Highly Efficient Synthesis of Hydrophilic Phytosterol Derivatives Catalyzed by Ionic Liquid

Phytosterol organic acid esters: Characterization, anti-inflammatory properties and a delivery strategy to improve mitochondrial function

Phytosterol organic acid esters are important food resources and the components of biomembrane structure. Due to the lack of extraction and synthesis techniques, more research has been focused on phytosterols, and the research on phytosterol acid esters have encountered a bottleneck, but phytosterol acid esters confer substantial benefits to human health. In this study, stigmasteryl vanillate (VAN), stigmasteryl protocatechuate (PRO) and stigmasteryl sinapate (SIN) were prepared through the Steglich reaction. The processes are promotable and the products reach up to 95% purity. In addition, their stability was evaluated by differential scanning calorimetry and thermogravimetric analysis. HPLC analysis revealed an enhancement in water solubility after esterification with phenolic acid. In an in vitro digestion model, the bioaccessibility of stigmasteryl phenolates was significantly higher than that of stigmasterols (STIs). Regarding the anti-inflammatory properties, VAN, PRO, and SIN exhibit superior effects against TNF-α induced pro-inflammatory responses compared to STI. All stigmasteryl phenolates supplementation increased the ATP production, the basal, and maximal oxygen consumption rate in mitochondrial stress test. Overall, we present a synthesis method for stigmasteryl phenolates. It will contribute to the development and research of phytosterol acid ester analysis, functions and utilization in food. Moreover, the nutrient-stigmasterol hybrids tactic we have constructed is practical and can become a targeted mitochondrial delivery strategy with enhanced anti-inflammatory effects.

Novel Synthesis of Phytosterol Ferulate Using Acidic Ionic Liquids as a Catalyst and Its Hypolipidemic Activity

Phytosterol ferulate (PF) is quantitively low in rice, corn, wheat, oats, barley, and millet, but it is potentially effective in reducing plasma lipids. In this study, PF was synthesized for the first time using acidic ionic liquids as a catalyst. The product was purified, characterized using Fourier transform infrared, mass spectroscopy, and nuclear magnetic resonance, and ultimately confirmed as the desired PF compound. The conversion of phytosterol surpassed an impressive 99% within just 2 h, with a selectivity for PF exceeding 83%. Plasma lipid-lowering activity of PF was further investigated by using C57BL/6J mice fed a high-fat diet as a model. Supplementation of 0.5% PF into diet resulted in significant reductions in plasma total cholesterol, triacylglycerols, and nonhigh-density lipoprotein cholesterol by 13.7, 16.9, and 46.3%, respectively. This was accompanied by 55.8 and 36.3% reductions in hepatic cholesterol and total lipids, respectively, and a 22.9% increase in fecal cholesterol excretion. Interestingly, PF demonstrated a higher lipid-lowering activity than that of its substrates, a physical mixture of phytosterols and ferulic acid. In conclusion, an efficient synthesis of PF was achieved for the first time, and PF had the great potential to be developed as a lipid-lowering dietary supplement.

Guggulsterone - a potent bioactive phytosteroid: synthesis, structural modification, and its improved bioactivities

Guggulsterone is a phytosteroid derived from the oleo-gum resin of the critically endangered plant Commiphora wightii. This molecule has attracted increasing attention due to its excellent biochemistry potential and the compound has consequently been evaluated in clinical trials. With a low concentration in natural resources but wide medicinal and therapeutic value, chemists have developed several synthetic routes for guggulsterone starting from various steroid precursors. Moreover, numerous studies have attempted to modify its structure to improve the biological properties. Nowadays, green and sustainable chemistry has also attracted more attention for advanced chemical processes and reactions in steroid chemistry. The present review aimed to summarize the literature and provide an update about the improvements in the chemical synthesis and structural modification of guggulsterone from the view of green chemistry. Moreover, this review encompasses the improved activities of structurally modified guggulsterone derivatives. We expect that the information provided here will be useful to researchers working in this field and on this molecule.

Study on the synthesis of pine sterol esters in solvent-free systems catalyzed by Candida rugosa lipase immobilized on hydrophobic macroporous resin

BACKGROUND

Pine sterol ester is a type of novel food source nutrient with great advantages in lowering blood cholesterol levels, inhibiting tumors, preventing prostate enlargement, and regulating immunity. Macroporous resins with large specific surface area, stable structures, and various functional groups (epoxy, amino, and octadecyl groups) have been selected for immobilization of Candida rugosa lipase (CRL) to improve its stability and efficiency in the synthesis of pine sterol esters. A solvent-free strategy using oleic acid (substrate) as an esterification reaction medium is an important alternative for avoiding the use of organic solvents.

RESULTS

The immobilization conditions of CRL immobilized on several types of commercial macroporous resins were optimized. Fortunately, by adsorption (hydrophobic interaction), a high immobilization efficiency of CRL was obtained using macroporous resins with hydrophobic octadecyl groups with an immobilization efficiency of 86.5%, enzyme loading of 138.5 mg g-1 and enzyme activity of 34.7 U g-1 . The results showed that a 95.1% yield could be obtained with a molar ratio of oleic acid to pine sterol of 5:1, an enzyme amount of 6.0 U g-1 (relative to pine sterol mass) at 50 °C for 48 h.

CONCLUSION

The hydrophobic macroporous resin (ECR8806M) with a large specific surface area and abundant functional groups was used to achieve efficient immobilization of CRL. CRL@ECR8806M is an efficient catalyst for the synthesis of phytosterol esters and has the potential for further large-scale applications. Therefore, this simple, green, and low-cost strategy for lipase immobilization provides new possibilities for the high-efficiency production of pine sterol esters and other food source nutrients. © 2023 Society of Chemical Industry.

A review on chemical and physical modifications of phytosterols and their influence on bioavailability and safety

Phytosterols have been shown to lower cholesterol levels and to have antioxidant, anti-inflammatory and other biological activities. However, the high melting point and poor solubility limit their bioavailability and practical application. It is advantageous to modify phytosterols chemically and physically. This article reviews and discusses the chemical and physical modifications of phytosterols, as well as their effects on the bioavailability and possible toxicity in vivo. The current research on chemical modifications is mainly focused on esterification to increase the oil solubility and water solubility. For physical modifications (mainly microencapsulation), there are biopolymer-based, surfactant-based and lipid-based nanocarriers. Both chemical and physical modifications of phytosterols can effectively increase the absorption and bioavailability. The safety of modified phytosterols is also an important issue. Phytosterol esters are generally considered to be safe. However, phytosterol oxides, which may be produced during the synthesis of phytosterol esters, have shown toxicity in animal models. The toxicity of nanocarriers also needs further studies.

Enhancement of Galloylation Efficacy of Stigmasterol and β-Sitosterol Followed by Evaluation of Cholesterol-Reducing Activity

In this study, incorporation of gallic acid into typical phytosterols (β-sitosterol and stigmasterol) through Steglich esterification was optimized employing the protection and deprotection strategy. A novel mechanism leading to side esterification was discovered. Complication of the phenolic hydroxyl groups and side reactions were successfully reduced under the optimized conditions. The structural identity and purity of galloyl stigmasterol and galloyl β-sitosterol were confirmed by NMR, FT-IR, and HPLC-MS. Evaluation of galloyl β-sitosterol and galloyl stigmasterol revealed their excellent antioxidant and cholesterol-reducing activities. Significant enhancement of cholesterol-reducing activity by galloylation was unveiled especially for β-sitosterol. Galloyl β-sitosterol had slightly better antioxidant activity at ambient temperature and better cholesterol-reducing activity. Molecular modeling suggested that a subtle difference of galloyl β-sitosterol and galloyl stigmasterol in activities could be attributed to variation of molecular rigidity and conformation. The excellent properties of galloyl β-sitosterol and galloyl stigmasterol suggested their great potential application in the food industry.

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.

Immunogenicity and protective efficacy of orally administered recombinant Lactobacillus plantarum expressing VP2 protein against IBDV in chicken

AIM

To develop an effective oral vaccine against the very virulent infectious bursal disease virus (vvIBDV), we generated two recombinant Lactobacillus plantarum strains (pPG612-VP2/LP and pPG612-T7g10-VP2/LP, which carried the T7g10 translational enhancer) that displayed the VP2 protein on the surface, and compared the humoral and cellular immune responses against vvIBDV in chickens.

METHODS AND RESULTS

We genetically engineered the L. plantarum strains pPG612-VP2/LP and pPG612-T7g10-VP2/LP constitutively expressing the VP2 protein of vvIBDV. We found that the T7g10 enhancer efficiently upregulates VP2 expression in pPG612-T7g10-VP2/LP. Orally administered, pPG612-T7g10-VP2/LP exhibited significant levels of protection (87·5%) against vvIBDV in chickens, indicating improved immunogenicity. Chickens in the pPG612-T7g10-VP2/LP group produced higher levels of interferons (IFN-γ) and interleukins (IL-2 and IL-4) than those in the pPG612-VP2/LP group. CD8+ and CD4+ lymphocyte counts indicated greater stimulation in the pPG612-T7g10-VP2/LP group (13·3 and 21·0% respectively) than in the pPG612-VP2/LP group (10·4 and 14·0% respectively). Thus, pPG612-T7g10-VP2/LP could induce strong humoral and cellular immune responses against vvIBDV.

CONCLUSIONS

The recombinant L. plantarum that expresses pPG612-T7g10-VP2 is a promising candidate for oral vaccine development against vvIBDV.

SIGNIFICANCE AND IMPACT OF THE STUDY

The recombinant Lactobacillus delivery system provides a promising strategy for vaccine development against vvIBDV in chickens.

Highly efficient synthesis of phytosterol linolenate in the presence of Bronsted acidic ionic liquid

Phytosterols are effective in reducing plasma cholesterol. However, phytosterols in a free form have some disadvantages because they have a high melting point and a poor oil solubility, thereby limiting their practical application in foods. The present study was to establish a green and highly efficient method to synthesize phytosterol linolenate for the first time by employing Bronsted acidic ionic liquid (IL) as a catalyst in order to improve its oil solubility. The product was separated, analyzed and subsequently characterized using thin layer chromatography, fourier transform infrared spectroscopy and mass spectroscopy. The conversion of phytosterols could reach above 96% in a very short time (30 min) under the following optimum conditions: 3% 1-butylsulfonate-3-methylimidazolium trifluoromethanesulfonate ([BSO₃HMim]OTf) as a catalyst, 110 °C and 1:1.75 M ratio of phytosterols to ethyl linolenate. The present method demonstrated that [BSO₃HMim]OTf would be a potential catalyst for phytosterol ester synthesis. Most importantly was that the oil solubility of phytosterol linolenate was much greater than its corresponding free phytosterols.