups typically disposed on one side of the steroid nucleus, i.e. 3β,4β,6β (or α),8,15α (or β) and 16β and the majority of them possess a 26-hydroxyl function. A selection of fifteen compounds were tested against human non-small-cell lung carcinoma cells and found to be moderately cytotoxic.

Ten new [1-10] and three known [11-13] polyhydroxysteroids were isolated, along with four known asterosaponins [14-17], from the starfish Luidia clathrata, collected from the offshore waters of the northern Gulf of Mexico. The EtOH extracts of this starfish showed feeding-deterrent properties against marine fish, and inhibited the settlement of larvae of barnacles and bryozoans, as well as the growth of several bacteria. The structures of the new compounds were determined by interpretation of their nmr spectral data and by comparison with the spectral data of known compounds. The assignment of the configurations of the side-chain stereogenic centers of compounds 1 and 3-10 were based on the comparison of their nmr data with those of the stereoisomeric model compounds after derivatization with the chiral auxiliary MTPA reagent. Larval settlement assays conducted on ten isolated compounds revealed they are all potent inhibitors of settlement. Two of these isolated compounds inhibited the growth of several bacteria.

Publisher Summary This chapter focuses on the more recent developments in the field of natural products from echinoderms. The phylum Echinodermata, which comprises about 6000 living species, is divided into five classes: Crinoidea (sea lilies and feather stars), Holoturoidea (sea cucumbers or holothurians), Echinoidea (sea urchins), Asteroidea (sea stars or starfishes), and Ophiuroidea (brittle stars). Among the echinoderms, starfishes and sea cucumbers usually contain saponins, which are responsible of their general toxicity. Chemically, saponins derived from sea cucumbers are triterpenoid glycosides, whereas those from starfishes are steroidal glycosides. The presence of oligoglycosides in both Holothuroidea and Asteroidea classes gives support to the opinion that sea cucumbers and starfishes are phylogenetically related. In starfishes and sea cucumbers Δ 7 -sterols, which are probably a consequence of the presence of haemolytic saponins, are also predominant, whereas the other three classes contain the usual Δ 5 -sterols. Haemolysis is caused by the abstraction of membrane cholesterol by the saponins. Saponins show a much lower affinity for Δ 7 -sterols and this helps to explain the apparent immunity of starfishes and sea cucumbers to their own saponins.

Two new 26-membered macrolides, reidispongiolide A (1) and B (2), have been isolated from the New Caledonian marine sponge Redispongia coerulea n.gen.n.sp. Levi and Levi and their structures elucidated. They are related to sphinxolides previously isolated from an unknown nudibranch and later from the sponge Neosiphonia superstes. 1 and 2 co-occurr with sphinxolide B (4) and D (3). These macrolides exhibited potent cytotoxicity against various human carcinoma cells.

Two new diastereomeric brominated tris-indole alkaloids occurring as enantiomeric pairs, (+/-)-gelliusines A [1] and B [2], have been isolated from a deep water New Caledonian sponge (Gellius or Orina sp.), whose crude extract exhibited cytotoxicity against KB cells. Their structures were elucidated by spectroscopic methods including one- and two-dimensional nmr spectroscopy. The major compound, (+/-) gelliusine A [1], which showed very weak cytotoxicity, proved to be active at the serotonin receptor.

6-( p -Hydroxyphenyl)-2H-3,4-dihydro-1,1-dioxo-1,4-thiazine ( 1 ) has been isolated from the marine sponge Anchinoe tenacior , along with a novel tripeptide with a C-terminal trans -4-hydroxystirylamino residue ( 2 ).

Two novel sesquiterpenes,fulvanin 1 [1] and fulvanin 2[2], have been isolated from the Mediterranean sponge Reniera fulva. Compound 2 is a sesquiterpenoid linked to a hydroquinone. Also found in Reniera fulva are four known paniceins, a group of aromatic sesquiterpenoids linked to a quinol, isolated previously from Halichondria panicea. The total assignments of C-13-nmr spectra of paniceins have been made with the aid of 2D(HC)-H-1-C-13 correlation techniques, confirming their structures. The paniceins were tested in the in vitro disease-oriented primary antitumor screen at NCI, Bethesda. Paniceins C and B3 showed cytotoxicity against NCI-H522 non-small lung cancer cells and CCRF-CEM leukemia cells, while panicein A hydroquinone revealed more selective cytotoxicity against the latter ones.

A reinvestigation of the extracts from the starfish Distolasterias nipon, collected at Mutsu Bay, Japan, has led to the isolation of six glycosides of polyhydroxysteroids and six asterosaponins. Four steroidal glycosides have been identified as distolasterosides D1 [1] and D2 [2] (previously isolated from the same organism), and pycnopodioside C [5] and pisasteroside A [6], previously found in the related species Pycnopodia helianthoides and Pisaster ochraceus (family Asteridae), respectively. Two asterosaponins have been identified as the common versicoside A [7] and thornasteroside A [7a]. The two remaining glycosides of polyhydroxysteroids, named distolasterosides D4 [3] and D5 [4], and four asterosaponins designated nipoglycosides A [8], B [9], C [10], and D [11] are new compounds, and their structures have been elucidated mainly by interpretation of spectral data and comparison with known compounds.

Two novel sulphated polyhydroxysteroids, 1, possessing potent cytotoxic activity, and 2, which proved to be cytoprotective against HIV-1, have been isolated from the Antarctic ophiuroid Ophiosparte gigas, together with the known tetrol disulphated 3. The structures of 1 and 2 have been determined to be cholest-5-ene-2α,3α,4β, 21-tetraol 3, 21-disulphate and cholest-5-ene-2β,3α, 21-triol 2, 21-disulphate, respectively.

The deep-water New Caledonian sponge #Cladocroce incurvata$ contains two "polyketide" metabolites. Cladocrocin A (1) appears to be derived from fatty acid with ethyl side chains, thus incorporating butyrate units. Cladocroic acid (2) is a straight chain fatty acid which incorporates a terminal enyne functionality and a cycloproprane ring directly attached to the carboxylic acid function. The structures were elucidated by interpretation of spectral data, and the cis stereochemistry of the cyclopropane ring in cladocroic acid (2) was derived after the synthesis of cis - and trans - 2, 3 - methanohexanoic acid models and nmr spectral comparisons. (Résumé d'auteur)

Three novel polyhydroxysteroid constituents have been isolated from the starfish #Stracaster caroli$ collected at a depht of 2000 m off New Caledonia. These, designated carolisterols A - C (1 - 3), are characterized by a polyhydroxycholanic acid moiety, in which the 24-carboxylic acid function is found as an amide derivative ofD-cysteinolic acid. (Résumé d'auteur)

The phylum Echinodermata, which comprises about 6,000 living species distributed in all seas from the tropics to the antarctic zone, is divided into five classes: Crinoidea (sea lilies and feather stars), Holothuroidea (sea cucumbers or holothurians), Echinoidea (sea urchins), Asteroidea (sea stars or starfishes) and Ophiuroidea (brittle stars). Among the echinoderms, sea cucumbers and starfishes invariably contain saponins which are generally responsible for their toxicity. Saponins, complex water soluble compounds composed of a carbohydrate moiety attached to a steroid or triterpenoid aglycone, have been isolated from a great number of terrestrial plants, but are uncommon animal constituents. In the animal kingdom they are almost ubiquitous in sea cucumbers and starfishes (1), while found only rarely in alcyonarians (2), gorgonians (3-5), sponges (6-10) and as potent shark-repelling compounds in fishes (11). Chemically, saponins from sea cucumbers are triterpenoid glycosides whereas those from starfishes are steroidal glycosides.

Three new macrolides 2–4 have been isolated with sphinxolide 1 from the marine sponge N. superstes collected off New Caledonia. The structures of the new compounds were determined by interpretation of NMR spectral data as well as by comparison of spectral data with those of 1. These compounds were highly cytotoxic against various human carcinoma cells.