Enzymatic synthesis of phytosteryl docosahexaneates and evaluation of their anti-atherogenic effects in apo-E deficient mice

Effects of dietary phytosterols or phytosterol esters supplementation on growth performance, biochemical blood indices and intestinal flora of C57BL/6 mice

This study was conducted to evaluate the effects of phytosterols (PS) and phytosterol esters (PSE) on C57BL/6 mice. Three groups of 34 six-week-old C57BL/6 mice of specific pathogen free (SPF) grade, with an average initial body weight (IBW) of 17.7g, were fed for 24 days either natural-ingredient diets without supplements or diets supplemented with 89 mg/kg PS or diets supplemented with 400 mg/kg PSE. Growth performance, blood biochemistry, liver and colon morphology as well as intestinal flora status were evaluated. Both PS and PSE exhibited growth promotion and feed digestibility in mice. In blood biochemistry, the addition of both PS and PSE to the diet resulted in a significant decrease in Total Cholesterol (TC) and Triglyceride (TG) levels and an increase in Superoxide Dismutase (SOD) activity. No significant changes in liver and intestinal morphology were observed. Both increased the level of Akkermansia in the intestinal tract of mice. There was no significant difference between the effects of PS and PSE. It was concluded that dietary PS and PSE supplementation could improve growth performance, immune performance and gut microbiome structure in mice, providing insights into its application as a potential feed additive in animals production.

Enzymatic synthesis and characterization of novel lipophilic inotodiol-oleic acid conjugates

In this study, we establish an efficient enzymatic approach for producing novel inotodiyl-oleates (IOs) from pure inotodiol and oleic acid to improve the properties of inotodiol. For the esterification between inotodiol and oleic acid, CALA and n-hexane were the optimal biocatalyst and solvents for forming IOs with 80.17% conversion yield. These IOs comprised two distinct monoesters, the C3 or C22 ester forms of inotodiol. Intriguingly, no diesters were detected. The IOs had a melting point of 53.48 °C, much lower than that of inotodiol (192.06 °C). The in vitro digestion rate of IOs (25-28%) was significantly (p < 0.05) lower than that of cholesteryl-oleate (60%). Additionally, IOs exhibited much lower in vivo absorption than inotodiol when orally administered using different formulations (p < 0.05). The results indicated that IOs were resistant to enzymatic digestion in the small intestine, which could be advantageous in targeting the large intestine for disease treatments.

Octadecyl and sulfonyl modification of diatomite synergistically improved the immobilization efficiency of lipase and its application in the synthesis of pine sterol esters

Phytosterols usually have to be esterified to various phytosterol esters to avoid their disadvantages of unsatisfactory solubility and low bioavailability. The enzymatic synthesis of phytosterol esters in a solvent-free system has advantages in terms of environmental friendliness, sustainability, and selectivity. However, the limitation of the low stability and recyclability of the lipase in the solvent-free system, which often requires a relatively high temperature to induce the viscosity, also increased the industrial production cost. In this context, a low-cost material, namely diatomite, was employed as the support in the immobilization of Candida rugosa lipase (CRL) due to its multiple modification sites. The Fe3 O4 was also then introduced to this system for quick and simple separation via the magnetic field. Moreover, to further enhance the immobilization efficiency of diatomite, a modification strategy which involved the octadecyl and sulfonyl group for regulating the hydrophobicity and interaction between the support and lipase was successfully developed. The optimization of the ratio of the modifiers suggested that the -SO3 H/C18 (1:1.5) performed best with an enzyme loading and enzyme activity of 84.8 mg·g-1 and 54 U·g-1 , respectively. Compared with free CRL, the thermal and storage stability of CRL@OSMD was significantly improved, which lays the foundation for the catalytic synthesis of phytosterol esters in solvent-free systems. Fortunately, a yield of 95.0% was achieved after optimizing the reaction conditions, and a yield of 70.0% can still be maintained after six cycles.

Lipases as Effective Green Biocatalysts for Phytosterol Esters’ Production: A Review

Lipases are versatile enzymes widely used in the pharmaceutical, cosmetic, and food industries. They are green biocatalysts with a high potential for industrial use compared to traditional chemical methods. In recent years, lipases have been used to synthesize a wide variety of molecules of industrial interest, and extraordinary results have been reported. In this sense, this review describes the important role of lipases in the synthesis of phytosterol esters, which have attracted the scientific community’s attention due to their beneficial effects on health. A systematic search for articles and patents published in the last 20 years with the terms “phytosterol AND esters AND lipase” was carried out using the Scopus, Web of Science, Scielo, and Google Scholar databases, and the results showed that Candida rugosa lipases are the most relevant biocatalysts for the production of phytosterol esters, being used in more than 50% of the studies. The optimal temperature and time for the enzymatic synthesis of phytosterol esters mainly ranged from 30 to 101 °C and from 1 to 72 h. The esterification yield was greater than 90% for most analyzed studies. Therefore, this manuscript presents the new technological approaches and the gaps that need to be filled by future studies so that the enzymatic synthesis of phytosterol esters is widely developed.

Enzymatic preparation of phytosterol esters with fatty acids from high-oleic sunflower seed oil using response surface methodology

Phytosterol esters are functional compounds that can effectively reduce plasma cholesterol concentration, and have wide applications in the food industry. In this study, a simple and efficient enzymatic method was successfully applied to synthesize phytosterol oleic acid esters with fatty acids from high-oleic sunflower seed oil. Among the tested lipases, Candida rugosa lipase (CRL) exhibited higher catalytic activity in the esterification of phytosterols with fatty acids (oleic acid 84%) from high-oleic sunflower seed oil. Box-Behnken design and response surface methodology were used to investigate the influence of reaction factors on the conversion of phytosterols. The maximum conversion of phytosterols (96.8%) and yield of phytosterol esters (92%) could be obtained under optimal conditions: reaction temperature 50 °C, a molar ratio of phytosterols to fatty acids at 1 : 2.3, enzyme loading of 5.8%, isooctane volume of 2 mL and reaction time of 2 h. It was noteworthy that this enzymatic esterification method indeed expended a much shorter reaction time (2 h) than that observed in previous reports. In general, the enzymatic preparation of phytosterol oleic acid esters with fatty acids from high-oleic sunflower seed oil will be a simple and rapid method for producing unsaturated fatty acid esters of phytosterol with both higher oil solubility and oxidative stability, which is beneficial as functional food ingredients.

Solvent-free synthesis of phytosterol linoleic acid esters at low temperature

Phytosterol unsaturated fatty acid esters show much higher oil solubility than free phytosterol. Thus, development of a green and low-cost method for the preparation of phytosterol fatty acid esters is highly desirable in the food industry. Herein, we have developed a simple chemical method toward efficient preparation of phytosterol linoleic acid esters at very mild temperature (60 °C) using 4-dodecylbenzenesulfonic acid (DBSA) as the catalyst. In this work, low-temperature esterification of phytosterols (soybean sterol) with linoleic acid could produce the corresponding phytosterol esters above 95% conversion under solvent-free conditions. In addition, this simple method could be applied to produce phytosterol esters through esterification of phytosterol with an unsaturated fatty acid mixture resulting from the hydrolysis of various vegetable oils. Importantly, no extra organic solvents and no extra water-removal operations or equipment were required in this chemical esterification method. The mechanism investigation suggested that the DBSA-catalyzed low-temperature esterification would form micro-emulsions of water-in-oil (W/O), which could achieve automatic separation of water from the hydrophobic system to avoid reverse reaction hydrolysis and rapidly promote the equilibrium reaction towards phytosterol esters.

Herein, we have developed a simple chemical method toward efficient preparation of phytosterol linoleic acid esters through esterification at very mild temperature (60 °C) using 4-dodecylbenzenesulfonic acid (DBSA) as the catalyst.

Omega-3 Polyunsaturated Fatty Acids and Their Health Benefits

Omega-3 polyunsaturated fatty acids (PUFAs) include α-linolenic acid (ALA; 18:3 ω-3), stearidonic acid (SDA; 18:4 ω-3), eicosapentaenoic acid (EPA; 20:5 ω-3), docosapentaenoic acid (DPA; 22:5 ω-3), and docosahexaenoic acid (DHA; 22:6 ω-3). In the past few decades, many epidemiological studies have been conducted on the myriad health benefits of omega-3 PUFAs. In this review, we summarized the structural features, properties, dietary sources, metabolism, and bioavailability of omega-3 PUFAs and their effects on cardiovascular disease, diabetes, cancer, Alzheimer's disease, dementia, depression, visual and neurological development, and maternal and child health. Even though many health benefits of omega-3 PUFAs have been reported in the literature, there are also some controversies about their efficacy and certain benefits to human health.

Mild and Efficient Preparation of Phytosteryl Amino Acid Ester Hydrochlorides and Their Emulsifying Properties

The aim of this work was to produce a series of phytosteryl amino acid ester hydrochlorides by a two-step method, which involved esterification of phytosterols with N- tert-butoxycarbonyl (BOC) amino acid and deprotection of the BOC group. The highest yield of over 95.0% was obtained when the catalysts were the mixtures of 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochlide, 4-dimethylaminopyridine, and triethylamine. It was found that batch charging of the reactants and catalysts was conducive to improving the yield. In addition, over 99.0% of the BOC group deprotection degree was achieved using the HCl/ethyl acetate deprotection method. All of the compounds were characterized by fourier transform infrared spectroscopy, mass spectroscopy, and nuclear magnetic resonance spectroscopy. The emulsifying properties of phytosterols and phytosteryl amino acid ester hydrochlorides were also investigated. The results showed higher emulsifying properties of phytosteryl amino acid ester hydrochlorides, which could favor its wide application in food systems.

Lipophilization of Resveratrol and Effects on Antioxidant Activities

Resveratrol (R), a polyphenol, was structurally modified via esterification with selected fatty acids to expand its potential application in lipophilic foods, drugs, and cosmetics. The esterification was carried out using 12 different fatty acids with varying chain lengths and degrees of unsaturation (C3:0-C22:6). Two monoesters, two diesters, and one triester were identified by high-performance liquid chromatography-mass spectrometry, and the monoesters (R-3-O-monodocosahexaenoate and R-4'-O-monodocosahexaenoate) were structurally confirmed by nuclear magnetic resonance. The lipophilicity of resveratrol and its alkyl esters was calculated using ALOGPS 2.1. Resveratrol exhibited greater antioxidant activity in both 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation scavenging assays. Resveratrol esters with long-chain fatty acids (C18:0 and C18:1) showed higher antioxidant activity in the DPPH radical scavenging assay, whereas short-chain fatty acid (C3:0, C4:0, and C6:0) showed higher antioxidant activity in the ABTS radical cation scavenging assay. The results may imply that resveratrol derivatives could be used in lipophilic media as health beneficial antioxidants.

Enzymatic deacidification of the rice bran oil and simultaneous preparation of phytosterol esters-enriched functional oil catalyzed by immobilized lipase arrays

Novel ordered mesoporous silica immobilized lipase arrays are described for enzymatic deacidification of the high-acid rice bran oil and simultaneous preparation of phytosterol esters-enriched functional oil.

Efficient synthesis and characterization of ergosterol laurate in a solvent-free system

Ergosterol and its derivatives have attracted much attention for a variety of health benefits, such as anti-inflammatory and antioxidant activities. However, ergosterol esters are advantageous because this compound has better solubility than the free ergosterol. In this work, ergosterol laurate was efficiently synthesized for the first time by direct esterification in a solvent-free system. The desired product was purified, characterized by Fourier transform infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance, and finally confirmed to be ergosterol laurate. Meanwhile, the effect of various catalysts, catalyst dose, reaction temperature, substrate molar ratio, and reaction time were studied. Both the conversion of ergosterol and the selectivity of the desired product can reach above 89% under the selected conditions: sodium dodecyl sulfate + hydrochloric acid as the catalyst, 2:1 molar ratio of lauric acid/ergosterol, catalyst dose of 4% (w/w), 120 °C, and 2 h. The oil solubility of ergosterol and its laurate was also compared. The results showed that the solubility of ergosterol in oil was significantly improved by direct esterification with lauric acid, thus greatly facilitating the incorporation into a variety of oil-based systems.

Animal models of atherosclerosis

In this mini-review several commonly used animal models of atherosclerosis have been discussed. Among them, emphasis has been made on mice, rabbits, pigs and non-human primates. Although these animal models have played a significant role in our understanding of induction of atherosclerotic lesions, we still lack a reliable animal model for regression of the disease. Researchers have reported several genetically modified and transgenic animal models that replicate human atherosclerosis, however each of current animal models have some limitations. Among these animal models, the apolipoprotein (apo) E-knockout (KO) mice have been used extensively because they develop spontaneous atherosclerosis. Furthermore, atherosclerotic lesions developed in this model depending on experimental design may resemble humans’ stable and unstable atherosclerotic lesions. This mouse model of hypercholesterolemia and atherosclerosis has been also used to investigate the impact of oxidative stress and inflammation on atherogenesis. Low density lipoprotein (LDL)-r-KO mice are a model of human familial hypercholesterolemia. However, unlike apo E-KO mice, the LDL-r-KO mice do not develop spontaneous atherosclerosis. Both apo E-KO and LDL-r-KO mice have been employed to generate other relevant mouse models of cardiovascular disease through breeding strategies. In addition to mice, rabbits have been used extensively particularly to understand the mechanisms of cholesterol-induced atherosclerosis. The present review paper details the characteristics of animal models that are used in atherosclerosis research.