A comprehensive review on vanilla flavor: Extraction, isolation and quantification of vanillin and others constituents

Sniffin' Away the Feeding Tube: The Influence of Olfactory Stimulation on Oral Food Intake in Newborns and Premature Infants

Because of their immaturity, many premature infants are fed via nasogastric tube. One objective of the neonatal care is to feed infants orally early. The olfactory function of premature infants is developed before birth and odorants have a significant impact on nutrition in infants. The aim of the study was to test whether odor stimulation has a positive effect on the transition from gavage to oral feeding in infants. Participants were premature infants with gestational age of more than 27 weeks, with full or partial gavage feeding, stable vital parameters and without invasive ventilation. Before each feeding procedure an odorant was presented in front of the infant's nose. Infants were randomized into 1 of 3 groups and received either rose odor (not food-associated), vanilla odor (food-associated), or placebo (no odor). The primary outcome of the study was defined as the time until complete oral nutrition. About 150 children born at a postnatal age of 9.5 ± 7.8 days were included in this study. The duration until complete oral nutrition was reached after 11.8 ± 7.7 (vanilla), 12.2 ± 7.7 (rose), and 12.9 ± 8.8 (control) days. A nearly linear relation between odor presentation frequency and effect size was detectable. For infants that received the intervention for more than 66.7% of the time the length of gavage feeding (8 ± 5.4) and hospitalization (11 ± 6.5) was significantly lower in the vanilla group when compared with control (15 ± 7.3 and 21 ± 13.7, respectively). Odor stimulation with vanilla has an impact on oral feeding in premature infants, however the odor has to be presented on regular basis.

Biotransformation of Isoeugenol into Vanillin Using Immobilized Recombinant Cells Containing Isoeugenol Monooxygenase Active Aggregates

For efficiently enhancing the activity of isoeugenol monooxygenase, a whole cell overproducing active aggregate IEM720-18A was successfully fabricated via the fusion of amphiphilic short peptide 18A (EWLKAFYEKVLEKLKELF) and isoeugenol monooxygenase and then efficiently expressed in E. coli BL21 (DE3). Such resulting bacteria, E. coli BL21 (DE3) harboring pET30a-IEM720-18A was applied in the biotransformation of isoeugenol to vanillin with the optimization of cultivation conditions. Our results revealed that the vanillin concentration reached to the highest level (14.5 mmol/L) under the optimized reaction conditions including 1.5-g cells containing active aggregate of IEM720-18A, 10% (v/v) dimethyl sulfoxide (DMSO), 100 mmol/L isoeugenol, 50 mmol/L glycine-sodium hydroxide buffer (pH 10.5) in 10 mL reaction volume, and 200 rpm at 25 °C for 36 h. Moreover, the active aggregate IEM720-18A was immobilized with 100 mmol/L glutaraldehyde at 4 °C to improve the operational stability. The highest activity could be achieved when the reactions were carried out at 25 °C and the relative activity of the immobilized enzyme maintained over 60% after seven recycles. Our study provides a new approach to the biotransformation of isoeugenol into vanillin.

Discovery of Novel N-(4-Hydroxybenzyl)valine Hemoglobin Adducts in Human Blood

Humans are exposed to a wide range of electrophilic compounds present in our diet and environment or formed endogenously as part of normal physiological processes. These electrophiles can modify nucleophilic sites of proteins and DNA to form covalent adducts. Recently, powerful untargeted adductomic approaches have been developed for systematic screening of these adducts in human blood. Our earlier untargeted adductomics study detected 19 unknown adducts to N-terminal valine in hemoglobin (Hb) in human blood. We now describe a full characterization of one of these adducts, which corresponds to the addition of a 4-hydroxybenzyl (4-OHBn) group to N-terminal valine in Hb to form N(4-hydroxybenzyl)valine (4-OHBn-Val). The adduct structure was determined by comparison of its accurate mass, HPLC retention time, and MS/MS fragmentation to that of authentic standards prepared by chemical synthesis. Average 4-OHBn-Val adduct concentrations in 12 human blood samples were estimated to 380 ± 160 pmol/g Hb. Two possible routes of 4-OHBnVal adduct formation are proposed using two different precursor electrophiles: 4-quinone methide (4-QM) and 4-hydroxybenzaldehyde (4-OHBA). We found that 4-QM reacts rapidly with valine to form the 4-OHBn-Val adduct; however, the quinone methide is unstable under physiological conditions due to hydrolysis. It was shown that 4-OHBA forms reversible Schiff base adducts with valine, which can be stabilized via reduction in blood generating the 4-OHBn-Val adduct. In addition, trace amounts of isomeric 2-hydroxybenzyl-valine (2-OHBn-Val) adducts were detected in 12 human blood samples (estimated mean adduct level, 5.0 ± 1.4 pmol/g Hb). Further studies are needed to quantify the contributions from identified possible precursor electrophiles to the observed hydroxybenzyl adducts in humans.

Morphological and phytochemical data of Vanilla species in Mexico

This systematic determination of morphological and phytochemical data was conducted with the purpose of conserving and identifying the phylogenetic relationship among the Vanilla species of the Totonacapan region in Mexico to increase awareness of the genetic biodiversity. Samples of Vanilla planifolia, V. planifolia cv. “oreja de burro”, V. pompona, V. insignis, and V. inodora, are distributed across 19 municipalities of the State of Veracruz and 19 municipalities of the State of Puebla. Morphological data parameters were determined in situ and included leaf length, leaf width, leaf thickness, stem diameter, stem thickness, node distance, stem texture degree, flower colour intensity, and fruit length. Similarly, alkaloids, tannins, saponins, phenols, flavonoids, and terpenes were determined by specifically phytochemical tests and quantified by thin layer chromatography. Both, morphological and phytochemical data parameters, were successfully used in assembling dendrograms by using the Euclidian distance method and by principal component analysis.

Proteomics analysis of Xiangcaoliusuobingmi-treated Capsicum annuum L. infected with Cucumber mosaic virus

Among different viruses, Cucumber mosaic virus (CMV) has the most extensive host range, being capable of infecting over 1200 species, and causes severe damage worldwide. Xiangcaoliusuobingmi (B1), a candidate plant immune activator drug, exhibited significant protective effects against CMV. However, its potential mechanism is still unknown. In this study, we found the defensive enzyme activities of peroxidase (POD), phenylalanine ammonia lyase (PAL), superoxide dismutase (SOD) and catalase (CAT) can be enhanced by B1. Meanwhile, we found RT-qPCR assay results of the defensive gene expression can be improved by B1 in capsicum. Moreover, we analyze the result of label-free proteomics, B1 could trigger abscisic acid (ABA) pathway. All data provide a more understanding about the response to infect CMV capsicum activeted by B1 in the level of the plant physiology and biochemistry, gene and protein.

Label-Free Electrochemical Detection of Vanillin through Low-Defect Graphene Electrodes Modified with Au Nanoparticles

Graphene is an excellent modifier for the surface modification of electrochemical electrodes due to its exceptional physical properties and, for the development of graphene-based chemical and biosensors, is usually coated on glassy carbon electrodes (GCEs) via drop casting. However, the ease of aggregation and high defect content of reduced graphene oxides degrade the electrical properties. Here, we fabricated low-defect graphene electrodes by catalytically thermal treatment of HPHT diamond substrate, followed by the electrodeposition of Au nanoparticles (AuNPs) with an average size of ≈60 nm on the electrode surface using cyclic voltammetry. The Au nanoparticle-decorated graphene electrodes show a wide linear response range to vanillin from 0.2 to 40 µM with a low limit of detection of 10 nM. This work demonstrates the potential applications of graphene-based hybrid electrodes for highly sensitive chemical detection.

The Intracellular Localization of the Vanillin Biosynthetic Machinery in Pods of Vanilla planifolia

Vanillin is the most important flavor compound in the vanilla pod. Vanilla planifolia vanillin synthase (VpVAN) catalyzes the conversion of ferulic acid and ferulic acid glucoside into vanillin and vanillin glucoside, respectively. Desorption electrospray ionization mass spectrometry imaging (DESI-MSI) of vanilla pod sections demonstrates that vanillin glucoside is preferentially localized within the mesocarp and placental laminae whereas vanillin is preferentially localized within the mesocarp. VpVAN is present as the mature form (25 kDa) but, depending on the tissue and isolation procedure, small amounts of the immature unprocessed form (40 kDa) and putative oligomers (50, 75 and 100 kDa) may be observed by immunoblotting using an antibody specific to the C-terminal sequence of VpVAN. The VpVAN protein is localized within chloroplasts and re-differentiated chloroplasts termed phenyloplasts, as monitored during the process of pod development. Isolated chloroplasts were shown to convert [14C]phenylalanine and [14C]cinnamic acid into [14C]vanillin glucoside, indicating that the entire vanillin de novo biosynthetic machinery converting phenylalanine to vanillin glucoside is present in the chloroplast.

In Vitro Enzymatic Depolymerization of Lignin with Release of Syringyl, Guaiacyl, and Tricin Units

New environmentally sound technologies are needed to derive valuable compounds from renewable resources. Lignin, an abundant polymer in terrestrial plants comprised predominantly of guaiacyl and syringyl monoaromatic phenylpropanoid units, is a potential natural source of aromatic compounds. In addition, the plant secondary metabolite tricin is a recently discovered and moderately abundant flavonoid in grasses. The most prevalent interunit linkage between guaiacyl, syringyl, and tricin units is the β-ether linkage. Previous studies have shown that bacterial β-etherase pathway enzymes catalyze glutathione-dependent cleavage of β-ether bonds in dimeric β-ether lignin model compounds. To date, however, it remains unclear whether the known β-etherase enzymes are active on lignin polymers. Here we report on enzymes that catalyze β-ether cleavage from bona fide lignin, under conditions that recycle the cosubstrates NAD+ and glutathione. Guaiacyl, syringyl, and tricin derivatives were identified as reaction products when different model compounds or lignin fractions were used as substrates. These results demonstrate an in vitro enzymatic system that can recycle cosubstrates while releasing aromatic monomers from model compounds as well as natural and engineered lignin oligomers. These findings can improve the ability to produce valuable aromatic compounds from a renewable resource like lignin.IMPORTANCE Many bacteria are predicted to contain enzymes that could convert renewable carbon sources into substitutes for compounds that are derived from petroleum. The β-etherase pathway present in sphingomonad bacteria could cleave the abundant β-O-4-aryl ether bonds in plant lignin, releasing a biobased source of aromatic compounds for the chemical industry. However, the activity of these enzymes on the complex aromatic oligomers found in plant lignin is unknown. Here we demonstrate biodegradation of lignin polymers using a minimal set of β-etherase pathway enzymes, the ability to recycle needed cofactors (glutathione and NAD+) in vitro, and the release of guaiacyl, syringyl, and tricin as depolymerized products from lignin. These observations provide critical evidence for the use and future optimization of these bacterial β-etherase pathway enzymes for industrial-level biotechnological applications designed to derive high-value monomeric aromatic compounds from lignin.

Natural aldehyde extraction and direct preparation of new blue light-emitting imidazo[1,5-a]pyridine fluorophores

This work describes the extraction of natural aldehydes and the use of extracts to synthesise new fluorescent imidazo[1,5-a]pyridine derivatives. The characterisation of the extracted aldehydes by different techniques and the optical study of the fluorescent products allow the design of new compounds suitable for pharmaceutical, down-shifting, microscopy and electronic applications. The fluorophores are generated by an easy one-pot cyclisation reaction in mild conditions without catalyst and with only water as by-product.

FCS and ECH dependent production of phenolic aldehyde and melanin pigment from l-tyrosine in Escherichia coli

In this study, we engineered E. coli cells to express l-tyrosine converting enzymes, including tyrosine ammonia-lyase (TAL), p-coumarate 3-hydroxylase (C3H), feruloyl-CoA synthetase (FCS), and enoyl-CoA hydratase/aldolase (ECH). A catabolic circuit, which consisted of the protocatechualdehyde and p-hydroxybenzaldehyde production pathways, was reconstituted through combinatorial production of discrete enzymes. First, cells expressing FCS and ECH could convert each 5mM of caffeic acid and ferulic acid into protocatechualdehyde (70.5%) and vanillin (96.5%), respectively. Second, TAL and C3H were co-expressed with FCS and ECH. This strain converted l-tyrosine into caffeic acid, which was then converted into protocatechualdehyde. Ascorbic acid was used as an inhibitor of catechol aldehyde-based melanin formation, and the production yields of protocatechualdehyde and p-hydroxybenzaldehyde were 31.0±5.6 and 24.0±4.2mg/L, respectively. Finally, caffeic acid-based melanin formation was observed with higher production rate of 40.9±6.2mg/L/h by co-expressing FCS and ECH in the presence of caffeic acid.

Facile Synthesis of Novel Vanillin Derivatives Incorporating a Bis(2-hydroxyethyl)dithhioacetal Moiety as Antiviral Agents

A series of vanillin derivatives incorporating a bis(2-hydroxyethyl)dithioacetal moiety was designed and synthesized via a facile method. A plausible reaction pathway was proposed and verified by computational studies. Bioassay results demonstrated that target compounds possessed good to excellent activities against potato virus Y (PVY) and cucumber mosaic virus (CMV), of which, compound 6f incorporating a bis(2-hydroxyethyl)dithioacetal moiety, exhibited the best curative and protection activities against PVY and CMV in vivo, with 50% effective concentration values of 217.6, 205.7 μg/mL and 206.3, 186.2 μg/mL, respectively, better than those of ribavirin (848.0, 808.1 μg/mL and 858.2, 766.5 μg/mL, respectively), dufulin (462.6, 454.8 μg/mL and 471.2, 465.4 μg/mL, respectively), and ningnanmycin (440.5, 425.3 μg/mL and 426.1, 405.3 μg/mL, respectively). Current studies provide support for the application of vanillin derivatives incorporating bis(2-hydroxyethyl)dithioacetal as new antiviral agents.

Vanillin biosynthetic pathways in plants

The present review compiles the up-to-date knowledge on vanillin biosynthesis in plant systems to focus principally on the enzymatic reactions of in planta vanillin biosynthetic pathway and to find out its impact and prospect in future research in this field. Vanillin, a very popular flavouring compound, is widely used throughout the world. The principal natural resource of vanillin is the cured vanilla pods. Due to the high demand of vanillin as a flavouring agent, it is necessary to explore its biosynthetic enzymes and genes, so that improvement in its commercial production can be achieved through metabolic engineering. In spite of significant advancement in elucidating vanillin biosynthetic pathway in the last two decades, no conclusive demonstration had been reported yet for plant system. Several biosynthetic enzymes have been worked upon but divergences in published reports, particularly in characterizing the crucial biochemical steps of vanillin biosynthesis, such as side-chain shortening, methylation, and glucoside formation and have created a space for discussion. Recently, published reviews on vanillin biosynthesis have focused mainly on the biotechnological approaches and bioconversion in microbial systems. This review, however, aims to compile in brief the overall vanillin biosynthetic route and present a comparative as well as comprehensive description of enzymes involved in the pathway in Vanilla planifolia and other plants. Special emphasis has been given on the key enzymatic biochemical reactions that have been investigated extensively. Finally, the present standpoint and future prospects have been highlighted.

Modulatory effect of vanillic acid on antioxidant status in high fat diet-induced changes in diabetic hypertensive rats

The worldwide incidence of diabetes has increased dramatically along with widespread lifestyle and dietary changes. Diets high in fat are strongly associated with the development of obesity and can induce insulin resistance in humans and animals. It is clear that obesity constitutes a risk factor for contributing to the development of type 2 diabetes. In the present study, we investigated the therapeutic potential action of vanillic acid on diabetes associated complications using a rat model. Rats were made diabetic hypertensive by high fat diet (HFD) for 20 weeks and were treated with vanillic acid (50mg/kg bw) for last 8 weeks. The effects of vanillic acid on glucose, plasma insulin, systolic and diastolic blood pressure, thiobarbituric acid reactive substances (TBARS), hydroperoxides as a lipid peroxidation marker, and the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), vitamin C and vitamin E as an antioxidant marker, AST and ALT as a liver function marker, urea, uric acid and creatinine as a kidney function marker were investigated. Histopathology of liver and kidney was also investigated as part of the pathology of diabetes. Treatment of diabetic rats with oral administration of vanillic acid at a dose of 50mgkg/body weight for 8 weeks resulted in a significant decrease in fasting plasma glucose, insulin and blood pressure levels in comparison with diabetic control group. The antioxidant activities were significantly increased and the levels of lipid peroxidation markers were significantly decreased in diabetic hypertensive rats treated with vanillic acid. These results suggest that vanillic acid offer a modulatory effect on control of diabetic hypertension by reduction of blood glucose, insulin and blood pressure, combating oxidative stress by activation of tissue antioxidants.

Synthesis of vanillin via a catalytically active Cu(ii)-metal organic polyhedron

Crystalline Cu (ii)-MOP 1 was employed for the first time in the catalytic conversion of trans-ferulic acid to vanillin.

Delivery of vanillin by poly(lactic-acid) nanoparticles: Development, characterization and in vitro evaluation of antioxidant activity

Poly(lactic acid) (PLA) nanoparticles containing vanillin were prepared using an emulsion-solvent evaporation technique and were characterized and assessed for their in vitro antioxidant potential. Physicochemical properties of the nanoparticles were characterized by size, polydispersity index, zeta potential, encapsulation efficiency and stability. Solid state and thermal properties were assessed using X-ray diffraction and differential scanning calorimetry, while in vitro drug release profile was also evaluated. Results showed PLA nanoparticles having a characteristic amorphous structure, sizes in the range of 240 nm with high homogeneity in size distribution, zeta potential of -22 mV and vanillin encapsulation efficiency of 41%. In vitro release study showed a slow and sustained release of vanillin governed by diffusion. Nanoparticles were stable over a period of three months. Antioxidant ability of the vanillin-loaded PLA nanoparticles in scavenging the radical 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was inferior to free vanillin and due to its prolonged release showed a profile that was both time and concentration dependent, while free vanillin showed concentration-dependent activity. The study concluded that PLA nanoparticles are potential carriers for vanillin delivery.

Synthesis, kinetic mechanism and docking studies of vanillin derivatives as inhibitors of mushroom tyrosinase

The purpose of the present study was to discover the extent of contribution to antityrosinase activity by adding hydroxy substituted benzoic acid, cinnamic acid and piperazine residues to vanillin. The study showed the transformation of vanillin into esters as shown in (4a-4d), (6a-6b), and (8a-8b). In addition, the relationship between structures of these esters and their mushroom tyrosinase inhibitory activity was explored. The kinetics of inhibition on mushroom tyrosinase by these esters was also investigated. It was found that hydroxyl substituted benzoic acid derivatives were weak inhibitors; however hydroxy or chloro substituted cinnamic acid and piperazine substituted derivatives were able to induce significant tyrosinase inhibition. The mushroom tyrosinase (PDBID 2ZWE) was docked with synthesized vanillin derivatives and their calculated binding energies were compared with experimental IC50 values which provided positive correlation. The most potent derivative 2-(4-formyl-2-methoxyphenoxy)-2-oxoethyl (2E)-3-(4-hydroxyphenyl)prop-2-enoate (6a) possesses hydroxy substituted cinnamic acid scaffold having IC50 value 16.13 μM with binding energy of -7.2 kcal/mol. The tyrosinase inhibitory activity of (6a) is comparable with standard kojic acid. Kinetic analysis indicated that compound 6a was mixed-type tyrosinase inhibitor with inhibition constant values Ki (13 μM) and Ki' (53 μM) and formed reversible enzyme inhibitor complex. The active vanillin analog (6a) was devoid of toxic effects as shown in cytotoxic studies.

Vanillin-bioconversion and bioengineering of the most popular plant flavor and its de novo biosynthesis in the vanilla orchid

In recent years, biotechnology-derived production of flavors and fragrances has expanded rapidly. The world's most popular flavor, vanillin, is no exception. This review outlines the current state of biotechnology-based vanillin synthesis with the use of ferulic acid, eugenol, and glucose as substrates and bacteria, fungi, and yeasts as microbial production hosts. The de novo biosynthetic pathway of vanillin in the vanilla orchid and the possible applied uses of this new knowledge in the biotechnology-derived and pod-based vanillin industries are also highlighted.