A novel array of interface-confined molecules: Assembling natural segments for delivery of multi-functionalities

Enrichment of mayonnaise with a high fat fish oil-in-water emulsion stabilized with modified DATEM C14 enhances oxidative stability

Enrichment of mayonnaise using delivery emulsions (DEs) containing 70% fish oil versus neat fish oil was investigated. DEs were produced with combined use of sodium caseinate, diacetyl tartaric acid esters of mono- and diglycerides (DATEM), and/or modified DATEMs with different length (C12 or C14) and covalently attached caffeic acid. Physical and oxidative stability of the mayonnaises were analyzed based on parameters including droplet size, viscosity, peroxide value, volatile compounds, and sensory properties. DEs addition to mayonnaise resulted in larger droplets and lower viscosity compared to neat fish oil. However, zeta potential was higher in mayonnaises with DEs containing DATEMs. Mayonnaise containing DATEM C14 had higher protein surface load leading to a thicker interfacial layer, lower formation of hexanal, (E)-2-hexenal, and (E)-2-heptenal as well as lower rancid odour intensity compared to mayonnaise containing DATEM and free caffeic acid, and thus benefitted from the location of the antioxidant at the interface.

Water-mediated catalyst-free synthesis of lysine-based ampholytic amphiphiles for multipurpose applications: Characterization and pH-responsive emulsifying properties

A novel series of lysine-based ampholytic amphiphiles, with alkylsuccinic anhydrides of varying chain lengths as hydrophobic acylating agents, were synthesized in medium to high yield (50.23-90.15%) based on a facile, catalyst-free method in water medium; and structurally confirmed by mass spectrometry (MS), Fourier transform infra-red (FTIR) spectroscopy, and ¹H/¹³C nuclear magnetic resonances (NMR) analysis. The resulting compounds were subjected to pH-dependent amphiphilic property, ferrous ion chelating, DPPH antioxidant capacity, and cytotoxicity analyses. Results showed that CMC values decrease, γ value increase, and emulsion stability increase with the increase of medium pH, suggesting that the surface activity of synthetic compounds at air/water and oil/water interface under neutral and alkaline conditions was remarkably higher than that under acidic condition. Lauryl O-acylated malic lysine (compound 4b) presented excellent foaming ability close to commercial detergent sodium dodecyl sulphate; dodecyl succinic lysine (compound 4a) afforded highly stable o/w nanoemulsion. Moreover, compound 4b displayed comparable ferrous ion chelating property to lysine and 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidative capacity similar to a commercial food ingredient, diacetyl tartaric acid esters of mono- and di-glycerides (DATEM), indicating its multi-faceted functionalities. A cytotoxicity study of compounds 3b &4b showed that they were non-toxic. Thus, these novel ampholytic amphiphiles may find multi-purpose applications in food, detergent, pharmaceutical, and cosmetic industry.

Grafting phenolics onto milk protein via conjugated polymerization for delivery of multiple functionalities: Synthesis and characterization

A synthetic scenario for functionalization of β-lactoglobulin (βLg) with polymeric units containing caffeic acid (βLg-polyCA) was developed; and all intermediates and final products were structurally confirmed using nuclear magnetic resonance spectroscopy, matrix assisted laser desorption ionization time-of-flight mass spectrometry, and physico-chemically characterized using differential scanning calorimetry and circular dichroism. The antioxidant properties and emulsion stability of βLg, βLg-CA conjugate and βLg-polyCA based systems containing high percentage of fish oil (50%) were evaluated; and βLg-polyCA presented the highest antioxidant and free radical-scavenging activity based on DPPH, ABTS and HS scavenging assays (92.4, 87.92 and 67.35% respectively). Thiobarbituric acid (TBARS) test demonstrated that compared to native βLg, βLg-polyCA afford up 4-5 fold of inhibition of oxidative rancidity and displayed drastic secondary structure changes. Compared to native βLg based emulsions, βLg-polyCA had larger oil droplet sizes, stronger negative zeta potentials (-69.9 mv), narrower size distributions (PDI: 0.22) and less creaming index.

Aspartic-Acid-Based Ampholytic Amphiphiles: Synthesis, Characterization, and pH-Dependent Properties at Air/Water and Oil/Water Interfaces

A facile and two-step strategy was employed to synthesize a series of novel aspartic-acid-based ampholytic amphiphiles from sustainable and commercially viable substances as starting materials. The molecular structures of the synthetic compounds were well-identified by mass spectrometry and ¹H/¹³C nuclear magnetic resonance analysis, and the physicochemical, pH-dependent foaming, and emulsifying properties were evaluated by the use of multiple techniques, such as Fourier transform infrared spectroscopy, differential scanning calorimetry, Langmuir-Blodgett study, and fluorescence microscopy imaging. As a result of the co-existence of amino and carboxyl groups in the synthetic compounds, the compounds presented varying charges (cationic, ampholytic, and anionic) depending upon the pH of the medium compared to the dissociation constants (p K_a). Compounds with cationic (pH 1.0) and anionic (pH 9.0) forms had significantly higher γ_0.1 and critical micelle concentration values than those with ampholytic forms (pH 7.0). sn-1-Lauroyl- sn-3-aspartic acid (compound 3) at neutral and alkaline conditions displayed comparable foaming properties, including foaming, calcium-tolerant, and temperature-resistant abilities, with commercial sulfonate sodium dodecyl sulfate (SDS), and thus might be a promising alternative to SDS, applied in personal care products and detergent formula. sn-1-Palmtoyl- sn-3-aspartic acid (compound 5a) with an ampholytic structure was proven as the most excellent stabilizer for the preparation of oil-in-water emulsions compared to palmityl aspartic acid (compound 5b), commercial food ingredient diacetyltartaric acid esters of mono- and diglycerides, and glyceride monopalmitate at aqueous phase pH 7.0. Thus, it has promising use as a pH-dependent emulsifying agent in various fields.

Caffeoyl maleic fatty alcohol monoesters: Synthesis, characterization and antioxidant assessment

HYPOTHESIS

Caffeoyl malate anhydride, as a good nucleophilic acceptor, can react with lipophilic fatty alcohols to yield interface-confined amphiphiles. The resulting novel molecules are hypothesized to deliver combined functionalities of parent natural building blocks, as emulsifier, stabilizer, ion chelator and free radical scavenger.

EXPERIMENTS

Ring-opening reactions of caffeoyl malate anhydride with fatty alcohols of different chain lengths generated a new group of antioxidant amphiphiles. Structural verification was by MS (mass spectrometry), ¹H/¹³C NMR (nuclear magnetic resonance) and FT-IR (Fourier transform infra-red) spectroscopy. Physicochemical characterization was done by use of DSC (differential scanning calorimetry), FT-IR, determinations of critical micelle concentrations (CMC) and calculations of HLB. Antioxidant activity was assessed by DPPH (2, 2-diphenyl-1-picrylhydrazyl) and hydroxyl radical scavenging activities. Dynamic light scattering (DLS) studies demonstrated surface-activity of G8-G18. Inhibition of iron- and thermally-accelerated lipid oxidation was monitored by thiobarbituric acid reactive substances (TBARS) assay.

FINDINGS

Derivatization of caffeoyl malate anhydride with fatty alcohols maintained free radical scavenging activity, and improved hydroxyl radical scavenging activity of caffeic acid. Lipid oxidation at 22 °C was significantly inhibited (up to 3.5 times) in emulsions stabilized by G8-G18 with or without chitosan compared to emulsions stabilized by commercial emulsifiers and stabilizers. Thermal oxidation (at 80 °C) was 10 times less in emulsions facilitated by G8-G18 in combination with chitosan compared to emulsions stabilized by commercial emulsifiers and stabilizers. This study has developed a simple and straightforward approach for developing value-added compounds from underexplored fatty alcohols.

Effects of Modified DATEMs with Different Alkyl Chain Lengths on Improving Oxidative and Physical Stability of 70% Fish Oil-in-Water Emulsions

The objective of this study was to produce oxidatively and physically stable 70% fish oil-in-water emulsions by combined use of sodium caseinate (CAS), commercial diacetyl tartaric acid esters of mono- and diglycerides (DATEM), and modified DATEM. First, the optimal formula was determined using DATEM and CAS. Subsequently, modified DATEMs (DATEM C12 and DATEM C14) were designed for investigating both the effects of different alkyl chain lengths and caffeic acid conjugation to the emulsifier on physical and oxidative stability of the emulsions. Emulsions produced with modified DATEMs showed better oxidative stability compared with emulsion using commercial DATEM plus an equivalent amount of free caffeic acid, confirming the advantage of having antioxidant covalently attached to the emulsifier. Results indicated that DATEM_C14 replaced more CAS compared with DATEM_C12 from the interface in 70% fish oil-in-water emulsion. Emulsions produced with DATEM_C14 had significantly decreased amounts of primary and secondary oxidation products compared with emulsions using DATEM_C12.

New phenophospholipids equipped with multi-functionalities: Regiospecific synthesis and characterization

HYPOTHESIS

In multi-phase systems, many complex reactions take place at the interface where a molecule equipped with manifold functionalities is demanded. By taking advantage of the surface-active property of phosphatidylcholine (PC) scaffold and antioxidant properties of phenolic acids, new multifunctional molecules are generated, which are expected to confer physical and oxidative stability to sensitive bioactive ingredients in delivery systems.

EXPERIMENTS

This work reports a successful synthesis of two new arrays of phenophospholipids sn-1-acyl(C12-C18)-sn-2-caffeoyl and sn-1-caffeoyl-sn-2-acyl phosphatidylcholines via mild scalable regiospecific pathways; as structurally verified by MS, ¹H/¹³C NMR analyses, and characterized by critical micelle concentrations (CMC), FTIR, and DSC analysis. Synthesized phenophospholipids are subjected to stabilizing o/w emulsion, and antioxidation tests as demonstrated by TBARS (Thiobarbituric Acid Reactive Substances) and DPPH (2,2-diphenyl-1-picrylhydrazyl) assays.

FINDINGS

This study has demonstrated that; (1) phenophospholipids with a broad spectrum of CMC are created, affording superior emulsion stability than soybean PC; (2) all phenophospholipids present improved oxidation inhibition and sn-2-caffeoyl phenophospholipids display superior performance to sn-1-caffeoyl phenophospholipids, soybean PC or admixture of caffeic acid and soybean PC; (3) incorporation of caffeoyl in PC scaffold does not sacrifice radical scavenging ability of caffeic acid, whilst the ion chelating capacity of sn-1-myristoyl(C14)-sn-2-caffeoyl PC enhance by 4.5 times compared to soy PC. Fluorescence Microscopy imaging verified the location of phenophospholipids in the interface as desired. Among synthetic phenophospholipids, sn-1-myristoyl(C14)-sn-2-caffeoyl PC commits the cut-off effect in most desired functionalities, which might be of great potential for multi-purpose applications.

A new group of synthetic phenolic-containing amphiphilic molecules for multipurpose applications: Physico-chemical characterization and cell-toxicity study

Nine synthetic amphiphilic phenolic lipids, varied in phenolic moiety (caffeoyl/dimethylcaffeoyl) and fatty acid chain lengths (8-18) were characterized by differential scanning calorimetry (DSC), temperature-ramp Fourier transform infra-red spectroscopy (FT-IR) and atomic force microscopy (AFM). FT-IR and DSC results revealed that the physical state and lateral packing of synthetic molecules were largely governed by fatty acyls. The critical micelle concentrations (CMC) of synthetic lipids was in the range of 0.1 mM to 2.5 mM, affording generation of stable oil-in-water emulsions; as evidenced by the creaming index (<5%) of emulsions stabilized by compounds C12‒C16, and C12a‒C16a after 7 days' storage. AFM analysis revealed that compound C14 formed stable double-layers films of 5.2 nm and 6.7 nm. Application studies showed that formulations stabilized by synthesized compounds containing 30% fish oil had superior physical and oxidative stability compared to formulations containing commercial emulsifiers or their mixtures with phenolic acids. Moreover, the synthetic compounds were non-toxic against in vitro transformed keratinocytes from histologically normal skin and Caco-2 cell lines. This study demonstrates the relevance of using a natural hydroxycarboxylic acid as a flexible linker between natural antioxidants, glycerol and fatty acids to generate multifunctional amphiphiles with potential applications in food, pharmaceutical and cosmetic industry.

Enzymatic alkylsuccinylation of tyrosol: Synthesis, characterization and property evaluation as a dual-functional antioxidant

This work reports a novel approach to generate a new group of tyrosol-based amphiphilic lipid alkylsuccinylated tyrosol by lipase-catalyzed succinylation of tyrosol with alkylsuccinic anhydrides of varying alkyl chain lengths, in high yields (80-95%). The structures of the compounds were confirmed by MS, FTIR &¹H NMR; and their properties were characterized by Temperature-Ramp FTIR, DSC & CMC measurements. The synthesized compounds integrate water-soluble phenylethanoid and hydrophobic alkyl into one molecule thus are endowed with dual functions: retaining the antioxidant property of tyrosol and entailing tyrosol with new surface-active property. The DPPH activity of tyrosol (13.77%) was significantly enhanced by 2-dodecen-1-ylsuccinylated tyrosol (16.01%). Compared to tyrosol-based emulsions (76.63%), the lipid oxidation is reduced to 21.57% and 42.32% in 2-octen-1-ylsuccinylated/2-dodecen-1-ylsuccinylated tyrosol emulsions, respectively. This work brings new members to the library of functional lipid excipients and open a novel and effective synthetic pathway for derivation of phenyl alcohols.