Esterification of black bean anthocyanins with unsaturated oleic acid, and application characteristics of the product.

Esterification of anthocyanins with saturated fatty acids have been widely investigated, while that with unsaturated fatty acids is little understood. In this study, crude extract (purity âˆ¼ 35 %) of cyanidin-3-O-glucoside (C3G) from black bean seed coat was utilized as reaction substrate, and enzymatically acylated with unsaturated fatty acid (oleic acid). Optimization of various reaction parameters finally resulted in the highest acylation rate of 54.3 %. HPLC-MS/MS and NMR analyses elucidated the structure of cyanidin-3-O-glucoside-oleic acid ester (C3G-OA) to be cyanidin-3-O-(6″-octadecene)-glucoside. Introduction of oleic acid into C3G improved the lipophilicity, antioxidant ability, and antibacterial activity. Further, the color and substance stability analyses showed that the susceptibility of C3G and C3G-OA to different thermal, peroxidative, and illuminant treatments were highly pH dependent, which suggested individual application guidelines. Moreover, C3G-OA showed lower toxicity to normal cell (QSG-7701) and better inhibitory effect on the proliferation of HepG2 cells than C3G, which indicated its potential anti-tumor bioactivity.

Biocatalytic Regioselective O-acylation of Sesquiterpene Lactones from Chicory: A Pathway to Novel Ester Derivatives.

We report the first biocatalytic modification of sesquiterpene lactones (STLs) found in the chicory plants, specifically lactucin (Lc), 11ß,13-dihydrolactucin (DHLc), lactucopicrin (Lp), and 11ß,13-dihydrolactucopicrin (DHLp). The selective O-acylation of their primary alcohol group was carried out by the lipase B from Candida antarctica (CAL-B) using various aliphatic vinyl esters as acyl donors. Perillyl alcohol, a simpler monoterpenoid, served as a model to set up the desired O-acetylation reaction by comparing the use of acetic acid and vinyl acetate as acyl donors. Similar conditions were then applied to DHLc, where five novel ester chains were selectively introduced onto the primary alcohol group, with conversions going from >99 % (acetate and propionate) to 69 % (octanoate). The synthesis of the corresponding O-acetyl esters of Lc, Lp, and DHLp was also successfully achieved with near-quantitative conversion. Molecular docking simulations were then performed to elucidate the preferred enzyme-substrate binding modes in the acylation reactions with STLs, as well as to understand their interactions with crucial amino acid residues at the active site. Our methodology enables the selective O-acylation of the primary alcohol group in four different STLs, offering possibilities for synthesizing novel derivatives with significant potential applications in pharmaceuticals or as biocontrol agents.

Metabolic transitions regulate global protein fatty acylation.

Intermediary metabolites and flux through various pathways have emerged as key determinants of post-translational modifications. Independently, dynamic fluctuations in their concentrations are known to drive cellular energetics in a bi-directional manner. Notably, intracellular fatty acid pools that drastically change during fed and fasted states act as precursors for both ATP production and fatty acylation of proteins. Protein fatty acylation is well regarded for its role in regulating structure and functions of diverse proteins; however, the effect of intracellular concentrations of fatty acids on protein modification is less understood. In this regard, we unequivocally demonstrate that metabolic contexts, viz. fed and fasted states, dictate the extent of global fatty acylation. Moreover, we show that presence or absence of glucose that influences cellular and mitochondrial uptake/utilization of fatty acids and affects palmitoylation and oleoylation, which is consistent with their intracellular abundance in fed and fasted states. Employing complementary approaches including click-chemistry, lipidomics, and imaging, we show the top-down control of cellular metabolic state. Importantly, our results establish the crucial role of mitochondria and retrograde signaling components like SIRT4, AMPK, and mTOR in orchestrating protein fatty acylation at a whole cell level. Specifically, pharmacogenetic perturbations that alter either mitochondrial functions and/or retrograde signaling affect protein fatty acylation. Besides illustrating the cross-talk between carbohydrate and lipid metabolism in mediating bulk post-translational modification, our findings also highlight the involvement of mitochondrial energetics.

Obtaining and characterizing polyphenol extracts based on anthocyanins from Melinis minutiflora inflorescences and Plinia cauliflora fruits and application in gelatins.

Anthocyanins are a class of compounds potentially used as food dyes. Thus, this study aimed to obtain and characterize natural extracts from Melinis minutiflora inflorescence (M), Plinia. cauliflora peel (JP) and P. cauliflora peel and seeds (JPS) and apply them as natural food dyes in gelatins. The extracts did not show statistically significant differences in pH values and water activity. The M and JPS extracts showed similar values of anthocyanins and total phenolic compounds and were higher than those from the JP extract. The M and JPS extracts showed a bathochromic effect, which was not observed for the JP extract. The bathochromic effect may indicate a possible complexation of anthocyanins. The color composition analysis revealed that the JP extract has a higher absorbance at a wavelength of 520 nm, indirectly suggesting the presence of more monomeric anthocyanins in its composition. The extract application test in gelatin did not change the texture properties of the gelatins. In addition, our findings revealed that the JPS extract had the best color stability after ten days of analysis, indicating that anthocyanin complexation with the phenolic compounds of P. cauliflora seeds contributed more effectively to anthocyanin stability in the model used.

Family characteristics, phylogenetic reconstruction, and potential applications of the plant BAHD acyltransferase family.

The BAHD acyltransferase family is a class of proteins in plants that can acylate a variety of primary and specialized secondary metabolites. The typically acylated products have greatly improved stability, lipid solubility, and bioavailability and thus show significant differences in their physicochemical properties and pharmacological activities. Here, we review the protein structure, catalytic mechanism, and phylogenetic reconstruction of plant BAHD acyltransferases to describe their family characteristics, acylation reactions, and the processes of potential functional differentiation. Moreover, the potential applications of the BAHD family in human activities are discussed from the perspectives of improving the quality of economic plants, enhancing the efficacy of medicinal plants, improving plant biomass for use in biofuel, and promoting stress resistance of land plants. This review provides a reference for the research and production of plant BAHD acyltransferases.

Metabolic, toxicological, chemical, and commercial perspectives on esterification of dietary polyphenols: a review.

Molecular modifications have been practiced for more than a century and nowadays they are widely applied in food, pharmaceutical, or other industries to manipulate the physicochemical, bioactivity, metabolic/catabolic, and pharmacokinetic properties. Among various structural modifications, the esterification/O-acylation has been well-established in altering lipophilicity and bioactivity of parent bioactive compounds, especially natural polyphenolics, while maintaining their high biocompatibility. Meanwhile, various classic chemical and enzymatic protocols and other recently emerged cell factory technology are being employed as viable esterification strategies. In this contribution, the main motivations of phenolic esterification, including the tendency to replace synthetic alkyl phenolics with safer alternatives in the food industry to improve the bioavailability of phenolics as dietary supplements/pharmaceuticals, are discussed. In addition, the toxicity, metabolism, and commercial application of synthetic and natural phenolics are briefly introduced. Under these contexts, the mechanisms and reaction features of several most prevalent chemical and enzymatic esterification pathways are demonstrated. In addition, insights into the studies of esterification modification of natural phenolic compounds and specific pros/cons of various reaction systems with regard to their practical application are provided.

Enzymatic Acylation of Flavonoids from Bamboo Leaves: Improved Lipophilicity and Antioxidant Activity for Oil-Based Foods.

The goal of this study was to expand the applications of bamboo leaf flavonoids (BLFs) by improving their lipophilicity through enzymatic acylation with vinyl cinnamate. Characterization of the acylated BLFs using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, high-resolution electrospray ionization mass spectrometry, electrospray ionization with tandem mass spectrometry, and 1H nuclear magnetic resonance spectroscopy indicated that acylation occurred at the C6-OH position of glucoside moieties. The highest degree of acylation (18.61%) was obtained by reacting BLFs with vinyl cinnamate (1:5, w/w) at 60 °C for 48 h. Acylation significantly improved the lipophilicity of BLFs and their capacity to inhibit lipid peroxidation, as evidenced by the reduced production of lipid hydroperoxides and malondialdehyde in rapeseed oil and rapeseed oil-in-water emulsions during storage at 37 °C for 15 days. The study findings provide important data that will enable the use of BLFs in lipid or lipophilic matrices, such as oil-based foods.

Quercetin Fatty Acid Monoesters (C2:0-C18:0): Enzymatic Preparation and Antioxidant Activity.

Quercetin monoesters were prepared via a one-step enzymatic transesterification. The main acylation products were eight quercetin ester derivatives, respectively, consisting of varying acyl groups ranging from 2 to 18 carbon atoms (acetate, butyrate, caproate, caprylate, caprate, laurate, myristate, and stearate). The purified quercetin esters were structurally characterized by LC-ESI-ToF and NMR HSQC. Meanwhile, several classical chemical (DPPH, ABTS, FRAP, and Fe2+ chelation assays), food (ß-carotene bleaching assay), and biological (LDL and DNA oxidation assays) models were constructed to evaluate and systematically compare their antioxidant efficacy. O-Acylation increased the lipophilicity of quercetin derivatives, and lipophilicity increased with the increasing chain length of the acyl group. The dual effect of the acyl chain length on biasing quercetin monoesters' antioxidant efficacies has been summarized and verified. Overall, the results imply that the acylated quercetin have great potential as functional/health-beneficial ingredients for use in lipid-based matrices of cosmetics, supplements, and nutraceuticals.

Assessing the diversity of anthocyanin composition in various tissues of purple corn (Zea mays L.).

Anthocyanins are natural pigments used in various foods, beverages, textiles, and nutraceuticals. Anthocyanins in the grain of purple corn (Zea mays L., Poaceae) have been a focus of many studies, but not much is known about anthocyanins in other maize tissues. In this study, purple corn variety Apache Red Cob was crossed to genetic stock 320 N, which is recessive for anthocyanin 3. The result was intense anthocyanin production in portions of the plant not normally pigmented. Anthocyanin extracts from anthers, cob glumes, husks, kernels, leaf sheaths, seedlings, silks, and tassels were assessed using UHPLC. A previously undescribed pigment produced in anthers was determined by NMR to be anthocyanidin 3-6″-phenylacetylglucoside. Multivariate analysis classified maize anthocyanins into 8 major compositional profiles. Results of this study show that maize produces anthocyanins abundantly in non-grain portions of the plant and that maize anthocyanin extracts have numerous applications due to the diversity in pigment profiles and hues.

Yeast Lipid Produced through Glycerol Conversions and Its Use for Enzymatic Synthesis of Amino Acid-Based Biosurfactants.

The aim of the present work was to obtain microbial lipids (single-cell oils and SCOs) from oleaginous yeast cultivated on biodiesel-derived glycerol and subsequently proceed to the enzymatic synthesis of high-value biosurfactant-type molecules in an aqueous medium, with SCOs implicated as acyl donors (ADs). Indeed, the initial screening of five non-conventional oleaginous yeasts revealed that the most important lipid producer was the microorganism Cryptococcus curvatus ATCC 20509. SCO production was optimised according to the nature of the nitrogen source and the initial concentration of glycerol (Glyc0) employed in the medium. Lipids up to 50% w/w in dry cell weight (DCW) (SCOmax = 6.1 g/L) occurred at Glyc0 ≈ 70 g/L (C/N ≈ 80 moles/moles). Thereafter, lipids were recovered and were subsequently used as ADs in the N-acylation reaction catalysed by aminoacylases produced from Streptomyces ambofaciens ATCC 23877 under aqueous conditions, while Candida antarctica lipase B (CALB) was used as a reference enzyme. Aminoacylases revealed excellent activity towards the synthesis of acyl-lysine only when free fatty acids (FAs) were used as the AD, and the rare regioselectivity in the α-amino group, which has a great impact on the preservation of the functional side chains of any amino acids or peptides. Aminoacylases presented higher α-oleoyl-lysine productivity and final titer (8.3 g/L) with hydrolysed SCO than with hydrolysed vegetable oil. The substrate specificity of both enzymes towards the three main FAs found in SCO was studied, and a new parameter was defined, viz., Specificity factor (Sf), which expresses the relative substrate specificity of an enzyme towards a FA present in a FA mixture. The Sf value of aminoacylases was the highest with palmitic acid in all cases tested, ranging from 2.0 to 3.0, while that of CALB was with linoleic acid (0.9-1.5). To the best of our knowledge, this is the first time that a microbial oil has been successfully used as AD for biosurfactant synthesis. This bio-refinery approach illustrates the concept of a state-of-the-art combination of enzyme and microbial technology to produce high-value biosurfactants through environmentally friendly and economically sound processes.

A comprehensive review on innovative and advanced stabilization approaches of anthocyanin by modifying structure and controlling environmental factors.

Anthocyanins are pigments abundant in fruits and vegetables, and commonly applied in foods due to attractive colour and health-promoting benefits. However, instability of anthocyanins leads to their easy degradation, reduced bioactivity, and colour fading in food processing, limiting their application and causing economic losses. Stability of anthocyanins depends on their own structures and environmental factors. For structural factors, modification including copigmentation, acylation and biosynthesis is a potential solution to increase anthocyanin stability due to forming stable structures. With regard to environmental factors, encapsulation such as microencapsulation, liposome and nanoparticles has been shown effectively to enhance the stability. We proposed the potential challenges and perspectives for the diversification of anthocyanin-rich products for food application, particularly, introduction of hazards, technical limitations, interaction with other ingredients in food system and exploration of pyranoanthocyanins. The integrated strategies are warranted for improving anthocyanin stabilization for promoting their further application in food industry.

The Cytoplasmic Tail of Influenza A Virus Hemagglutinin and Membrane Lipid Composition Change the Mode of M1 Protein Association with the Lipid Bilayer.

Influenza A virus envelope contains lipid molecules of the host cell and three integral viral proteins: major hemagglutinin, neuraminidase, and minor M2 protein. Membrane-associated M1 matrix protein is thought to interact with the lipid bilayer and cytoplasmic domains of integral viral proteins to form infectious virus progeny. We used small-angle X-ray scattering (SAXS) and complementary techniques to analyze the interactions of different components of the viral envelope with M1 matrix protein. Small unilamellar liposomes composed of various mixtures of synthetic or "native" lipids extracted from Influenza A/Puerto Rico/8/34 (H1N1) virions as well as proteoliposomes built from the viral lipids and anchored peptides of integral viral proteins (mainly, hemagglutinin) were incubated with isolated M1 and measured using SAXS. The results imply that M1 interaction with phosphatidylserine leads to condensation of the lipid in the protein-contacting monolayer, thus resulting in formation of lipid tubules. This effect vanishes in the presence of the liquid-ordered (raft-forming) constituents (sphingomyelin and cholesterol) regardless of their proportion in the lipid bilayer. We also detected a specific role of the hemagglutinin anchoring peptides in ordering of viral lipid membrane into the raft-like one. These peptides stimulate the oligomerization of M1 on the membrane to form a viral scaffold for subsequent budding of the virion from the plasma membrane of the infected cell.

Characterization of Glucuronosyl-diacyl/monoacylglycerols and Discovery of Their Acylated Derivatives in Tomato Lipid Extracts by Reversed-Phase Liquid Chromatography with Electrospray Ionization and Tandem Mass Spectrometry.

Glucuronic acid containing diacylglycerols (3-(O-α-d-glucuronopyranosyl)-1,2-diacyl-sn-glycerols, GlcA-DAG) are glycolipids of plant membranes especially formed under phosphate-depletion conditions. An analytical approach for the structural characterization of GlcA-DAG in red ripe tomato (Solanum lycopersicum L.) extracts, based on reversed-phase liquid chromatography (RPLC) coupled with electrospray ionization (ESI) and tandem mass spectrometry (MS/MS) using a linear ion trap, is described in this paper. At least 14 GlcA-DAG (R1/R2) species, including four regioisomers, containing three predominant fatty acyl chains C16:0, C18:2, and C18:3, were identified for the first time. Moreover, 29 GlcA-DAG acylated on the glucuronosyl ring (acyl-R3 GlcA-DAG) were discovered, alongside 15 acylated lyso-forms, i.e., acylated 3-(O-α-d-glucuronosyl)monoacylglycerols, abbreviated as acyl-R3 GlcA-MAG (R1/0) or (0/R2). Although many of these acylated lyso-forms were isomeric with GlcA-DAG (i.e., acyl chains with equivalent sum composition), they were successfully separated by reversed-phase liquid chromatography (RPLC) using a solid-core C18 column packed with 2.6 µm particle size. Tandem MS (and eventually MS3) data obtained from sodium adducts ([M + Na]+) and deprotonated molecules ([M - H]-) were fundamental to detect diagnostic product ions related to the glucuronosyl ring and then determine the identity of all investigated glycolipids, especially to recognize the acyl chain linked to the ring. A classification of GlcA-MAG, GlcA-DAG, and acylated GlcA-DAG and GlcA-MAG was generated by an in house-built database. The discovery of acylated derivatives emphasized the already surprising heterogeneity of glucuronic acid-containing mono- and diacylglycerols in tomato plants, stimulating interesting questions on the role played by these glycolipids.

Recent Research Progress in Taxol Biosynthetic Pathway and Acylation Reactions Mediated by Taxus Acyltransferases.

Taxol is one of the most effective anticancer drugs in the world that is widely used in the treatments of breast, lung and ovarian cancer. The elucidation of the taxol biosynthetic pathway is the key to solve the problem of taxol supply. So far, the taxol biosynthetic pathway has been reported to require an estimated 20 steps of enzymatic reactions, and sixteen enzymes involved in the taxol pathway have been well characterized, including a novel taxane-10ß-hydroxylase (T10ßOH) and a newly putative ß-phenylalanyl-CoA ligase (PCL). Moreover, the source and formation of the taxane core and the details of the downstream synthetic pathway have been basically depicted, while the modification of the core taxane skeleton has not been fully reported, mainly concerning the developments from diol intermediates to 2-debenzoyltaxane. The acylation reaction mediated by specialized Taxus BAHD family acyltransferases (ACTs) is recognized as one of the most important steps in the modification of core taxane skeleton that contribute to the increase of taxol yield. Recently, the influence of acylation on the functional and structural diversity of taxanes has also been continuously revealed. This review summarizes the latest research advances of the taxol biosynthetic pathway and systematically discusses the acylation reactions supported by Taxus ACTs. The underlying mechanism could improve the understanding of taxol biosynthesis, and provide a theoretical basis for the mass production of taxol.

Acylated Anthocyanins from Red Cabbage and Purple Sweet Potato Can Bind Metal Ions and Produce Stable Blue Colors.

Red cabbage (RC) and purple sweet potato (PSP) are naturally rich in acylated cyanidin glycosides that can bind metal ions and develop intramolecular π-stacking interactions between the cyanidin chromophore and the phenolic acyl residues. In this work, a large set of RC and PSP anthocyanins was investigated for its coloring properties in the presence of iron and aluminum ions. Although relatively modest, the structural differences between RC and PSP anthocyanins, i.e., the acylation site at the external glucose of the sophorosyl moiety (C2-OH for RC vs. C6-OH for PSP) and the presence of coordinating acyl groups (caffeoyl) in PSP anthocyanins only, made a large difference in the color expressed by their metal complexes. For instance, the Al3+-induced bathochromic shifts for RC anthocyanins reached ca. 50 nm at pH 6 and pH 7, vs. at best ca. 20 nm for PSP anthocyanins. With Fe2+ (quickly oxidized to Fe3+ in the complexes), the bathochromic shifts for RC anthocyanins were higher, i.e., up to ca. 90 nm at pH 7 and 110 nm at pH 5.7. A kinetic analysis at different metal/ligand molar ratios combined with an investigation by high-resolution mass spectrometry suggested the formation of metal-anthocyanin complexes of 1:1, 1:2, and 1:3 stoichiometries. Contrary to predictions based on steric hindrance, acylation by noncoordinating acyl residues favored metal binding and resulted in complexes having much higher molar absorption coefficients. Moreover, the competition between metal binding and water addition to the free ligands (leading to colorless forms) was less severe, although very dependent on the acylation site(s). Overall, anthocyanins from purple sweet potato, and even more from red cabbage, have a strong potential for development as food colorants expressing red to blue hues depending on pH and metal ion.

Ascorbic acid-induced degradation of liposome-encapsulated acylated and non-acylated anthocyanins of black carrot extract.

BACKGROUND: In the presence of ascorbic acid, the degradation of acylated (sinapic, ferulic and p-coumaric acid derivatives of cyanidin-3-xylosylglucosylgalactoside) and non-acylated anthocyanins of black carrot extract (BCE) encapsulated in liposomes was studied. BCEs (0.2% and 0.4% w/w) were encapsulated in liposomes using different lecithin concentrations (1%, 2% and 4% w/w). RESULTS: The liposomes were prepared with particle diameters of less than 50 nm and zeta potentials of about -21.3 mV for extract-containing liposomes and -27.7 mV for control liposomes. The encapsulation efficiency determined using high-performance liquid chromatography (HPLC) showed that increasing lecithin levels increased the efficiency to 59% at the same extract concentration. The concentrations of total anthocyanins and individual anthocyanins were determined for ascorbic acid (0.1% w/w)-degraded extract and liposomes (containing 0.2% w/w extract). Anthocyanin quantification of both liposomal and extract samples was performed by HPLC using cyanidin-3-O-glucoside chloride as standard. Five anthocyanins in the extract and encapsulated liposomes were quantified during 24 h (0-24 h): cyanidin-3-xylosylglucosylgalactoside 1.0-0.51 and 0.82-0.58 mg g-1 , cyanidin-3-xylosylgalactoside 2.5-1.1 and 2.2-1.7 mg g-1 , cyanidin-3-xylosyl(sinapoylglucosyl)galactoside 0.51-0.14 and 0.35-0.28 mg g-1 , cyanidin-3-xylosyl(feruloylglucosyl)galactoside 1.37-0.41 and 1.06-0.98 mg g-1 , and cyanidin-3-xylosyl(coumaroylglucosyl)galactoside 0.28-0.08 mg g-1 for extract and 0.27-0.26 mg g-1 for liposomes, respectively. CONCLUSIONS: This study demonstrates the potential beneficial effect of liposomal encapsulation on individual, particularly acylated, anthocyanins after addition of ascorbic acid during a storage time of 24 h.

Different Reactivity of Raw Starch from Diverse Potato Genotypes.

Potato starch is one of the most important renewable sources for industrial manufacturing of organic compounds. Currently, it is produced from mixed potato varieties that often are harvested from different fields. Meanwhile, tuber starches of various potato breeds differ in their crystallinity, granule morphology, and other physical and chemical parameters. We studied the reactions of raw potato starches of different origins to chemical and biochemical reactions typically used for industrial starch modification. The results clearly demonstrate that there is a significant difference in the reactivity of the starches of different potato genotypes. While the main products of the transformations are the same, their preparative yields differ significantly. Thus, tuber starch of certain potato varieties may be more suitable for specific industrial purposes. Starch reactivity may potentially be a phenotypical trait for potato breeding to obtain potato starches for various industrial applications.

Lipase-catalysed synthesis of mono- and di-acyl esters of glyceryl caffeate in propylene carbonate and their antioxidant properties in tuna oil.

Development of new non-toxic antioxidants with diverse hydrophobic properties is important due to growing concerns about the toxicity of artificial oil-soluble antioxidants, the comparatively low effectiveness of natural options, and the complex role hydrophobicity plays in antioxidant effectiveness. Using caffeic acid, a naturally occurring phenolic acid with potent antioxidant activity, a range of glyceryl caffeate esters (decanoate and palmitate) were prepared using lipase-catalysed esterification reactions. Glyceryl-1-caffeate (GC) was prepared from ethyl caffeate and glycerol (acting as both the solvent and the substrate), catalysed by immobilised Candida Antarctica lipase B (Novozym-435) at 80 °C under vacuum. Esterification of GC with decanoic acid using immobilised Thermomyces lanuginosus lipase (TLIM) or Novozym-435 was found to be selective towards mono-acylated or di-acylated products, respectively. The reaction was performed in an unconventional solvent, propylene carbonate (PC), which has many of the attributes of a green solvent. Product conversions in PC were comparable to the best performing conventional solvents. In contrast to conventional volatile solvents, the low volatility of PC allowed the reaction to be performed under vacuum, without the need for molecular sieves for removal of water produced during the reaction. Diisopropyl ether was effective at extracting the more lipophilic products from PC. Both the lipase (Novozym-435) and PC were reused four times with only a small loss in conversion efficiency. Glyceryl caffeate esters performed much better than α-tocopherol at protecting bulk tuna oil from oxidation (analysed using Rancimat). A comparison of glyceryl caffeate esters (decanoate/palmitate and mono-/di-acylated) showed that their antioxidant effectiveness in bulk tuna oil was not affected by chain-length, but compounds containing only one fatty ester were slightly more effective than those containing two fatty esters.

Preparation of acylated pectin with gallic acid through enzymatic method and their emulsifying properties, antioxidation activities and antibacterial activities.

In this study, native pectin (Na-Pe) was acylated with gallic acid through enzymatic method. UV-Vis, Fourier transform infrared spectroscopy and proton NMR analyses demonstrated that the phenolic hydroxyl group on gallic acid attacked the carbomethoxy of Na-Pe and replaced the methoxy group to form a new ester group under catalysis. The galloyl content of acylated pectin prepared via 24-h reaction (Ac1-Pe) was 16.8%, while that prepared via 48-h reaction (Ac2-Pe) reached 20.7%. The emulsifying properties, antioxidation activities and antibacterial activities of acylated pectin was significantly improved compared with those of Na-Pe. The emulsion activity and emulsion stability of the pectin emulsion improved from 1.08% and 56.13% (Na-Pe) to 1.57% and 88.27% (Ac1-Pe) and 1.71% and 93.3% (Ac2-Pe), respectively. The DPPH clearance of the pectin improved from 2.68% (Na-Pe) to 68.92% (Ac1-Pe) and 76.98% (Ac2-Pe) and the inhibition ratio in the ß-carotene bleaching assay of the pectin increased from 3.15% (Na-Pe) to 73.02% (Ac1-Pe) and 78.96% (Ac2-Pe). The inhibition rate of the pectin against Escherichia coli and Staphylococcus aureus also improved from 2.93% and 8.92% (Na-Pe) to 26.95% and 42.18% (Ac1-Pe) and 31.56% and 47.87% (Ac2-Pe), respectively.

Preparation of Lipid-Soluble Bilberry Anthocyanins through Acylation with Cinnamic Acids and their Antioxidation Activities.

To enable the use of anthocyanins in food with high oil content, bilberry anthocyanins were acylated with cinnamic acids to address their poor lipid solubility. Structural analyses based on Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and 1H nuclear magnetic resonance analyses indicated that cinnamic acids were efficiently grafted onto 6-OH of glucoside and galactoside and 5-OH of arabinose through an esterification reaction. The higher the dose of the acylating agent, the higher the acylation degree (AD) and the lower the total anthocyanidin content (TAC) of bilberry anthocyanins. An-Ci4 presented the highest AD value (6.61%), and An-Ci3 exhibited the lowest TAC value (50.16 mg/g). After acylating with lipophilic cinnamic acids, the lipid solubility of acylated bilberry anthocyanins significantly improved. The color of the native bilberry anthocyanin solution dissolved in ethyl acetate and dioxane was transparent. By contrast, the acylated anthocyanin solution dissolved in these solvents was unmistakably red. In terms of the antioxidant activity, acylated bilberry anthocyanins demonstrated inferior performance in 2,2-diphenyl-1-picrylhydrazyl (DPPH) clearance but a better inhibition ratio in ß-carotene bleaching assay compared with native bilberry anthocyanins. As AD value increased, the DPPH clearance of acylated anthocyanins decreased and their inhibition ratio increased in ß-carotene bleaching assay.