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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.

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.

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.

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.