Long-chain Aldehydes Research Articles

Fluorescent-based micellar incorporated hydrogel materials for selective determination of long-chain aldehydes.

A highly sensitive micelle-induced sensory has been developed for detection of long-chain aldehydes as potential biomarkers of respiratory cancers. The micelle-like sensor was fabricated through the partial self-assembly of CTAB and S2 surfactants, containing a fluorescent hydrazine-functionalized dye (Naph-NH2). In principle, long-chain aldehydes with amphiphilic character act as the induced-fit surfactants to form well-entrapped micellar particles, as well as react with Naph-NH2 to form hydrazone derivatives resulting in fluorescent enhancement. The limit of detection (LOD) of micellar Naph-NH2/CTAB/S2 platform was calculated to be 64.09-80.98µM for detection of long-chain aldehydes, which showed fluorescent imaging in lung cancer cells (A549). This micellar sensory probe demonstrated practical applicability for long-chain aldehyde sensing in human blood samples with an accepted percent recovery of ~ 94.02-102.4%. Beyond Naph-NH2/CTAB/S2 sensor, the milcellar hybrid sensor was successfully developed by incorporating a micelle-like platform with supramolecular gel regarding to carboxylate-based gelators (Gel1), which showed a tenfold improvement in sensitivity. Expectedly, the determination of long-chain aldehydes through these sensing platforms holds significant promise for point-of-care cancer diagnosis and therapy.

Combining lipase enzymatic techniques and antioxidants on the flavor of structured lipids (SLs) prepared from goat butter and coconut oil

Enzymatic transesterification can improve the quality of goat butter, however, the high temperature may lead to oil oxidation and produce a bad taste. In this study, goat butter (GB) and coconut oil (CO) were combined to synthesize structured lipids (SLs) by enzymatic transesterification, and antioxidants were added to inhibit oxidation to improve the oils’ flavor. The Lipozyme TLIM and tert-butylhydroquinone (TBHQ) were screened for SLs synthesis. The contents of SLs were 56.24% under the optimal conditions of 8 h reaction time, 5°C reaction temperature, 8% enzyme dosage, and 3:1 (w/w) substrate ratio, and the addition of antioxidants had no significant effect on the contents of SLs. It was demonstrated that short-chain fatty acids in the SLs were significantly reduced by 59.2%, and the medium-chain fatty acids were increased by 54.9% compared to GB. One hundred volatile compounds were identified in the lipid samples and classified as (1) long-chain alkane aromatic components and aromatic components, which remarkably decreased by 58.9%, and (2) alcohols, aldehydes, and ketones, which increased by 12.9%, through using solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS) and electronic nose. The relative aroma activity value (ROAV) of 9 key volatile aroma components was higher than 1 in the SLs, which greatly contributed to the reduction of goaty flavor and increasing cream flavor. The results suggested that the goaty flavor of GB could be significantly reduced by decreasing the short-chain fatty acids contents in SLs through enzymatic transesterification with CO, while the addition of antioxidants efficiently inhibited excessive lipids oxidation and increased the content of long-chain aldehydes, ketones, and lactones, thus enhancing the cream flavor, which had great potential to be utilized as natural food flavor additives.

Response of protonated, adduct, and fragmented ions in Vocus proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS)

Abstract. Volatile organic compounds (VOCs) affect secondary pollutant formation via active chemistry. Proton-transfer-reaction mass spectrometry (PTR-MS) is one of the most important techniques to study the highly variable spatial and temporal characteristics of VOCs. The response of protonated, adduct, and fragmented ions in PTR-MS in changing instrument settings and varying relative humidity (RH) requires rigorous characterization. Herein, we present dedicatedly designed laboratory experiments conducted to investigate the response of these ions for 21 VOCs, including 12 oxygenated VOCs and 2 nitriles, using the recently developed Vocus PTR-MS. Our results show that the focusing ion–molecule reactor (FIMR) axial voltage increases sensitivity by 3 to 4 orders of magnitude but does not significantly change the fractions of protonated ions. Reducing the FIMR pressure, however, substantially increases fragmentation. Applying a high radio frequency (RF) amplitude radially to the FIMR can enhance sensitivity by 1 to 2 orders of magnitude without affecting the protonated ion fractions. The change in big segmented quadrupole (BSQ) amplitude mainly affects sensitivity and protonated ion fraction by modifying ion transmission. The relationship between sensitivity and proton-transfer reaction rate constant is complicated by the influences from both ion transmission and protonated ion fraction. The protonated ions of most VOCs studied (19 out of 21) show less than 15 % variations in sensitivity as RH increases from ∼ 5% to ∼ 85 %, except for some long-chain aldehydes which show a positive RH variation of up to 30 %. Our results suggest that the Vocus PTR-MS can reliably quantify the majority of VOCs under ambient conditions with varying RH. However, caution is advised for small oxygenates such as formaldehyde and methanol due to their low sensitivity and for long-chain aldehydes due to their slight RH dependence and fragmentation.

Contribution of cooking emissions to the urban volatile organic compounds in Las Vegas, NV

Abstract. Cooking is a source of volatile organic compounds (VOCs), which degrade air quality. Cooking VOCs have been investigated in laboratory and indoor studies, but the contribution of cooking to the spatial and temporal variability in urban VOCs is uncertain. In this study, a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) is used to identify and quantify cooking emission in Las Vegas, NV, with supplemental data from Los Angeles, CA, and Boulder, CO. Mobile laboratory data show that long-chain aldehydes, such as octanal and nonanal, are significantly enhanced in restaurant plumes and regionally enhanced in areas of Las Vegas with high restaurant densities. Correlation analyses show that long-chain fatty acids are also associated with cooking emissions and that the relative VOC enhancements observed in regions with dense restaurant activity are very similar to the distribution of VOCs observed in laboratory cooking studies. Positive matrix factorization (PMF) is used to quantify cooking emissions from ground site measurements and to compare the magnitude of cooking with other important urban sources, such as volatile chemical products and fossil fuel emissions. PMF shows that cooking may account for as much as 20 % of the total anthropogenic VOC emissions observed by PTR-ToF-MS. In contrast, emissions estimated from county-level inventories report that cooking accounts for less than 1 % of urban VOCs. Current emissions inventories do not fully account for the emission rates of long-chain aldehydes reported here; thus, further work is likely needed to improve model representations of important aldehyde sources, such as commercial and residential cooking.

Dynamic relationships among pathways producing hydrocarbons and fatty acids of maize silk cuticular waxes.

The hydrophobic cuticle is the first line of defense between aerial portions of plants and the external environment. On maize (Zea mays L.) silks, the cuticular cutin matrix is infused with cuticular waxes, consisting of a homologous series of very long-chain fatty acids (VLCFAs), aldehydes, and hydrocarbons. Together with VLC fatty-acyl-CoAs (VLCFA-CoAs), these metabolites serve as precursors, intermediates and end-products of the cuticular wax biosynthetic pathway. To deconvolute the potentially confounding impacts of the change in silk microenvironment and silk development on this pathway, we profiled cuticular waxes on the silks of the inbreds B73 and Mo17, and their reciprocal hybrids. Multivariate interrogation of these metabolite abundance data demonstrates that VLCFA-CoAs and total free VLCFAs are positively correlated with the cuticular wax metabolome, and this metabolome is primarily affected by changes in the silk microenvironment and plant genotype. Moreover, the genotype effect on the pathway explains the increased accumulation of cuticular hydrocarbons with a concomitant reduction in cuticular VLCFA accumulation on B73 silks, suggesting that the conversion of VLCFA-CoAs to hydrocarbons is more effective in B73 than Mo17. Statistical modeling of the ratios between cuticular hydrocarbons and cuticular VLCFAs reveals a significant role of precursor chain length in determining this ratio. This study establishes the complexity of the product-precursor relationships within the silk cuticular wax-producing network by dissecting both the impact of genotype and the allocation of VLCFA-CoA precursors to different biological processes, and demonstrates that longer chain VLCFA-CoAs are preferentially utilized for hydrocarbon biosynthesis.

Computational Design of an Electro-Organocatalyst for Conversion of CO2 into Formaldehyde.

Density functional theory calculations employing a hybrid implicit/explicit solvation method were used to explore a new strategy for electrochemical conversion of CO2 using an electro-organocatalyst. A particular structural motif is identified that consists of an electron-rich vicinal enediamine (>N-C═C-N<) backbone, which is capable of activating CO2 by the formation of a C-C bond while subsequently facilitating the transfer of electrons from a chemically inert cathode to ultimately produce formaldehyde. Unlike transition metal-based electrocatalysts, the electro-organocatalyst is not constrained by scaling relations between the formation energies of activated CO2 and adsorbed CO, nor is it expected to be active for the competing hydrogen evolution reaction. The rate-limiting steps are found to occur during two proton-coupled electron transfer (PCET) sequences and are associated with the transfer of a proton from a proton transfer mediator to a carbon atom on the electro-organocatalyst. The difficulty of this step in the second PCET sequence necessitates an electrode potential of -0.85 V vs RHE to achieve the maximum turnover frequency. In addition, it is postulated that the electro-organocatalyst should also be capable of forming long-chain aldehydes by successively carrying out reductive aldol condensation to grow the alkyl chain one carbon at a time.

Iterative real-time optimization of a reductive amination process in a thermomorphic multiphase system

In this paper, we discuss the optimization of the operation of a reductive amination (RA) reaction process in a miniplant without an accurate process model using iterative real-time optimization (RTO). The rhodium-catalyzed RA of undecanal with diethylamine produces a tertiary amine from a long-chain aldehyde and is performed in a thermomorphic multiphase system (TMS) to recover and reuse the expensive catalyst efficiently. An iterative RTO method called modifier adaptation with quadratic approximation (MAWQA) is used in combination with guaranteed model adequacy (GMA) to drive the RA process to its optimum iteratively. MAWQA utilizes online measurements to overcome model deficiencies. GMA ensures that the model used in MAWQA satisfies the model adequacy conditions. The optimal operating conditions of the RA process in the miniplant were identified during an experimental run of the plant, thereby validating the applicability and efficiency of MAWQA with GMA. The results illustrate the benefits of process optimization using iterative RTO methods without accurate process models.

Chain scission modification mode in plasma catalytic n-undecane decomposition: In situ probing of intermediates and reaction pathways

To provide insight into the mechanism of plasma-catalytic long-chain alkane oxidation from the aspect of chain scission, n-undecane (C11H24) decomposition over γ-Al2O3 and Ag/γ-Al2O3 were investigated in a coaxial dielectric barrier discharge (DBD) reactor. The highest n-undecane conversion (89.7 %) and CO2 selectivity (SCO2, 40.0 %) were achieved in Plasma + Ag/γ-Al2O3 system. It was found that the simultaneous activation of O3 and C11H24 played a very important role in chain scission, which could be promoted by the formation of Ag-O-Al entity introduced by the strong interaction between Ag and γ-Al2O3. Different chain scission behaviors and reaction pathways were proposed by a combined analysis of GC-MS and in-situ DRIFTS. In Plasma + Ag/γ-Al2O3 system, the reaction of chain scission and oxidation preferred to take place in the middle of the chain, producing the ketone and aldehyde species with low carbon number, which were easy to be converted to CO2 and H2O. Instead, without the highly efficient activation of O3 and C11H24, the oxidation of the C11H24 over the surface of γ-Al2O3 was more likely to take place on the edge of the chain, leading to the accumulation of long-chain aldehyde, which lower values of C11H24 conversion and SCO2 (45.6 % and 21.7 %, respectively) in Plasma + γ-Al2O3 system.

Chemosensory proteins as putative semiochemical carriers in the desert isopod Hemilepistus reaumurii

The order Isopoda contains both aquatic and terrestrial species, among which Hemilepistus reaumurii, which lives in arid environments and is the most adapted to terrestrial life. Olfaction has been deeply investigated in insects while it has received very limited attention in other arthropods, particularly in terrestrial crustaceans. In insects, soluble proteins belonging to two main families, Odorant Binding Proteins (OBPs) and Chemosensory Proteins (CSPs), are contained in the olfactory sensillar lymph and are suggested to act as carriers of hydrophobic semiochemicals to or from membrane-bound olfactory receptors. Other protein families, namely Nieman-Pick type 2 (NPC2) and Lipocalins (LCNs) have been also reported as putative odorant carriers in insects and other arthropod clades. In this study, we have sequenced and analysed the transcriptomes of antennae and of the first pair of legs of H. reaumurii focusing on soluble olfactory proteins. Interestingly, we have found 13 genes encoding CSPs, whose sequences differ from those of the other arthropod clades, including non-isopod crustaceans, for the presence of two additional cysteine residues, besides the four conserved ones. Binding assays on two of these proteins showed strong affinities for fatty acids and long-chain unsaturated esters and aldehydes, putative semiochemicals for this species.

Hazard and risk assessment for indoor air pollutants: alicyclic compound, 1-butanol, long-chain aldehydes, chlorinated organic compounds, and acrolein

Hazard and risk assessment for indoor air pollutants: alicyclic compound, 1-butanol, long-chain aldehydes, chlorinated organic compounds, and acrolein

Evaluation of Linkers' Influence on Peptide-Based Piezoelectric Biosensors' Sensitivity to Aldehydes in the Gas Phase.

Recent findings qualified aldehydes as potential biomarkers for disease diagnosis. One of the possibilities is to use electrochemical biosensors in point-of-care (PoC), but these need further development to overcome some limitations. Currently, the primary goal is to enhance their metrological parameters in terms of sensitivity and selectivity. Previous findings indicate that peptide OBPP4 (KLLFDSLTDLKKKMSEC-NH2) is a promising candidate for further development of aldehyde-sensitive biosensors. To increase the affinity of a receptor layer to long-chain aldehydes, a structure stabilization of the peptide active site via the incorporation of different linkers was studied. Indeed, the incorporation of linkers improved sensitivity to and binding of aldehydes in comparison to that of the original peptide-based biosensor. The tendency to adopt disordered structures was diminished owing to the implementation of suitable linkers. Therefore, to improve the metrological characteristics of peptide-based piezoelectric biosensors, linkers were added at the C-terminus of OBPP4 peptide (KLLFDSLTDLKKKMSE-linker-C-NH2). Those linkers consist of proteinogenic amino acids from group one: glycine, L-proline, L-serine, and non proteinogenic amino acids from group two: β-alanine, 4-aminobutyric acid, and 6-aminohexanoic acid. Linkers were evaluated with in silico studies, followed by experimental verification. All studied linkers enhanced the detection of aldehydes in the gas phase. The highest difference in frequency (60 Hz, nonanal) was observed between original peptide-based biosensors and ones based on peptides modified with the GSGSGS linker. It allowed evaluation of the limit of detection for nonanal at the level of 2 ppm, which is nine times lower than that of the original peptide. The highest sensitivity values were also obtained for the GSGSGS linker: 0.3312, 0.4281, and 0.4676 Hz/ppm for pentanal, octanal, and nonanal, respectively. An order of magnitude increase in sensitivity was observed for the six linkers used. Generally, the linker's rigidity and the number of amino acid residues are much more essential for biosensors' metrological characteristics than the amino acid sequence itself. It was found that the longer the linkers, the better the effect on docking efficiency.

Effect of interaction between Pd and Fe in modified red mud on catalytic decomposition of toluene.

As an industrial solid waste produced by alumina industry, red mud was modified as support of Pd catalysts for toluene catalytic oxidation in this paper. The xPd/MRM catalysts had high activity for toluene catalytic oxidation, and the 0.3Pd/MRM catalyst showed the best catalytic performance (T50 = 175 °C and T100 = 200 °C). The results indicated that the prepared 0.3Pd/MRM catalyst had more ratio of surface-adsorbed oxygen and Fe3+, rather than MRM and RM, which benefitted to the toluene oxidation. The excessive Pd species and the growth of the PdO nanoparticles negatively affected the catalytic efficiency of toluene. 0.4Pd/MRM activity decreased because of PdO aggregation in the catalyst, which could be confirmed by TEM analysis. The results of XPS, H2-TPR, FT-IR, O2-TPD, and Raman examination revealed that the formation of Pd-O-Fe under the interaction between Fe in MRM and Pd (Pd2+ + Fe 2+ → Pd0 + Fe3+) increased the electron transfer and raised the mobility of surface-adsorbed oxygen. Furthermore, in situ DRIFTS and GC-MS were used to detect intermediate products of catalytic reactions, and the reaction mechanism of catalysts was also studied. The catalytic oxidation of toluene on 0.3Pd/MRM catalyst might have two reaction paths simultaneously. The first reaction path would be toluene → species benzyl → benzaldehyde → benzoic acid → long-chain aldehydes or carboxylic acids → CO2 and H2O. The second reaction path would be toluene → benzene → phenol → long-chain aldehydes or carboxylic acids → CO2 and H2O.

Inhibit ALDH3A2 reduce ovarian cancer cells survival via elevating ferroptosis sensitivity

Ovarian cancer (OC) is a malignant gynecologic tumor with high morbidity and mortality. As a newly discovered mode of programmed cell death, ferroptosis has been involved in various pathological processes of kinds of tumors in recent years. Aldehyde dehydrogenase 3 family member A2 (ALDH3A2) catalyzes the oxidation of long-chain aliphatic aldehydes to fatty acid. ALDH3A2 has been shown to be associated with ferroptosis in acute myeloid leukemia (AML), but the mechanism remains unclear. In this study, we analyzed the TCGA and GTEx databases and showed that high ALDH3A2 expression predicted poor prognosis in ovarian cancer. Further studies found that knockout or overexpression of ALDH3A2 correspondingly increased or attenuated the ferroptosis sensitivity of ovarian cancer cells. And sequencing revealed that ALDH3A2 knockout led to the activation of lipid metabolic, GSH metabolic, phospholipid metabolic, and aldehyde metabolic pathways, suggesting that ALDH3A2 induced changes in the sensitivity of ovarian cancer cells to ferroptosis by affecting these metabolic processes. Our results provide a new promising therapeutic strategy for the treatment of OC.

Physiological responses, nutritional quality and aroma volatiles of the red-fleshed kirkwood navel and ruby valencia oranges during postharvest cold storage

This study evaluates the postharvest performance and responses of the red-fleshed Kirkwood Navel and Ruby Valencia oranges to cold storage (28 d at 2 °C) and shelf-life (5 d at 20 °C) in comparison with the standard varieties Washington Navel and Valencia late, respectively. Fruit of Kirkwood and Ruby exhibited lower chilling injury than the reference varieties while maintained similar weight loss and peel firmness. Moreover, the large concentration and the original composition of carotenoids in the pulp of Kirkwood and Ruby was preserved during the postharvest storage. Similarly, the content of vitamin C, phenolics and flavonoids, and the higher lipophilic antioxidant capacity and the capacity to quench singlet oxygen of the red-fleshed oranges remained unaltered after the whole storage period. The content of other compounds as tocopherols and sugars increased at the end of the storage period in fruit of the red-fleshed varieties. Monoterpenes, norisoprenoids, ethanol, aldehydes and ethyl esters were the compounds that exhibited the major changes during the postharvest storage, especially in the red-fleshed varieties. The profile of volatile compounds of Kirkwood and Ruby fruit was characterized by higher levels of norisoprenoids, monoterpenes, long-chain aldehydes, and variable content of aliphatic esters compared to the reference varieties. Altogether, our results indicated that Kirkwood Navel and Ruby Valencia oranges show good postharvest performance and potential for long-term cold storage, ensuring their quality and retaining their enhanced properties and added value to consumers. Data availabilityAll data are available in the manuscript or supplementary materials.

Differential impact of crown rust (Puccinia coronata) infection on photosynthesis and volatile emissions in the primary host Avena sativa and the alternate host Rhamnus frangula.

Rust infection results in decreases in photosynthesis and stress volatile emissions, but how these changes vary among host species has not been studied. We demonstrated that the impact of the obligate biotrophic fungus, Puccinia coronata f. sp. avenae, on foliage physiological processes is stronger in the primary host, Avena sativa (cultivated oat), than in the alternate host, Rhamnus frangula (alder buckthorn). Photosynthesis decreased with increasing percentage of damaged leaf area (DA) in both species, but reductions were greater in A. sativa. In A. sativa, photosynthetic reductions resulted from reductions in stomatal conductance and photosynthetic capacity; in R. frangula, reductions were due to reduced capacity. Infection reduced photosynthetic biomass and key nutrients in A. sativa, but not in R. frangula. In A. sativa, stress-elicited emissions (methyl jasmonate, green leaf volatiles, long-chain saturated aldehydes, mono- and sesquiterpenes, benzenoids, and carotenoid breakdown products) increased with increasing DA from 0% to 40%, but decreased with further increases in DA. In R. frangula, volatile emissions were slightly elicited but, surprisingly, constitutive isoprene emissions were enhanced. Different hosts had characteristic volatile fingerprints, indicating differential activation of biochemical pathways. Fungal-elicited reductions in photosynthesis scale uniformly with stress severity. In the sensitive host, biphasic scaling of volatiles indicates that heavy spread of chlorosis/necrosis leads to an overall cessation of physiological functioning.

Supramolecular self-assembled polymeric nanospheres based on hydrazino naphthalimide functionalised pillar[5]arene for long chain aldehyde detection.

A novel fluorescent sensor HNP5A is constructed consisting of bis-hydrazine naphthalimide decorated pillar[5]arene. Interestingly, this sensor possessed the potential for sensitive and selective detection of long-chain aldehydes, particularly nonanal (C9), and subsequently formed supramolecular pseudorotaxane polymeric nanoparticles inducing a strong fluorescence enhancement. In addition, this as-produced HNP5A⊂C9 exhibited an unexpected reduction of Ag+ to produce AgNPs in an aqueous system and the resulting AgNPs-HNP5A⊂C9 demonstrated a significant fluorescence enhancement under metal-enhanced fluorescence (MEF) behaviour.

Phytochemical Composition and Antibacterial Properties of Surface Extracts of Six Salvia Species

The chemistry and biological activity of cuticular waxes and the secondary metabolites produced in the indumentum of different plant organs has been attracting the interest of botanists. This work was aimed to investigate the chemistry and antibacterial activity of the surface extracts (SE) of different organs of six Salvia species. The cuticles and indumenta of the leaves, calyxes, and stems of Salvia atropatana Bunge., S. lachnocalyx Hedge., S. ceratophylla L., S. palaestina Benth., S. persepolitana Boiss., and S. hydrangea DC. ex Benth. were extracted with dichloromethane. The SEs were analyzed using gas chromatography-mass spectrometry (GC/MS). The antibacterial activity of each extract was assessed against Escherichia coli, Staphylococcus epidermidis, and Bacillus subtilis strains using the agar disc diffusion bioassay. The yields of extracts were in the range from 1.1- 2.3% w/w, while the detected compounds constituted 59.3-95.4% of the total extract composition. All species except S. persepolitana contained the sesquiterpenes, including β-caryophyllene (0.5-19.5%) and germacrene D (0.4-12.9%), while sclareol (2.1-75.6%) was the major labdane diterpenoid in the examined Salvia species excepting S. hydrangea. In addition to terpenoids, the analyzed SEs contained long-chain n-alkanes, fatty acids, alcohols, and aldehydes in the range from 4.8-78.5%. E. coli was the most susceptible microorganism to the tested extracts of S. persepolitana calyxes and stems (20 and 18 mm) and the S. lachnocalyx stems (17 mm), respectively. The antibacterial properties of the SEs of the plants suggested their protective role against pathogenic microorganisms, which can be attributed to their major phytochemicals such as sclareol and abienol.

Reverse chemical ecology indicates long-chain aldehydes as new potential semiochemicals for the African elephant Loxodonta africana

Chemical communication between sexes in the elephants has been well studied at the chemical and behavioural levels, but little is known about the proteins mediating the exchange of chemical signals. Two sex pheromones have been identified in Asian elephants: (Z)-7-dodecenyl acetate and frontalin, and their effects on the elephants’ behaviour have been described in detail. The genomes of both the Asian (Elephas maximus) and the African elephant (Loxodonta africana) have been poorly annotated. In particular, the complete sequences of two odorant-binding proteins and a VEG protein are available for the African elephant, together with isoforms and other members of the same families, which however are incomplete or unreliable. In a previous study, we have expressed the OBP1 of both elephant species, and investigated their binding properties. We showed that OBP1 is tuned to the pheromone (Z)-7-dodecenyl acetate and few structurally related linear esters, but also binds (E)-β-farnesene and farnesol with good affinity. In this work we have explored the characteristics of the second OBP of the African elephant (LafrOBP2). This protein, which was not found in the trunk wash, does not bind any of the above listed semiochemicals. Instead, it shows selected affinity to unsaturated linear aldehydes of 16 carbon atoms, specifically (Z)-9-hexadecenal, (Z)-11-hexadecenal and (10E,12Z)-hexadecadienal (bombykal). Fourteen and 18 carbon orthologues show only much reduced binding affinity. Some linear alcohols, fatty acids and esters also weakly bind this protein with dissociation constants about one order of magnitude higher.

2-Hexadecenal Regulates ROS Production and Induces Apoptosis in Polymorphonuclear Leucocytes.

2-Hexadecenal (2-HD)-a biologically active long-chain fatty aldehyde formed in organism enzymatically or nonenzymatically in the reaction of free-radical destruction of sphingolipids under the action of hypochlorous acid, producing by myeloperoxidase. This research aimed to study 2-HD effects on polymorphonuclear leukocytes' (PMNLs) functions. It has been shown that at submicromolar concentrations, 2-HD causes an elevation in ROS production by PMNLs. It has been found that such effect is associated with signal transduction pathways modification and expressed in elevation of NADPH oxidase, MPO, and JNK-MAPK contributions to this process. At higher concentrations, 2-HD induces apoptosis, which correlates with a significant increase in free Ca2+ in the cytoplasm, a decrease in ROS production, and a decline in mitochondrial potential. Both of these processes are accompanied by cytoskeleton reorganization.

Helicene-Hydrazide Encapsulated Ethyl Cellulose as a Potential Fluorescence Sensor for Highly Specific Detection of Nonanal in Aqueous Solutions and a Proof-of-Concept Clinical Study in Lung Fluid.

Over the past years, lung cancer has been one of the vital cancer-related mortalities worldwide and has inevitably exhibited the highest death rate with the subsequent need for facile and convenient diagnosis approaches to identify the severity of cancer. Previous research has reported long-chain aldehyde compounds such as hexanal, heptanal, octanal, and nonanal as potential biomarkers of lung cancer. Herein, the helicene dye-encapsulated ethyl cellulose (EC@dye-NH) nanosensors have been applied for the potentially sensitive and specific detection of long-chain aldehydes in aqueous media. The sensors contain the intrinsic hydrazide group of dye-NH, which is capable of reacting an aldehyde group via imine formation and the EC backbone. This offers the synergistic forces of hydrophobic interactions with alkyl long-chain aldehydes, which could induce self-assembly encapsulation of EC@dye-NH nanosensors and strong fluorescence responses. The addition of long-chain aldehyde would induce the complete micellar-like nanoparticle formation within 15 min in acetate buffer pH 5.0. The limit of detection (LOD) values of EC@dye-NH nanosensors toward heptanal, octanal, and nonanal were 40, 100, and 10 μM, respectively, without interference from the lung fluid matrices and short-chain aldehydes. For practical applicability, this sensing platform was developed for quantification of the long-chain aldehydes in lung fluid samples with 98-101% recoveries. This EC@dye-NH nanosensor was applied to quantify nonanal contents in lung fluid samples. The results of this method based on EC@dye-NH nanosensors were then validated using standard gas chromatography-mass spectrometry (GC-MS), which gave results consistent with the proposed method. With intracellular imaging application, the EC@dye-NH nanosensors demonstrated excellent intracellular uptake and strong green fluorescence emission upon introducing the nonanal into the lung cancer cells (A549). Thus, the developed nanosensing approach served as the potential fluorescent probes in medical and biological fields, especially for lung cancer disease diagnosis based on highly selective and sensitive detection of long-chain aldehydes.