Pd-Senphos Catalyzed trans-Selective Cyanoboration of 1,3-Enynes

The first trans-selective cyanoboration reaction of an alkyne, specifically a 1,3-enyne, is described. The reported palladium-catalyzed cyanoboration of 1,3-enynes is site-, regio-, and diastereoselective, and is uniquely enabled by the 1,4-azaborine-based Senphos ligand structure. Tetra-substituted alkenyl nitriles are obtained providing useful boron-dienenitrile building blocks that can be further functionalized. The utility of our method has been demonstrated with the synthesis of Satigrel, an anti-platelet aggregating agent.

Self-Assembling Behavior of Glycerol Monoundecenoate in Water

The self-assembling properties of glycerol esters in water are well known. Still, few data on glycerol monoesters of undecylenic acid are available. The aim of this study was to highlight the behavior of glycerol monoundecenoate (GM-C11:1) in different diluted and concentrated states. Its self-assembling properties in water and upon solid inorganic surfaces were investigated in the diluted state using surface tension experiments, atomic force microscopy, and cryogenic transmission electron microscopy studies. In the concentrated state, the gelling properties in the presence of water were investigated using polarized light microscopy, differential scanning calorimetry (DSC), and small-angle X-ray scattering (SAXS) experiments. GM-C11:1 at 100 mg/L self-assembles at the liquid/air interfaces as aggregates of approximately 20 nm in diameter, organized into concentric forms. These aggregates are spherical globules composed of several molecules of GM-C11:1. At higher concentrations (1000 and 10⁴ mg/L), GM-C11:1 is able to uniformly coat liquid/air and liquid/solid interfaces. In bulk, GM-C11:1 forms spontaneously aggregates and vesicles. In a more concentrated state, GM-C11:1 assembles into lamellar L_β and L_α forms in water. By cross-referencing SAXS and DSC findings, we were able to distinguish between interlamellar water molecules strongly bound to GM-C11:1 and other molecules remaining unbound and considered to be "mobile" water. The percentage of water strongly bound was proportional to the percentage of GM-C11:1 in the system. In this case, GM-C11:1 appears to be an effective molecule for surface treatments for which water retention is important.

Synthesis of both enantiomers of 12-methyl-13-tridecanolide and 14-methyl-15-pentadecanolide (muscolide)

Both enantiomers of 12-methyl-13-tridecanolide{(R)-(+)-1, (S)-(-)-1} and 14-methyl-15-pentadecanolide (muscolide) {(R)-(+)-2, (S)-(-)-2} were synthesized from either (S)-(+)- or (R)-(-)-3-bromo-2-methyl-1-propanol 8 as a chiral building block.

Concentrations and assessment of exposure to siloxanes and synthetic musks in personal care products from China

We investigated the concentrations and profiles of 15 siloxanes (four cyclic siloxanes, D(4)-D(7); 11 linear siloxanes, L(4)-L(14)), four synthetic musks (two polycyclic musks, HHCB and AHTN; two nitro musks, MX and MK), and HHCB-lactone, in 158 personal care products marketed in China. Siloxanes were detected in 88% of the samples analyzed, at concentrations as high as 52.6 mg g(-1); Linear siloxanes were the predominant compounds. Among synthetic musks, more than 80% of the samples contained at least one of these compounds, and their total concentrations were as high as 1.02 mg g(-1). HHCB was the predominant musk in all of the samples analyzed, on average, accounting for 52% of the total musk concentrations. Based on the median concentrations of siloxanes and musks and the average daily usage amounts of consumer products, dermal exposure rates in adults were calculated to be 3.69 and 3.38 mg d(-1) for siloxanes and musks, respectively.

[Ecotoxicity of synthetical musks on wheat (Triticum aestivum) based on seed germination]

With soil culture the ecotoxicological effects of galaxolide (HHCB) and tonalide (AHTN) on the germination of wheat (Triticum aestivum) seeds were investigated. And the influence of these two synthetical musks on the wheat germination rate, inhibition rate of root elongation and inhibition rate of shoot elongation were studied. The results showed that there were no obvious dose-effect relationship between wheat germination rate and concentrations of these two synthetical musks. Lower dose (HHCB < or = 150 mg x kg(-1), AHTN < or = 200 mg x kg(-1)) could accelerate the germination of wheat. Under the test concentrations of synthetical musks, the wheat germination rates treated with HHCB and AHTN were 77.78%-95.56% and 84.44%-97.78%, respectively. There were good dose-effect relationship between inhibition rate of root elongation (or inhibition rate of shoot elongation) and synthetical musks concentrations. The EC50 of HHCB and AHTN based on shoot were 155.84 mg x kg(-1) and 290.58 mg x kg(-1), and were 215.66 mg x kg(-1) and 323.10 mg x kg(-1) based on root from linear model. The EC50 of wheat sensitive positions showed that the toxicity of HHCB was stronger than AHTN.

Fingolimod (FTY720): a recently approved multiple sclerosis drug based on a fungal secondary metabolite

Fingolimod (Gilenya; FTY720), a synthetic compound based on the fungal secondary metabolite myriocin (ISP-I), is a potent immunosuppressant that was approved (September 2010) by the U.S. FDA as a new treatment for multiple sclerosis (MS). Fingolimod was synthesized by the research group of Tetsuro Fujita at Kyoto University in 1992 while investigating structure-activity relationships of derivatives of the fungal metabolite ISP-I, isolated from Isaria sinclairii. Fingolimod becomes active in vivo following phosphorylation by sphingosine kinase 2 to form fingolimod-phosphate, which binds to extracellular G protein-coupled receptors, sphingosine 1-phosphates, and prevents the release of lymphocytes from lymphoid tissue. Fingolimod is orally active, which is unique among current first-line MS therapies, and it has the potential to be used in the treatment of organ transplants and cancer. This review highlights the discovery and development of fingolimod, from an isolated lead natural product, through synthetic analogues, to an approved drug.

Total Synthesis and Correct Absolute Configuration of Malyngamide U

The enantioselective synthesis of the previously proposed structure of malyngamide U (1) was accomplished in 18 steps from (S)-(+)-carvone. The key steps involved a hydroxymethylation of (S)-(+)-carvone and an asymmetric Henry reaction of aldehyde (+)-5, as well as condensation with the acid 3. The 1H and 13C NMR data of the synthetic compound 1 were not consistent with the data of the reported malyngamide U. The C-2' epimer of compound 1 was therefore synthesized by a similar reaction sequence. While the NMR data of C-2' epimer 23 were in full agreement with those of the reported product, the discrepancy in the specific rotation data suggested the correct structure of malyngamide U should be structure 2, in which the absolute configuration of the amine part was enantiomeric with that in compound 23. Then the correct absolute configuration of revised malyngamide U (2) was confirmed by the similar synthesis from (R)-(-)-carvone.

First total syntheses of (Z)-15-methyl-10-hexadecenoic acid and the (Z)-13-methyl-8-tetradecenoic acid

The first total syntheses for the (Z)-15-methyl-10-hexadecenoic acid and the (Z)-13-methyl-8-tetradecenoic acid were accomplished in seven steps and in 31-32% overall yields. The (trimethylsilyl)acetylene was the key reagent in both syntheses. It is proposed that the best synthetic strategy towards monounsaturated iso methyl-branched fatty acids with double bonds close to the omega end of the acyl chain is first acetylide coupling of (trimethylsilyl)acetylene to a long-chain bifunctional bromoalkane followed by a second acetylide coupling to a short-chain iso bromoalkane, since higher yields are thus obtained. Spectral data is also presented for the first time for these two unusual fatty acids with potential as biomarkers and as topoisomerase I inhibitors.

Fate of synthetic musks in a domestic wastewater treatment plant and in an agricultural field amended with biosolids

Synthetic musks are widely used as fragrance ingredients in personal care products, and they enter domestic wastewater treatment plants (WWTPs) through discharges into municipal sewage systems. Samples of aqueous sewage and biosolids collected from the Peterborough Wastewater Treatment Plant (WWTP), Ontario, Canada were analyzed for 11 synthetic musk compounds using GC/MS. The results showed that 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta[g]-2-benzopyrane (HHCB, 173.1+/-43.4 ng/L) and 7-acetyl-1,1,3,4,4,6-hexamethyl-tetrahydronaphthalene (AHTN, 41.6+/-15.8 ng/L) were the dominant fragrances in sewage, but other polycyclic musks and nitro musks were present at lower concentrations. The concentrations of HHCB and AHTN in the aqueous phase of the sewage were highly correlated with both BOD5 and TOC. The overall removal efficiency of synthetic musks from the aqueous sewage in the WWTP ranged from 43.3% to 56.9%, but removal occurred mainly by partitioning into the biosolids. Based on a mass balance model, the daily input and output of HHCB and AHTN in the Peterborough WWTP were 47 g and 46 g, respectively. In an agricultural field amended with biosolids from the Peterborough WWTP, HHCB and AHTN were detected in soil immediately after application at mean concentrations of 1.0 and 1.3 mug/kg, respectively, but concentrations declined relatively rapidly over the next 6 weeks, post-application.

In Vivo Studies of Dialkynoyl Analogues of DOTAP Demonstrate Improved Gene Transfer Efficiency of Cationic Liposomes in Mouse Lung

A novel set of dialkynoyl analogues of the cationic, gene delivery lipid DOTAP (1) was synthesized. Structure-activity studies demonstrate that replacement of the cis-double bonds of DOTAP with triple bonds in varying positions alters both the physical properties of the resultant cationic liposome-DNA complexes and their biological functionalities, both in vitro and in vivo. Particularly, in vivo studies demonstrate that pDNA transfection of mouse lung endothelial cells with lead analogue DS(14-yne)TAP (4):cholesterol lipoplexes exhibits double the transfection level with less associated toxicity relative to the well-established DOTAP:cholesterol system. In fact, 4:cholesterol delivers up to 3 times the dose of pDNA in mice than can be tolerated by DOTAP, leading to nearly 3 times greater marker-gene expression. X-ray diffraction studies suggest that lipoplexes containing analogue 4 display increased stability at physiological temperatures. Our results thus suggest that analogue 4 is a potentially strong candidate for the gene therapy of lung tumors.

Total synthesis and further scrutiny of the in vitro antifungal activity of 6-nonadecynoic acid

The antifungal, naturally occurring acetylenic fatty acid 6-nonadecynoic acid was synthesized in three steps (18 % overall yield), for the first time starting with commercially available 1-tetradecyne. The synthesis developed herein will facilitate the further study of the antifungal properties of this naturally occurring acetylenic fatty acid. The 6-nonadecynoic acid exhibited the best antifungal activity (< 4.3 microM) against Cryptococcus neoformans ATCC 66031 in Sabouraud Dextrose Broth (SDB) media. In our hands, it was not active against Candida albicans ATCC 14053 and Candida albicans ATCC 60193.

Combination of antimicrobial and endotoxin-neutralizing activities of novel oleoylamines

A combination of antimicrobial and endotoxin-neutralizing activities is desired in order to prevent progression from infection to sepsis due to the release of lipopolysaccharide from dying gram-negative bacteria. Lipopolyamines have emerged as a new type of endotoxin-neutralizing compound, but their antimicrobial activity has not been investigated. We synthesized a series of 10 oleoylamines differing in the polyamino head group, particularly in the number and separation between nitrogen atoms and the position of the oleoyl moiety. Compounds showed activity against both gram-negative and gram-positive bacteria in the micromolar range. Compounds were able to provide penetration of ethidium bromide into bacteria, indicating effects on the bacterial membrane. Oleoylamines neutralized endotoxin in Limulus amoebocyte lysate assays and by neutralization of tumor necrosis factor alpha release in human blood. Comparison of biological activities of compounds identified structural properties responsible for antimicrobial activity, and quantitative structure-property relationship analysis provided a quantitative model for prediction of activity of oleoylamines.

?Brain Aided? Musk Design

This brief review, including new experimental results, is the summary of a talk at the RSC/SCI conference flavours & fragrances 2004 in Manchester, United Kingdom, 12-14 May, 2004. Musk odorants have been a classical domain for computer aided structure-odor relationship (SOR) studies, but, contrary to sandalwood or amber odorants, they belong to structurally very different substance classes, e.g., macrocycles, aromatic polycycles, and nitro arenes. Most SOR computer models are restricted to one class, excluding structural diversity to increase predictability. But even within a musk family, structural similarities are often due to a common synthetic access, and do not reflect binding requirements for the musk receptor. Beyond that, the importance of structural key features can be missed, which is discussed on the example of the (4S)-Me group of Galaxolide. By synthesis and olfactory evaluation of Galaxolide-like shaped macrobicycles as model compounds for conformationally constrained (12R)-12-methyltridecano-13-lactone, it was investigated how likely there is more than one musk receptor. Finally, the new family of so-called linear musks is discussed, especially with respect to the conformational importance of the gem-2',2'-dimethyl moiety in Helvetolide and the additional 2'-carbonyl group of Romandolide--structural features that strongly diminish the musk odor of macrocycles. On the example of 2-methyl-2-[(E)-1,2,4-trimethylpent-2-enyloxy]propyl esters, the 'brain-aided' design and conformational analysis of musk odorants is illustrated. The overview concludes with the synthesis, odor evaluation, and conformational discussion of the new musk odorant 2-(3,3-dimethylcyclohexyl)propanoic acid ethoxycarbonylmethyl ester.

New Alicyclic Musks: The Fourth Generation of Musk Odorants

Musk odorants are one of the most important classes of fragrances in perfumery because they impart sensuality to perfume-oil compositions. Among the three well-known classes of musks, a new and very exciting generation of musk odorants, the so-called alicyclic musks, was discovered recently, of which Helvetolide (2) and Romandolide (3) are the most popular representatives so far. To find new, structurally related alicyclic musks, we have synthesized a library of 114 unique alicyclic molecules with modified cyclohexyl moieties. The olfactory properties of all compounds were evaluated to identify the structural requirements to be met for a musk odorant.

New Macrocyclic Musk Compounds

The syntheses and olfactory evaluations of eight new macrocyclic musks with a 1,6-dioxa structure (1a-d and 1'a-d) as well as of twelve optically active 3-methyl macrolides (5a-c and 5'a-c) are reported. These macrocycles were synthesized via intramolecular metathesis mediated by the Grubbs catalyst. Despite the absence of a C=O function, the 1,6-dioxa compounds, both unsaturated (1) and saturated (1'), possess musky odors similar to those of macrocyclic ketones and lactones. Especially 16-membered rings were found to display an intense and pleasant musk character. However, in the case of optically active 3-methyl macrolides (5, 5'), only the (R)-configured 15- and 16-membered rings had intense and pleasant musk notes.

Facile synthesis of (Z)-tetracos-5-enoic acid and racemic cis-4-(2-octadecylcyclopropane-1-yl)-butanoic acid

(Z)-tetracos-5-enoic acid and racemic cis-4-(2-octadecylcyclopropane-1-yl)-butanoic acid have been prepared from 1-eicosene by a new facile route. Periodic acid cleavage of the epoxide of 1-eicosene gave nonadecanal which was condensed with 4-carboxybutyltriphenylphosphonium bromide to give predominately (Z)-tetracos-5-enoic acid. Simmons-Smith type cyclopropanation of (Z)-tetracos-5-enoic acid gave a minor proportion of racemic cis-4-(2-octadecylcyclopropane-1-yl)-butanoic acid accompanied by major amounts of its methyl ester.

Degradation of α-pinene oxide and [2H7]-2,5,6-trimethyl-hept-(2E)-enoic acid by Pseudomonas fluorescens NCIMB 11761

When submerged cultured Pseudomonas fluorescens NCIMB 11761 was fed-batch supplemented with alpha-pinene oxide, a rapid formation of 2,6-dimethyl-5-methylene-hept-(2Z)-enal (I) (isonovalal) was observed. Biotransformation and isomerisation of (I) to the (2E)-isomer (II) (novalal) were enhanced by Lewatit OC 1064, a macroporous polystyrene adsorbent. Accelerated isomerisation in the presence of an amino donor (glycine) at pH 7.3 pointed to a merely chemical mechanism. A maximum yield of 48 g of aldehydesl(-1) was achieved, but quantitative analysis of the volatile fraction showed that the molar conversion of the pinene oxide substrate reached no more than 67%. To fill this gap of the mass balance, the acidic fraction was isolated. It contained several compounds which suggested a beta-oxidation-like catabolism starting from 2,6-dimethyl-5-methylene-hept-(2E)-enoic acid (III) (novalic acid). Using [2H7]-2,5,6-dimethyl-hept-(2E)-enoic acid as a conversion substrate and gas chromatography coupled to atomic emission detection and mass spectrometry a degradation pathway via labelled 3,4-dimethylpentenoic and methylpropanoic acids was evidenced. This pathway may play a predominant role in isoprenoid degradation by soil bacteria.

Synthetic musk toxicity to early life stages of zebrafish (Danio rerio)

Synthetic musk substances have been found in a number of environmental samples. Some of these chemicals have been detected in concentrations above 1 microg/L in water, which raises concern about possible effects on aquatic life. The toxicity of four synthetic musks, 4-tert-butyl-2,6-dimethyl-3,5-dinitrophenylethanone (musk ketone), 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (musk xylene), 1-(5,6,7,8-tetrahydro-3,5,5,6,8,8-hexamethyl-2-naphthalenyl)ethanone (AHTN, tonalide) and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-[g]-2-benzopyrane (HHCB, galaxolide), were studied in zebrafish by the use of two different early life-stage methods. In the first method, specific developmental characteristics during the first 48 hours were studied. In the second method, hatching and survival times were studied on eggs and larvae. The results on heart rate in the first test gave the following LOECs: musk ketone 10 microg/L, musk xylene and AHTN 33 microg/L, and HHCB showed no effect up to 1000 microg/L. In the study of survival time, LOEC for musk ketone was 100 microg/L, for musk xylene 33 microg/L, and AHTN gave no effect on survival time up to 100 microg/L. The LOECs for musk ketone, musk xylene, and AHTN in this study are in the range of what has been measured in sewage effluents and recipients, and consequently these substances may have adverse impact on wild fish.

On the structure of passifloricin A: asymmetric synthesis of the delta-lactones of (2Z,5S,7R,9S,11S)- and (2Z,5R,7R,9S,11S)tetrahydroxyhexacos-2-enoic acid

Stereoselective syntheses of the delta-lactone of (2Z,5S,7R,9S,11S)-tetrahydroxyhexacos-2-enoic acid, the structure reported for passifloricin A, and of its (5R)-epimer are described. The creation of all stereogenic centers relied upon Brown's asymmetric allylation methodology. The lactone ring was created via ring-closing metathesis. The NMR data of both synthetic products, however, were different from those of the natural product. The published structure of passifloricin A is thus erroneous and will require further synthetic work to be unambiguously assigned. [structure: see text]

Reactions of hydro(pero)xy derivatives of polyunsaturated fatty acids/esters with nitrite ions under acidic conditions. Unusual nitrosative breakdown of methyl 13-hydro(pero)xyoctadeca-9,11-dienoate to a novel 4-nitro-2-oximinoalk-3-enal product

13(S)-hydroperoxy- and 13(S)-hydroxyoctadeca-9,11-dienoic acids (1a/b), 15(S)-hydroperoxy- and 15(S)-hydroxyeicosa-5,8,11,13-tetraenoic acids (2a/b), and their methyl esters reacted smoothly with NO2- in phosphate buffer at pH 3-5.5 and at 37 degrees C to afford mixtures of products. 1b methyl ester gave mainly the 9-nitro derivative 3b methyl ester (11% yield) and a peculiar breakdown product identified as the novel 4-nitro-2-oximinoalk-3-enal derivative 4 methyl ester (15% yield). By GC-MS hexanal was also detected among the products. Structures 3b and 4 methyl esters were secured by 15N NMR analysis of the products prepared from 1b methyl ester upon reaction with Na15NO2. 4 methyl ester (14% yield) was also obtained from 1a methyl ester along with the nitrated hydroperoxy derivative 3a methyl ester (10% yield). Under the same conditions, 2a/b methyl esters gave mainly the corresponding nitrated derivatives 5a/b, with no detectable breakdown products, whereas the model compound (E,E)-2,4-hexadienol (6) afforded two main nitrated derivatives identified as 7 and 8. A reaction pathway for 1a/b methyl esters was proposed involving conversion of nitronitrosooxyhydro(pero)xy intermediates which would partition between two competing routes, viz., loss of HNO2, to give 3a/b methyl esters, and a remarkably facile fission leading to 4 methyl ester and hexanal.

Synthesis of (-)-Vulcanolide by enantioselective protonation

Two efficient enantioselective syntheses of the more active (S,S)-enantiomer of the powerful musk odorant Vulcanolide are described. In both syntheses, the key step is an enantioselective protonation of a ketone enolate. A third enantioselective protonation, of a thiol ester enolate, was applied for the determination of the absolute configuration of Vulcanolide by comparison with a known compound.

Total synthesis of the novel bacterial fatty acid 16-methyl-8(Z)-heptadecenoic acid

The recently discovered bacterial fatty acid 16-methyl-8(Z)-heptadecenoic acid was synthesized for the first time in four steps (22% overall yield) starting from commercially available 8-methylnonanoic acid. The synthetic approach provided enough material to corroborate the structure and stereochemistry of the acid, which was recently identified in a Micrococcus bacterium from Lake Pomorie in Bulgaria. Reference equivalent-chain length values in nonpolar capillary gas chromatography for methyl 16-methyl-8(Z)-heptadecenoate and methyl 16-methyl-8(E)-heptadecenoate are also reported. This information will be helpful in subsequent characterizations of these fatty acids, as well as in the total identification of the fatty acid profile of bacteria producing these compounds.

Identification and total synthesis of novel fatty acids from the Siphonarid limpet Siphonaria denticulata

The novel fatty acids 17-methyl-6(Z)-octadecenoic acid and 17-methyl-7(Z)-octadecenoic acid were identified for the first time in nature in the mollusk Siphonaria denticulata from Queensland, Australia. The principal fatty acids in the limpet were hexadecanoic acid, octadecanoic acid, and (Z)-9-octadecenoic acid, while the most interesting series of monounsaturated fatty acids was a family of five nonadecenoic acids with double bonds at either Delta(7), Delta(9), Delta(11), Delta(12), or Delta(13). The novel compounds were characterized using a combination of GC-MS and chemical transformations, such as dimethyl disulfide derivatization. The first total syntheses for the two novel methyl-branched nonadecenoic acids are also described, and these were accomplished in four to five steps and in high yields.

Stereoselective total synthesis of (+)-myriocin from D-mannose

The stereoselective total synthesis of myriocin 1 from D-mannose is described; the carbon framework with three contiguous chiral centers including a tetra-substituted carbon with nitrogen was effectively constructed using Overman rearrangement as the key reaction.

An enantio- and stereocontrolled synthesis of (-)-mycestericin E via cinchona alkaloid-catalyzed asymmetric Baylis-Hillman reaction

A new enantiocontrolled synthesis of a potent immunosuppressant(-)-mycestericin E has been accomplished by using cinchona alkaloid-catalyzed asymmetric Baylis-Hillman reaction of an aldehyde with 1,1,1,3,3,3-hexafluoroisopropyl acrylate and Lewis acid-promoted cyclisation of an epoxytrichloroacetimidate as the key steps.

Constructing conformationally constrained macrobicyclic musks

To investigate the structure-odor correlation of musks, (12R)-12-methyl-13-tridecanolide (1), a macrocyclic musk, and 13-tridecanolide, its non-musky demethyl analogue, were conformationally constrained by introduction of methylene bridges between C-3 and C-8 or C-9. These [7.5.1]- and [8.4.1]-macrobicycles were synthesized starting from bicyclo[5.3.1]undec-8-en-9-one (3) and bicyclo[4.3.1]dec-7-en-8-one (8), respectively, by a sequence consisting of catalytic hydrogenation, alpha-alkylation with a TBS-protected (tert-butyldimethylsilyl) hydroxy halide, acid-catalyzed cyclization, oxidative cleavage of the formed enol ether double bond, and subsequent reduction of the carbonyl group via its tosylhydrazone. The compound (1R,6R,9R)-(+)-6-methyl-4-oxa-bicyclo[7.5.1]pentadecan-3-one (22) was found to possess the most pronounced musk odor, and this was rationalized by a superposition analysis with the polycyclic aromatic musk odorant (4S,7R)-Galaxolide (2). In its (1S,6R,9S)-(+)-stereoisomer 23 as well as in (1S,6R, 10R)-(+)-6-methyl-4-oxabicyclo[8.4.1]-pentadecan-3-one (18) the (6R)-methyl group seems to hinder the interaction with the musk receptor, while the demethyl compounds 7 and 12 showed only very faint odors.

A simple approach to DOTAP and its analogs bearing different fatty acids

A simple synthesis of N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium methyl sulfate (DOTAP) and its analogs differing in the fatty acids is presented. The synthesis is designed as quasi-one-pot reaction and the precipitating products are purified by simple recrystallization.

Antibody against a novel, myriocin (ISP-I)-based immunosuppressant, FTY720

An antibody was prepared by immunizing rabbits with an ovalbumin conjugate of 2-amino-2-(2-(4-(4-mercaptobutyl)phenyl)ethyl)propane-1,3-diol HCl (AMPD-4), which contains the essential structure of the novel immunosuppressant FTY720. As the antibody reacted to not only AMPD-4, but also FTY720, it should be useful for immunoassay of FTY720 in body fluids, tissues and cells.

[Synthesis of carbohydrate related compounds by using aldolase catalyzed reaction]

Enzymes proceed the reaction with high regio- and stereoselectivity under mild conditions, i.e. in an aqueous medium at room temperature. However, enzymatic reactions that catalyze carbon-carbon bond formation have not been utilized in organic synthesis until recently. We had an interest in an aldolase-catalyzed reaction which proceed carbon-carbon bond formation referred to aldol condensation, by which many bioactive compounds have been rationally synthesized. On the other hand, recent biological studies on cell recognition (cell adhesion) have disclosed the important roles of oligosaccharides on cell surfaces, especially which include glucuronic acid, 3-deoxy-D-manno-oct-2-ulosonic acid (KDO), and sialic acid in the structures e.g., sialyl Lewis X and endotoxins, in differentiation, induction, viral and bacterial infections, and immune response. As well as acidic oligosaccharides, basic ones have been utilized as practical medicines in the clinical level, like acarbose that acts as an amylase inhibitor. Based on these background, we embarked the synthesis of carbohydrate related compounds which can control the interaction between carbohydrates and carbohydrate recognition protein by the use of several aldolases. Azasugars, potent inhibitors toward glycosidases, were synthesized using fructose-1,6-diphosphate (FDP)-aldolase and other dihdroxyacetonephosphate (DHAP)-dependent aldolases in the key step. Sialyl Lewis X mimetic, peptidic mimetic of RNA having anti-Vero toxin activity, mycestericin D, and aza-idulonic acid were prepared by taking advantage of L-threonine aldolase catalyzed reaction, which afford beta-hydroxy-alpha-L-amino acids. A precursor of KDO, featured acidic sugar of endotoxins was provided by the reaction catalyzed with kynureninase, which generates beta-anion of L-alanine in its active site during the metabolic reaction from kynurenine to anthranilic acid.

Synthetic musks in environmental samples: indicator compounds with relevant properties for environmental monitoring

Synthetic musks (nitro and polycyclic musks) are a group of chemicals offering a wide range of important properties for environmental monitoring programs. They are produced as odorous chemicals and added to a wide variety of perfumes, toiletry products and other household products. As such, they are directly applied in cosmetic products or in washed textiles to the human body in considerable concentrations and accumulate owing to dermal resorption. In addition, synthetic musks also enter the environment via waste water treatment. Several polycyclic musks are chiral. By using chiral gas chromatographic methods, it is possible to determine the enantiomeric ratio and assess their bioavailability. Although an comprehensive quality assurance program must be followed during the analysis of synthetic musks in environmental samples, the determination of these compounds is not very demanding and can be carried out by a standard analytical laboratory specialising in trace analysis of organic pollutants. Owing to the pheromone-like behavior of some synthetic musks, the induction of receptors in olfactory systems should be investigated. For HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2-benzopyran, e.g., Galaxolide), three-dimensional structural similarities with androstenone (5 alpha-androst-16-en-3-one), a mammalian steroid pheromone, were found, which support the hypothesis of HHCB as an artificial pheromone. Owing to their environmental abundance, their relation to human activities and their potential for pheromone-like environmental behavior, synthetic musks are especially valuable as future indicator chemicals for environmental monitoring.

The identification of myriocin-binding proteins

BACKGROUND

Myriocin is a natural product that potently induces apoptosis of a murine cytotoxic T lymphocyte cell line (CTLL-2) and inhibits a serine palmitoyltransferase (SPT) activity that has been detected in cell extracts and is thought to initiate sphingolipid biosynthesis. Because SPT has never been biochemically purified and a comprehensive appraisal of myriocin-binding proteins has not been conducted, we isolated specific targets using myriocin-based affinity chromatography.

RESULTS

Myriocin derivatives were synthesized and evaluated using CTLL-2 proliferation and SPT activity assays. Guided by these results, affinity chromatography matrices were prepared and two specific myriocin-binding proteins were isolated from CTLL-2 lysates. Analyses of these polypeptides establish conclusively that they are murine LCB1 and LCB2, mammalian homologs of two yeast proteins that have been genetically linked to sphingolipid biosynthesis.

CONCLUSION

The ability of myriocin-containing matrices to bind factors that have SPT activity and the exclusive isolation of LCB1 and LCB2 as myriocin-binding proteins demonstrates that the two proteins are directly responsible for SPT activity and that myriocin acts directly upon these polypeptides.

Synthesis of racemic 9-methyl-10-hexadecenoic acid

The marine bacterial fatty acid 9-methyl-10-hexadecenoic acid was conveniently prepared in 6 steps and in a 22% overall yield, starting from commercially available methyl 10-hydroxydecanoate. The naturally occurring fatty acid has the E double bond configuration as confirmed by gas chromatographic co-elution experiments.

Facile total synthesis and antimicrobial activity of the marine fatty acids (Z)-2-methoxy-5-hexadecenoic acid and (Z)-2-methoxy-6-hexadecenoic acid

The total synthesis of the naturally occurring (Z)-2-methoxy-5-hexadecenoic acid and (Z)-2-methoxy-6-hexadecenoic acid was accomplished using as a key step Mukaiyama's trimethylsilyl cyanide addition to 4- and 5-pentadecenal, respectively. These syntheses further confirm the structures of the natural marine fatty acids and corroborate their cis double-bond stereochemistry. The title compounds were antimicrobial against the Gram-positive bacteria Staphylococcus aureus (MIC 0.35 micromol/mL) and Streptococcus faecalis (MIC 0.35 micromol/mL).

Cytochrome P450-dependent desaturation of lauric acid: isoform selectivity and mechanism of formation of 11-dodecenoic acid

Cytochrome P450-catalyzed desaturation reactions have been reported infrequently in the literature. Previously, we documented the formation of the terminal olefinic metabolite of valproic acid by various members of the CYP2B and CYP4B sub-families. However, despite the extensive use of fatty acid substrates in drug metabolism studies, other examples of terminal desaturation at non-activated carbon centers are lacking. The goals of the present studies were to determine whether the archetypal P450 substrate, lauric acid (dodecanoic acid; DDA), also undergoes desaturation reactions, identify specific rabbit P450 isoforms which catalyze this reaction and examine its mechanism. A highly sensitive, capillary GC/MS assay was developed to separate and quantitate the trimethylsilyl derivatives of 11-ene-DDA, cis- and trans-10-ene-DDA and cis- and trans-9-ene-DDA. Among all of these potential olefinic metabolites, only 11-ene-DDA was formed at a significant rate by rabbit liver microsomes. The formation of 11-ene-DDA was NADPH-dependent, and was induced markedly by acetone pre-treatment, but not by phenobarbital, rifampin or Arochlor 1254. Studies with seven purified, reconstituted rabbit P450 isoforms showed that the most rapid rates of desaturation were obtained with CYP2E1, CYP4A5/7 and CYP4B1. Non-competitive, intermolecular isotope effect experiments, conducted with [12,12,12-2H3]DDA and [11,11-2H2]DDA, demonstrated further that CYP4B1-mediated terminal desaturation of DDA is initiated by removal of a hydrogen atom from the omega-1 rather than the omega position.

Characterization of thiol-conjugated metabolites of 2-propylpent-4-enoic acid (4-ene VPA), a toxic metabolite of valproic acid, by electrospray tandem mass spectrometry

The hepatotoxicity of the anticonvulsant drug valproic acid (VPA) is most likely associated with the bioactivation of its metabolite 2-propylpent-4-enoic acid (4-ene VPA), which is known to induce hepatic microvesicular steatosis in rats. This paper presents an on-line liquid chromatographic/tandem mass spectrometric (LC/MS/MS) identification of new glutathione (GSH)-related conjugates of the reactive metabolites of 4-ene VPA. Bile samples collected from male Sprague-Dawley rats dosed intraperitoneally with 4-ene VPA or its [2H7]-analogue (100 mg kg-1) were injected on to an ODS column interfaced to a LC/MS/MS instrument using electrospray ionization. LC was developed such that no overlapping of peaks occurred among those metabolites which may potentially produce common fragment ions of interest. Subsequent comparison of LC retention times and MS/MS full fragment ion spectra generated for putative metabolites with that of authentic reference compounds made available by chemical synthesis confirmed the presence of the GSH, cysteinylglycine, cysteine and N-acetylcysteine (NAC) conjugates of 2-(2'-carboxypentanyl)oxirane (4,5-epoxy VPA) and (E)-2-propylpenta-2,4-dienoic acid ((E)-2,4-diene VPA), respectively. Quantitatively, the biliary thiol conjugates accounted for 5% of the dose. This observation is novel for 4-ene VPA metabolism in terms of the degradation of GSH conjugates to the corresponding mercapturic acids possibly occurring within the liver as opposed to an inter-organ process which involves the kidney. In addition, the GSH- and NAC-glucuronide di-conjugates of (E)-2,4-diene VPA were also identified as the biliary metabolites with the GSH-glucuronide di-conjugate being 10% of the corresponding mono-GSH conjugate. Taken together, these data clearly indicate that reactive metabolites of VPA can react with hepatic GSH via several different metabolic pathways and may subsequently produce depletion of GSH that leads to toxic consequences.

Effect of monounsaturation of a branched fatty acid on organ selectivity

1-[11C]-3-R,S-methylheptadecanoic acid (BMHA) is a branched chain fatty acid analog that is transported into the myocardium. Due to incomplete metabolism, however, radiolabeled products are trapped within myocytes. Recently, we demonstrated that this compound is an excellent tracer to monitor fatty acid metabolism.

METHOD

To evaluate the effect of mono-unsaturation on myocardial substrate utilization, we prepared 1-[11C]-3-R,S-methyl-trans--heptadec-7-enoic acid (t-7-BMHA) and measured its biodistribution in rats. In addition, preliminary PET studies were performed on dogs.

RESULTS

Biodistribution studies demonstrated that myocardial-to-lung and myocardial-to-blood ratios for t-7-BMHA are higher than those for BMHA. Fifteen minutes after injection, heart-to-lung ratios were 5.23 compared to 2.92 and heart-to-liver ratios were 3.07 compared to 1.41 for t-7-BMHA and BMHA. By 30 min postinjection heart-to-lung ratios were 7.03 compared to 5.88 and heart-to-liver ratios were 4.43 compared to 1.09. The heart-to-blood ratio of t-7-BMHA was greater than 11:1. PET imaging with 1-[11C]-t-7-BMHA demonstrated high myocardial extraction, prolonged retention of radioactivity and excellent image quality. Accumulation of radioactivity in the myocardium reached a plateau within 10 min postinjection, with heart-to-blood ratios exceeding 20:1 and heart-to-lung ratios exceeding 10:1. Blood clearance of radioactivity was biphasic with half-times of 1.46 and 14.7 min, respectively.

CONCLUSION

These data suggest that introduction of a trans-double bond in BMHA improves myocardial selectivity and results in a potentially superior imaging agent.

Syntheses, immunosuppressive activity, and structure-activity relationships of myriocin analogs, 2-epi-myriocin, 14-deoxomyriocin, Z-14-deoxyomyriocin, and nor-deoxomyriocins

Nine myriocin analogs, 2-epi-myriocin, 14-deoxomyriocin, Z-14-deoxomyriocin, and nor-deoxomyriocins, were synthesized from 2-deoxy-D-glucose via common intermediates used in previous myriocin and Z-myriocin syntheses. Immunosuppressive activities of those myriocin analogs on mouse allogeneic mixed lymphocyte reaction were examined, and Z-14-deoxomyriocin was found to show the most potent activity among them. The structure-activity relationships are discussed.

Synthesis of new immunosuppressive myriocin analogs, 2-epi-myriocin, 14-deoxomyriocin, Z-14-deoxomyriocin, and nor-deoxomyriocins: their structure-activity relationships

Eight new myriocin analogs, 2-epi-myriocin, Z-14-deoxomyriocin, and nor-deoxomyriocins, and a known myriocin derivative, 14-deoxomyriocin, were synthesized from 2-deoxy-D-glucose via common intermediates in previous myriocin and Z-myriocin syntheses. The immunosuppressive activities of new myriocin analogs and Z-myriocin on mouse allogeneic mixed lymphocyte reaction were examined, and, by comparing with those of myriocin and 14-deoxomyriocin, some structure-activity relationships have been found.

Total synthesis of a novel immunosuppressant, myriocin (thermozymocidin, ISP-I), and Z-myriocin

Myriocin (thermozymocidin, ISP-I), which was known to exhibit several interesting biological properties such as potent immunosuppressive and antifungal activities, and a new analog Z-myriocin were synthesized from 2-deoxy-D-glucose. This synthetic pathway comprises a stereoselective formation of the chiral alpha, alpha-disubstituted amino acid structure in myriocin and Z-myriocin from the isopropylidene six-membered ketone by using a modified Darzen reaction as its key step.

Fungal metabolites. Part 12. Potent immunosuppressant, 14-deoxomyriocin, (2S,3R,4R)-(E)-2-amino-3,4-dihydroxy-2-hydroxymethyleicos-6-enoic acid and structure-activity relationships of myriocin derivatives

In order to investigate the structure-activity relationships, fourteen derivatives of myriocin ((2S,3R,4R)-(E)-2-amino-3,4-dihydroxy-2-hydroxymethyl-14-oxoeicos- 6-enoic acid) were prepared and examined for immunosuppressive activity on mouse allogeneic mixed lymphocyte reaction in vitro. Among them, 14-deoxomyriocin ((2S,3R,4R)-(E)-2-amino-3,4-dihydroxy-2- hydroxymethyleicos-6-enoic acid) was the most potent. It also suppressed the generation of allo-reactive cytotoxic T lymphocytes in mice upon intraperitoneal administration, with a potency 10-fold greater than that of myriocin.

Covalent attachment of palmitoleic acid (C16:1 delta 9) to proteins in Saccharomyces cerevisiae. Evidence for a third class of acylated proteins

Saccharomyces cerevisiae was used as a model system to characterize the covalent attachment of palmitoleic acid to proteins. Chemically synthesized cis-[9,10-3H]hexadecenoic acid (palmitoleic acid) was used to demonstrate the attachment of this lipid species to at least six proteins (m = 122, 58, 45, 41, 31, and 17 kDa). The majority of the labeled proteins are distinct from those labeled with [3H]palmitic acid (16:0). Based on the lability of the bond in the presence of methanolic KOH or hydroxylamine (pH 8), we propose that [3H] palmitoleic acid is attached to proteins via a thioester linkage. The identity of the palmitoleic acid was established by C-18 reverse phase high performance thin layer chromatography and argentation thin layer chromatography analysis after the fatty acid was liberated from the proteins by either transesterification or saponification. Incorporation of [3H]palmitoleic acid into proteins was only slightly inhibited (relative to [3H] myristic acid) by the presence of cycloheximide, indicating that the attachment of [3H]palmitoleic acid occurs post-translationally. This report is the first description of multiprotein acylation by a long chain unsaturated fatty acid.

Synthesis of methyl (Z)-tetracos-5-enoate and both enantiomers of ethyl (E)-6-methyltetracos-4-enoate: possible intermediates in the biosynthesis of mycolic acids in mycobacteria

The high molecular weight 2-alkyl-3-hydroxy mycolic acids are key structural components of the cell envelope of pathogenic mycobacteria, such as Mycobacterium tuberculosis. A prime target for action would be the initial stages where the biosynthetic pathways diverge from those of ordinary fatty acids. It has been postulated that the pathway for the alpha-mycolates, without oxygen functions in addition to the hydroxy-acid unit, appears to diverge from (Z)-tetracos-5-enoic acid. The biosynthesis of oxygenated mycolic acids is considered to possibly diverge from (E)-6-(R)-methyltetracos-4-enoic and (E)-6-(S)-methyltetracos-4-enoic acids. This communication describes the synthesis of esters of these acids in order to test their potential role in the biosynthesis of mycolic acids.

Mechanism-based inhibitors of prostaglandin omega-hydroxylase: (R)- and (S)-12-hydroxy-16-heptadecynoic acid and 2,2-dimethyl-12-hydroxy-16-heptadecynoic acid

12-Hydroxy-16-heptadecynoic acid has been shown to selectively inactivate cytochrome P450 4A4, a pulmonary cytochrome P450 enzyme that catalyzes the omega-hydroxylation of prostaglandins [Muerhoff, A. S.; Williams, D. E.; Reich, N. O.; CaJacob, C. A.; Ortiz de Montellano, P. R.; Masters, B. S. S. J. Biol. Chem. 1989, 264, 749-756]. Potent, specific inhibitors of this enzyme are required to explore its physiological role. In a continuing effort to develop such agents, the two enantiomers of 12-hydroxy-16-heptadecynoic acid have been stereospecifically synthesized, their absolute stereochemistry confirmed, and the dependence of enzyme inactivation on absolute stereochemistry determined using cytochrome P450 4A4 purified from the lungs of pregnant rabbits. The 12S enantiomer is roughly twice as active (KI = 1.8 microM, t1/2 = 0.7 min) as the 12R enantiomer (KI = 3.6 microM, t1/2 = 0.8 min), but the chirality of the hydroxyl group is not a major determinant of the specificity for the prostaglandin omega-hydroxylase. The flexibility of the acyclic skeleton of the inhibitor may account for the relatively low enantiomeric discrimination. 2,2-Dimethyl-12-hydroxy-16-heptadecynoic acid, an analogue that cannot undergo beta-oxidation, has also been synthesized as a potential in vivo inhibitor of the enzyme and has been shown to inactivate the purified enzyme with KI = 4.9 microM and t1/2 = 1.0 min. These acetylenic agents, particularly the dimethyl analog, are promising in vivo inhibitors of cytochrome P450 4A4.

Improved synthesis of (5Z)-7-(3-endo-[(benzenesulfonamido)-bicyclo[2.2.1]heptyl]hept-5-enoic acid (S-145) derivatives and their iodine-125-labeled radioligands for the study of thromboxane A2 receptor

An improved synthetic scheme for (5Z)-7-(3-endo-[(benzenesulfonamido)-bicyclo[2.2.1]heptyl)-h ept-5-enoic acid (S145) and its analogs has been designed. The procedure involves direct sulfonylation of 2-allyl-3-aminobicyclo[2.2.1]heptane intermediate followed by ozonolysis and addition of a C5 carboxyl unit. The yield of the final product was significantly improved. (5Z)-7-(3-endo-[(4-iodobenzenesulfonamido)-bicyclo [2.2.1]heptyl)hept-5-enoic acid (HS-145) and (5Z)-7-(3-endo-[(4-hydroxy-benzensulfonamido)-bicyclo [2.2.1]heptyl)hept-5-enoic acid (HS-145) were synthesized directly without any protection and deprotection steps. [125I](5Z)-7-(3-endo-[(4- iodobenzensulfonamido)-bicyclo[2.2.1]heptyl)hept-5-enoic acid ([125I]HS-145) was prepared from IS-145 through an organotin intermediate and [125I]sodium iodide with high specific radioactivity and good recovery of radioactivity. [125I](5Z)-7-(3-endo-[(4-hydroxy 3-iodo-benzenesulfonamido)-bicyclo[2.2.1]-heptyl)hept-5-enoic acid ([125I]HS-145) was prepared by direct iodination with sodium iodide using a modified chloramine-T method. Both [125I]HS-145 and [125I]HS-145 were found to be valuable radioligands for studying thromboxane A2 (TXA2) receptor.

The enantiomers of the valproic acid analogue 2-n-propyl-4-pentynoic acid (4-yn-VPA): asymmetric synthesis and highly stereoselective teratogenicity in mice

The teratogenic activities of R(+)- and S(-)-2-n-propyl-4-pentynoic acid (R and S-4-yn-VPA), the enantiomers of the highly teratogenic valproic acid (VPA) analogues (+/-)-4-yn-VPA, were investigated in mice. The enantiomers were prepared via asymmetric synthesis, each in three steps employing the chiral auxiliaries (4R,5S)-4-methyl-5-phenyl-2-oxazolidinone and S-4-benzyl-2-oxazolidinone. The determination of the absolute configurations and the optical purities is described. R(+)-4-yn-VPA contained 7%, and S(-)-4-yn-VPA 8%, of the respective antipodes. The aqueous solutions of the sodium salts of R- and S-4-yn-VPA were administered as single i.p. injections during early organogenesis in the mouse (day 8 of gestation) using the induction of exencephaly as the teratological end point. Dose/exencephaly curves indicated that S-4-yn-VPA is 7.5 times more teratogenic than its antipode, 1.9 times more teratogenic than (+/-)-4-yn-VPA and 3.9 times more teratogenic than the parent drug VPA. In contrast, the neurotoxicity (maternal toxicity) of the 4-yn-VPA enantiomers was found to be independent of the stereo-chemical configuration and lower than achieved after VPA administration. Due to its low neurotoxicity and highly stereoselective neural tube-inducing activity, S-4-yn-VPA should prove an important tool for the investigation of molecular mechanism of the teratogenic action in this class of compounds; R-4-yn-VPA could act as the negative control in these studies.

Synthesis of metabolites of S-1452, an orally active thromboxane A2 receptor antagonist

The synthesis of 16 metabolites of S-1452, an orally active thromboxane A2 (TXA2) receptor antagonist, is described. Regioselective hydroxylation at C-5 or C-6 of the bicyclo[2.2.1]heptane skeleton of the optically active intermediate 16 was attempted by using 9-borabicyclo[3.3.1]nonane followed by H2O2 or m-chloroperbenzoic acid (m-CPBA) and then LiA1H4, to obtain the hydroxylated product 17a or 17b, respectively. Modification of the C-2 substituent of 17a and 17b afforded eight metabolites of S-1452. Eight non-hydroxylated metabolites were synthesized by using a similar reaction sequence.

Lack of teratogenicity of trans-2-ene-valproic acid compared to valproic acid in rats

The teratogenicity of trans-2-ene-valproic acid (300 and 400 mg/kg) was compared with that of valproic acid (VPA; 300 mg/kg) and controls (corn oil) administered by gavage to Sprague-Dawley CD rats on embryonic (E) days 7-18. At the 300 mg/kg dose, trans-2-ene-VPA produced no change in maternal weight, number of implantations, proportion of resorptions, proportion of malformations, or fetal weight. By contrast, the same dose of VPA (300 mg/kg) reduced maternal weight during gestation, increased malformations (12.0% vs. 0.7% in controls), and reduced fetal body weight by 25.1%. An even higher dose of trans-2-ene-VPA (400 mg/kg) produced a reduction in maternal body weight during treatment and reduced fetal body weight (by 7.9%), but did not increase resorptions or malformations in the fetuses. On day E18, maternal serum drug concentrations of VPA were higher in the VPA-treated group compared with those of trans-2-ene-VPA in the trans-2-ene-VPA-treated groups at 1 hr posttreatment. At 6 hr posttreatment the reverse was seen. trans-2-ene-VPA may be absorbed more rapidly and distributed differently than VPA. Overall, the data support the view that trans-2-ene-VPA at equal or higher doses than VPA is not teratogenic in rats.