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Wax esters play critical roles in biological systems, serving functions from energy storage to chemical signaling. Their diversity is attributed to variations in alcohol and acyl chains, including their length, branching, and the stereochemistry of double bonds. Traditional analysis by mass spectrometry with collisional activations (CID, HCD) offers insights into acyl chain lengths and unsaturation level. Still, it falls short in pinpointing more nuanced structural features like the position of double bonds. As a solution, this study explores the application of 213-nm ultraviolet photodissociation (UVPD) for the detailed structural analysis of wax esters. It is shown that lithium adducts provide unique fragments as a result of Norrish and Norrish-Yang reactions at the ester moieties and photoinduced cleavages of double bonds. The product ions are useful for determining chain lengths and localizing double bonds. UVPD spectra of various wax esters are presented systematically, and the effect of activation time is discussed. The applicability of tandem mass spectrometry with UVPD is demonstrated for wax esters from natural sources. The UHPLC analysis of jojoba oil proves the compatibility of MS 2 UVPD with the chromatography time scale, and a direct infusion is used to analyze wax esters from vernix caseosa. Data shows the potential of UVPD and its combination with CID or HCD in advancing our understanding of wax ester structures., (© 2024. The Author(s).)

Aureispira marina is a marine bacterium with gliding motility isolated from the southern coastline of Thailand. It contained ceramide as a major cellular lipid composed of saturated or unsaturated branched chain 2-hydroxy-fatty acid and sphingosine. The structure of unsaturated 2-hydroxy-fatty acid was investigated in our previous study, but the geometric configuration of the double bond remained unclear. In the present study, 14-methyl-∆ 2 -pentadecenol (∆ 2 -iso-C 16:1 -ol) was prepared from D-2-hydroxy-15-methyl-∆ 3 -hexadecenoic acid (D-2-OH-∆ 3 -iso-C 17:1 ) of the ceramide component, and analyzed by 1 H and 13 C NMR in comparison with ∆ 2 -trans-hexadecenol (∆ 2 -trans-n-C 16:1 -ol) derived from commercially available D-sphingosine. From the coupling constants of protons in the double bond and the chemical shift value of allylic carbon, the configuration of the double bond was determined as trans. Since the structure of 2-hydroxy-fatty acids was clarified, cellular fatty acids of A. marina and A. maritima, another species of the genus Aureispira, were reexamined, and the description on the cellular fatty acid composition of the genus Aureispira in the previous papers (Hosoya et al., 2006, Int. J. System. Evol. Microbiol., 56, 2931-2935; Hosoya et al., 2007, Int. J. System. Evol. Microbiol., 57, 1948-1951) lacking the description of 2-hydroxy-fatty acids was emended.

Fatty acids (FAs) contain a vast amount of structural diversity, and differences in fatty acid structure have been associated with various disease states. Accurate identification and characterization of fatty acids is critical to fully understand the biochemical roles these compounds play in disease progression. Conventional tandem mass spectrometry (MS/MS) workflows do not provide sufficient structural information, necessitating alternative dissociation methods. Gas-phase charge inversion ion/ion reactions can be used to alter the ion type subjected to activation to provide improved or complementary structural information. Herein, we have used an ion/ion reaction between fatty acid (FA) anions and magnesium tris-phenanthroline [Mg(Phen) 3 ] dications to promote charge remote fragmentation of carbon-carbon bonds along the fatty acid chain, allowing for localization of carbon-carbon double bond (C=C) positions to successfully differentiate monounsaturated fatty acid isomers. Relative quantification was also performed to obtain the relative abundance of fatty acid isomers in different biological tissues. For example, the relative abundance of FA 18:1 (9) was determined to vary across regions of rat brain, rat kidney, and mouse pancreas, and FA 16:1 (9) was found to have a higher relative abundance in the dermis layer compared to the sebaceous glands in human skin tissue.

The tetrasilyl-substituted distannene, (tBu 2 HSi) 2 Sn=Sn(SiHtBu 2 ) 2 6, was synthesized by mild thermolysis (70 °C in hexane) of tris(di-tert-butyl-hydridosilyl)stannane 4. The X-ray crystallography structure of 6 reveals the following unusual structural properties: a planar geometry around both Sn atoms (Σ∡Sn=359.87°), a non-twisted Sn=Sn double bond, and the shortest Sn=Sn double bond of 2.599 Å among all acyclic distannenes. Thus, compound 6 is the first reported distannene having a structure closely analogous to a classic alkene. Reactions of 6 with CCl 4 or with 2,3-dimethylbuta-1,3-diene to produce 1,2-dichlorodistannane 9 and the [2+4] cycloadduct 10, respectively, are characteristic for a Sn=Sn double bond., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The saturated LPC18:0 and unsaturated LPC18:1 lysophosphatidylcholines have important roles in inflammation and immunity and are interesting targets for immunotherapy. The synthetic cationic lipid DODAB has been successfully employed in delivery systems, and would be a suitable carrier for those lysophosphatidylcholines. Here, assemblies of DODAB and LPC18:0 or LPC18:1 were characterized by Differential Scanning Calorimetry (DSC) and Electron Paramagnetic Resonance (EPR) spectroscopy. LPC18:0 increased the DODAB gel-fluid transition enthalpy and rigidified both phases. In contrast, LPC18:1 caused a decrease in the DODAB gel-fluid transition temperature and cooperativity, associated with two populations with distinct rigidities in the gel phase. In the fluid phase, LPC18:1 increased the surface order but, differently from LPC18:0, did not affect viscosity at the membrane core. The impact of the different acyl chains of LPC18:0 and 18:1 on structure and thermotropic behavior should be considered when developing applications using mixed DODAB membranes., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests. Julio H K Rozenfeld reports equipment, drugs, or supplies was provided by Fapesp., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Due to the existence of water, it is still a challenge to conduct chemical modification on cellulose nanofiber (CNF) hydrogels with active double bonds. A simple one-pot and one-step method for constructing "living" CNF hydrogel with double bond was created at room temperature. The chemical vapor deposition (CVD) of methacryloyl chloride (MACl) was used to introduce physical-trapped, chemical-anchored and functional double bonds into TEMPO-oxidized cellulose nanofiber (TOCN) hydrogels. TOCN hydrogel could be fabricated within just 0.5 h, the minimum dosage of MACl could be reduced to 3.22 mg/g (MACl/TOCN hydrogel). Furthermore, the CVD methods showed high efficiency for mass production and recyclability. Moreover, the chemical "living" reactivity of the introduced double bonds were verified by the freezing and UV crosslinking, radical polymerization and thiol-ene click reaction. Compared with pure TOCN hydrogel, the obtained functionalized TOCN hydrogel exhibited remarkable improvements in mechanical properties, with enhancements of 12.34 times and 2.04 times, as well as an increase in hydrophobicity by 2.14 times and a fluorescence performance improvement of 2.93 times., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

A facile synthesis for unprecedented stibastannene (10) featuring a Sn=Sb-double bond together with the homologous arsa- (9) and phosphastannenes (8) is presented. Chloride abstraction from respective stannyl pnictinidenes [E=P (5), As (6), Sb (7)], which were made accessible by reduction of ECl 3 addition products at an intramolecular phosphine-stabilized stannylene, gave the pnictastannenes in moderate yields. The pnictastannenes coordinate Pd(PPh 3 ) 2 fragments (12-14) and the phosphastannene forms also a nickel coordination compound with the Ni(PPh 3 ) 2 -fragment (11). 2,3-Dimethylbutadiene shows a [2+4]-cycloaddition (15-17) in reaction with the pnictastannenes (8-10). Products of a [2+2]-addition (18, 19) were isolated as the phosphaalkyne reaction products for 8 and 9. Addition of an O-H bond at the Sn=P-bond was found in reaction of water with phosphastannene 8. Reaction with ammonia afforded the NH 3 -adducts (21-23) at the tin atom for pnictastannenes 8-10. Only in the case of the arsastannene an azide reaction product featuring a three membered Sn-As-N-ring was obtained., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

In this review, the latest achievements in the field of multiply bonded organogermanium derivatives, mostly reported within the last two decades, are presented. The isolable Ge-containing analogues of alkenes, alkynes, 1,3-dienes, allenes, and vinylidenes are discussed, and for each class of unsaturated organogermanium compounds, the most representative examples are given. The synthetic approaches toward homonuclear multiply bonded combinations solely consisting of germanium atoms, and their heteronuclear variants containing germanium and other group 14 elements, both acyclic and cyclic, are discussed. The peculiar structural features and nonclassical bonding nature of the abovementioned compounds are discussed based on their spectroscopic and structural characteristics, in particular their crystallographic parameters (double bond length, trans -bending at the doubly bonded centers, and twisting about the double bond). The prospects for the practical use of the title compounds in synthetic and catalytic fields are also briefly discussed.

Hypochlorous acid/hypochlorite (HOCl/ClO - ) plays important roles in killing bacterial and causing damage to living tissues, and its abnormal levels could lead to many diseases. Although great efforts have been devoted, fluorescent probes for HOCl/ClO - with near-infrared fluorescence, good selectivity/sensitivity, and low background are still important and urgent. In this work, a novel double-bond-linked TCF-aza-BODIPY-based near-infrared fluorescent probe (3) was rationally designed, successfully prepared, and applied for sensing HOCl/ClO - in both solutions and living RAW264.7 cells, showing good selectivity and fluorescence "turn-on" phenomenon at 670 nm with low background. The limit of detection towards ClO - was determined to be 0.36 μM through the linear fluorescence changes at 670 nm in a broad ClO - -concentration range of 0-150 μM. Furthermore, the sensing mechanism was investigated by mass spectrometry and compared with 1, suggesting that the remarkable spectroscopic changes could be ascribed to the oxidization of the double bond to the aldehyde group, accompanied with the leaving of the TCF group. Confocal imaging experiments also confirmed the remarkable intracellular fluorescence enhancements through incubation of ClO - and phorbol ester 12-myristate 13-acetate (PMA) in RAW264.7 cells. Therefore, for the first time, we reported a near-infrared TCF-aza-BODIPY-based fluorescent probe for highly sensitive and fluorescence "turn-on" detection of both exogenous and endogenous HOCl in living RAW264.7 cells through the quick oxidation of a conjugated double bond., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Nanospray desorption electrospray ionization (nano-DESI) is a technique that can be used for mass spectrometry imaging (MSI) experiments. Due to the separation of sampling and ionization events, the nano-DESI solvent can be doped with additives to alter the specificity and selectivity of the experiment. In this chapter, we describe the addition of silver ions to the nano-DESI solvent for increased specificity and sensitivity of double bond containing analyte molecules for nano-DESI MSI., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

The topic of heavier main group compounds possessing multiple bonds is the subject of momentous interest in modern organometallic chemistry. Importantly, there is an excitement involving the discovery of unprecedented compounds with unique bonding modes. The research in this area is still expanding, particularly the reactivity aspects of these compounds. This article aims to describe the overall developments reported on the stable derivatives of silicon and germanium involved in multiple bond formation with other group 13, and heavier groups 14, 15, and 16 elements. The synthetic strategies, structural features, and their reactivity towards different nucleophiles, unsaturated organic substrates, and in small molecule activation are discussed. Further, their physical and chemical properties are described based on their spectroscopic and theoretical studies., (© 2020 Wiley-VCH GmbH.)

Conjugated linoleic and linolenic acids (CLA and CLnA) can be found in dairy, ruminant meat and oilseeds, these types of unsaturated fatty acids consist of various positional and geometrical isomers, and have demonstrated health-promoting potential for human beings. Extensive reviews have reported the physiological effects of CLA, CLnA, while little is known regarding their isomer-specific effects. However, the isomers are difficult to identify, owing to (i) the similar retention time in common chromatographic methods; and (ii) the isomers are highly sensitive to high temperature, pH changes, and oxidation. The uncertainties in molecular structure have hindered investigations on the physiological effects of CLA and CLnA. Therefore, this review presents a summary of the currently available technologies for the structural determination of CLA and CLnA, including the presence confirmation, double bond position determination, and the potential stereo-isomer determination. Special focus has been projected to the novel techniques for structure determination of CLA and CLnA. Some possible future directions are also proposed., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

Local nature of the boron-nitrogen (BN) bonding with different formal multiplicities (B≡N, B=N, B-N) have been investigated for 25 experimentally established organoboron molecules in both real and the Hilbert space, using topological analysis of electron localization function (ELF), electron density (AIM), and natural bond orbital (NBO) method. Each BN bond has been represented (ELF) by the bonding disynaptic attractor V(B,N), with the basin electron population between 5.72e and 1.83e, confirming possible existence of all the three bond types. A covalent character of bonding can be associated with the dative mechanism due to the V(B,N) bonding basin formed mainly (91-96%) by the N electron density. Similarly, the NBO method shows 2-center natural orbitals, consisting largely of the hybrids from the N atom. The AIM analysis yields the features typical for shared (H (3,-1) (r) < 0) and closed-shell (∇ 2 ρ (3,-1) (r) > 0) interactions. The delocalization indices, describing electron exchanges between B and N quantum atoms, are smaller than 1.5, even for formally very short triple B≡N bonds. Graphical abstract .

The first divinyldiarsenes [{(NHC)C(Ph)}As] 2 (NHC=IPr 3 a, SIPr 3 b; IPr=C{(NAr)CH} 2 ; SIPr=C{(NAr)CH 2 } 2 ; Ar=2,6-iPr 2 C 6 H 3 ) are reported. Compounds 3 a and 3 b were prepared by the reduction of corresponding chlorides {(NHC)C(Ph)}AsCl 2 (NHC=IPr 2 a, SIPr 2 b) with Mg. Calculations revealed a small HOMO-LUMO energy gap of 3.86 (3 a) and 4.24 eV (3 b). Treatment of 3 a with (Me 2 S)AuCl led to the cleavage of the As=As bond to restore 2 a, which is expected to proceed via the diarsane [{(IPr)C(Ph)}AsCl] 2 (4). Remarkably, 4 as well as 2 a can be selectively accessed on treatment of 3 a with an appropriate amount of C 2 Cl 6 . Moreover, 3 a readily reacts with PhEEPh (E=Se or Te) at room temperature to give {(IPr)C(Ph)}As(EPh) 2 (E=Se 5 a; Te 5 b), revealing the cleavage of As=As and E-E bonds and the formation of As-E bonds. Such highly selective stepwise oxidation (3 a→4→2 a) and bond metathesis (3 a→5 a,b) reactions are unprecedented in main-group chemistry., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In the present investigation, 48 new tertiary amine derivatives of cinnamic acid, phenylpropionic acid, sorbic acid and hexanoic acid (4d-6g, 10d-12g, 16d-18g and 22d-24g) were designed, synthesized and evaluated for the effect on AChE and BChE in vitro. The results revealed that the alteration of aminoalkyl types and substituted positions markedly influences the effects in inhibiting AChE. Almost of all cinnamic acid derivatives had the most potent inhibitory activity than that of other acid derivatives with the same aminoalkyl side chain. Unsaturated bond and benzene ring in cinnamic acid scaffold seems important for the inhibitory activity against AChE. Among them, compound 6g revealed the most potent AChE inhibitory activity (IC 50 value: 3.64 µmol/L) and highest selectivity over BChE (ratio: 28.6). Enzyme kinetic study showed that it present a mixed-type inhibition against AChE. The molecular docking study suggested that it can bind with the catalytic site and peripheral site of AChE.

This work studies the effects of length and unsaturation of alkyl chain on the hydrophobic binding of curcumin with Tween 20, 60 and 80 micelles. While Tween 20 and 60 possess 12 and 18 saturated carbons, respectively, in their alkyl chains, the alkyl chain of Tween 80, with one double bond, has the same length as Tween 60. Tween 60 micelles are superior to Tween 20 and 80 micelles for improving curcumin stability. The fluorescence measurement suggests that Tween 60 micelles provide curcumin with the most hydrophobic microenvironment, owing to the long and saturated alkyl chain of Tween 60. The pK a1 and binding constants of curcumin have the same order of Tween 60 > Tween 20 > Tween 80. These results show that the length increase, and unsaturation, of the alkyl chain of Tween surfactants have opposite effects on the hydrophobic binding of curcumin with Tween micelles., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Two 2-phenyl-benzofurans, moracin C {2-[3',5'-dihydroxy-4'-(3-methlbut-2-enyl)phenyl]-6-hydroxybenzofuran} and its isomer iso- moracin C{2-[3',5'-dihydroxy-4'-(3-methlbut-1-enyl)phenyl]-6-hydroxybenzofuran}, were comparatively studied using redox-related antioxidant assays and non-redox antioxidant assays. Moracin C always resulted in higher IC 50 values than iso -moracin C in the redox-related antioxidant assays, including •O₂ - -inhibition, Cu 2+ -reducing power, DPPH•-inhibition, and ABTS⁺•-inhibition assays. In the non-redox antioxidant assay, moracin C and iso -moracin C underwent similar radical-adduct-formation (RAF), evidenced by the peaks at m/z 704 and m/z 618 in HPLC-MS spectra. In conclusion, both moracin C and iso -moracin C can act as 2-phenyl-benzofuran antioxidants; their antioxidant mechanisms may include redox-related ET and H⁺-transfer, and non-redox RAF. A double bond at the conjugation position can enhance the redox-related antioxidant potential, but hardly affects the RAF potential., Competing Interests: The authors declare that they have no competing interests.

Obtaining structural information for lipids such as phosphatidylcholines, in particular the location of double bonds in their fatty acid constituents, is an ongoing challenge for mass spectrometry (MS) analysis. Here, we present a novel method utilizing the doping of liquid matrix-assisted laser desorption/ionization (MALDI) samples with divalent metal chloride salts, producing ions with the formula [L+M] 2+ (L = lipid, M = divalent metal cation). Multiply charged lipid ions were not detected with the investigated trivalent metal cations. Collision-induced dissociation (CID) product ions from doubly charged metal-cationized lipids include the singly charged intact fatty acids [snx+M-H] + , where 'x' represents the position of the fatty acid on the glycerol backbone. The preference of the divalent metal cation to locate on the sn2 fatty acid during CID was found, enabling stereochemical assignment. Pseudo-MS 3 experiments such as in-source decay (ISD)-CID and ion mobility-enabled time-aligned parallel (TAP) MS of [snx+M-H] + provided diagnostic product ion spectra for determining the location of double bonds on the acyl chain and were applied to identify and characterize lipids extracted from soya milk. This novel method is applicable to lipid profiling in the positive ion mode, where structural information of lipids is often difficult to obtain. Graphical abstract MALDI of liquid lipid samples doped with divalent metal salt (e.g. BaCl 2 ) produces doubly charged lipid-barium ions and enables structural elucidation via MS/MS and MS 3 analysis.

Polyhydroxyalkanoates (PHAs) incorporating vinyl-bearing 3-hydroxyalkanoates were prepared in 8.5-12.9 g L(-1) yield. The molar ratios (0-16 mol%) of the vinyl-bearing 3-hydroxyalkanoate derivatives were controlled by the continuous feeding of undecylenate at various concentrations. Subsequently, the PHAs were functionalized by UV-initiated thiol-ene click reaction and chemical modification. (1)H NMR spectra suggested that 3-mercaptopropionic acid and 2-aminoethanethiol were successfully introduced into the vinyl-bearing PHA. Subsequently, chemical modification using fluorescein or a fibronectin active fragment (GRGDS) was attempted. The former yielded a PHA derivative capable of emitting fluorescence under UV irradiation, which was useful for determining the miscibility of PHA in a composite film comprising poly-ʟ-lactic acid (PLLA) and PHA. In the latter case, PHA bearing GRGDS peptides exhibited cell adhesiveness, suggesting that its biocompatibility was improved upon peptide introduction. Taken together, the UV-initiated thiol-ene click reaction was demonstrated to be useful in PHA modification.

Dietary unsaturated fatty acids (FA) are intensively hydrogenated in the rumen, resulting in reduced amount of poly-unsaturated fatty acids (PUFA) and accumulation of several biohydrogenation (BH) products. In this study, BH of PUFA originating from different oilseeds (linseed, soya beans, sunflower seed and rapeseed) present in crushed oilseeds or their free oils were assessed in vitro. The assay substrates were incubated in buffered rumen fluid for 0, 6, 12 and 24 h. After incubation, the FA pattern of the incubated samples was analysed using gas chromatography. Biohydrogenation is defined as disappearance of double bonds (DB) calculated from the contents of unsaturated FA. After 24-h incubation, the DB contents of all oilseeds were reduced (p < 0.001) by 40-60%. The reduction was higher (p < 0.001) for the crushed form compared with the oil form. In addition, linseed and sunflower seed known as oilseeds with high contents of linolenic acid C18:3 c9,12,15 (LNA) and linoleic acid C18:2 c9,12 (LA), respectively, showed a higher (p < 0.001) accumulation of the BH intermediates conjugated linoleic acid (CLA, isomer C18:2 c9t11) and vaccenic acid (C18:1 t11) for the crushed form, when compared with the oil. These results suggest an inherent effect of the physical form of the assay oilseeds on in vitro BH. Changes in FA pattern during BH in vitro can be attributed to both source and physical form of the assay oilseeds. However, further investigations are warranted to ensure whether the observed in vitro effects on ruminal BH can be confirmed in vivo., (Journal of Animal Physiology and Animal Nutrition © 2015 Blackwell Verlag GmbH.)

Knowledge about tautomer forms of a structure is important since, e.g., a property prediction for a molecule can yield to different results which depend on the individual tautomer. Tautomers are isomers that can be transformed to each other through chemical equilibrium reactions. In this paper the first exact Branch-and-Bound (B&B) algorithm to calculate tautomer structures is proposed. The algorithm is complete in the sense of tautomerism and generates all possible tautomers of a structure according to the tautomer definition, it is initialized with. To be efficient, the algorithm takes advantage of symmetric and formation properties. Some restrictions are used to enable an early pruning of some branches of the B&B tree. This is important, since a simple enumeration strategy would lead to number of candidate tautomers that is exponentially increasing with the number of hydrogen atoms and their attachment sites. The proposed implementation of the B&B algorithm covers the majority of the prototropic tautomer cases, but can be adapted to other kinds of tautomerism too. Furthermore, a computer processable definition of tautomerism is given in the form of the moving hydrogen atom problem., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)