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The present work demonstrates the synthesis of new bio-based benzoxazine monomers via Mannich-like condensation of naturally occurring raw materials, for example, phloretic acid (PA) and furfurylamine (fa)/stearylamine (sa). The structure of the benzoxazine monomers has been established using proton nuclear magnetic resonance, carbon nuclear magnetic resonance and Fourier transform infrared spectroscopies. The monomers undergoes thermally activated ring opening polymerization to form polybenzoxazine networks, as revealed by non-isothermal differential scanning calorimetry, and the curing temperature for both was observed to be less than 473 K. Curing parameters of the developed monomers have also been compared with the reported bio-based monomers. The rheological behaviour of PA-fa monomer shows that the monomer has narrow processing window with liquefaction temperature at 426 K and gelation temperature at 437 K. Thermal degradation behaviour of polybenzoxazines was studied using thermogravimetric analysis which reveals that polybenzoxazine based on furfurylamine shows relatively high thermal stability and char yield which is credited to the additional cross-linking sites provided by the furan ring.

This study investigated the effect of lactic acid bacteria (LAB) fermentation on the chemical profile of autoclaved broccoli puree, using 7 broccoli-derived LAB isolates (named F1-F5, BF1 and BF2). The total concentrations of glucosinolates (glucoiberin, progoitrin and glucoraphanin) and 10 major phenolics significantly increased from trace level and 289 μg total phenolics/g dry weight (DW) respectively in autoclaved broccoli to 55 to ∼359 μg/g DW and 903 to ∼3105 μg/g DW respectively in LAB fermented broccoli puree. Differential impacts of LAB isolates on the chemical composition of autoclaved broccoli were observed, with the major differences being the significant increase in phloretic acid after fermentation by F1-F5 and an elevated glucoraphanin level in ferments by F1 and BF2. LAB fermentation is a promising way to increase the content of glucosinolates and polyphenolic compounds in broccoli, making the ferments attractive for use as functional ingredients or as a whole functional food.

Phloretic acid, phloretin and phlorizin (phloretin 2′-O-glucoside), plant-derived natural products, are well known for human health benefits and medical application. Here, we construct an artificial biosynthetic pathway of phlorizin by modular engineering strategy and realize the production of phloretic acid, phloretin and phlorizin in Escherichia coli. Extending from L-tyrosine biosynthetic pathway, we firstly established the phloretic acid module comprised of heterologous TAL and ER enzymes, and highest titer of phloretic acid was achieved from glucose. Then, through biochemical screening of functional microbial Aa4CL and structure-based mutagenesis of MdCHS3 in phloretin module, we successfully constructed the phloretin biosynthetic pathway. Finally, we tested several glycosyltransferases in phlorizin module, and phloretic acid was bioconverted to phlorizin. This is the first report on biosynthesis of phloretin and phlorizin in engineered E. coli, indicating the promising potential of microbial cell factories to produce natural and unnatural dihydrochalcones.

Graphical abstract, Highlights • Co-pigmentation pretreatment protected blackberry anthocyanins during drying. • Ethanol pretreatment with phenolic acids only enhanced water effective diffusivity. • Non-anthocyaninic soluble phenolics were better preserved under contact sonication. • Bound phenolics were less affected by pretreatments and ultrasound-assisted drying., In this work, the spraying of ethanol solution containing phenolic acid (ferulic acid or caffeic acid) was performed before subjecting to contact ultrasound-assisted air drying of blackberry. The mass transfer modeling results revealed that sonication intensified both internal water diffusion and external water exchange during drying, and ethanol pretreatment enhanced the effective diffusivity of water. Compared with air drying alone, the drying time for sequential ferulic acid pretreatment and drying with sonication was shortened by 89.2%. Owing to the co-pigmentation between phenolic acid and anthocyanins, the retention of anthocyanins was significantly enhanced after dehydration. At the end of drying, the total anthocyanin contents in the ultrasound-dried samples pretreated with ferulic acid and caffeic acid were 25.3% and 10.5% higher than the sonicated samples without pretreatments, respectively. Furthermore, drying simultaneously with sonication promoted the preservation of non-anthocyaninic soluble phenolics including catechin, phloretic acid, rutin in blackberry compared to air drying alone. Besides, bound phenolics in blackberry were less influences by the applied dehydration treatments. This study demonstrates that the combination of phenolic acid co-pigmentation pretreatment and ultrasound drying could be a promising method to protect anthocyanin pigments during dehydration of berry fruits.

Chemical investigation of a methanolic extract of leaves from Araucaria bidwillii (Araucariaceae) from Egypt afforded four new labdane diterpenoidal metabolites (1–4) together with one known diterpene, 7-oxocallitrisic acid (5), two triterpenoidal metabolites, 2-O-acetyl-11-keto-boswellic acid (6) and β-sitosterol-3-O-glucopyranoside (7), phloretic acid (8), and two methylated bisflavonoids, agathisflavone-4′,7,7″-trimethyl ether (9) and cupressuflavone-4′,7,7″-trimethyl ether (10). The new metabolites 1–4 were unambiguously identified by applying extensive 1D and 2D NMR spectroscopic studies as well as HRESIMS. The relative and absolute configurations of 1–4 were determined using ROESY and the modified Mosher's method, respectively. All isolated compounds were assessed for their antimicrobial, antitubercular and cytotoxic activities. Among the tested compounds, the new labdane diterpenes 1–4 revealed significant cytotoxic activity against mouse lymphoma L5178Y cell line with IC50 values ranging from 1.4 to 12.9 μM, respectively.

In this work, a sustainable chemical process was developed through the Fischer esterification of Protobind® lignin, a wheat straw soda lignin, and phloretic acid, a naturally occurring phenolic acid. It aimed at increasing the reactivity of lignin by enhancing the number of unsubstituted phenolic groups via a green and solvent-free chemical pathway. The structural features of the technical and esterified lignins were characterized by complementary spectroscopic techniques, including 1H, 13C, 31P, and two-dimensional analysis. A substantial increase in p-hydroxyphenyl units was measured (+64%, corresponding to an increase of +1.3 mmol g−1). A full factorial design of the experiment was employed to quantify the impact of critical variables on the conversion yield. The subsequent statistical analysis suggested that the initial molar ratio between the two precursors was the factor predominating the yield of the reaction. Hansen solubility parameters of both the technical and esterified lignins were determined by solubility assays in multiple solvents, evidencing their high solubility in common organic solvents. The esterified lignin demonstrated a better thermal stability as the onset of thermal degradation shifted from 157 to 220 °C, concomitantly to the shift of the glass transition from 92 to 112 °C. In conclusion, the esterified lignin showed potential for being used as sustainable building blocks for composite and thermoset applications.

3-(4-Hydroxyphenyl)propanoic acid, so-called phloretic acid (PA), is a naturally occurring phenolic compound which can be produced by the hydrogenation of p-coumaric acid or synthesized from phloretin, a by-product of apple tree leaves. It is explored herein as a renewable building block for enhancing the reactivity of –OH bearing molecules towards benzoxazine (Bz) ring formation instead of phenol. PA is used to bring phenolic functionalities by its reaction with model molecules (ethylene glycol, as well as two polyethylene glycol molecules with molar masses corresponding to 400 g·mol−1 and 2000 g·mol−1) via solvent-free Fischer esterification. These phenolic groups are further reacted with a bio-based amine (furfurylamine) to form almost 100% bio-based benzoxazine end-capped molecules. Very interestingly, the whole synthesis of Bz monomers from PEG400 and PEG2000 does not require a solvent or purification, and their polymerization led to a set of materials with thermal and thermo-mechanical properties suitable for a wide range of applications. These results show that renewable phloretic acid is a sustainable alternative to phenol to provide easily the specific properties of benzoxazine to aliphatic –OH bearing molecules or macromolecules. This novel approach paves the way towards a multitude of applications given the large number of –OH bearing compounds in materials science.

In this report, bienzymatic crosslinking approach was applied to prepare biopolymer hydrogel fibers composed of gelatin and chitosan with an interpenetrating polymer network (IPN) structure. The IPN biopolymer hydrogel fibers were prepared by wet spinning while microbial transglutaminase (mTG) catalyzed the formation of one network of gelatin and horseradish peroxidase (HRP) in the presence of H2O2 induced another network of chitosan grafted with phloretic acid (chitosan-PA) intertwining with the former. The mechanical performances of the hydrogel fibers were measured by an electronic single fiber strength tester. It was found that the mechanical properties of the gelatin/chitosan IPN hydrogel fibers had a significant improvement with the increase of the concentration of gelatin and chitosan, and the IPN fiber has the highest tension of 38.6 cN and elongation of 387.2%. Accelerated degradation in the presence of papin indicated that the gelatin/chitosan-PA IPN hydrogel fibers own controllable degradability. In addition, biological evaluation indicated the IPN hydrogel fibers can support cell adhesion and proliferation. Moreover, hand weaving trail showed the knittablity of the IPN hydrogel fibers. Therefore, the gelatin/chitosan IPN hydrogel fibers prepared by bienzymatic crosslinking approach possess excellent biocompatibility and mechanical strength, which may be desirable candidates for engineering tissue scaffolds.

International audience; Nanocomposites based on poly(butylene succinate) (PBS) and hydrotalcite-type anionic clays (HTs) organo-modified with biomolecules characterized by antibacterial and/or antioxidant activities, such as L-ascorbic acid (ASA), phloretic acid (HPP), L-tyrosine (TYR) and L-tryptophan (TRP), have been prepared by in situ polymerization. From XRD analysis and rheology experiments in a molten polymer state, intercalated HT hybrid platelets acting here as a hybrid filler are found to be well dispersed into polymers while providing a chain extension effect on PBS. Moreover, the molecules, when hosted within a HT interlayer gap, do preserve their pristine antibacterial activity, both in HT and in the resulting PBS composites. In particular, under the experimental conditions tested, HT/ASA and HT/TYR present the best combination of both properties (chain extension effect and antibacterial), especially versus E. coli as high as 90 and 97% of inhibition, respectively, using 2.5 wt% hybrid filler only. These findings open future applications for PBS associated with the hybrid HT filler as multifunctional materials in active packaging applications.

A solution of N-vinyl imidazole (VIm), ethylene glycol dimethylacrylate (EGDMA), and phloretic acid (p-hydroxyphenylpropionic acid, HPPA) as functional monomer, crosslinker and template, respectively, were used to graft molecularly imprinted polymer (MIP) onto polyethylene/polypropylene (PE/PP) nonwoven fabric via gamma radiation at room temperature. Control grafted films were also synthesized using the same procedure in the absence of HPPA. Binding performance of the MIP grafts was investigated for different template molecule concentrations and contact time. An imprinting factor for the sample prepared at 5 kGy dose was determined as 2.41 for 50 ppm HPPA solution for 3-h incubation. MIP graft layers were investigated by positron annihilation lifetime spectroscopy (PALS) as well as SEM.

Phloretin hydrolase from Eubacterium ramulus (Phy) catalyzes the hydrolysis of the dihydrochalcone phloretin to phloroglucinol and phloretic acid, performing a formal retro- Friedel–Crafts acylation reaction on its substrate. Its closest sequence homolog, of 25 % amino acid sequence identity, is diacetyl phloroglucinol hydrolase (Phlg) from Pseudomonas fluorescens, which catalyses a similar, hydrolytic, de-acylation of its substrate. The structure of Phlg has been determined and a catalytic mechanism proposed (J Biol Chem 285:4603–4611, 2010). In order to compare the catalytic characteristics of Phy with Phlg, the gene encoding Phy was expressed and the enzyme purified and crystallised. An X-ray fluorescence scan identified zinc within the crystals. A homology model of Phy, based on the structure of Phlg (PDB code 3HWP), informed the construction of a point mutant library of the enzyme, targeting residues shared with Phlg that are thought to be involved in zinc binding and the recognition of acyl and phenol functionality on the aromatic ring of the substrates. Mutation of His123, His251, Glu154 and Glu255 (conserved zinc binding residues) resulted in variants that were either poorly expressed, or of much reduced activity; Mutation of Tyr115 and His203, thought to bind the phenol groups in the 1-and 3-positions of the phloroglucinol ring respectively, resulted in variants of 15-fold reduced activity and an inactive variant. These results are suggestive of conservation of some aspects of mechanism and substrate recognition between Phy and Phlg, and of the catalytic characteristics of Zn-dependent C–C hydrolases of this type in general.

Injectable hydrogels have been widely investigated in biomedical applications, and increasing demand has been proposed to achieve dynamic regulation of physiological properties of hydrogels. Herein, a new type of injectable and biomolecule-responsive hydrogel based on poly(l-glutamic acid) (PLG) grafted with disulfide bond-modified phloretic acid (denoted as PLG-g-CPA) was developed. The hydrogels formed in situ via enzymatic cross-linking under physiological conditions in the presence of horseradish peroxidase and hydrogen peroxide. The physiochemical properties of the hydrogels, including gelation time and the rheological property, were measured. Particularly, the triggered degradation of the hydrogel in response to a reductive biomolecule, glutathione (GSH), was investigated in detail. The mechanical strength and inner porous structure of the hydrogel were influenced by the addition of GSH. The polypeptide hydrogel was used as a three-dimensional (3D) platform for cell encapsulation, which could release the cells through triggered disruption of the hydrogel in response to the addition of GSH. The cells released from the hydrogel were found to maintain high viability. Moreover, after subcutaneous injection into rats, the PLG-g-CPA hydrogels with disulfide-containing cross-links exhibited a markedly faster degradation behavior in vivo compared to that of the PLG hydrogels without disulfide cross-links, implying an interesting accelerated degradation process of the disulfide-containing polypeptide hydrogels in the physiological environment in vivo. Overall, the injectable and biomolecule-responsive polypeptide hydrogels may serve as a potential platform for 3D cell culture and easy cell collection.

Lycopodium sporopollenin, a natural copolymer, shows exceptional stability under high hydrostatic pressures (10 GPa) as determined by in situ high pressure synchrotron source Fourier transform infrared spectroscopy. This stability is evaluated in terms of the component compounds of the sporopollenin: p-coumaric acid, phloretic acid, ferulic acid, and palmitic and sebacic acids, which represent the additional n-acid and n-diacid components. This high stability is attributed to interactions between these components, rather than the exceptional stability of any one molecular component. This study proposes a biomimetic solution for the creation of polymer materials that can withstand high pressures for a multitude of uses in aeronautics, vascular autografts, ballistics, and light-weight protective materials.

Phlorizin ( 1 ) was anaerobically incubated with human intestinal bacteria and five biotransformation products ( 2 – 6 ) were obtained. Their structures were elucidated as phloretin ( 2 ), phloroglucinol ( 3 ), phloretic acid ( 4 ), 2,3,4-trihydroxybenzenepropanoic acid ( 5 ), and phloretic acid methyl ester ( 6 ) on the basis of their spectroscopic data. Using high-performance liquid chromatography equipped with a diode array detector, chromatographic separation of 1 – 4 was performed on an analytical C 18 column. The time course of the biotransformation was studied to probe into the biotransformation mechanism of 1 by human intestinal flora. The abilities of isolated strains to transform 1 were also investigated in order to find an optimal transformation strain. In addition, the inhibitory activity of parent compound 1 and its three main biotransformation products 2 – 4 on mushroom tyrosinase was estimated. The result showed that 2 has better inhibitory effect on tyrosinase activity than 1 .

Summary The potential usage of nitric oxide (NO) as a powerful anti-browning agent in fresh-cut chestnut kernels was investigated. Chestnut kernels were dipped in 0, 1, 5 or 10 μm NO solutions for 10 min, respectively, and then stored at 20 °C. Changes of browning index and colour were evaluated, while content of total phenols, activities of polyphenol oxidase (PPO) and peroxidase (POD) and individual phenolic compounds were measured. The results showed that NO treatment delayed browning and lightness of chestnut kernels and 5 μm NO treatment had the best control effect compared with others. PPO and POD activities were inhibited and total phenolic content was increased in NO-treated fruit, and 5 μm NO significantly increased the content of catechin, chlorogenic acid, syringic acid, phloretic acid and ferulic acid but inhibited that of tannic acid. However, it had no significant effect on caffeic acid.

Phloretic acid (3-(4’-hydroxyphenyl)propanoic acid) is one of the most abundant colon metabolites of various classes of polyphenols (e.g., polymeric proanthocyanidins, tea catechins, and ellagitannins). Its concentration in fecal water may reach value of 210mol/L [1], which could be high enough to exert at least in situ antioxidant activity [2]. Thermodynamics of 2H+/2e free radical scavenging mechanisms of phloretic acid was studied by DFT method using Gaussian 09 package [3]. Geometry optimizations and frequency calculations were carried out using the M06-2X/6-311++G(d, p) level of theory, in conjunction with the SMD continuum solvation model. For the first time direct involvement of carboxylic group in free radical scavenging mechanisms was investigated considering double hydrogen atom transfer (HAT), double single electron transferproton transfer (SET-PT) and double sequential proton loss electron transfer (SPLET) processes producing dienone lactone [4]. Obtained results indicate that phloretic acid possesses potential for inactivating free radicals of different characteristics (HO•, HOO•, CH3O•, CH3OO•, CH2=CH–O–O•, PhO•, Cl3COO• etc.) by direct scavenging via double HAT and double SPLET mechanisms. In this way, because phloretic acid is produced in highM concentrations and it is usually better absorbed than its precursor molecules, it may contribute to health benefits associated with regular intake of polyphenol-rich diet. References: [1] B. Halliwell, J. Rafter, A. Jenner, Am. J. Clin. Nutr. 81 (2005) 268S−276S. [2] M. Galleano, S.V. Verstraeten, P.I. Oteiza, C.G. Fraga, Arch. Biochem. Biophys. 501 (2010) 23−30. [3] M.J. Frisch, G.W. Trucks, H.B. Schlegel et al., Gaussian 09, Wallingford, CT, 2009. [4] H. Iwasaki, L.A. Cohen, B. Witkop, J. Am. Chem. Soc. 85 (1963) 3701-3702.

Phloretic acid is one of the most abundant colon catabolites of various classes of polyphenols (e.g., polymeric proanthocyanidins, tea catechins, and ellagitannins). In this paper thermodynamics of 2H+/2e– radical scavenging mechanisms of phloretic acid was studied. For the first time the involvement of carboxyl group in double hydrogen atom transfer (dHAT), double electron transfer-proton transfer (dET-PT) and sequential double proton loss double electron transfer (SdPLdET) processes was investigated. Obtained results indicate that phloretic acid possesses potential for inactivating radicals of different characteristics (HO•, HOO•, CH3O•, CH3OO•, CH2=CH–O–O•, PhO•, Cl3COO• etc.) via dHAT and SdPLdET mechanisms. Because phloretic acid is usually better absorbed than its precursor molecules, it may contribute to health benefits associated with regular intake of polyphenol-rich diet by direct scavenging of radicals. This work is licensed under a Creative Commons Attribution 4.0 International License.

Reactions of 4-alkyl-2,6-di-tert-butylphenols containing OH, SH, COOH, and COOMe groups in their para substituents with hydrogen chloride and hydrohalic acids were studied. One-step transformations of 2,6-di-tert-butyl-4-(ω-hydroxyalkyl)phenols to the corresponding 4-(ω-halogenoalkyl)phenols, as well as of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and its esters to phloretic acid were proposed. 4-(3-Mercaptopropyl)phenol upon heating with conc. HBr undergoes condensation to 3-(4-hydroxyphenyl)propyl 4-(3-mercaptopropyl)phenyl sulfide as the main product.

Because olives represent an important component of the Mediterranean diet, it is necessary to establish unequivocal identification and quantitation of the major potential antioxidant phenolic compounds they contain. The major phenolic antioxidants in two types of brined olives were isolated and purified by semi-preparative high performance liquid chromatography. Structural analysis was conducted using UV spectrophotometry, mass spectrometry and nuclear magnetic resonance spectroscopy. In particular, completely assigned 1H and 13C NMR data are presented and errors in literature data are corrected. The data show that tyrosol, hydroxytyrosol, 3-(3, 4-dihydroxyphenyl) propanoic acid (dihydrocaffeic acid), dihydro-p-coumaric acid (phloretic acid), the phenylpropanoid glucosides acteoside (verbascoside) and isoacteoside, along with the flavonoids luteolin and apigenin are major components of the phenolic fraction of brined black olives. Brined green olives contain only hydroxytyrosol and traces of other minor phenolics. Brined olives contain even higher concentrations of phenolic antioxidants than olive oil and may, therefore, be more important modulators of cancer chemopreventive activity.

The present study investigated the antifungal activity of Lactobacillus amylovorus DSM19280 as a starter culture for gluten-free quinoa sourdough bread under pilot-plant conditions to extend the microbial shelf life. Challenge tests against environmental moulds were conducted and a negative control with non-antifungal strain, L. amylovorus DSM20531(T), as well as a chemically acidified and a non-acidified control were included. Organic acid production, antifungal metabolites, carbohydrates changes during fermentation and bread quality were compared to wheat counterparts. The application of quinoa sourdough fermented with the antifungal L. amylovorus DSM19280 extended the mould free shelf life by 4 days compared to the non-acidified control. No significant difference in lactic acid production was found between the lactobacilli strains. HPLC-UV/DAD was used to quantify antifungal compounds. The concentration of 4-hydroxyphenyllactic acid, phloretic acid, 3-phenyllactic acid and hydroferulic acid were significantly higher (P

Two new multifunctional monomers (1a, 2a) were prepared by acylation of silylated 4-aminobenzoic acid or 3,5-bisaminobenzoic acid with trisacetyl gallic acid chloride. All attempts to prepare soluble hyperbranched homopolyesters from the monomers 1a or 2a failed because of crosslinking. In contrast, copolycondensations of the “branching monomers” 1a or 2a with the trimethylsilyl esters of acetylated vanillic acid or phloretic acid yielded soluble randomly branched copoly(ester-amide)s at a maximum reaction temperature of 220°C or 230°C. As evidenced by 1H NMR spectroscopy, all these copoly(ester-amide)s possess acetamide endgroups in addition to the acetate endgroups due to ester-amide interchange reactions. All copoly(ester-amide)s are amorphous materials with glass-transition temperatures (Tg's) between 170 and 230°C. The Tg's increase with the molar fraction of amide groups.

In contrast to a-a/b-b type monomers, the a-b monomers(e.g.hydroxy- or amino carboxylic acids) possess a much greater synthetic potential. Using 3- or 4-hydroxybenzoic acid and 4-hydroxyphenylpropionic acid (phloretic acid) starshaped polyesters with controlled molecular weight were prepared. Analogously, starshaped liquid-crystalline copolyesters were synthesized, and the influence of star-centers on the stability of the nematic phase was studied. Three polycondensation methods were elaborated and compared for the synthesis of hyperbranched homo- and copolyesters. Both the degree of branching and the nature of the endgroups were varied and their influence on the solubility, crystallinity and melt rheology was investigated. Furthermore, A-B-A triblock co-polymers with hyperbranched A-blocks, and hyperbranched poly(ester-amide)s were synthesized and characterized.

The trimethylsilylester of β-(4-acetoxyphenyl) propionic acid (APPA), which is easier to isolate than the free acid, was used as monomer for all polycondensations. Copolycondensations with small amounts of 4-tert-butylbenzoic acid or 4-tert-butylphenol acetate yielded oligo- and polyesters with two different endgroups. All oligoesters show a reversible first order phase transition between 240 and 265°C yielding a solid mesophase upon heating. The formation of an isotropic melt occurs between 340 and 380°C depending on the degree of polymerization (DP). The glasstransition temperatures increased from 48–50°C to values around 63–65°C with increasing molecular weight. Copolycondensations with acetylated bisphenol-P yielded telechelic oligoesters with two identical endgroups. Four-armed star-shaped polyesters were prepared by copolycondensation of a tetraacetoxyspirobisindan. Since the bisphenol-P and the spirobisindane units are unfavourable for the crystallization, the crystallinity depends on the DP, and the solubility depends in turn on the crystallinity. Hyperbranched copolyesters were synthesized by copolycondensation of silylated APPA with silylated or free 3,5-bisacetoxybenzoic acid with variation of the molar ratio. The hyperbranched character of these copolyesters was demonstrated by their reluctance to crystallize and by 13C n.m.r. spectroscopic sequence analyses. The Tgs of these hyperbranched copolyesters follow almost exactly the Fox equation. G.p.c. measurements revealed number average molecular weights (Mn) up to 31 000 g mol−1 (for the 1 1 copolyester) and Mw/Mn ratios in the range of 3.5–6.5.

A new cyclobutane ring system related to plicatin B has been isolated from the methanol soluble fraction of Psoralea plicata seeds and named as -diplicatin B. In addition, the anti-repellent (-)-loliolide and phloretic acid ethyl ester [3-(4-hydroxyphenyl) propanoic acid ethyl ester) have been isolated from the same extract, their structures being determined on the basis of 1D ( 1 HNMR and 13 CNMR) and 2D (DQF-COSY, HMQC and HMBC) NMR and mass spectra. Stereoisomers of -diplactin B have been optimized by means of density functional theory using the hybrid functional B3LYP.

Phenylpropanoids, such as flavonoids and stilbenoids, are of great commercial interest, and their production in Saccharomyces cerevisiae is a very promising strategy. However, to achieve commercially viable production, each step of the process must be optimised. We looked at carbon loss, known to occur in the heterologous flavonoid pathway in yeast, and identified an endogenous enzyme, the enoyl reductase Tsc13, which turned out to be responsible for the accumulation of phloretic acid via reduction of p-coumaroyl-CoA. Tsc13 is an essential enzyme involved in fatty acid synthesis and cannot be deleted. Hence, two approaches were adopted in an attempt to reduce the side activity without disrupting the natural function: site saturation mutagenesis identified a number of amino acid changes which slightly increased flavonoid production but without reducing the formation of the side product. Conversely, the complementation of TSC13 by a plant gene homologue essentially eliminated the unwanted side reaction, while retaining the productivity of phenylpropanoids in a simulated fed batch fermentation., Replacement of essential yeast reductase with corresponding gene from apple allows more efficient production of flavonoids by eliminating formation of side products.

Polyphenols are ubiquitous in plant foods, and many have been associated with a variety of biological activities, including antimutagenic and anticarcinogenic properties. Some African foodstuffs have been analyzed for antimutagenic polyphenols by High-Performance Liquid Chromatography–Electrospray Ionization–Mass Spectrometry (HPLC-ESI-MS). The results showed that Dacryodes edulis fruit, Moringa oleifera and Syzygium aromaticum contained polyphenols like ellagic acid, gallate, methylgallate, catechol, kaempferol quercetin and their derivatives. Also Canarium schweinfurthii Engl oil contained phenolic compounds and lignans, namely; catechol, p-hydroxybenzaldehyde, dihydroxyphenylacetic acid, tyrosol, p-hydroxybenzoic acid, dihydroxybenzoic acid, vanillic acid, phloretic acid, pinoresinol, secoisolariciresinol. In addition, tomatoes (Lycopersicun esculentum Mill) contained the powerful antioxidant, lycopene; cabbage (Brassica oleracea) contained indole-3-carbinol; citrus fruits contained pectin; So...

Micropropagated shoots of wild cherry (Prunus avium L.) produced roots in auxin-free medium. Phloroglucinol (PG) increased the proportion of shoots that rooted, while phloretic acid reduced this response in medium with or without PG, and cancelled the promotive effect of PG. Concentration of PG also significantly affected rooting in media with and without auxin. The proportion of shoots rooting in media containing auxin, or auxin plus PG, increased with the number of successive subculture, but the proportion that rooted with PG alone was unaffected by the number of subcultures. Before the shoots had become responsive to auxin, 1 mM PG was more effective than auxin in inducing root formation.

Phytochemical investigation of the whole plant of Lepisorus contortus (Christ) Ching led to the isolation of five new phenylethanoid glycosides (1-5), each containing a caffeoyl group, a new flavonoid glycoside (10), and 14 known compounds (6-9 and 11-15, syringic acid, vanillic acid, phloretic acid, diplopterol, and β-sitosterol). This is the first report of phenylethanoid glycosides from the family Polypodiaceae. Compounds 1-15 were evaluated for their cancer chemopreventive potential based on their ability to inhibit tumor necrosis factor alpha (TNF-α)-induced NF-κB activity, nitric oxide (NO) production, and aromatase, quinone reductase 2 (QR-2), and COX-1/-2 activities. Quercetin-3-O-β-d-glucoside (15) demonstrated inhibition against QR2 with an IC(50) value of 3.84 μM, which confirmed kaempferol/quercetin glycosides as the active compounds to inhibit QR2. The compound also demonstrated NF-κB activity with an IC(50) value of 33.6 μM. In addition, compounds 1, 2, 4, and 6 showed aromatase activity with IC(50) values of 30.7, 32.3, 26.8, and 35.3 μM, respectively.

The metabolism of flavoneC-glucosides andp-coumaric acid from antioxidant of bamboo leaves (AOB) in rats is discussed systematically in the present study. Following single oral administration of AOB,p-coumaric acid was detected in plasma but not in gastrointestinal tract extracts and faeces, and the corresponding absorption pharmacokinetic curve at different time points showed a prolonged elimination phase withp-coumaric acid being detected in the kidneys and excreted as its original form (1·80 (sd0·24) % and 1·90 (sd0·26) % at 12 and 24 h, respectively). However, the four flavoneC-glucosides orientin, homoorientin, vitexin and isovitexin were poorly absorbed in the gastrointestinal tract. More than 50 % recovery of flavoneC-glucosides was determined at 12 h and faeces containing these four analytes (21·23 (sd1·92) %) were excreted at 24 h. These data suggested that the effective time these compounds were in the colon was long enough so that they could exert their antioxidant activity and scavenge free radicals. Besides the excretion of the original forms, moieties of the flavoneC-glucosides were hydrolysed by deglycosylation and the opening of the heterocyclic C ring. Some small molecules such as phloroglucinol (PG), hydrocaffeic acid (HCA) and phloretic acid (PA) were detected and identified as metabolites of the flavoneC-glucosides. In the present work, we compared the metabolic fate of flavoneC-glucosides to that of flavoneO-glucosides in rats, and evaluated the absorption, tissue distribution and excretion of flavoneC-glucosides in AOB on their metabolism for the first time.

Dihydro-p-coumaric (phloretic) and dihydroferulic acids have been identified in Pteridium aquilinum. Whereas the latter has been located in cyanogenic and acyanogenic plants, the first has only been detected in cyanogenic forms.

SummaryTwo phloridzin breakdown products, phloroglucinol and phloretic acid, more than doubled the proportion of M.7 apple rootstock shoots which rooted when cultured in vitro with auxins. Caffeic acid, catechol and pyrogallol did not significantly increase rooting.