Omega-3 polyunsaturated lipophenols, how and why?

Controlled dual release of phenol compounds from phospholipid complexes of short-chain lipophenols

Ethanol evaporation method was applied to synthesize phospholipid complexes from phosphatidylcholine (PC) and short-chain alkyl gallates (A-GAs, a typical representative of lipophenols) including butyl-, propyl- and ethyl gallates. 1H NMR, UV and FTIR showed that A-GAs were interacted with PC through weak physical interaction. Through the analysis of concentrations of A-GAs and gallic acid (GA) by an everted rat gut sac model coupled with HPLC-UV detection, phospholipid complexes were found to gradually release A-GAs. These liberated A-GAs were further hydrolyzed by intestinal lipases to release GA. Both of GA and A-GAs could cross intestinal membrane. Especially, the transmembrane A-GAs could also be hydrolyzed to produce GA. Undoubtedly, the dual release of phenol compounds from phospholipid complexes of short-chain lipophenols will be effective to extend the in vivo residence period of phenol compounds. More importantly, such behavior is easily adjusted by changing the acyl chain lengths of lipophenols in phospholipid complexes.

Overview of alkyl quercetin lipophenol synthesis and its protective effect against carbonyl stress involved in neurodegeneration

Oxidative stress and carbonyl stress resulting from the toxicity of small aldehydes are part of the detrimental mechanisms leading to neuronal cell loss involved in the progression of neurodegenerative diseases such as Alzheimer's disease. Polyunsaturated alkylated lipophenols represent a new class of hybrid molecules that combine the health benefits of anti-inflammatory omega-3 fatty acids with the anti-carbonyl and oxidative stress (anti-COS) properties of (poly)phenols in a single pharmacological entity. To investigate the therapeutic potential of quercetin-3-docosahexaenoic acid-7-isopropyl lipophenol in neurodegenerative diseases, three synthetic pathways using chemical or chemo-enzymatic strategies were developed to access milligram or gram scale quantities of this alkyl lipophenol. The protective effect of quercetin-3-DHA-7-iPr against cytotoxic concentrations of acrolein (a carbonyl stressor) was assessed in human SHSY-5Y neuroblastoma cells to underscore its ability to alleviate harmful mechanisms associated with carbonyl stress in the context of neurodegenerative diseases.

Lipid oxidation in emulsions: New insights from the past two decades

Lipid oxidation constitutes the main source of degradation of lipid-rich foods, including food emulsions. The complexity of the reactions at play combined with the increased demand from consumers for less processed and more natural foods result in additional challenges in controlling this phenomenon. This review provides an overview of the insights acquired over the past two decades on the understanding of lipid oxidation in oil-in-water (O/W) emulsions. After introducing the general structure of O/W emulsions and the classical mechanisms of lipid oxidation, the contribution of less studied oxidation products and the spatiotemporal resolution of these reactions will be discussed. We then highlight the impact of emulsion formulation on the mechanisms, taking into consideration the new trends in terms of emulsifiers as well as their own sensitivity to oxidation. Finally, novel antioxidant strategies that have emerged to meet the recent consumer's demand will be detailed. In an era defined by the pursuit of healthier, more natural, and sustainable food choices, a comprehensive understanding of lipid oxidation in emulsions is not only an academic quest, but also a crucial step towards meeting the evolving expectations of consumers and ensuring the quality and stability of lipid-rich food products.

The potential of hydroxytyrosol fatty acid esters to enhance oral bioavailabilities of hydroxytyrosol and fatty acids: Continuous and slow-release ability in small intestine and blood

HPLC-UV analysis in rat everted gut sac and in vitro simulated digestion models indicated that hydroxytyrosol fatty acid esters (HTy-Es) could be hydrolyzed by pancreatic lipase to slow-release of free fatty acids (FAs) and HTy. Meanwhile, the HTy-Es, the liberated FAs and the HTy could cross the membrane and were transported into blood circulation. HTy-Es were further hydrolyzed by carboxylesterase in in vitro rat plasma hydrolysis model, which also showed slow-release of FAs (C1-C4) and HTy. Especially, the rates of hydrolysis and transport initially increased and then decreased with the increasing alkyl chain length. Besides, the above rates of the HTy-Es with a straight chain were greater than those of its isomer with a branched chain. Therefore, the above-mentioned continuous and slow-release of FAs and HTy in small intestine and blood clearly demonstrated that HTy-Es would be an effective approach to enhance oral bioavailabilities of free fatty acids and hydroxytyrosol.

Studies on the Anticancer and Antioxidant Activities of Resveratrol and Long-Chain Fatty Acid Esters

Resveratrol (RES) is gaining recognition as a natural bioactive compound. To expand the possible applications of RES with its enhanced bioactivity as well as to increase the health benefits of long-chain fatty acids, a lipophilization process of RES was performed using three fatty acids: palmitic acid (PA), oleic acid (OA), and conjugated linoleic acid (CLA). The obtained mono-, di-, and tri-esters of RES were evaluated for their anticancer and antioxidant properties against lung carcinoma (A549), colorectal adenocarcinoma (HT29), and pancreatic ductal adenocarcinoma (BxPC3) cell lines. Human fibroblast (BJ) cells were used as a control. Several parameters were investigated: cell viability and apoptosis, including the expression of major pro- and anti-apoptotic markers, as well as the expression of superoxide dismutase, a key enzyme of the body's antioxidant barrier. Three of the obtained esters: mono-RES-OA, mono-RES-CLA, and tri-RES-PA, which significantly reduced the tumor cell viability up to 23%, at concentrations 25, 10, 50 μg/mL, respectively, turned out to be particularly interesting. The above-mentioned resveratrol derivatives similarly increased the tumor cells' apoptosis by modifying their caspase activity of pro-apoptotic pathways (p21, p53, and Bax). Moreover, among the mentioned esters, mono-RES-OA induced apoptosis of the analyzed cell lines most strongly, reducing the number of viable cells up to 48% for HT29 cells versus 36% for pure RES. Furthermore, the selected esters exhibited antioxidant properties towards the normal BJ cell line by regulating the expression of major pro-antioxidant genes (superoxide dismutases-SOD1 and SOD2) without the effect on their expression in the tumor, and therefore reducing the defense of cancer cells against increased oxidative stress induced by high ROS accumulation. The obtained results indicate that the esters of RES and long-chain fatty acids allow enhancement of their biological activity. The RES derivatives have the potential for being applied in cancer prevention and treatment, as well as for oxidative stress suppression.

Targeting Interfacial Location of Phenolic Antioxidants in Emulsions: Strategies and Benefits

It is important to have larger proportions of health-beneficial polyunsaturated lipids in foods, but these nutrients are particularly sensitive to oxidation, and dedicated strategies must be developed to prevent this deleterious reaction. In food oil-in-water emulsions, the oil-water interface is a crucial area when it comes to the initiation of lipid oxidation. Unfortunately, most available natural antioxidants, such as phenolic antioxidants, do not spontaneously position at this specific locus. Achieving such a strategic positioning has therefore been an active research area, and various routes have been proposed: lipophilizing phenolic acids to confer them with an amphiphilic character; functionalizing biopolymer emulsifiers through covalent or noncovalent interactions with phenolics; or loading Pickering particles with natural phenolic compounds to yield interfacial antioxidant reservoirs. We herein review the principles and efficiency of these approaches to counteract lipid oxidation in emulsions as well as their advantages and limitations.

Gastrointestinal Digestion and Microbial Hydrolysis of Alkyl Gallates: Potential Sustained Release of Gallic Acid

Phenolipids such as alkyl gallates (A-GAs) have been approved by the food industry as non-toxic antioxidant additives, which are also regarded as an emerging source of functional food ingredients. However, comprehensive understanding of their digestive absorption is needed. Thus, the models of live mice and anaerobic fermentation were used to clarify the distribution and microbial hydrolysis characteristics of A-GAs in the gastrointestinal tract. HPLC-UV results demonstrated that A-GAs could be hydrolyzed by intestinal lipases and gut microorganisms including Lactobacillus to produce free gallic acid (GA). Through regulating the chain length of the lipid part in A-GAs, the sustained and controllable release of the GA can be easily achieved. Furthermore, A-GAs were also able to reach the colon and the cecum, which would lead to potential gastrointestinal protective effects. Therefore, A-GAs may be applied as possible ingredient for functional foods.

Enzymatic lipophilization of bioactive compounds with high antioxidant activity: a review

Food products contain bioactive compounds such as phenolic and polyphenolic compounds and vitamins, resulting in a myriad of biological characteristics such as antimicrobial, anticarcinogenic, and antioxidant activities. However, their application is often restricted because of their relatively low solubility and stability in emulsions and oil-based products. Therefore, chemical, enzymatic, or chemoenzymatic lipophilization of these compounds can be achieved by grafting a non-polar moiety onto their polar structures. Among different methods, enzymatic modification is considered environmentally friendly and may require only minor downstream processing and purification steps. In recent years, different systems have been suggested to design the synthetic reaction of these novel products. This review presents the new trends in this area by summarizing the essential enzymatic modifications in the last decade that led to the synthesis of bioactive compounds with attractive antioxidative properties for the food industry by emphasizing on optimization of the reaction conditions to maximize the production yields. Lastly, recent developments regarding characterization, potential applications, emerging research areas, and needs are highlighted.

Modification of flavonoids: methods and influences on biological activities

Flavonoids are important active ingredients in plant-based food, which have many beneficial effects on health. But the low solubility, poor oral bioavailability, and inferior stability of many flavonoids may limit their applications in the food, cosmetics, and pharmaceutical industries. Structural modification can overcome these shortcomings to improve and extend the application of flavonoids. The study of how to modify flavonoids and the influence of various modifications on biological activity have drawn great interest in the current literature. In this review, the working principles and operating conditions of modification methods were summarized along with their potential and limitations in terms of operational safety, cost, and productivity. The influence of various modifications on biological activities and the structure-activity relationships of flavonoids derivatives were discussed and highlighted, which may give guidance for the synthesis of highly effective active agents. In addition, the safety of flavonoids derivatives is reviewed, and future research directions of flavonoid modification research are discussed.

Gastrointestinal Distribution of Tyrosol Acyl Esters in Orally Infected Mice and Their Hydrolysis by Lactobacillus Species Isolated from the Feces of Mice

Phenolipids, which have been widely used as food antioxidants, are also a potential functional ingredient. However, their characteristics of gastrointestinal distribution and microbial hydrolysis remain unexplored. In this study, an in vivo mouse model and an in vitro anaerobic fermentation model were used to evaluate the above characteristics of tyrosol acyl esters (TYr-Es) with fatty acids (FAs) of C12:0, C18:0, and C18:2. HPLC-UV measurements indicated that oral TYr-Es were remarkably stable in the stomach environment of mice. However, TYr-Es were hydrolyzed to free TYr by lipase in the small intestine, which showed a sustained-release behavior. Specially, TYr was rapidly and almost completely absorbed in the small intestine. By contrast, detectable amounts of TYr-Es were found in the cecum and colon and could be further hydrolyzed to free TYr and FAs by Lactobacillus. These TYr and FAs can participate in regulating the composition of the intestinal microorganisms, which may lead to some health benefits.

Fatty Acid Hydroxytyrosyl Esters of Olive Oils Are Bioaccessible According to Simulated In Vitro Gastrointestinal Digestion: Unraveling the Role of Digestive Enzymes on Their Stability

Recently, new bioactive compounds were identified in olive oil, lipophenols, which are composed of a fatty acid (FA) and a phenolic core, such as HT (HT-FA). However, their bioaccessibility remains unknown. Thus, the present study uncovers the impact of the separate phases of gastrointestinal digestion on the release and stability of HT-FAs from oily matrices under in vitro simulated conditions. Accordingly, it was found that the bioaccessibility of HT derivatives is largely dependent on the type of FA that esterifies HT, as well as the food matrix. Also, the generation of HT-FAs during intestinal digestion was observed, with pancreatin being the enzyme responsible, to a higher extent, for the de novo formation of lipophenolic derivatives. These findings prompt us to identify new applications to oily matrices and their byproducts as potential functional ingredients for the promotion of health, where the possible formation of new lipophenols during digestion should be taken into consideration.

The effects of the esterified Quercetin with omega3 and omega6 fatty acids on viability, nanomechanical properties, and BAX/BCL-2 gene expression in MCF-7 cells

Quercetin is one of the major flavonoids and it appears to have cytotoxic effects on various cancer cells through regulating the apoptosis pathway genes such as BAX and BCL2. Combination of Quercetin (Q) with other compounds can increase its effectiveness. In the present study, the effects of the Quercetin and its esterified derivatives on viability, nanomechanical properties of cells, and BAX/BCL-2 gene expression were investigated. Using the MTT and flow cytometry assays, the cytotoxic potential, apoptosis, and necrosis were investigated. The AFM assay was performed to find the nanomechanical properties of cells as the elastic modulus value and cellular adhesion forces. The BAX/BCL2 gene expression was investigated through the Real-Time PCR. The results showed that the esterification of Quercetin with linoleic acid (Q-LA) and α-linolenic acid (Q-ALA) increased the cytotoxic potential of Q. The elastic modulus value and cellular adhesion forces were increased using the esterified derivatives and the highest ratio of BAX/BCL2 gene expression was observed in Q-LA. Esterified Quercetin derivatives have a higher cytotoxic effect than the un-esterified form in a dose-dependent manner. Esterified derivatives caused the nanomechanical changes and pores formation on the cytoplasmic membrane. One of the internal apoptosis pathway regulation mechanisms of these compounds is increasing the BAX/BCL2 gene expression ratio.

Bioactive Compounds in Edible Oils and Their Role in Oxidative Stress and Inflammation

Diet and inflammatory response are recognized as strictly related, and interest in exploring the potential of edible fats and oils for health and chronic diseases is emerging worldwide. Polyunsaturated fatty acids (PUFAs) present in fish oil (FO), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may be partly converted into oxygenated bioactive lipids with anti-inflammatory and/or pro-resolving activities. Moreover, the co-presence of phenolic compounds and vitamins in edible oils may prevent the development of chronic diseases by their anti-inflammatory, antioxidant, neuroprotective, and immunomodulatory activities. Finally, a high content in mono-unsaturated fatty acids may improve the serum lipid profile and decrease the alterations caused by the oxidized low-density lipoproteins and free radicals. The present review aims to highlight the role of lipids and other bioactive compounds contained in edible oils on oxidative stress and inflammation, focusing on critical and controversial issues that recently emerged, and pointing to the opposing role often played by edible oils components and their oxidized metabolites.

Polyphenols and Fish Oils for Improving Metabolic Health: A Revision of the Recent Evidence for Their Combined Nutraceutical Effects

Polyphenols and omega-3 polyunsaturated fatty acids from fish oils, i.e., eicosapentaenoic and docosahexaenoic acids, are well-recognized nutraceuticals, and their single antioxidant and anti-inflammatory properties have been demonstrated in several studies found in the literature. It has been reported that the combination of these nutraceuticals can lead to three-fold increases in glutathione peroxidase activity, two-fold increases in plasma antioxidant capacity, decreases of 50-100% in lipid peroxidation, protein carbonylation, and urinary 8-isoprotanes, as well as 50-200% attenuation of common inflammation biomarkers, among other effects, as compared to their individual capacities. Therefore, the adequate combination of those bioactive food compounds and their single properties should offer a powerful tool for the design of successfully nutritional interventions for the prevention and palliation of a plethora of human metabolic diseases, frequently diet-induced, whose etiology and progression are characterized by redox homeostasis disturbances and a low-grade of chronic inflammation. However, the certain mechanisms behind their biological activities, in vivo interaction (both between them and other food compounds), and their optimal doses and consumption are not well-known yet. Therefore, we review here the recent evidence accumulated during the last decade about the cooperative action between polyphenols and fish oils against diet-related metabolic alterations, focusing on the mechanisms and pathways described and the effects reported. The final objective is to provide useful information for strategies for personalized nutrition based on these nutraceuticals.

Green Synthesized Magnetic Nanoparticles as Effective Nanosupport for the Immobilization of Lipase: Application for the Synthesis of Lipophenols

In this work, hybrid zinc oxide-iron oxide (ZnOFe) magnetic nanoparticles were synthesized employing Olea europaea leaf aqueous extract as a reducing/chelating and capping medium. The resulting magnetic nanoparticles were characterized by basic spectroscopic and microscopic techniques, namely, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared (FTIR) and atomic force microscopy (AFM), exhibiting a spherical shape, average size of 15-17 nm, and a functionalized surface. Lipase from Thermomyces lanuginosus (TLL) was efficiently immobilized on the surface of ZnOFe nanoparticles through physical absorption. The activity of immobilized lipase was found to directly depend on the enzyme to support the mass ratio, and also demonstrated improved pH and temperature activity range compared to free lipase. Furthermore, the novel magnetic nanobiocatalyst (ZnOFe-TLL) was applied to the preparation of hydroxytyrosyl fatty acid esters, including derivatives with omega-3 fatty acids, in non-aqueous media. Conversion yields up to 90% were observed in non-polar solvents, including hydrophobic ionic liquids. Different factors affecting the biocatalyst performance were studied. ZnOFe-TLL was reutilized for eight subsequent cycles, exhibiting 90% remaining esterification activity (720 h of total operation at 50 °C). The green synthesized magnetic nanoparticles, reported here for the first time, are excellent candidates as nanosupports for the immobilization of enzymes with industrial interest, giving rise to nanobiocatalysts with elevated features.

New lipophenols prevent carbonyl and oxidative stresses involved in macular degeneration

Dry age-related macular degeneration and Stargardt disease undergo a known toxic mechanism caused by carbonyl and oxidative stresses (COS). This is responsible for accumulation in the retinal pigment epithelium (RPE) of A2E, a main toxic pyridinium bis-retinoid lipofuscin component. Previous studies have shown that carbonyl stress in retinal cells could be reduced by an alkyl-phloroglucinol-DHA conjugate (lipophenol). Here, we performed a rational design of different families of lipophenols to conserve anti-carbonyl stress activities and improve antioxidant properties. Five synthetic pathways leading to alkyl-(poly)phenol derivatives, with phloroglucinol, resveratrol, catechin and quercetin as the main backbone, linked to poly-unsaturated fatty acid, are presented. These lipophenols were evaluated in ARPE-19 cell line for their anti-COS properties and a structure-activity relationship study is proposed. Protection of ARPE-19 cells against A2E toxicity was assessed for the four best candidates. Finally, interesting anti-COS properties of the most promising quercetin lipophenol were confirmed in primary RPE cells.

Targeted Lipidomics Profiling Reveals the Generation of Hydroxytyrosol-Fatty Acids in Hydroxytyrosol-Fortified Oily Matrices: New Analytical Methodology and Cytotoxicity Evaluation

Lipophenols have been stressed as an emerging class of functional compounds. However, little is known about their diversity. Thus, this study is aimed at developing a new method for the extraction, cleanup, and ultrahigh-performance liquid chromatography-electrospray ionization-triple quadrupole mass spectrometry (UHPLC-ESI-QqQ-MS/MS)-based analysis of the lipophenols derived from hydroxytyrosol (HT): α-linolenic (HT-ALA), linoleic acid (HT-LA), and oleic acid (HT-OA). The method validated provides reliable analytical data and practical applications. It was applied to an array of oily (extra virgin olive oil, refined olive oil, flaxseed oil, grapeseed oil, and margarine) and aqueous (pineapple juice) matrices, nonfortified and fortified with HT. Also, the present work reported the formation of fatty acid esters of HT (HT-FAs) that seem to be closely dependent on the fatty acid profile of the food matrix, encouraging the further exploration of the theoretical basis for the generation of HT-FAs, as well as their contribution to the healthy attributions of plant-based foods.

Evaluation of Absorption and Plasma Pharmacokinetics of Tyrosol Acyl Esters in Rats

Lipophenols are regarded as an emerging source of functional food ingredients. However, little is known about their in vivo digestion, absorption, and metabolism. Thus, the pharmacokinetic characteristics in rat and the gut microbial degradation of tyrosol acyl esters (TYr-Es) with fatty acids of C12:0, C18:0, and C18:2 were investigated for the first time. Major metabolites including tyrosol sulfate and tyrosol glucuronide, rather than the parent compounds, were detected in rat plasma after oral administration of TYr-Es. The increased plasma half-life (T_1/2) and mean residence time demonstrated that TYr-Es display a longer duration of action in vivo than TYr, potentially leading to higher oral bioavailability. TYr-Es could be hydrolyzed by the gut microbiota to free TYr, which may result in the appearance of the second absorption peak in pharmacokinetic profiles. Therefore, TYr-Es exhibit improved bioavailability compared to that of TYr because of their prolonged duration of action.

Polydatin-fatty acid conjugates are effective antioxidants for stabilizing omega 3-containing bulk fish oil and fish oil emulsions

Candida antarctica lipase B-catalysed synthesis of lipophilic esters of polydatin was investigated along with their antioxidant activities. The effects of synthesis parameters such as solvent, substrate molar ratio, enzyme concentration, addition of molecular sieves, reaction temperature and time on the production of ester were studied and optimised. The highest production of esters was obtained with acetone as the reaction solvent. The antioxidant activities of the esters were compared with those of commercial butylated hydroxytoluene (BHT) and α-tocopherol. All polydatin esters inhibited the oxidative destruction of β-carotene more effectively than did BHT and α-tocopherol. Results of thiobarbituric acid tests showed that in bulk fish oil, all esters were more effective than α-tocopherol at 2 mmol/kg concentration but were not as effective as BHT. In fish oil-emulsions, all esters were more effective than both BHT and α-tocopherol at 2 mmol/kg concentration. The synthesized polydatin esters are promising antioxidants for oil/fat-based foods.

New Lipophenol Antioxidants Reduce Oxidative Damage in Retina Pigment Epithelial Cells

Age-related macular degeneration (AMD) is a multifactorial pathology and its progression is exacerbated by oxidative stress. Oxidation and photo-oxidation reactions modify lipids in retinal cells, contribute to tissue injury, and lead to the formation of toxic adducts. In particular, autofluorescent pigments such as N-retinylidene-N-retinylethanolamine (A2E) accumulate as lipofuscin in retinal pigment epithelial cells, contribute to the production of additional reactive oxygen species (ROS), and lead to cell degeneration. In an effort to develop efficient antioxidants to reduce damage caused by lipid oxidation, various natural polyphenols were structurally modified to increase their lipophilicity (lipophenols). In this study, resveratrol, phloroglucinol, quercetin and catechin were selected and conjugated to various polyunsaturated fatty acids (PUFAs) using classical chemical strategies or enzymatic reactions. After screening for cytotoxicity, the capacity of the synthesized lipophenols to reduce ROS production was evaluated in ARPE-19 cells subjected to H₂O₂ treatment using a dichlorofluorescein diacetate probe. The positions of the PUFA on the polyphenol core appear to influence the antioxidant effect. In addition, two lipophenolic quercetin derivatives were evaluated to highlight their potency in protecting ARPE-19 cells against A2E photo-oxidation toxicity. Quercetin conjugated to linoleic or α-linolenic acid were promising lipophilic antioxidants, as they protected ARPE-19 cells from A2E-induced cell death more effectively than the parent polyphenol, quercetin.

Study of the Effect of Tyrosyl Oleate on Lipid Oxidation in a Typical Italian Bakery Product

Tyrosyl oleate (TO), synthesized using oleic acid and tyrosol, was added to the original receipt of tarallini, to evaluate its antioxidant effectiveness. Lipid oxidation in control sample and samples with 1%, 4%, and 7% of TO at different storage times (0, 15, 30, 37, and 45 days) was evaluated. Accelerated oxidation analysis showed that the control sample took more than four times to complete the oxidation compared tarallini with TO. The control sample and tarallini with 1% of TO exceeded the peroxide value limit after 30 days of storage and the other two final products after 45 days. The control sample registered a oxidized fatty acid concentration higher than all the samples formulated with TO. The concentration of volatile compounds from lipid oxidation in tarallini with TO showed a lower concentration than the control sample. All the determinations carried out confirm, for the first time, that TO can counteract lipid oxidation in a real lipid system.

Stability of resveratrol esters with caprylic acid during simulated in vitro gastrointestinal digestion

Lipophenols, esterified phenols with fatty acids, have attracted increasing attention because of their better protective effects in lipid-based food matrices from oxidation. However, little is known about their digestion. In this study, the digestive stability of resveratrol (RSV) esters with caprylic acid (RCAPs) in a model gastrointestinal digestion system was evaluated. The results demonstrated that RCAPs were relatively stable without hydrolysis in mouth and gastric phases. However, in the intestinal phase, pancreatic lipase rather than phospholipase A₂ could hydrolyze monoester and diesters to free RSV. After 120 min of incubation at 37 °C, 53.68% of monoester and 11.36% of diesters were hydrolyzed. However, no hydrolysis of the triester was noticed. Obviously, the level of hydrolysis of RCAPs was negatively correlated with the degree of substitution. Therefore, it was speculated that RSV in fatty acid ester forms could partially be absorbed by intestinal lumen in the form of free RSV.

Polyphenols and Their Interactions With Other Dietary Compounds: Implications for Human Health

Regular and optimal intake of polyphenols associates with numerous health-promoting effects. Bioavailability and activity of polyphenols depend on foods' structure and interactions with other food constituents, especially proteins, lipids, and carbohydrates. Polyphenols-proteins interactions can result in various biological effects, such as sense of astringency. So far, polyphenols interactions with food lipids have not been of special importance, except in case of plant oils. Polyphenols-carbohydrates interactions can influence the organoleptic properties, while interactions with dietary fibers are particularly significant. Polyphenols can decrease the synthesis of fats and fatty acids in the liver, or delay their absorption in intestines. Also, polyphenols can slow down digestion of carbohydrates, through the inhibition of digestive enzymes or modulation of glucose uptake. Both animal and plant proteins have low impact on the bioavailability of polyphenols, but some in vitro studies reported that milk proteins could enhance intestinal absorption of polyphenols from tea. Dietary fats may alter the passage of polyphenols through gastrointestinal tract and impact absorption of more hydrophobic polyphenols in particular. While some studies reported that associations with carbohydrates could decrease bioavailability of polyphenols, the others showed the opposite effects. Macronutrients can be used for encapsulation of polyphenols, which can increase their bioavailability and ensure controlled and targeted release. Polyphenols' interactions in the body include their incorporation in cell membranes which causes changes in fatty acid profile and impacts membrane-bound transporters and enzymes. Finally, gut microbiota plays essential role in metabolism of both polyphenols and macronutrients and thus can have great impact on their interactions.

Evaluation of the stability of tyrosol esters during in vitro gastrointestinal digestion

Lipophenols such as tea polyphenol palmitate derivatives (palmitoyl esters of tea polyphenols) have been classified as non-toxic food additives due to their better protective effects on lipidic food matrices from oxidation, but their digestion and absorption have remained unexplored.

Synthesis and evaluation of anti-oxidant and cytotoxic activities of novel 10-undecenoic acid methyl ester based lipoconjugates of phenolic acids

The synthesis of five novel methyl 10-undecenoate-based lipoconjugates of phenolic acids from undecenoic acid was carried out. Undecenoic acid was methylated to methyl 10-undecenoate which was subjected to a thiol–ene reaction with cysteamine hydrochloride. Further amidation of the amine was carried out with different phenolic acids such as caffeic, ferulic, sinapic, coumaric and cinnamic acid. All synthesized compounds were fully characterized and their structures were confirmed by spectral data. The anti-oxidant activity of the synthesized lipoconjugates of phenolic acids was studied by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and also by the inhibition of linoleic acid oxidation in micellar medium by differential scanning calorimetry (DSC). The prepared compounds were also screened for their cytotoxic activity against five cell lines. It was observed that the lipoconjugates of caffeic acid, sinapic acid, ferulic acid, and coumaric acid displayed anticancer and anti-oxidant properties. The anticancer properties of these derivatives have been assessed by their IC₅₀ inhibitory values in the proliferation of MDA-MB231, SKOV3, MCF7, DU 145 and HepG2 cancer cell lines.