Trans Double Bond Research Articles

The bacterial catabolism of polycyclic aromatic hydrocarbons: Characterization of three hydratase-aldolase-catalyzed reactions

Summary Polycyclic aromatic hydrocarbons (PAHs) are highly toxic, pervasive environmental pollutants with mutagenic, teratogenic, and carcinogenic properties. There is interest in exploiting the nutritional capabilities of microbes to remove PAHs from various environments including those impacted by improper disposal or spills. Although there is a considerable body of literature on PAH degradation, the substrates and products for many of the enzymes have never been identified and many proposed activities have never been confirmed. This is particularly true for high molecular weight PAHs (e.g., phenanthrene, fluoranthene, and pyrene). As a result, pathways for the degradation of these compounds are proposed to follow one elucidated for naphthalene with limited experimental verification. In this pathway, ring fission produces a species that can undergo a non-enzymatic cyclization reaction. An isomerase opens the ring and catalyzes a cis to trans double bond isomerization. The resulting product is the substrate for a hydratase-aldolase, which catalyzes the addition of water to the double bond of an α,β-unsaturated ketone, followed by a retro-aldol cleavage. Initial kinetic and mechanistic studies of the hydratase-aldolase in the naphthalene pathway (designated NahE) and two hydratase-aldolases in the phenanthrene pathway (PhdG and PhdJ) have been completed. Crystallographic work on two of the enzymes (NahE and PhdJ) provides a rudimentary picture of the mechanism and a platform for future work to identify the structural basis for catalysis and the individual specificities of these hydratase-aldolases.

Fluorescent Farnesyl Diphosphate Analogue: A Probe To Validate trans-Prenyltransferase Inhibitors.

Some trans-prenyltransferases, such as long-chain C40 octaprenyl diphosphate synthase (OPPS), short-chain C15 farnesyl diphosphate synthase (FPPS), and C20 geranylgeranyl diphosphate synthase (GGPPS), are important drug targets. These enzymes catalyze chain elongation of FPP or geranyl diphosphate (GPP) through condensation reactions with isopentenyl diphosphate (IPP), forming designated numbers of trans-double bonds in the final products. To facilitate drug discovery, we report here a sensitive and reliable fluorescence-based assay for monitoring their activities in real time. MANT-O-GPP, a fluorescent analogue of FPP, was used as an alternative substrate and converted by the wild-type OPPS and the engineered FPPS and GGPPS into sufficiently long products with enhanced fluorescence intensities. This fluorescence probe was used to reveal the inhibitory mechanism of zoledronate, a bisphosphonate drug that targets human FPPS and possibly GGPPS.

A novel series of C18–C22 trans ω3 PUFA from Northern and Southern Hemisphere strains of the marine haptophyte Imantonia rotunda

A series of novel C18–C22trans ω3 polyunsaturated fatty acids (PUFA) with a single trans double bond in the ω3 position was found in Northern and Southern Hemisphere strains of the marine haptophyte Imantonia rotunda. The novel ω3 PUFA were identified as 18:3(9c,12c,15t) (0.2–1.8 % of total fatty acids), 18:4(6c,9c,12c,15t) (1.9–4.1 %), 18:5 (3c,6c,9c,12c,15t) (0.7–8.8 %), 20:5(5c,8c,11c,14c,17t) (1.2–4.1 %) and 22:6(4c,7c,10c,13c,16c,19t) (0.3–4.3 %), and were accompanied by larger proportions of the all cis isomers: 18:3ω3(9,12,15) (2.7–3.5 %), 18:4ω3(6,9,12,15) (9.3–14.3 %), 18:5ω3(3,6,9,12,15) (7.8–18.5 %), 20:5ω3(5,8,11,14,17) (3.2–3.9 %), 22:5ω3(7,10,13,16,19) (0.1–0.3 %) and 22:6ω3(4,7,10,13,16,19) (2.3–5.2 %). GC analysis of FAME using a non-polar column did not reveal the trans isomers as they coeluted with the all cis PUFA. However, GC using a polar column resolved the trans PUFA from the all cis PUFA, with the trans isomers eluting before the all cis isomers. GC-MS of FAME fractionated by argentation solid-phase chromatography confirmed the molecular ions of all components. FAME were derivatized to form 4,4-dimethyloxazoline (DMOX) derivatives, and GC-MS revealed the same double bond positions for each trans and cis FAME. The results suggest that the ω3 trans double bond originated from the Δ15/ω3 desaturation of 18:2(9c,12c), suggesting that this desaturase has dual cis/trans activity in these species. These results indicate that 18:3(9c,12c,15 t) was the precursor trans isomer produced for the trans series and further desaturation by the common Δ6 desaturase to produce the trans tetraene and successive elongations and desaturations led to the subsequent series of trans ω3 PUFA isomers. To our knowledge, this is the first report of these trans ω3 isomers occurring in strains of I. rotunda. These trans ω3 PUFA may be used as biomarkers in marine food webs for this species and with their unique structure may be biologically active.

Enhancing Topical Delivery of Resveratrol through a Nanosizing Approach.

Resveratrol is a naturally occurring polyphenol with strong antioxidant and free radical scavenging properties, recently proposed as a therapeutic agent for skin diseases. In this study, we investigated the possibility of improving the dermal bioavailability of the poorly water-soluble drug resveratrol by nanocrystal technology. To this purpose, nanosuspensions were prepared by the wet media milling technique, using Poloxamer 188 or Tween 80 as stabilizers, and characterized by means of both solid state and morphological and dimensional studies. All analytical data demonstrated that neither a modification of the drug crystalline pattern nor the isomerization of the trans double bond were observed after the wet media milling particle size reduction process, which produced rounded and smooth nanocrystals with a mean diameter ranging between 0.2-0.3 µm. Resveratrol skin delivery from nanosuspension formulations was evaluated by the pig ear skin model via tape stripping. Results of the experiments showed that after application of nanosuspension formulations, higher amounts of resveratrol could penetrate the skin at deeper levels compared to drug coarse suspensions. The antioxidant activity of resveratrol in nanocrystals was assessed by the DPPH assay, which demonstrated that the size reduction process as well as the formulation compositions did not modify the drug antioxidant activity.

Liprotides made of α-lactalbumin and cis fatty acids form core–shell and multi-layer structures with a common membrane-targeting mechanism

α-Lactalbumin (aLA) has been shown to form complexes with oleic acid (OA), which may target cancer cells. We recently showed that aLA and several other proteins all form protein–OA complexes called liprotides with a generic structure consisting of a micellar OA core surrounded by a shell of partially denatured protein. Here we report that a heat treatment and an alkaline treatment method both allow us to prepare liprotide complexes composed of aLA and a range of unsaturated fatty acids (FA), provided the FAs contain cis (but not trans) double bonds. All liprotides containing cis-FA form both small and large species, which all consist of partially denatured aLA, though the overall shape of the species differs. Small liprotides have a simple core–shell structure while the larger liprotides are multi-layered, i.e. they have an additional layer of both FA and aLA surrounding the outside of the core–shell structure. All liprotides can transfer their entire FA content to vesicles, releasing aLA as monomers and softening the lipid membrane. The more similar to OA, the more efficiently the different FAs induce hemolysis. We conclude that aLA can take up and transfer a wide variety of FA to membranes, provided they contain a cis-bond. This highlights liprotides as a general class of complexes where both protein and cis-FA component can be varied without departing from a generic (though sometimes multi-layered) core–shell structure.

Total Synthesis of δ-Sanshool and Analogues Thereof

Two simple synthetic approaches were developed for the total synthesis of δ-sanshool, an isobutylamide characterized by a C 14 pentaunsaturated chain with all trans double bonds and proposed as a promising lead for the treatment of type-1 diabetes due to its dual activity on cannabinoid (CB) receptors. The syntheses are based on a suitably protected core fragment derived from 1,4-butanediol. These strategies also enable the preparation of small libraries of chemical analogues modified at either the polyunsaturated alkyl chain or the amidic head for use in SAR studies.

Regioselective Ring-Opening Metathesis Polymerization of 3-Substituted Cyclooctenes with Ether Side Chains.

Allyl-substituted cyclooctenes with ether side-chains [methoxy, methoxy-terminated oligo(ethylene glycol)s, and tetrahydrofurfuryloxy group] were prepared as monomers and polymerized by ring-opening metathesis polymerization (ROMP) using Grubbs second-generation catalyst. In all cases, the ROMP of allyl-substituted monomers proceeded in a regio- and stereoselective manner to afford polymers with remarkably high head-to-tail regioregularity with high trans-stereoregularity. The regio- and stereoregularity of polymers were affected by the bulkiness of the substituent, and the ROMP of tetrahydrofurfuryloxy-substituted cyclooctene exhibited nearly perfect regio- (head-to-tail = 99%) and stereoselectivity (trans-double bond = 99%). Chemical hydrogenation of obtained polymers afforded model poly(ethylene-co-vinyl ether)s with precisely placed ether branches on every eighth backbone carbon. Differential scanning calorimetry (DSC) was used to study the thermal properties, and the hydrophilicity of polymers was ev...

Mitigating crystallization of saturated fames in biodiesel: 1. Lowering crystallization temperatures via addition of metathesized soybean oil

The addition of self-MSBO (metathesized soybean oil) to biodiesel significantly depresses the onset temperature of crystallization (Ton). MSBO and self-MTO (metathesized triolein), used as model systems, were separated into their constituent “molecular families” using column chromatography and crystallization fractionation and tested as crystallization modifiers of biodiesel. The results indicate that cis-unsaturation combined with a straight chain moiety is a critical structural architecture for disrupting biodiesel crystallization. The data obtained with TAGs (triacylglycerols) propose that the most effective stereospecificity is when the two fatty acids in the cis-configuration are in the sn-1 and sn-3 positions and a trans-/saturated fatty acid is at the sn-2 position. The conversion of cis-double bonds to trans-double bonds by self-metathesis explains the lowering of Ton of biodiesel. The fractionation of MSBO, leading to a liquid fraction enriched with molecules having cis-unsaturated fatty acids out-performed MSBO in lowering Ton of biodiesel. This knowledge can be used for the design of economical and more functional materials from MSBO and other metathesized vegetable oils using selective and practical fractionation methods. The findings of the study suggest that the use of biodiesel with significant saturated methyl ester content can be extended in colder months of the year.

Photocrosslinkable polynorbornene-based block copolymers with enhanced dielectric and thermal properties

Block copolymers poly(endo-N-3,5-bis(trifluoromethyl)biphenyl-norbornene-pyrrolidine)-block-poly(exo-N-(cinnamoyloxyethyl)-7-oxanorborn-5-ene-2,3-dicarboximide) (endo-PTNP-b-exo-PCONBI) and poly(exo-N-3,5-bis(trifluoromethyl)biphenyl-norbornene-pyrrolidine)-block-poly(exo-N-(cinnamoyloxyethyl)-7-oxanorborn-5-ene-2,3-dicarboximide) (exo-PTNP-b-exo-PCONBI) were synthesized by ring-opening metathesis polymerization. The endo- or exo-PTNP served as the high dielectric functional chain, and exo-PCONBI acted as the crosslinking segment. The endo-PTNP-b-exo-PCONBI, in which endo-PTNP has a high content of trans double bond and adopts isotactic configuration, shows a dielectric constant (ε) of 15.5, whereas exo-PTNP-b-exo-PCONBI, in which exo-PTNP has 67% trans double bonds and atactic microstructure, displays relatively low ε of 7.1. The cinnamate groups in exo-PCONBI were crosslinked to form three-dimensional network by cycloaddition reaction under UV irradiation. Exposed to UV-light for 10 min, the cinnamate group in polymer films has a crosslinking conversion of 36%, as determined by UV-Vis absorption measurements. By photocrosslinking, the polymer film has an increased ε of 16.6, a dielectric loss of 0.03, an elevated glass-transition temperature of 137 °C, and an enhanced decomposition temperature of 405 °C, compared to those of polymer films without irradiation.

The Influence of Hydrogen Bonding on Sphingomyelin/Colipid Interactions in Bilayer Membranes

The phospholipid acyl chain composition and order, the hydrogen bonding, and properties of the phospholipid headgroup all influence cholesterol/phospholipid interactions in hydrated bilayers. In this study, we examined the influence of hydrogen bonding on sphingomyelin (SM) colipid interactions in fluid uni- and multilamellar vesicles. We have compared the properties of oleoyl or palmitoyl SM with comparable dihydro-SMs, because the hydrogen bonding properties of SM and dihydro-SM differ. The association of cholestatrienol, a fluorescent cholesterol analog, with oleoyl sphingomyelin (OSM) was significantly stronger than its association with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, in bilayers with equal acyl chain order. The association of cholestatrienol with dihydro-OSM, which lacks a trans double bond in the sphingoid base, was even stronger than the association with OSM, suggesting an important role for hydrogen bonding in stabilizing sterol/SM interactions. Furthermore, with saturated SM in the presence of 15 mol % cholesterol, cholesterol association with fluid dihydro-palmitoyl SM bilayers was stronger than seen with palmitoyl SM under similar conditions. The different hydrogen bonding properties in OSM and dihydro-OSM bilayers also influenced the segregation of palmitoyl ceramide and dipalmitoylglycerol into an ordered phase. The ordered, palmitoyl ceramide-rich phase started to form above 2 mol % in the dihydro-OSM bilayers but only above 6 mol % in the OSM bilayers. The lateral segregation of dipalmitoylglycerol was also much more pronounced in dihydro-OSM bilayers than in OSM bilayers. The results show that hydrogen bonding is important for sterol/SM and ceramide/SM interactions, as well as for the lateral segregation of a diglyceride. A possible molecular explanation for the different hydrogen bonding in SM and dihydro-SM bilayers is presented and discussed.

Trans Fatty Acids, does Exist Safety Dosage?

Recent data regarding Trans Fatty Acids (TFAs) have implicated this lipid as being particularly deleterious to human health. TFAs are unsaturated fatty acids that contain at least one non conjugated double bond in the trans configuration, resulting in a more linear shape. The presence of a trans double bond in a fatty acid chain results in a smaller bond angle, or kink, than in a cis double bond, resulting in a fatty acid chain conformation that is more similar to a saturated fatty acid than to an unsaturated fatty acid. Several studies have identified an association between trans-fat intake and a risk of neurodiseases, cardiometabolic disease and pro-inflammatory effects. It focuses on a series of recent studies that have supporting the pathogenic role through human or animal experiments in vitro or in vivo. Overall, the findings of this short communication suggest that fat composition is more important than the quantity of fat consumed in terms of dietary cis and trans fatty acids.

Interactions of Molecules with cis and trans Double Bonds: A Theoretical Study of cis- and trans-2-Butene.

Noncovalent interactions of cis- and trans-2-butene, as the smallest model systems of molecules with cis and trans double bonds, were studied to find potential differences in interactions of these molecules. The study was performed using quantum chemical methods including very accurate CCSD(T)/CBS method. We studied parallel and displaced parallel interactions in 2-butene dimers, in butane dimers, and between 2-butene and saturated butane. The results show the trend that interactions of 2-butene with butane are the strongest, followed by interactions in butane dimers, whereas the interaction in 2-butene dimers are the weakest. The strongest calculated interaction energy is between trans-2-butene and butane, with a CCSD(T)/CBS energy of -2.80 kcal mol(-1) . Interactions in cis-2-butene dimers are stronger than interactions in trans-2-butene dimers. Interestingly, some of the interactions involving 2-butene are as strong as interactions in a benzene dimer. These insights into interactions of cis- and trans-2-butene can improve understanding of the properties and processes that involve molecules with cis and trans double bonds, such as fatty acids and polymers.

Total Synthesis and Structural Reassignment of the γ‐Lactone Polyketide from Diaporthe sp. SXZ‐19

AbstractThe first stereoselective total synthesis of the proposed structure of the γ‐lactone from Diaporthe sp. SXZ‐19 was achieved by utilizing a convergent pathway. The four stereogenic centers were formed by employing Brown's asymmetric alkoxyallylboration reaction, and a cross‐metathesis reaction was used to construct the trans double bond of the γ‐lactone side chain. This synthesis led to a revision of proposed structural assignment of the natural product.

Topologies, structures and parameter files for lipid simulations in GROMACS with the OPLS-aa force field: DPPC, POPC, DOPC, PEPC, and cholesterol.

In this data article we provide topologies and force field parameters files for molecular dynamics simulations of lipids in the OPLS-aa force field using the GROMACS package. This is the first systematic parameterization of lipid molecules in this force field. Topologies are provided for four phosphatidylcholines: saturated DPPC, mono-cis unsaturated POPC and DOPC, and mono-trans unsaturated PEPC. Parameterization of the phosphatidylcholines was achieved in two steps: first, we supplemented the OPLS force field parameters for DPPC with new parameters for torsion angles and van der Waals parameters for the carbon and hydrogen atoms in the acyl chains, as well as new partial atomic charges and parameters for torsion angles in the phosphatidylcholine and glycerol moieties [1]. Next, we derived parameters for the cis and trans double bonds and the neighboring them single bonds [2]. Additionally, we provide GROMACS input files with parameters describing simulation conditions (md.mdp), which are strongly recommended to be used with these lipids models. The data are associated with the research article “Cis and trans unsaturated phosphatidylcholine bilayers: a molecular dynamics simulation study” [2] and provided as supporting materials.

Green and Efficient: In Situ Oxidation Kinetics of Some Tailor-Made γ-Styrylpyridinium Dyes in Aqueous Medium Using the β-CD-CTAP Complex

β-CD-CTAP (β-cyclodextrin-cetyltrimethylammonium permanganate) complex, a novel functionalized oxidant, has been used to investigate the oxidation kinetics of some water-soluble γ-styrylpyridinium dyes containing a trans-double bond. In absence of acid or base catalysis and in neutral medium, the in situ oxidation process successfully demonstrates the potential of β-CD-CTAP complex as a green oxidant, in contrast to earlier reports on permanganate reagents. β-CD lends a supramolecular catalysis during the reaction due to its noncovalent interaction with CTAP. Substituent effect, reaction coefficient, deuterium isotope effect, effect of β-CD concentration, and the values of thermodynamic parameters help in proposing suitable mechanisms for the oxidation process. Proportionate variation of the rate constant values with the concentration of CTAP demonstrates the absence of any reverse micellization phenomenon of the oxidant, in contrast to earlier findings.

Cis and trans unsaturated phosphatidylcholine bilayers: A molecular dynamics simulation study

Trans unsaturated lipids are uncommon in nature. In the human diet, they occur as natural products of ruminal bacteria or from industrial food processing like hydrogenation of vegetable oils. Consumption of trans unsaturated lipids has been shown to have a negative influence on human health; in particular, the risk of cardiovascular disease is higher when the amount of trans unsaturated lipids in the diet is elevated. In this study, we first performed quantum mechanical calculations to specifically and accurately parameterize cis and trans mono-unsaturated lipids and subsequently validated the newly derived parameter set. Then, we carried out molecular dynamics (MD) simulations of lipid bilayers composed of cis or trans unsaturated lipids with and without cholesterol. Our results show that trans mono-unsaturated chains are more flexible than cis mono-unsaturated chains due to lower barriers for rotation around the single bonds next to the trans double bond than those next to the cis double bond. In effect, interactions between cholesterol and trans unsaturated chains are stronger than cis unsaturated chains, which results in a higher ordering effect of cholesterol in trans unsaturated bilayers.

Does hydrogen bonding contribute to lipoperoxidation-dependent membrane fluidity variation? An EPR-spin labeling study

This study is aimed at making clear the relationship between oxidative stress of the phospholipid bilayer and membrane fluidity. Di-(hydroperoxylinoleoyl)-phosphatidylcholine (diHpLPC) was used as a highly hydroperoxidized and unsaturated phospholipid species in order to investigate the issue. Hydrophylic Interaction Liquid Chromatography–ElectroSpray Ionization–Mass Spectrometry (HILIC-ESI-MS) and NMR spectroscopy were employed to define the structure of the peroxidized phospholipid as 1-(9-hydroperoxy-10c,12t)octadecadienoyl-2-(9t,11c-13-hydroperoxy)octadecadienoyl-sn-glycero-3-phosphorylcholine. This phospholipid's ability to form vesicular structures was confirmed by Sepharose 4B gel filtration and Dynamic Light Scattering (DLS) of its aqueous suspensions. Fatty acid misalignment and fluidity gradient were studied in the bilayer of both supported planar bilayers (SPB) and multilamellar vesicles (MLV) made of different DLPC/diHpLPC mixtures by means of spin labelling-EPR spectroscopy of either n-DSPC or 3-doxylcholestane spin labels embedded in the membranes. It was found that diHpLPC increases both fatty acid misalignment and rigidification with increasing molar ratio in spite of increasing unsaturation of the fatty acid core. Basing on our observations, the observed ability of pure diHpLPC to form rigid and disordered SPB and MLV bilayers is proposed to be dependent on the cross bridging of oxidized linoleoyl chains by mutual hydrogen bonding of hydroperoxyl groups. However, the contribution to the observed overall rigidification of the model membranes by trans double bonds in the peroxidized chains should not be neglected, as a second membrane fluidity effector also arising from lipid peroxidation.

Probing the role of the ceramide acyl chain length and sphingosine unsaturation in model skin barrier lipid mixtures by (2)H solid-state NMR spectroscopy.

We investigated equimolar mixtures of ceramides with lignoceric acid and cholesterol as models for the human stratum corneum by differential scanning calorimetry and (2)H solid-state NMR spectroscopy. Our reference system consisted of lignoceroyl sphingosine (Cer[NS24]), which represents one of the ceramides in the human stratum corneum. Furthermore, the effect of ceramide acyl chain truncation to 16 carbons as in Cer[NS16] and the loss of the C4 trans double bond as in dihydroceramide Cer[NDS24] were studied. Fully relaxed (2)H NMR spectra were acquired for each deuterated component of each mixture separately, allowing the quantitative determination of the individual lipid phases. At skin temperature, the reference system containing Cer[NS24] is characterized by large portions of each component of the mixture in a crystalline phase, which largely restricts the permeability of the skin lipid barrier. The loss of the C4 trans double bond in Cer[NDS24] leads to the replacement of more than 25% of the crystalline phase by an isotropic phase of the dihydroceramide that shows the importance of dihydroceramide desaturation in the formation of the skin lipid barrier. The truncated Cer[NS16] is mostly found in the gel phase at skin temperature, which may explain its negative effect on the transepidermal water loss in atopic dermatitis patients. These significant alterations in the phase behavior of all lipids are further reflected at elevated temperatures. The molecular insights of our study may help us to understand the importance of the structural parameters of ceramides in healthy and compromised skin barriers.

A comparative calorimetric and spectroscopic study of the effects of cholesterol and of the plant sterols β-sitosterol and stigmasterol on the thermotropic phase behavior and organization of dipalmitoylphosphatidylcholine bilayer membranes

We performed comparative DSC and FTIR spectroscopic measurements of the effects of β-sitosterol (Sito) and stigmasterol (Stig) on the thermotropic phase behavior and organization of DPPC bilayers. Sito and Stig are the major sterols in the biological membranes of higher plants, whereas cholesterol (Chol) is the major sterol in mammalian membranes. Sito differs in structure from Chol in having an ethyl group at C24 of the alkyl side-chain, and Stig in having both the C24 ethyl group and trans-double bond at C22. Our DSC studies indicate that the progressive incorporation of Sito and Stig decrease the temperature and cooperativity of the pretransition of DPPC to a slightly lesser and greater extent than Chol, respectively, but the pretransition persists to 10mol % sterol concentration in all cases. All three sterols produce essentially identical effects on the thermodynamic parameters of the sharp component of the DPPC main phase transition. However, the ability to increase the temperature and decrease the cooperativity and enthalpy of the broad component decreases in the order Chol>Sito>Stig. Nevertheless, at higher Sito/Stig concentrations, there is no evidence of sterol crystallites. Our FTIR spectroscopic studies demonstrate that Sito and especially Stig incorporation produces a smaller ordering of the hydrocarbon chains of fluid DPPC bilayers than does Chol. In general, the presence of a C24 ethyl group in the alkyl side-chain reduces the characteristic effects of Chol on the thermotropic phase behavior and organization of DPPC bilayer membranes, and a trans-double bond at C22 magnifies this effect.

Production of Jet Fuel Range Hydrocarbons as a Coproduct of Algal Biodiesel by Butenolysis of Long-Chain Alkenones

Long-chain (35–40 carbons) alkenones are a unique class of lipids biosynthesized by certain species of algae including the industrially grown marine microalgae Isochrysis. Their structures are characterized by a very long linear carbon-chain with trans double bonds and a methyl or ethyl ketone. A method is presented for the isolation of pure alkenones from Isochrysis biomass in parallel with biodiesel production. Yields for the isolated alkenones and biodiesel relative to the starting dry Isochrysis biomass were routinely 3.5 and 12% (w/w), respectively. Alkenones were then converted to smaller hydrocarbon fragments (jet-fuel range) by cross-metathesis with 2-butene (butenolysis) using several commercial ruthenium-based metathesis initiators. Butenolysis with the second-generation Hoveyda-Grubbs catalyst occurred rapidly at 4 °C, yielding near quantitative conversion within 30 min to a mixture containing mostly 8-decen-2-one (C10), 2,9-undecadiene (C12), and 2-heptadecene (C17) as both cis- and trans isomers based on analysis by comprehensive two-dimensional gas chromatography.