Vanillin Research Articles

Influence of phenolic acids/aldehydes on color intensification of cyanidin-3-O-glucoside, the main anthocyanin in sugarcane (Saccharum officinarum L.)

Sugarcane contains various anthocyanins, which are responsible for the colors present in sugarcane. In this study, the color intensification of the major anthocyanin, cyanidin-3-O-glucoside, by phenolic acids/aldehydes (ferulic acid, vanillic acid, p-coumaric acid, syringic aldehyde and vanillic aldehyde) was investigated. The color enhancement of cyanidin-3-O-glucoside (hyperchromic effect and bathochromic shift) was affected by the temperature and concentration of phenolic acids/aldehydes present. Reactions were spontaneous and exothermic, as determined using different thermodynamic parameters (ΔG0, ΔH0, ΔS0). Quantum chemical calculations demonstrated their intermolecular interaction differences, and AIM analysis indicated that hydrogen bonds and van der Waals force interactions contributed to color. Pyranoanthocyanins derived from cyanidin-3-O-glucoside and ferulic/p-coumaric acids during storage were recognized as cyanidin-3-O-glucoside-vinylphenol and cyanidin-3-O-glucoside-vinylguaiacol, respectively, by UPLC-ESI-QTOF-MS/MS. The electron-donating substituents on the aromatic ring of ferulic/p-coumaric acids stabilized the intermediately formed carbenium ion. Decarboxylation and further oxidation of the pyran moieties to the aromatic heterocycles resulted in the final products.

Vanillin의 Polypropylene 항산화 효과 연구: Cotton Stalk Lignin 추출 천연 항산화제

Vanillin (VA) was extracted from cotton stalk lignin by UV photocatalysis method using CoSUP2+/SUP/NiSUP2+/SUP as a catalyst, the yield of which was quantitative analyzed through gas chromatography-mass spectrometer and high performance liquid chromatography. The structure and thermal properties were compared between extracted and standard VA, which showed basically consistent. PP/VA materials characterized by fourier transform infrared spectroscopy were prepared by melt intercalation and subjected to 20 days thermal oxygen aging. Thermal gravimetric analysis and oxidation induction time results showed VA (0.9 wt%) could improve the thermal stability of polypropylene (PP) by 33.4 ℃ and 49.03%. Differential scanning calorimetry confirmed that VA increased the crystallinity of PP reaching to 15.70%. After 20 days aging, mechanical test showed the impact strength and breaking elongation retention of PV-3 (0.9 wt%) were 10.0% and 14.8% higher than those of PP; surface scanning electron microscopy showed that PV-3 had the most smooth surface.

Size-controlled nanoscale octahedral HKUST-1 as an enhanced catalyst for oxidative conversion of vanillic alcohol: The mediating effect of polyvinylpyrrolidone

While 2,2,6,6-tetramethylpiperidin-oxyl (TEMPO) accompanied with Cu is a promising oxidative catalytic process for converting vanillic alcohol (VL), to vanillic aldehyde (VE), the Cu-based metal organic frameworks (MOFs), HKUST-1, appears as a useful heterogeneous catalyst for VL conversion. Nevertheless, since the typical HKUST-1 is micrometer-scaled, it would be more advantageous to make HKUST-1 into nanoscale to increase outer surfaces of HKUST-1. Thus, the goal of this study is to develop a useful approach to prepare nanoscale HKUST-1 which can still exhibit octahedral morphology. Specifically, nano-HKUST-1 is developed here via mediation by polyvinylpyrrolidone (PVP). These PVP-mediated nano-HKUST-1 not only retains the crystalline structure of HKUST-1 but also maintains the octahedral morphology of HKUST-1. Interestingly, the introduced PVP would not just alter the size of HKUST-1 but also deposit PVP molecules into these nano-HKUST-1, increasing hydrophilicity of nano-HKUST-1 to attract VL in solvents. Thus, nano-HKUST-1 could exhibit noticeably higher VL conversion efficiencies then the conventional HKUST-1 owing to the smaller size, and the more hydrophilic surficial properties. Moreover, nano-HKUST-1 could also exhibit a high YVE= 91% with SVE= 100% at 120 °C for 120 min, outperforming many other reported values. Nano-HKUST-1 can be also reusable and exhibit stable YVE and 100% of SVE. These features all indicate that nano-HKUST-1 prapred by mediation of PVP is a more advantageous Cu-based catalyst for converting VL to VE, and the mediating effect of PVP revealed here also gives insights to further engieer MOFs materials for enhancing their applications.

Sensitive and selective electrochemical detection of vanillin at graphene based poly (methyl orange) modified electrode

Vanillin (VN) is a flavouring substance commonly used in the food and pharmaceutical industry. The rampant use of VN has significant implications on human health. In this work, a sensitive and selective voltammetric sensor to detect VN in food essences and natural vanilla beans was elucidated using a poly(methyl orange) modified graphene paste electrode (PMOMGPE). The surface morphology of PMOMGPE and a bare graphene paste electrode (BGPE) was compared using field emission - scanning electron microscopy (FE-SEM) and electron transfer kinetics were analysed by Electrochemical impedance spectroscopy (EIS). The electrochemical activities of PMOMGPE and BGPE were assessed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in 0.2 M phosphate buffer solution (PBS) of an optimum pH of 6.5 with an accumulation time of 20 s in a potential window of 0.2 V–1 V. Superior electrocatalytic activity was observed by PMOMGPE for the oxidation of VN, which is attributed to the high surface area and interactions between the polymer film and analyte. The VN sensor exhibited a low detection limit of 7.35 × 10−8 M by the DPV method and 20.19 × 10−8 M by the CV method. Various parameters like heterogeneous rate constant (ko = 1.7 × 10−5 cm s−1), number of electrons transferred (n = 2), and surface concentration (Γ = 0.8 nmol cm−2) were calculated. The selectivity of the prepared sensor for VN detection in the presence of common interferents such as metal ions and organic species was noteworthy. PMOMGPE was reliably used for the simultaneous analysis of VN along with indigo carmine (IC) and tartrazine (TZ). This facile VN sensor can be effectively used for real sample analysis, due to its simplicity and stability.

MOF-Encapsulating Metal–Acid Interfaces for Efficient Catalytic Hydrogenolysis of Biomass-Derived Aromatic Aldehydes

Developing an efficient and selective catalyst for C–O hydrogenolysis of biomass-derived aromatic aldehydes, such as 5-methylfurfural (MF), 5-hydroxymethylfurfural (HMF), and vanillin (VA), is highly significant for the synthesis of biofuel and fine chemicals. Herein, metal–organic framework (MOF)-encapsulating metal–acid interfaces (Pd@UiO–CH2SO3H, Pd@UiO–PhSO3H) were first reported. Compared with traditionally supported catalysts (Pd/UiO–SO3H, Pd/UiO–NH2), Pd–acid-interface-encapsulated MOFs show much higher activity and selectivity for MF to 2,5-dimethylfuran (DMF), HMF to DMF, and VA to 2-methoxy-4-methylphenol (MMP) reactions. In particular, Pd@UiO–SO3H shows the best catalytic performance with 89.0 and 86.0% DMF yield from MF and HMF and a 99.4% MMP yield from VA based on its suitable hydrophilicity, high hydrogen activation ability, and abundant Pd–SO3H interface active sites. According to the catalytic performance of Pd/UiO–NH2 and the results of an ATR-IR test, the acidic sites on the Pd–acid interface can accelerate the activation of the hydroxyl group for these hydrogenolysis reactions. This work provides an effective design strategy for the preparation of MOF-encapsulating metal–acid interfaces and shows the powerful synergistic effect of hydrogenation and acid catalysis.

Experiment of subcritical water (Fenton) oxidation treatment of methyl vanillin wastewater

In this paper the oxidative degradation process of methyl vanillin wastewater was studied by the subcritical water oxidation (HCWO) technology. A subcritical Fenton oxidation (HCFO) system formed while Fe2+ was added as a catalyst. The oxidation degradation kinetics of methyl vanillin wastewater was also studied. The results showed that the suitable process conditions for degradation of methyl vanillin wastewater by HCWO were as follows: temperature of 340 ​°C, pressure of 24 ​MPa, oxidant multiple of 1.5, residence time of 217.3 ​s (flow rate of 2.0 ​mL ​min-1). For methyl vanillin wastewater, the HCFO system has no obvious advantages compared to the HCWO system. The activation energy (Ea) of HCWO oxidized methyl vanillin wastewater reaction was 32.6 ​kJ ​mol-1, and the pre-exponential factor A was 5.64 s-1.

Interaction of Bioactive Mono-Terpenes with Egg Yolk on Ice Cream Physicochemical Properties.

Using natural multi-function phytochemicals could be one of the best solutions for clean-label production. In this study, dairy ice creams were prepared containing 14% egg yolk and 0.1% of thymol (THY), trans-cinnamaldehyde (TC), menthol (MEN), or vanillin (VAN). Then, the physical, chemical, and structural characteristics were evaluated. Magnetic resonance imaging (MRI) analysis (a rapid, chemical-free, and non-invasive tool) was carried out to evaluate the water distribution. A multivariate analysis was conducted among all studied variables. According to the results, the overrun of the MEN ice cream was significantly increased as compared to the control sample. The density was also reduced in the MEN sample. Meanwhile, the spreadability (%) of VAN was significantly increased after 6 min as compared to the control treatment. MRI analysis revealed that water distribution was significantly changed in the THY group. The firmness and viscosity of THY samples were significantly increased (p < 0.05). Multivariate analysis indicated that viscosity index and consistency were the top parameters affected by THY. The authors concluded that THY and VAN are promising stabilizers for ice-cream clean production.

Nanopetal-like copper hydroxide nitrate as a highly selective heterogeneous catalyst for valorization of vanillic alcohol via oxidation

Valorization of lignin derivative, vanillic alcohol (VL), to vanillic aldehyde (VE) represents a critical move towards sustainable utilization of lignocellulosic biomass. As conversion of VL into VE requires the specific oxidation of alcohol moiety of VL into an aldehyde moiety, it is crucial to develop effective processes to selectively oxidize the alcohol group of VL. Lately, 2,2,6,6-tetramethylpiperidin-oxyl (TPO) accompanied with Cu has been validated as a promising oxidative catalytic process for oxidizing alcohols. Since Cu-O cluster plays an important role in TPO-based oxidation of alcohols, and N-O moiety would facilitate the catalytic cycle of TPO regeneration, an interesting solid-phase material, copper hydroxide nitrate (CHN) is proposed here for the first time for co-catalyzing TPO to oxidize VL into VE. In particular, a convenient method is developed to fabricate CHN with a special morphology of 2D elliptical nanopetal, forming nanopetal CHN (NPCHN). As TPO or NPCHN could not convert VL into VE separately, the combination of NPCHN/TPO quickly oxidizes VL to VE with a selectivity of 100%. With higher concentrations of NPCHN and TPO, the conversion efficiency of VL into VE could be considerably enhanced and reached ~99% of CVL and YVE with SVE = 100%. The extended reaction duration and elevated reaction temperature would also lead to the significantly high VL conversion efficiency, which also outperforms many reported conversion efficiencies. NPCHN could be also recyclable for co-catalyzing with TPO for converting VL to VE. These findings confirm that NPCHN is certainly an advantageous heterogeneous catalyst for valorizing VL via selective oxidation.

Ceratonia Siliqua L seeds extract as eco-friendly corrosion inhibitor for carbon steel in 1 M HCl: Characterization, electrochemical, surface analysis, and theoretical studies

Electrochemical and theoretical behaviors of the carbon steel was investigated in 1 M HCl solution using the Ceratonia Siliqua L seeds (CFE) extract. This extract was analyzed using GC–MS technique; it was found that the extract contains 18 compounds on which the main constituents represent 27.78 wt.% vanillin (VN), 25.69 wt.% α-tumerone (AT), 11.68 wt.% 2-heptanal (HP), 9.49 wt.% mome-inositol (MI), 4.94 wt.% 1-dotiacontanol(DT), and 2.92 wt.% linoleic acid (LA). The corrosion inhibition and adsorption (CIA) behavior were investigated using the electrochemical measurements (open circuit potential (OCP), polarization curves (PC) and impedance spectroscopy (IS)), and both thermodynamic and kinetic parameters (ΔHa, ΔSa and Ea). The outcomes show that CFE extract exhibits a worthy anti-corrosion action with an inhibition efficiency (η%) of 95% at 100 mg/l at 298 °K. This result could be attributed probably to the adsorption of CFE extract matrix on carbon steel surface, and this was confirmed by surface visualization using SEM-EDS technique. The adsorption of CFE extract onto carbon steel surface is controlled by a Langmuir adsorption isotherm, which suggests that there are no interactions between molecules of the CFE during adsorption. The computational chemistry calculations by density functional theory (DFT), natural bond orbital (NBO), molecular electrostatic potential surface (MESP) and Metropolis Monte Carlo (MC) methods were performed to better understand the inhibition and adsorption behavior of the main constituents of CFE extract on the Fe (110) surface.

Physicochemical impact of bioactive terpenes on the microalgae biomass structural characteristics

This study aimed to evaluate the functionality of bioactive terpenes on Spirulina (Arthrospira platensis; AP) and Chlorella (Chlorella vulgaris; CV) biomasses. The two microalgae species were treated with 0.01%, 0.05%, and 0.1% of thymol (THY), trans-cinnamaldehyde (TC), menthol (MEN), and vanillin (VAN). Raman micro-spectroscopy (RMS) was correlated with other physicochemical methods to confirm their functional mechanisms. In results, THY (0.1%) decreased (P < 0.05) RMS intensity at 1196 cm−1 that represents the protein’s secondary amines wavenumber. Also, VAN (0.1%) decreased significantly A. platensis α-helix to 16.60 ± 0.52% compared to the control with 19.83 ± 0.32%. While, 0.1% TC increased (P < 0.05) the viscosity to 2.52 ± 0.61 Pa.s. This work demonstrated that terpenes could differently affect the physicochemical structure of microalgae biomass. The RMS's uniqueness comes from its ability to evaluate the functionality of terpenes during microalgae cultivation. Besides, chemometrics led to focus on the most important variances.

Simultaneous determination of vanillin, ethyl vanillin and methyl vanillin in Chinese infant food and other dairy products by LC-MS/MS

ABSTRACT An efficient and simple method for determining vanillin, methyl vanillin and ethyl vanillin in milk and dairy products was developed using a liquid-liquid extraction (LLE) procedure coupled to high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Different extraction procedures were tested and optimised by spiking three vanillin compounds into a blank matrix in which none of any food additives were detected, and the extraction with acetonitrile solution and n-hexane as cleaning sorbent allowed an efficient recovery of 87.6–101.7% with RSDs less than 5%. The limit of detection (LOD) ranged from 6.2 to 20.1 μg/kg. High sensitivity, accuracy and selectivity were found for the in-house validated method, which can eliminate the interferences from complicated matrices effectively, and fulfil the quality criteria for routine laboratory application for real samples. The developed method was then finally applied to screen the three analytes in 65 milk and dairy products including infant formula milk powders from local markets to check for compliance with Chinese Regulation. Concentrations of the total vanillin and ethyl vanillin ranged from 0.0323 to 246.3 mg/kg, which is within the limits of Chinese regulations.

Development of Chitosan Microspheres through a Green Dual Crosslinking Strategy Based on Tripolyphosphate and Vanillin.

Microencapsulation procedures have recently focused attention on designing novel microspheres via green synthesis strategies. The use of chitosan (CS) as an encapsulating material has increased interest due to its unique bioactive properties and the various crosslinking possibilities offered by their functional groups. The consolidation of the microspheres by physical crosslinking using sodium tripolyphosphate (TPP) combined with chemical crosslinking using vanillin (VA) open new opportunities in the framework of green dual crosslinking strategies. The developed strategy, a straightforward technique based on an aqueous medium avoiding complex separation/washing steps, offers advantages over the processes based on VA, mostly using water-in-oil emulsion approaches. Thus, in this work, the combination of TPP crosslinking (3, 5, and 10 wt.%) via spray-coagulation technique with two VA crosslinking methods (in situ and post-treatment using 1 wt.% VA) were employed in the preparation of microspheres. The microspheres were characterized concerning morphology, particle size, physicochemical properties, thermal stability, and swelling behavior. Results revealed that the combination of 5 wt.% TPP with in situ VA crosslinking led to microspheres with promising properties, being an attractive alternative for natural bioactives encapsulation due to the green connotations associated with the process.

Surfactant and Polymer Composite Modified Electrode for the Sensitive Determination of Vanillin in Food Sample

AbstractIn this work, the active poly (titan yellow) and octoxynol‐9 modified carbon nanotube paste electrode (PTOMCNPE) was prepared and characterized through a Field emission scanning electron microscope (FE‐SEM), Energy‐dispersive X‐ray spectroscopy (EDX), and Electrochemical impedance spectroscopy (EIS). PTOMCNPEpromotes the detection and quantification of vanillin (VA). The electrochemical parameters such as the number of electropolymerization cycles, effect of surfactant,pH, and scan rate were optimized to get an enhanced current signal for the targetmolecule. Under calibrated conditions, the concentration linearity for vanillin was obtained from 2.0‐40.0 μM using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The limitof detection(LOD) for VA was found to be 4.9×10−8 M and 9.31×10−8 M using DPV and CV, respectively. The stable and selective VA sensor was applied to food analysis with excellent recovery.

The antifungal mechanism of konjac flying powder extract and its active compounds against wood decay fungi

Wood products are vulnerable to fungal degradation that reduces service life. Traditional wood preservatives can provide excellent service life but efforts are underway to develop more natural methods for wood protection. Konjac flying powder is a residual waste produced during the processing of corms of Konjac (Amorphophallus konjac K. Koch) to produce Konjac flour. This waste material contains a number of compounds including salicylic acid (SA), 2,4,6-trichlorophenol (TCP), vanillin (VL), and cinnamaldehyde (CMA) has been found to be active against decay fungi; however, the antifungal mode of action is uncertain. The effects of konjac flying powder extract (KFPE) and its active compounds on cellulase, hemicellulose and ligninase activity, respiratory metabolism, cell membrane permeability, protein, and energy metabolism was studied on the white-rot fungus, Trametes versicolor (L. ex Fr.) Quél. (T. versicolor) and brown-rot fungus, Gloeophyllum trabeum (Pers.: Fr.) Murr. (G. trabeum). Konjac flying powder inhibited cellulase and hemicellulase activity of both fungi and ligninase activity of T. versicolor. Respiratory metabolism and energy metabolism were also inhibited. The four active compounds had different effects on activities suggesting that konjac flying powder functioned against multiple metabolic activities of the test fungi, potentially increasing its ability to provide broad spectrum wood protection.

Voltammetric Determination of Vanillin in Commercial Food Products Using Electrochemically Fabricated Graphene Oxide Modified Electrode

Determination of vanillin, which is used increasingly common in the food, beverage, and drug industry, is important for human health. Therefore; it is essential to determine the amount of vanillin using a fast, simple and reliable method. In this study; an electrode modified with graphene oxide prepared in one-step, in a one-pot, with an environmentally friendly method, was prepared and used for the electrochemical determination of vanillin (VAN), as flavoring. The electrochemically fabricated graphene oxide electrode (EGO/GE) was prepared by electrochemically producing the graphene oxide structure on the graphite electrode surface. The characterization of the prepared EGO/GE was performed using techniques such as field emission scanning electron microscopy and atomic force microscopy and it was concluded that the proposed EGO/GE material was successfully prepared. While the investigation of the electrochemical behavior of the VAN was performed by the cyclic voltammetry, the differential pulse voltammetry method was used for the voltammetric determination. It was determined that EGO/GE, is used in the electrochemical determination of VAN, exhibits high electrocatalytic performance, a wide linear range (0.1-1000 µM), and a low detection limit (0.05 µM) compared to unmodified GE. The selectivity of the prepared sensor was studied in the presence of ions and organic substances. The sensor (EGO/GE) was used for VAN detection in ice-cream, coffee, and cookie samples and high recovery values were obtained. As a result of the stability and reproducibility studies carried out for the sensor, it has been observed that it is quite stable and suitable for reproduction.

Fullerene-MWCNT nanostructured-based electrochemical sensor for the detection of Vanillin as food additive

In this paper, a simple, economical, selective and sensitive electrochemical sensor is proposed for the quantification of vanillin (VAN) in real food samples. It consists of a carbon paste electrode (CPE) nanostructured with Fullerene (FNTs) and functionalized multi-walled carbon nanotubes (f-MWCNTs). The developed electroanalytical method was performed with cyclic voltammetry after optimization of operating conditions, such as supporting electrolytes, pH values and accumulation time. After optimization, the nanostructured sensor showed wide linear responses in the range from 5 × 10−8 to 9 × 10-6 mol.L-1 for VAN trace levels and from 10-5 to 10-4 mol.L-1 for higher concentrations, with a low detection limit of 3.4 × 10−8 mol.L-1. For concentrations lower than 10-5 mol.L-1, VAN was stripped after a previous quick adsorption step (300 s). The f-MWCNTs-FNTs/CPE sensor showed a good stability, repeatability and reproducibility (less than 7 %). This nanostructured sensor was successfully applied to determine VAN concentration as additive in commercial vanilla sugar samples with a satisfactory recovery and a good accuracy (< 6.5 %) in comparison with UPLC/UV control method.

HPLC-DAD-MS and Antioxidant Profile of Fractions from Amontillado Sherry Wine Obtained Using High-Speed Counter-Current Chromatography.

In the present work, the polyphenolic profile of a complex matrix such as Amontillado sherry has been processed by means of high-speed counter-current chromatography (HSCCC) and characterized by HPLC-DAD-MS. An Amberlite XAD-7 column was used to obtain the wine extract, and three different biphasic solvent systems were applied for HSCCC separation: MTBE (methyl tert-butyl ether)/n-butanol/acetonitrile/water (1.1/3/1.1/5+0.1% trifluoroacetic acid), MTBE/n-butanol/acetonitrile/water (2/2/1/5), and hexane/ethyl acetate/ethanol/water (1/5/1/5). As a result, 42 phenolic compounds and furanic derivatives have been identified by means of HPLC-DAD-MS, with 11 of them being identified for the first time in Sherry wines: 3-feruloylquinic acid, isovanillin, ethyl vanillate, furoic acid, dihydro-p-coumaric acid, 6-O-feruloylglucose, ethyl gallate, hydroxytyrosol, methyl protocatechuate, homoveratric acid and veratraldehyde. In addition, the antioxidant capacity (ABTS) of the obtained fractions was determined, revealing higher values in those fractions in which compounds such as gallic acid, protocatechuic acid, protocatechualdehyde, trans-caftaric acid, syringic acid, isovanillin or tyrosol, among others, were present. This is the first time that HSCCC has been used to characterize the phenolic composition of Sherry wines.

PANI blended MoS2 decorated GO ternary nanocomposite for efficient electrochemical sensing of crucial components in food and beverages

An electrochemical detection dependent on Polyaniline (PANI) blended MoS2 decorated GO (MoS2/PANI@GO) ternary nanocomposite has been developed and used for selective and concomitant determination of Vanillin (VAN), Theophylline (TP) and Caffeine (CAF). The surface morphology and structural properties of the composite are denoted by various scientific methods. The electrochemical behaviour of MoS2/PANI@GO has been investigated by Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV). The electrochemical oxidation (anodic) peaks have been observed at 0.59, 1.1 and 1.36v in phosphate buffer (pH 7) for Vanillin, Theophylline and Caffeine, respectively. A good linear current response and limit of detection of 0.043, 0.062 and 0.07 of VAN, TP and CAF, are obtained respectively. The concocted electrode reveals low detection limit, wide linear range, excellent reproducibility, high acuteness and stability. The study is also continued to the analysis of the certain components in the commercial foods and beverage samples.

Ionic strength effect on the formation of organonitrate compounds through photochemical degradation of vanillin in liquid water of aerosols

The ionic strength can affect the photochemical reactions occurring in the liquid core of the aerosol deliquescent particles. Yet, the investigations related to ionic strength effect on aqueous-phase reactions are limited. Here we assess the photochemical degradation of a typical lignin-derived compound, vanillin (VL), upon addition of either sodium nitrate (NaNO3) or sodium sulfate (Na2SO4). The UV-VIS absorption spectra of VL exhibits a hyperchromic effect and a bathochromic shift of the n→π* absorption band, in going from λmax = 310 nm in the dilute aqueous phase to λmax = 346 nm at I = 0.3 M adjusted by Na2SO4. A hypsochromic shift of the n→π* absorption band of VL, in going from λmax = 310 nm in the dilute liquid water to λmax = 303 nm at Ieff = 0.124 M is observed when the ionic strength was adjusted with NaNO3.At fixed pH ≈ 4, representing both the cloud droplets and the liquid core of the aerosol particles, the pseudo-first-order rate constant, k1st (Ieff.→0) = (1.5 ± 0.2) x 10−5 s−1, in dilute aqueous solution (Ieff = 0 M, NaNO3), linearly decreases to (k1st = (3.7 ± 0.2) x 10−6 s−1), at Ieff = 0.124 M (NaNO3) with kinetic salting coefficient b = -(4.8 ± 0.2) L mol−1. The very subtle pH change of the absorption spectra of irradiated VL is observed due to the formation of carboxylic acids, hydroxylated compounds and oligomers which presence was confirmed by FT-ICR MS analysis. Most likely aliphatic like CHO compounds are formed upon photodegradation of VL in dilute aqueous phase while the condensed aromatic CHO and CHON compounds are produced in presence of nitrate ions (Ieff = 0.124 M). These results suggest that inorganic ions present in the liquid water of aerosols alters the kinetics and the product formation of photochemical degradation of organic compounds which in turn can affect the light absorption properties of aerosols.

Influence of methoxylation on the anti-diabetic activity of ρ-hydroxybenzaldehyde in type 2 diabetic rat model

The present study was designed to investigate the role of methoxylation on the anti-diabetic potential of ρ-hydroxybenzaldehyde (ρ-BN) and its derivatives vanillin (VN) and syringaldehyde (SN) in type 2 diabetes (T2D). Fructose-fed streptozotocin-induced T2D rat model was used and orally treated with 50 and 100 mg/kg body weight of ρ-BN, VN and SN for 28 days. From the results, the diabetic control (DBC) group showed significant (p < 0.05) elevation in insulin resistance, blood glucose, fructosamine, glycogen phosphorylase (GP) activity, lipid profiles, and a significant (p < 0.05) decrease in β-cell functions, insulin, liver glycogen contents, and glycogen synthase (GS) activity. The insulin receptor substrate-1 (IRS-1) and glucose transporter-4 (GLUT-4) mRNA expression in the hepatocyte and skeletal muscle were decreased in DBC group compared to the normal control (NC) group. Oral treatment of the compounds improved the above diabetes-induced alterations to near normal and were comparable to the metformin treated group. Variation in methoxylation of ρ-BN, VN, and SN displayed an inconsistent pattern on the measured indices of diabetes (insulin resistance, β-cell functions, blood glucose, insulin, fructosamine, GS, GP, lipid profiles, IRS-1 and GLUT-4). However, in the case of oral glucose tolerance ability, serum insulin and fructosamine levels, liver glycogen contents and cardiovascular risk indices, the methoxylation mediated positive effects. The phenolic aldehydes (ρ-BN, VN, and SN) possessed anti-T2D activity while methoxylation partly influenced the anti-diabetic effects of the phenolic aldehyde skeleton.