Hydrolysis and Transport Characteristics of Tyrosol Acyl Esters in Rat Intestine

Hydrolysis and transport characteristics of starch inclusion complexes with long-chain alkyl gallates: Controlled two-step release of gallic acid and retardation of starch digestion

Corn starch inclusion complexes of alkyl gallates (typical phenololipid representatives), including stearyl gallate, dodecyl gallate, octyl gallate, and hexadecyl gallate, were synthesized by using a heat treatment method. Such inclusion complexes exhibited significantly improved two-step release properties for gallic acid. In other words, gallic acid was generated via the breakdown of alkyl gallates that were released from inclusion complexes in an everted rat intestinal sac model, as determined by HPLC-UV analysis. The produced gallic acid could subsequently pass through intestinal membranes. On the other hand, a glucose oxidase-peroxidase analysis revealed that starch inclusion complexes can slow down starch digestion by increasing the proportion of resistant starch (from 12.2 % to 14.5-30.8 %) and decreasing the proportion of rapidly digestible starch (from 51.2 % to 39.4-49.2 %). Importantly, the two-step release characteristics of gallic acid and the retardation behavior of starch digestion can be easily regulated by modifying the acyl carbon chain length.

Photoinduced Ag-Mediated Azaspirocyclic Approach Involves Cyclization and Dearomatization

A visible-light-promoted protocol for azaspirocyclic synthesis from N-benzylacrylamides and alkyl chlorooxoacetates has been established. This cascade reaction proceeds through sequential free radical addition, cyclization, and dearomatization, enabling the convenient construction of key azaspirocyclic derivatives and the introduction of valuable ester groups in a single step. In addition, this transformation demonstrates broad substrate compatibility and high tolerance toward different functional groups, showcasing remarkable efficiency in functional group insertion and bond formation.

Controlled release characteristics of alkyl gallates and gallic acid from β-cyclodextrin inclusion complexes of alkyl gallates

The freeze-drying approach was used to create inclusion complexes utilizing alkyl gallates and β-cyclodextrin, namely dodecyl gallate, octyl gallate, butyl gallate, and ethyl gallate, which are exemplary examples of phenolic esters. The everted-rat-gut-sac model demonstrated that the inclusion complexes released alkyl gallates, which were subsequently hydrolyzed to generate free gallic acid, as evidenced by HPLC-UV analysis. Both gallic acid and short-chain alkyl gallates were capable of permeating the small intestinal membrane. The transport rate of gallic acid (or alkyl gallates) exhibited an initial rise followed by a drop when the carbon-chain lengths varied. The inclusion complex groups exhibited a superior sustained-release effect compared to the comparable alkyl gallates groups, thus possibly leading to higher bioavailability and stronger bioactivity. Moreover, altering the length of the carbon chain will allow for the effortless achievement of regulated release of phenolic compounds and short-chain phenolic esters from such β-cyclodextrin inclusion complexes.

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.

Bioaccessible Phenolic Alkyl Esters of Wine Lees Decrease COX-2-Catalyzed Lipid Mediators of Oxidative Stress and Inflammation in a Time-Dependent Manner

Lipophenols, phenolic compounds esterified with fatty alcohols or fatty acids, provide greater health benefits upon dietary ingestion of plant-based foods than unesterified (poly)phenols. Based on this premise, the present study aimed to demonstrate the role of gastrointestinal enzymes (pepsin, pancreatin, and pancreatic lipase) in releasing alkyl gallates and trans-caffeates from wine lees, providing bioactive compounds with enhanced capacities against oxidative stress (OS) and para-inflammation. The UHPLC-ESI-QqQ-MS/MS-based analysis revealed ethyl gallate and ethyl trans-caffeate as the most prominent compounds (1.675 and 0.872 μg/g dw, respectively), while the bioaccessibility of the derivatives of gallic and caffeic acids was dependent on the alkyl chain properties. The de novo formation of alkyl gallates during gastric and intestinal digestion resulted from intestinal enzyme activity. Moreover, the in vitro capacity of bioaccessible alkyl esters of gallic and trans-caffeic acids to reduce cyclooxygenase-2 concentration and modulate oxilipins related to OS (8-iso-PGF2α) and inflammation (PGF2α and PGE2) was demonstrated in a time-dependent manner. In conclusion, the presence of alkyl esters of gallic and trans-caffeic acids in wine lees and their subsequent formation during digestion of this byproduct emphasize their value as a source of antioxidant and anti-inflammatory compounds, encouraging the consideration of wine lees as a valuable ingredient for health-promoting coproducts.

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.

β-cyclodextrin inclusion complexes with short-chain phenolipids: An effective formulation for the dual sustained-release of phenolic compounds

The β-cyclodextrin and short-chain alkyl gallates (A-GAs), which are representative of phenolipids, such as butyl, propyl, ethyl, and methyl gallates, were chosen to form inclusion complexes by the use of the freeze-drying process. In the everted rat gut sac model, HPLC-UV analysis demonstrated that the released A-GAs from inclusion complexes were degraded to yield free gallic acid (GA) (sustained-release function 1). The small intestine membrane may be crossed by both the GA and the A-GAs. A-GAs may also undergo hydrolysis to provide GA (sustained-release function 2) following transmembrane transfer. Clearly, a helpful technique for the dual sustained-release of phenolic compounds is to produce β-cyclodextrin inclusion complexes with short-chain phenolipids. This will increase the bioactivities of phenolic compounds and prolong their in vivo residence length. Moreover, changing the carbon-chain length of these β-cyclodextrin inclusion complexes would readily modify the dual sustained-release behavior of the phenolic compounds. Thus, our work effectively established a theoretical foundation for the use of β-cyclodextrin inclusion complexes containing short-chain phenolipids as new source of functional food components to provide the body with phenolic compounds more efficiently.

Hydrolysis and Transport Characteristics of Phospholipid Complex of Alkyl Gallates: Potential Sustained Release of Alkyl Gallate and Gallic Acid

Phospholipid complexes of alkyl gallates (A-GAs) including ethyl gallate (EG), propyl gallate (PG), and butyl gallate (BG) were successfully prepared by the thin film dispersion method. HPLC-UV analysis in an everted rat gut sac model indicated that A-GAs can be liberated from phospholipid complexes, which were further hydrolyzed by intestinal lipase to generate free gallic acid (GA). Both A-GAs and GA are able to cross the membrane, and the hydrolysis rate of A-GAs and the transport rate of GA are positively correlated with the alkyl chain length. Especially, compared with the corresponding physical mixtures, the phospholipid complexes exhibit slower sustained-release of A-GAs and GA. Therefore, the formation of phospholipid complexes is an effective approach to prolong the residence time in vivo and additionally enhance the bioactivities of A-GAs and GA. More importantly, through regulating the carbon skeleton lengths, controlled-release of alkyl gallates and gallic acid from phospholipid complexes will be achieved.

The Effect of Heat Treatment on the Digestion and Absorption Properties of Protein in Sea Cucumber Body Wall

This study was designed, for the first time, to investigate the effect of oxidation on the digestion and absorption properties of protein in boiled sea cucumber body wall (BSCBW) via simulated digestion combined with everted-rat-gut-sac models. Boiling heat treatments led to protein oxidation in SCBW, manifested by increases in free radical intensity, thiobarbituric acid reactive substances, carbonyl groups, disulfide bonds, dityrosine bonds, advanced glycation end products, protein hydrophobicity and aggregation, and declines in both free sulfhydryl groups and secondary structure transition from α-helix to β-sheet. Boiling for 2 h caused anti-digestion collagen unfolding, provided the action site for protease and improved protein digestion and absorption levels. On the contrary, excessive oxidative modification of 4 h BSCBW resulted in decreased protein digestion and absorption levels. From the perspective of texture, digestion and absorption properties, boiling for 2 h can obtain sea cucumber products with better edible and digestible properties, which is considered to be a better processing condition.

Hydrolysis and transport characteristics of tyrosol-SCFA esters in rat intestine and blood: Two-step release of tyrosol and SCFAs to enhance the beneficial effects

The models of rat everted gut sac and hydrolysis by rat plasma were used to clarify the hydrolysis and transport characteristics of tyrosol-SCFA esters (TYr-SEs). HPLC-UV results indicated that TYr-SEs could be hydrolyzed by intestinal lipase, which showed sustained release of SCFAs and TYr. Meanwhile, TYr-SEs and the liberated SCFAs and TYr could cross the membrane and were transported into blood circulation. TYr-SEs were further hydrolyzed by carboxylesterase in plasma. Obviously, the hydrolysis of TYr-SEs in blood also showed sustained release of SCFAs and TYr. Especially, the rates of hydrolysis and transport correlated positively with the acyl chain lengths. Besides, the above rates of the TYr-SE with a straight chain were greater than those of its isomer with a branched chain. Therefore, the above-mentioned two-step release of SCFAs and TYr clearly demonstrated that TYr-SEs would be an effective approach to enhance the beneficial health effects of SCFAs and TYr.

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.

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.

Effects of antioxidants of bamboo leaves on protein digestion and transport of cooked abalone muscles

The effects of oxidation on protein digestion and transport in cooked abalone muscles were investigated using a combination of simulated digestion and everted-rat-gut-sac models for the first time. Boiling heat treatments caused protein oxidation in the abalone muscles, reflected by increases in the carbonyl group and disulfide bond contents, protein hydrophobicity and aggregation degree, as well as decreases in the free sulfhydryl group and amino acid contents. Protein oxidation significantly inhibited the degree of hydrolysis, digestion rate, and digestibility of the abalone muscles in the simulated digestion model. The results from the everted-rat-gut-sac model showed that amino acid and peptide transport levels from the digestion products of the cooked abalone muscles were lower than those of the uncooked samples. In contrast, the addition of antioxidants of bamboo leaves mitigated heat-treatment-induced protein oxidation, aggregation and increased hydrophobicity, and consequently improved abalone muscle protein digestibility and transport levels.

The Effects of Acyl Chain Length on Antioxidant Efficacy of Mono- and Multi-Acylated Resveratrol: A Comparative Assessment

Acylated derivatives of the dietary phenolic, resveratrol, were prepared via enzymatic and chemical transesterification modification with selected vinyl fatty acids to expand the potential application of resveratrol and its acylated derivatives in functional supplement, cosmetic/skincare, and pharmaceutical fields. The acylation was implemented using eight vinyl fatty acids with varying chain lengths (C2:0-C18:0). Eight monoesters enzymatically prepared, eight diesters and four triesters, chemically prepared, were isolated and purified and identified via MS (mass spectra) or/and NMR (nuclear magnetic resonance). The lipophilicity of resveratrol and its acylated derivatives was calculated using ALOGPS 2.1. Compared with related acylated products, resveratrol itself rendered higher antioxidant efficacy in all the antioxidant assays, namely DPPH, ABTS, FRAP, and ferrous chelation tests. Within various ester derivatives of resveratrol, short-chain fatty acid mono- and di-substituted resveratrols, especially the resveratrol monoacetate/diacetate, exhibited higher antioxidant efficacy in DPPH and ABTS assays than the rest of resveratrol derivatives, but the medium-chain monoesters of resveratrol, including caproate, caprylate, caprate, and laurate, showed a higher metal ion chelation ability compared to other acylated resveratrols. These results imply that resveratrol derivatives may be used in lipidic media as health-beneficial antioxidants.

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.

Distribution of tyrosol fatty acid esters in the gastrointestinal tract of mice and their hydrolysis characteristic by the gut microbiota

Phenolic lipids have been approved as safe and effective antioxidants, are also a potential ingredient for functional foods. However, the characteristics of gastrointestinal distribution and microbial hydrolysis in the gastrointestinal...

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.

Effect of carbon chain length on the hydrolysis and transport characteristics of alkyl gallates in rat intestine

Phenolipids such as alkyl gallates (A-GAs) have been approved by food industry as non-toxic antioxidant additives. However, their digestion and absorption mechanisms in the intestine have not yet been clarified. In this research, the hydrolysis and transport characteristics of A-GAs with fatty alcohols of various chain lengths (C1:0, C2:0, C3:0, C4:0, C8:0, C12:0 and C16:0) were estimated by the everted-rat-gut-sac model (ERGSM) for the first time. High-performance liquid chromatography measurements proved that measurable peaks corresponding to methyl gallate (G-C1:0), ethyl gallate (G-C2:0), propyl gallate (G-C3:0) and butyl gallate (G-C4:0) were discovered in the serosal fluids, which showed the short-chain alkyl gallates can cross the membrane in the form of esters. Besides, all A-GAs were hydrolyzed to GA in the mucosal solution, which contributed evidently to the transport of GA across the membrane of the small intestine. Meanwhile, the hydrolysis rate of A-GAs and transport rate of GA initially increased and then decreased with the chain length, exhibiting a maximum for octyl gallate (G-C8:0). In general, all A-GAs have the behavior of sustained-release. In consequence, the production of A-GAs should be an effective method to extend action time and further increases biological activities of GA.

Identification of Tyrosyl Oleate as a Novel Olive Oil Lipophenol with Proliferative and Antioxidant Properties in Human Keratinocytes

Lipophenols are an emerging subclass of phenolic compounds characterized by the presence of a lipid moiety. Recently, hydroxytyrosyl oleate (HtyOle), a derivative of hydroxytyrosol, has been identified in olive oil and by-products. Furthermore, HtyOle possesses anti-inflammatory, antioxidant, and tissue regenerating properties. In this work, the potential occurrence of tyrosyl oleate (TyOle) in olive oil was investigated based on the hypothesis that its precursors tyrosol and oleic acid, both present in relatively high amount can be coupled together. Moreover, TyOle effects have been investigated in human keratinocytes to verify its proliferative and antioxidant properties. The quantitative determination of TyOle was carried out by the external standard method in liquid chromatography coupled with mass spectrometry (LC/MS), in negative mode using multiple reaction monitoring (MRM). The proliferative properties of TyOle on immortalized human keratinocytes (HaCat) were evaluated by 3-(4,5-dimethylthiasol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Morphological changes were observed by fluorescent staining with phalloidin (for F-actin) or 4,6-diamidino-2-phenylindole (DAPI, for chromatin) dye. The antioxidant activity was assessed at the level of production of mitochondrial reactive oxygen species (ROS) induced with UV exposure. TyOle was identified in all the oil samples investigated. Interestingly, TyOle concentration was higher in defective or low-quality oils than in extra virgin oils. The formation of TyOle likely occurs during the crushing and kneading processes and its concentration is related to the increase of rancidity and of the concentration of free precursors. Herein we show that TyOle induced an increase in the viability of HaCat cells and cytoskeletal remodeling.

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.

Protein corona formation of human serum albumin with carbon quantum dots from roast salmon

When food-borne nanoparticles enter biological systems, they can interact with various proteins to form protein coronas, which can affect their physicochemical properties and biological identity. In this study, the protein corona formation of carbon quantum dots (CQDs) from roast salmon with human serum albumin (HSA) was explored. Furthermore, the biological identity of the HSA-CQD coronas, in relation to cell apoptosis, energy, glucose and lipid metabolism and acute toxicity in mice, was also investigated. The HSA-CQD coronas were formed between HSA and CQDs via a static binding mechanism, and the binding site of CQDs on HSA was located at both Sudlow's site I and site II. After entering the cytoplasm, the HSA-CQD coronas became localized in the lysosomes and autolysosomes. Importantly, the HSA coronas reduced the cytotoxicity of the CQDs from 18.65% to 9.26%, and the energy metabolism was rectified by changing from glycolytic to aerobic metabolism. The glucose and lipid metabolite profile of cells exposed to the HSA-CQD coronas differed from that of those treated with CQDs, indicating that the HSA-CQD coronas rectified metabolic disturbances caused by CQDs. Histopathological and blood biochemical analysis revealed no statistically significant differences between the treated and control mice after a single CQDs dose of 2000 mg per kg body weight. Overall, the results confirmed the formation of protein coronas between HSA and food-borne fluorescent CQDs, and could be helpful for evaluating the safety of fluorescent CQDs in cooked food items.

Antiglycative and anti-inflammatory effects of lipophilized tyrosol derivatives

Abstract

To expand the application of tyrosol, a series of lipophilized tyrosol derivatives were synthesized via esterification of tyrosol with fatty acids of different chain lengths. The antiglycative activity of tyrosol esters so prepared was subsequently examined in the bovine serum albumin/glucose system. A quasi-parabolic shape was observed when the activity was plotted against alkyl chain length. Additionally, the anti-inflammatory effects of these derivatives were evaluated against methylglyoxal-induced inflammation in RAW264.7 cells. The same trend on anti-inflammatory activity was found as in the antiglycation study. The results showed that tyrosol esters with C12:0 and C14:0 were two most efficient ones among all the tested derivatives. Thus, some lipophilized tyrosol derivatives were stronger antiglycative and anti-inflammatory agents compared to the parent compound, tyrosol.

Graphical abstract

Toxicity Alleviation of Carbon Dots from Roast Beef after the Formation of Protein Coronas with Human Serum Albumin

The unique properties of nanoparticles produced during food thermal processing have attracted considerable attention. In this study, the formation of protein coronas of fluorescent carbon dots (CDs) in roast beef with human serum albumin (HSA) and the corona effect on toxicity were reported. The CDs were roughly spherical with a size in the range of 1-5 nm, which were mainly composed of carbon (68.68%), nitrogen (10.6%), and oxygen (15.98%). The CDs could readily pass through the intestine wall due to their small size and good water solubility. There was an obvious interaction between HSA and CDs, suggesting that the CDs could form protein coronas. Thermodynamic analysis results of ΔH < 0 (-13.17 ± 3.74 kJ/mol) and ΔS > 0 ( 28.04 J/mol/K) indicated that the binding of HSA-CDs was due to electrostatic interactions or hydrophobic forces. The HSA-CD coronas were distributed in the lysosomes of the cells, alleviated swelling caused by the CDs, and inhibited the decrease of mitochondrial membrane potential caused by CDs. Furthermore, the protein coronas reduced cellular reactive oxygen species production and alleviated the consumption of glutathione by the CDs, thus protecting the cells from damage. This finding provided valuable information about protein coronas in ameliorating cytotoxicity.

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.