Keto Product Research Articles

The effect of social media influencer traits on consumer purchasing decisions for keto products: examining the moderating influence of advertising repetition

ABSTRACT Social media’s effect has become one of the important business topics these days and is largely discussed in terms of influencing consumer decisions. This study aims to investigate the effect of some social media influencer characteristics on consumer decisions with respect to the moderation role of advertising repetition. While the number of social media followers is increasing daily, and most organisations are using social media platforms to promote their products and services, this paper adds additional insight into how social media influencer traits may influence follower decisions to buy, especially within the context of healthy food. A quantitative research method was used to collect data from Keto product buyers in Jordan. A PLS-SEM approach was used for analysis, with a total of 543 responses from active buyers of these products. The findings reveal the significant effect of all hypothesised research assumptions and a significant moderating effect of advertising repetition on the relationship between social media influencer characteristics and consumer decisions. The research findings also provide expected implications and support the evidence in the literature, but its knowledge gaps could be covered by integrating a new model with new variables within a single unique research framework.

Facile Photochemical/Thermal Assisted Hydration of Alkynes Catalysed under Aqueous Media by a Chalcogen Stabilized, Robust, Economical, and Reusable Fe3Se2(CO)9 Cluster

In this report, the catalytic potential of chalcogen-stabilized iron carbonyl clusters [Fe3E2(CO)9 (E = S, Se, Te)] for the photolytic hydration of alkynes has been explored. The iron chalcogenide clusters bring excellent transformations of terminal and internal alkynes to their respective keto products in just 25 min photolysis at −5 °C in inert free and aqueous conditions. After the completion of the reaction, the product can be extracted from organic solvent, and due to the lower solubility of the catalyst in water, it can also be isolated and further reused several times prior to any activation. The catalyst was also found to be active in thermal conditions and bring about the desired transformations with average to good catalytic efficiency. Moreover, during the thermal reaction, the catalyst decomposed and formed the nanoparticles of iron selenides, which worked as a single-source precursor for FeSe nanomaterials. The presented photolysis methodology was found to be most feasible, economical, instantly produce the desired product, and work for a wide range of internal and terminal alkynes; hence, all these features made this method superior to the other reported ones. This report also serves as the first catalytic report of chalcogen-stabilized iron carbonyl clusters for alkyne hydrations.

Excited-State Deactivation Mechanism of 3,5-bis(2-hydroxyphenyl)-1H-1,2,4-triazole: Electronic Structure Calculations and Nonadiabatic Dynamics Simulations.

3,5-bis(2-Hydroxyphenyl)-1H-1,2,4-triazole (bis-HPTA) has attracted wide attention due to the important application in the detection of microorganisms and insecticidal activity. However, the mechanisms of excited-state intramolecular proton transfer (ESIPT) process and decay pathways are still a matter of debate. In this work, we have comprehensively investigated the photodynamics of bis-HPTA by executing combined electronic structure calculations and nonadiabatic surface-hopping dynamics simulations. Based on the computed electronic structure and dynamics information, we propose two nonadiabatic deactivation channels that efficiently populate the ground state from the Franck-Condon region. In the first one, after being excited to the bright S1 state, bis-HPTA molecule undergoes an ultrafast and barrierless ESIPT-1 process. Then, the system encounters with an energetically accessible S1/S0 conical intersection (CI), which funnels the system to the ground state speedily. Afterward, the keto species either arrives at the keto product or return to its enol species via a ground-state proton transfer in the S0 state. In the other excited-state decay channel, the S1 system hops to the ground state through a different CI, which involves the ESIPT-2 process. In our dynamics simulations, about 79.6% of the trajectories decay to the S0 state via the first CI, while the remaining ones employ the second conical intersection. The results of dynamics simulations also demonstrated that the lifetime of the S1 state is estimated as 315 fs. The present work will give elaborating mechanistic information of similar compounds in various environments.

The effect of social media influencers’ characteristics on consumer intention and attitude toward Keto products purchase intention

Social media influencers have become a more effective modern marketing approach used by businesses to influence consumers' intention and attitude. This study explores this influence by involving several factors of influencer’s characteristics on both consumers’ attitude and intention. Also, a moderation role of vloggers as a new emerging marketing tool is also examined in this research. To conduct this research and achieve its key objective, the study uses a quantitative research method to collect data from TikTok users which has also become a more worldwide favorable web device for short videos. PLS-SEM method is conducted in the phase of analysis and the results show a significant influence of the hypothesized research model except the influence of source relatability on consumer attitude and the moderating role of vloggers on consumer intention. The research findings provided unsurprisingly implications and supported the existing related literature in this field but contribute to cover the research knowledge gap through the integrated new model including numerous variables that have not been examined previously together in a unique framework.

Excited-state photochemistry dynamics of 2-(1-naphthyl) phenol: electronic structure calculations and non-adiabatic dynamics simulations.

The excited-state proton transfer processes and the formation mechanism of quinone methide of (1-naphthyl)phenol were investigated by combining static electronic structure calculations and non-adiabatic dynamics simulations in vacuum. The results indicated the existence of two minimum energy structures (S0-ENOL-1 and S0-ENOL-2) in the ground and excited states, which correspond to two ESIPT pathways. Upon excitation of S0-ENOL-1 to the bright S1 state, the system relaxes to the S1 minimum quickly in the enol region, for which two decay pathways have been described. The first is a barrierless ESIPT-1 process that generates keto species. Afterwards, the system encounters a keto conical intersection, which funnels the system to the ground state. The generated keto species, in the S0 state, either regenerated the starting material via ground-state proton transfer or yielded the keto product at the end of the simulations. In the other pathway, the system de-excites from the S1 state to the S0 state via one enol-type conical intersection. The dynamics simulations showed that 58.8% of trajectories experience keto-type conical intersection and the rest undergo enol-type conical intersection. Besides the ESIPT-1 process, a new-type ESIPT (ESIPT-2), which was not observed experimentally, was found with the irradiation of S0-ENOL-2. The ESIPT-2 process occurs after overcoming a small barrier (0.9 kcal mol-1) and yields a distinct quinone methide. Our simulation results also showed that the S1 lifetime of S0-ENOL-1 (S0-ENOL-2) would be 437 (617) fs in the gas phase. These results provide detailed and important mechanistic insights into the systems in which ESPT to carbon atoms occurs.

Synergy between 15-lipoxygenase and secreted PLA2 promotes inflammation by formation of TLR4 agonists from extracellular vesicles

Damage-associated endogenous molecules induce innate immune response, thus making sterile inflammation medically relevant. Stress-derived extracellular vesicles (stressEVs) released during oxidative stress conditions were previously found to activate Toll-like receptor 4 (TLR4), resulting in expression of a different pattern of immune response proteins in comparison to lipopolysaccharide (LPS), underlying the differences between pathogen-induced and sterile inflammation. Here we report that synergistic activities of 15-lipoxygenase (15-LO) and secreted phospholipase A2 (sPLA2) are needed for the formation of TLR4 agonists, which were identified as lysophospholipids (lysoPLs) with oxidized unsaturated acyl chain. Hydroxy, hydroperoxy, and keto products of 2-arachidonoyl-lysoPI oxidation by 15-LO were identified by mass spectrometry (MS), and they activated the same gene pattern as stressEVs. Extracellular PLA2 activity was detected in the synovial fluid from rheumatoid arthritis and gout patients. Furthermore, injection of sPLA2 promoted K/BxN serum-induced arthritis in mice, whereby ankle swelling was partially TLR4 dependent. Results confirm the role of oxidized lysoPL of stressEVs in sterile inflammation that promotes chronic diseases. Both 15-LO and sPLA2 enzymes are induced during inflammation, which opens the opportunity for therapy without compromising innate immunity against pathogens.

Application of differential reactivity towards synthesis of lamellarin and 8-oxoprotoberberine derivatives: Study of photochemical properties of aryl-substituted benzofuran-8-oxoprotoberberines

A unique differential reactivity between dihydroisoquinolines and 3-nitrocoumarins was observed and was exploited for the efficient construction of lamellarins and their isomeric benzofuran-8-oxoprotoberberine derivatives under acid-catalyzed or base-promoted conditions. Further, these prepared aryl-substituted benzofuran-8-oxoprotoberberine derivatives bearing electron-donating substituents on benzofuran moiety are found to be benchtop stable but light-sensitive, and can undergo oxidative ring-opening reaction to give the corresponding keto products when exposed to visible light under aerobic conditions.

Investigation of Keto-enol Tautomers during the Synthesis of Aryl-bis (2-hydroxy-1-naphthyl)Methanes

This study investigated the existence of keto-enol tautomers for the first time during the synthesis of aryl-bis(2-hydroxy-1-naphthyl)methane from 2-naphthol and p-tolualdehyde or 4-chlorobenzaldehyde in methanol using CuSO4.5H2O as catalyst under reflux condition. The exclusive formation of aryl-bis(2-hydroxy-1-naphthyl)methanes was observed in dichloromethane at room temperature in the presence of BF3.OEt2/AcOH as catalyst. The keto products were isolated and characterized by 1H NMR, 13C NMR, COSY and DEPT spectra. The existence of keto tautomer (3) of aryl-bis (2-hydroxy-1-naphthyl)methanes (4) was identified in the reaction of 2-napthol with p-tolualdehyde and 4-chlorobenzaldehyde using CuSO4.5H2O as catalyst under reflux in methanol. Exclusive formations of (4) was observed at mild conditions in dichloromethane with BF3.OEt2/AcOH as catalyst.

On the Catalytic Mechanism of (S)‐2‐Hydroxypropylphosphonic Acid Epoxidase (HppE): A Hybrid DFT Study

The mechanism of oxidative epoxidation catalyzed by HppE, which is the ultimate step in the biosynthesis of fosfomycin, was studied by using hybrid DFT quantum chemistry methods. An active site model used in the computations was based on the available crystal structure for the HppE-Fe(II)-(S)-HPP complex and it comprised first-shell ligands of iron as well as second-shell polar groups interacting with the substrates. The reaction energy profiles were constructed for three a priori plausible mechanisms proposed in the literature, and it was found that the most likely scenario for the native substrate, that is, (S)-HPP, involves generation of the reactive Fe(III)-O·/Fe(IV)=O species, which is responsible for the C-H bond-cleavage. At the subsequent reaction stage, the OH-rebound, which would lead to a hydroxylated product, is prevented by a fast protonation of the OH ligand and, as a result, ring closure is the energetically preferred step. For the R enantiomer of the substrate ((R)-HPP), which is oxidized to a keto product, comparable barrier heights were found for the C-H bond activation by both the Fe(III)-O(2)· and Fe(IV)=O species.

Scope of Metal Loaded Microporous Zeolite-Y as Catalyst in Ozone Initiated Oxidation of n-hexadecane

AbstractThe efficiency of metal loaded microporous materials, zeolite-Y as catalysts in the ozone initiated oxy-functionalisation of long chained n-alkanes is investigated at moderate temperature (20 ± 1 °C) and pressure conditions (1 atm.). The efficiencies of 0.5% Pd, Ni, V and U loaded microporous zeolite-Y catalysts on ozonation of higher alkanes (n-hexadecane), with respect to the conversion and transformation towards keto products are compared. In the catalysed ozonation, n-hexadecane is converted to 4-, 3- and 2- keto isomers as major products with varied selectivity and % conversions. A plausible mechanism assuming the chemisorption of the substrate molecule on the catalyst surface and further electron transfer between the metal ion loaded on the zeolite support and the active intermediate formed in course of reaction for the ozone initiated oxidation of n-hexadecane with heterogeneous Ni loaded Na-Y zeolite catalyst is proposed.

The interplay of skeletal deformations and ultrafast excited-state intramolecular proton transfer: Experimental and theoretical investigation of 10-hydroxybenzo[ h]quinoline

The excited-state intramolecular proton transfer in the aromatic polycycle 10-hydroxybenzo[ h]quinoline is investigated by means of transient absorption experiments with 30 fs time resolution, classical dynamics and wavepacket dynamics. The experiments establish the ultrafast transfer after UV excitation and show signatures of coherent vibrational motion in the keto product. To elucidate details of the proton transfer mechanism, the classical dynamics is also performed for 2-(2′-hydroxyphenyl)benzothiazole and the results are compared. For both systems the proton transfer takes place on the ultrafast scale of 30–40 fs, with good agreement between the theoretical investigations and the measurements. The dynamics simulations show that for both molecules the proton is handed over by means of skeletal deformation of the molecule. Due to the more rigid structure of 10-hydroxybenzo[ h]quinoline the hydrogen migration mode participates more actively than in 2-(2′-hydroxyphenyl)benzothiazole.

Dynamics of Intramolecular Hydrogen-Atom Migrations in 2-Hydroxy-3-nitropyridine Studied by Low-Temperature Matrix-Isolation Infrared Spectroscopy and Density Functional Theory Calculation

Intramolecular hydrogen-atom migrations in 2-hydroxy-3-nitropyridine have been investigated by low-temperature matrix-isolation infrared (IR) spectroscopy with the aid of density functional theory (DFT) calculation. An IR spectrum measured after deposition was assigned to an enol isomer, the conformation of which is anti in relation to OH versus N in the pyridine ring. When the matrix sample was exposed to UV and visible light (lambda>350 nm), an IR spectrum consistent with a keto product was observed. During the irradiation, an IR spectrum of a transient species, a photoreaction intermediate between anti-enol and keto, was observed, which was assigned to syn-enol. The bands of syn-enol disappeared completely when the irradiation was stopped, while those of the original isomer, anti-enol, reappeared. No reverse isomerization was observable in the corresponding deuterated species. This led to the conclusion that the isomerization from syn to anti occurs through hydrogen-atom tunneling. On the other hand, an aci-nitro form was produced by UV irradiation (lambda=365+/-10 nm) without visible light. The conformation around the aci-nitro group was determined to be cis-cis by comparison with the spectral patterns obtained by the DFT/B3LYP/6-31++G** calculation. The dynamics of the hydrogen-atom migrations between anti- and syn-enols, syn-enol and keto, and anti-enol and aci-nitro are discussed in terms of the potential surfaces obtained by the DFT calculation.

The Structure of 2-Oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline Decarboxylase Provides Insights into the Mechanism of Uric Acid Degradation

The complete degradation of uric acid to (S)-allantoin, as recently elucidated, involves three enzymatic reactions. Inactivation by pseudogenization of the genes of the pathway occurred during hominoid evolution, resulting in a high concentration of urate in the blood and susceptibility to gout. Here, we describe the 1.8A resolution crystal structure of the homodimeric 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase, which catalyzes the last step in the urate degradation pathway, for both ligand-free enzyme and enzyme in complex with the substrate analogs (R)-allantoin and guanine. Each monomer comprises ten alpha-helices, grouped into two domains and assembled in a novel fold. The structure and the mutational analysis of the active site have allowed us to identify some residues that are essential for catalysis, among which His-67 and Glu-87 appear to play a particularly significant role. Glu-87 may facilitate the exit of the carboxylate group because of electrostatic repulsion that destabilizes the ground state of the substrate, whereas His-67 is likely to be involved in a protonation step leading to the stereoselective formation of the (S)-allantoin enantiomer as reaction product. The structural and functional characterization of 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase can provide useful information in view of the potential use of this enzyme in the enzymatic therapy of gout.

Importance in Catalysis of the 6-Phosphate-binding Site of 6-Phosphogluconate in Sheep Liver 6-Phosphogluconate Dehydrogenase

The 6-phosphate of 6-phosphogluconate (6PG) is proposed to anchor the sugar phosphate in the active site and aid in orientating the substrate for catalysis. In order to test this hypothesis, alanine mutagenesis was used to probe the contribution of residues in the vicinity of the 6-phosphate to binding of 6PG and catalysis. The crystal structure of sheep liver 6-phosphogluconate dehydrogenase shows that Tyr-191, Lys-260, Thr-262, Arg-287, and Arg-446 contribute a mixture of ionic and hydrogen bonding interactions to the 6-phosphate, and these interactions are likely to provide the majority of the binding energy for 6PG. All mutant enzymes, with the exception of T262A, exhibit an increase in K(6PG) that ranges from 5- to 800-fold. There is also a less pronounced increase in K(NADP), ranging from 3- to 15-fold, with the exception of T262A. The R287A and R446A mutant enzymes exhibit a dramatic decrease in V/E(t) (600- and 300-fold, respectively) as well as in V/K(6PG)E(t) (10(5) - and 10(4)-fold), and therefore no further characterization was carried out with these two mutant enzymes. No change in V/E(t) was observed for the Y191A mutant enzyme, whereas 20- and 3-fold decreases were obtained for the K260A and T262A mutant enzymes, respectively, resulting in a decrease in V/K(6PG)E(t) range from 3- to 120-fold. All mutant enzymes also exhibit at least an order of magnitude increase in 13C-isotope effect -1, indicating that the decarboxylation step has become more rate-limiting. Data are consistent with significant roles for Tyr-191, Lys-260, Thr-262, Arg-287, and Arg-446 in providing the binding energy for 6PG. In addition, these residues also likely ensure proper orientation of 6PG for catalysis and aid in inducing the conformation change that precedes, and sets up the active site for, catalysis.

The lipoxygenase gene ALOXE3 implicated in skin differentiation encodes a hydroperoxide isomerase.

Lipoxygenase (LOX) enzymes form fatty acid hydroperoxides used in membrane remodeling and cell signaling. Mammalian epidermal LOX type 3 (eLOX3) is distinctive in totally lacking this typical oxygenase activity. Surprisingly, genetic evidence has linked mutations in eLOX3 or a colocalizing enzyme, 12R-LOX, to disruption of the normal permeability barrier of the skin [Jobard, F., Lefèvre, C., Karaduman, A., Blanchet-Bardon, C., Emre, S., Weissenbach, J., Ozgüc, M., Lathrop, M., Prud'homme, J. F. & Fischer, J. (2002) Hum. Mol. Genet. 11, 107-113]. Herein we identify a logical link of the biochemistry to the genetics. eLOX3 functions as a hydroperoxide isomerase (epoxyalcohol synthase) by using the product of 12R-LOX as the preferred substrate. 12R-Hydroperoxyeicosatetraenoic acid (12R-HPETE) is converted to 8R-hydroxy-11R,12R-epoxyeicosa-5Z,9E,14Z-trienoic acid, one of the isomers of hepoxilin A3, and to 12-ketoeicosatetraenoic acid in a 2:1 ratio. Other hydroperoxides, including 8R-HPETE, 12S-HPETE, and 15S-HPETE, as well as the 13S- and 13R-hydroperoxides of linoleic acid are converted less efficiently. Mass spectrometric analysis of the epoxyalcohol formed from [18O]15S-HPETE showed that both hydroperoxy oxygens are retained in the product. We propose that the ferrous form of eLOX3 initiates a redox cycle, unprecedented among LOX in being autocatalytic, in which the hydroperoxy substrate is isomerized to the epoxyalcohol or keto product. Our results provide strong biochemical evidence for a functional linkage of 12R-LOX and eLOX3 and clues into skin biochemistry and the etiology of ichthyosiform diseases in humans.

Transition structures for the dieckmann condensation

Transition structures for the Dieckmann condensation have been located using the ab initio MO method. The reaction path through TS-Ia and subsequent MeOH elimination ( TS-II) from intermediate ( B1) leading to enolate ( C), was found to be more favorable than that through TS-Ib, which gave the keto product ( D), by MeOLi elimination ( TS-III).

The effect of the methyl substituent on the bioconversion of cyclohexene derivatives

The absence of the methyl substituent at the 2′position of the cyclohexene ring of TCHP enhances the conversion rate as well as the yields of the 3′-hydroxy product obtained byStreptomyces natalensis and the 3′-keto product obtained byMycobacterium smegmatis.

Autoxidation of cholanic acid in the presence of ferrous ions.

Autoxidation of cholanic acid in an aqueous acetone solution containing 0.2M acetate buffer (pH 5.0) and ferrous sulfate gave three C (12)-keto products, A, B, and C. The main product A was elucidated to be 12-oxo-5β-cholan-24-oic acid. The minor product B was probably 12, 23-dioxo-5β-cholan-24-oic acid. The other carbonyl function of the diketo minor product C was assumed to be situated in ring A or B at a position strongly affected by the angular C (19)-methyl group.

Deconjugation of bile salts by Bacteroids and Clostridium.

Deconjugation of bile salts by four strains of Bacteroides and four strains of Clostridium was studied by use of resting cells and cell-free culture supernatants. Bacteroids strains yielded active cells but showed relatively low bile salt hydrolase (BSH) activity in the culture supernatants while the reverse was the case for the spore-forming clostridial strains. BSH was formed constitutively and was oxygen insensitive. The optimum pH was between 4.5 and 5.0. Marked substrate specificity was found in two strains, one Clostridium and one Bacteroides, which showed restricted activity against taurine conjugates. Bacteroides in general attacked the taurine conjugates of dihydroxy bile acids more readily than the trihydroxy taurine conjugates. Deconjugated bile acid moieties were further modified by some resting cells, depending on the bacterial strain while no enzymatic activity other than that of BSH was found in the culture supernatants. Cells of B. fragilis 2536 performed 7 alpha-dehydrogenation when the pH of the medium allowed the reaction, and this oxidative process was markedly enhanced in the presence of an abundant supply of oxygen as a terminal electron acceptor. C. perfringens PB 6K produced the 3- keto product in addition to the 3 beta-hydroxy derivative of the liberated bile acids and the formation of the latter derivative seemed to take place without preliminary deconjugation.

Quino[1,2‐c]quinazolines. II. Synthesis of 12,13‐dihydro‐11bH‐quino‐[1,2‐c]quinazolines via the versatile intermediates 2‐(2‐amino‐4,5‐dimethoxyphenyl)‐6,7‐disubstituted‐1,2,3,4‐tetrahydroquinolines

AbstractThe versatile intermediates 2‐(2‐amino‐4,5‐dimethoxyphenyl)‐6,7‐dimethoxy‐1,2,3,4‐tetrahydroquinoline (2a) and 6‐(2‐amino‐4,5‐dimethoxyphenyl)‐5,6,7,8‐tetrahydro[1,3]dioxolo[4,5‐g]quinoline (2b) were used in the preparation of a wide variety of 12,13‐dihydro‐11bH‐quino[1,2‐c]quinazolines by reaction with triethyl orthoformate, cyanogen bromide, urea and carbon disulfide in pyridine. Reaction of the thio and keto products with methyl iodide and phosphorus oxychloride, respectively, gave the requisite methylthio and chloro derivatives. Novel Reissert type reactions occurred when the intermediates 2a,b were reacted with acetic anhydride or benzoyl chloride. The attempted dehydrogenation of 12,13‐dihydro‐2,3,9,10‐tetramethoxy‐11bH‐quino[1,2‐c]quinazoline (3a) is also reported.