MOF-derived nanozyme CuOx@C and its application for cascade colorimetric detection of phytosterols.

Phytosterols (PSs), a class of naturally occurring bioactive lipid compounds, have been found to possess a significant cholesterol-lowering effect. In developing countries, the consumption of rapeseed oil is the primary pathway of PS intake for the general population. However, developing low-cost, real-time, and high-throughput screening techniques for PSs remains a challenge. Here, a Cu-based nanocomposite CuOx@C was synthesized via a simple method of the calcination of HKUST-1 and systematically characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The CuOx@C demonstrated excellent peroxidase-like (POD-like) activity, functioning as a peroxidase mimic to facilitate the catalysis of 3,3',5,5'-tetramethylbenzidine (TMB) into its oxidized form (oxTMB), thereby initiating a discernible color response. On the basis of this discovery, a CuOx@C-based colorimetric method for detecting total sterols in rapeseed was successfully constructed via cascade reactions. After optimizing the conditions, the high-throughput screening of total sterols in rapeseed could be completed in only 21 min, which significantly facilitated the sensing of PSs. A linear range of 0.6-6 mg/g was achieved for the detection of total sterols in rapeseed samples, thereby satisfying the requirements for detection. In addition, due to the high stability of CuOx@C and the specificity of cholesterol oxidase, the developed method had excellent stability and selectivity toward PSs, indicating that this work has huge prospects for commercial application. This innovative work overcomes the limitation of the instrumental method and provides a portable and reliable tool for total sterols detection. It can also facilitate the development of oilseeds with a high content of PSs.

Synthesis of a Side Chain Alkyne Analogue of Sitosterol as a Chemical Probe for Imaging in Plant Cells.

Clickable chemical tools are essential for studying the localization and role of biomolecules in living cells. For this purpose, alkyne-based close analogs of the respective biomolecules are of outstanding interest. Here, in the field of phytosterols, we present the first alkyne derivative of sitosterol, which fulfills the crucial requirements for such a chemical tool as follows: very similar in size and lipophilicity to the plant phytosterols, and correct absolute configuration at C-24. The alkyne sitosterol FB-DJ-1 was synthesized, starting from stigmasterol, which comprised nine steps, utilizing a novel alkyne activation method, a Johnson-Claisen rearrangement for the stereoselective construction of a branched sterol side chain, and a Bestmann-Ohira reaction for the generation of the alkyne moiety.

On the structural and mechanical properties of mixed coconut and olive oil oleogels and bigels.

The interaction of monoglycerides and phytosterols in olive- and coconut oil on the structuring of oleogels was analyzed. Specifically, bigels with gelatin hydrogel in different ratios (40:60 and 60:40 w/w) were formed. The physicochemical and microstructural attributes of these systems were assessed. The olive oil to coconut oil ratio (0-100 w/w) and the added oleogelators affected the crystal structure and the mechanical properties of the oleogels. Polarized light microscopy revealed that the addition of coconut oil created a denser triglycerides crystal network and the presence of phytosterols created more needle-like crystals, enhancing the textural properties of the oleogels and of the resulting bigels. The hardness of the oleogels ranged from 0.50 N to 1.24 N and for bigels was 5.96-36.75 N. Bigels hardness decreased as the oleogel ratio in the bigel increased. Microscopy and FTIR revealed that the addition of coconut oil in oleogels hampered the formation of a distinct crystalline monoglycerides network. Also, the absence of new peaks in the bigels indicated that the two structured phases interact with each other mostly physically, without the formation of new chemical bonds. Consequently, the oleogels and bigels developed, comprise a promising hard fat substitute with improved nutritional profile.

Supercritical CO2 Extraction of Fatty Acids, Phytosterols, and Volatiles from Myrtle (Myrtus communis L.) Fruit.

BACKGROUND: Myrtle (Myrtus communis L.) is a coastal Mediterranean aromatic medicinal plant rich in essential oil components, flavonoids, and phenolic acids. Studies highlight the potential health benefits of myrtle bioactive compounds with antioxidant and antiproliferative properties. Since limited research exists on myrtle fruit's lipid fraction, the aim of this study was to apply supercritical CO2 extraction to obtain bioactive compounds from myrtle berries focusing on the fatty acids, sterols, and essential oils. METHODS: The optimization of the supercritical CO2 extraction of myrtle fruit using CO2 as solvent was carried out using the response surface methodology with Box-Behnken experimental design. The following conditions were tested: temperature (40, 50, and 60 °C), pressure (200, 300, and 400 bar), and flow rate (20, 30, and 40 g min-1) on the yield of lipid extract as well as on the yield of fatty acids, phytosterols, and volatiles present in the extract and constituting its bioactive potential. RESULTS: In the extracts examined, 36 fatty acids, 7 phytosterols, and 13 volatiles were identified. The average yield of the extract was 5.20%, the most abundant identified fatty acid was essential cis-linolenic acid (76.83%), almost 90% of the total phytosterols were ß-sitosterol (12,465 mg kg-1), while myrtenyl acetate (4297 mg kg-1) was the most represented volatile compound. The optimal process conditions obtained allow the formulation of extracts with specific compositions.

Solving the Jigsaw puzzle of phytosterol diversity by a novel sterol methyltransferase from Zea mays.

Phytosterols are vital structural and regulatory components in plants. Zea mays produces a series of phytosterols that are specific to corn. However, the underline biosynthetic mechanism remains elusive. In this study, we identified a novel sterol methyltransferase from Z. mays (ZmSMT1-2) which showed a unique feature compared with documented plant SMTs. ZmSMT1-2 showed a substrate preference for cycloartenol. Using S-adenosyl-L-methionine (AdoMet) as a donor, ZmSMT1-2 converted cycloartenol into alkylated sterols with unique side-chain architectures, including Δ25(27) (i.e., cyclolaudenol and cycloneolitsol) and Δ24(25) (i.e., cyclobranol) sterols. Cycloneolitsol is identified as a product of SMTs for the first time. Our discovery provides a previously untapped mechanism for phytosterol biosynthesis and adds another layer of diversity of sterol biosynthesis.

Chitosan-coated soybean protein isolate/lecithin nanoparticles for enhancing the stability and bioaccessibility of phytosterol.

BACKGROUND: Phytosterols (PS) have various beneficial effects on human health, especially the property of reducing blood cholesterol. However, the low solubility and bioaccessibility of PS have greatly limited their application in functional food ingredients. RESULTS: To improve the bioaccessibility and stability of PS, chitosan-coated PS nanoparticles (CS-PNP) were successfully prepared by self-assembly. The properties of CS-PNP, including size, zeta potential, encapsulation efficiency (EE) and loading amount (LA) were characterised. The optimisation of CS concentration (0.4 mg mL-1) and pH (3.5) resulted in the formation of CS-PNP with an EE of over 90% and a particle size of 187.7 nm. Due to the special properties of CS chitosan, the interaction between CS and soybean protein isolate (SPI)/lecithin (SL) led to the formation of a soluble complex. CS-PNP exhibited good stability to temperature variations but was more sensitive to salt ions. During in vitro digestion, CS efficiently maintained the stability of nanoparticles against the hydrolysis of SPI by pepsin under acidic conditions. However, these nanoparticles tended to aggregate in a neutral intestinal environment. After 3 h of in vitro digestion, the bioaccessibility of PS increased from 18.2% of free PS to 63.5% of CS-PNP. CONCLUSION: Overall, these results highlight the potential of chitosan-coated nanoparticles as effective carriers for the oral administration of PS. This multilayer construction may serve as a promising for applications in food products as delivery vehicles for nutraceuticals. © 2024 Society of Chemical Industry.

Current and New Insights on Delivery Systems for Plant Sterols in Food.

Plant sterols are minor bioactive components of food lipids, which are often used for the formulation of functional foods due to their cholesterol-lowering properties. However, they have low solubility and tend to crystallize, which may affect their biological effects, the sensory profile of the sterol-enriched food, and its consumer acceptability. Moreover, due to the unsaturated structure of sterols, they are susceptible to oxidation, so different encapsulation systems have been developed to improve their dispersibility/solubility, stability, delivery, and bioaccessibility. This chapter provides an overview of the main encapsulation systems currently used for plant sterols and their application in model and food systems, with a particular focus on their efficiency and impact on sterol bioaccessibility.

In Situ Rapid Analysis of Squalene, Tocopherols, and Sterols in Walnut Oils Based on Supercritical Fluid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry.

Quantification of liposoluble micronutrients in large-scale vegetable oil samples is urgently needed, because their health benefits are increasingly emphasized. However, current analytical methods are limited to either labor-intensive preparation processes or time-consuming chromatography separation. In this work, an online oil matrix separation strategy for direct, rapid, and simultaneous determination of squalene, tocopherols, and phytosterols in walnut oil (WO) was developed on the basis of the lipid class separation mode of supercritical fluid chromatography. A single run was completed in 13 min containing 6 min of column cleaning and balancing. Satisfactory limit of detections (0.05-0.20 ng/mL), limit of quantifications (0.15-0.45 ng/mL), recoveries (70.61-101.44%), and matrix effects (78.43-91.62%) were achieved, indicating the reliability of this method. In addition, eight sterol esters were identified in WO, which have not previously been reported. The proposed method was applied to characterize the liposoluble micronutrient profile of WO samples obtained from different walnut cultivars, geographical origins, and processes.

Advances and Challenges in Plant Sterol Research: Fundamentals, Analysis, Applications and Production.

Plant sterols (PS) are cholesterol-like terpenoids widely spread in the kingdom Plantae. Being the target of extensive research for more than a century, PS have topped with evidence of having beneficial effects in healthy subjects and applications in food, cosmetic and pharmaceutical industries. However, many gaps in several fields of PS's research still hinder their widespread practical applications. In fact, many of the mechanisms associated with PS supplementation and their health benefits are still not fully elucidated. Furthermore, compared to cholesterol data, many complex PS chemical structures still need to be fully characterized, especially in oxidized PS. On the other hand, PS molecules have also been the focus of structural modifications for applications in diverse areas, including not only the above-mentioned but also in e.g., drug delivery systems or alternative matrixes for functional foods and fats. All the identified drawbacks are also superimposed by the need of new PS sources and technologies for their isolation and purification, taking into account increased environmental and sustainability concerns. Accordingly, current and future trends in PS research warrant discussion.

Towards the development of novel bicomponent phytosterol-based oleogels with natural phenolics.

Structuring liquid oils into edible oleogels from natural and abundant plant ingredients has great significance in fields ranging from foods to pharmaceuticals but has proven challenging. Herein, novel bicomponent phytosterol-based oleogels were developed with natural phenolics. Investigating diverse natural phenolics, cinnamic acid (CA) and ethyl ferulate (EF) successfully formed oleogels in combination with phytosterols (PS), where a synergistic effect on the oleogelation and crystallization was observed compared to the corresponding single component formulations. FTIR and UV-vis spectra showed that the gel network was primarily driven by hydrogen bonding and π-π stacking. Furthermore, oscillatory shear demonstrated oleogels featured higher elastic and network structure deformation at molar ratio of 5:5 and 3:7. Moreover, the bicomponent phytosterol-based oleogels displayed partially reversible shear deformation and a reversible solid-liquid transition. Such information was useful for engineering the functional properties of oleogel-based lipidic materials, providing significance for the application in foods, cosmetics and pharmaceuticals industries.

A targeted GC-MS/MS approach for the determination of eight sterols in microgreen and mature plant material.

Over the past decades, a remarkable number of scientific studies supported the correlation between an adequate dietary intake of phytosterols (PS) and the reduced risk of cardiovascular diseases. PS are known to inhibit the intestinal absorption of cholesterol, thus promoting the reduction of the low-density lipoproteins (LDL) amount in the bloodstream. Despite the fact that a non-negligible atherogenicity was recognized to PS, thus requiring a careful risk-benefits assessment for plant sterol supplementation, the potential role of PS as cholesterol-lowering agents has been contributing to the spreading awareness of the health benefits associated with the consumption of plant-based foods. In recent years, this has been fueling the market of innovative vegetable products, such as microgreens. Surprisingly, the recent literature concerning microgreens exhibited the lack of studies focusing on the characterization of PS. To fill this gap, a validated analytical method based on the hyphenation of gas chromatography and tandem mass spectrometry is proposed here for the quantitative analysis of eight phytosterols, namely ß-sitosterol, campesterol, stigmasterol, brassicasterol, isofucosterol, and cholesterol, lathosterol and lanosterol. The method was exploited for the characterization of the PS content in 10 microgreen crops, i.e., chia, flax, soybean, sunflower, rapeseed, garden cress, catalogna chicory, endive, kale and broccoli raab. Finally, these results were compared to the PS content of mature forms of kale and broccoli raab. A remarkable amount of PS was detected in chia, flax, rapeseed, garden cress, kale, and broccoli raab microgreens. 100 g (wet weight) of these microgreen crops were found to contain from 20 to 30 mg of the investigated PS. Interestingly, in the case of kale and broccoli raab microgreens, the overall PS content was higher than the one measured in the edible parts of the corresponding mature forms. Additionally, a symmetric change of the PS inner profile was observed between the two growth stages of the latter two crops. Here, the overall decrease of the PS sterol content in the mature forms was associated with the increase of the relative amount of ß-sitosterol and campesterol at the expense of minor PS species, such as brassicasterol.

Effects of food formulation on bioavailability of phytosterols: phytosterol structures, delivery carriers, and food matrices.

Daily intake of phytosterols (PSs) as a diet supplement can lower blood-cholesterol levels and reduce the risks of cardiovascular diseases. However, the high crystallinity, low water solubility, easy oxidizability, and other characteristics of PSs restrict their application and bioavailability in food products. The formulation parameters including the structures of PSs, delivery carriers, and food matrices may play an important role in the release, dissolution, transport, and absorption of PSs in functional foods. In this paper, the effects of formulation parameters, including phytosterol structures, delivery carriers, and food matrices, on the bioavailability of phytosterols are summarized and suggestions are provided for the formulation design of functional foods. The side chain and hydroxyl esterification group of PSs may significantly affect their lipid or water solubilities and micellization capacities, which in turn affect the bioavailability of PSs. Selecting suitable delivery carriers based on the characteristics of the food system can reduce the crystallinity and oxidation of PSs and control the release of PSs, thereby improving the PS stability and delivery efficiency. Moreover, the ingredients of the carriers or food products would also influence the release, solubility, transport, and absorption of PSs in the gastrointestinal tract (GIT).

A comprehensive update on phytochemistry, analytical aspects, medicinal attributes, specifications and stability of stigmasterol.

Phytosterols are bioactive substances naturally found in plant cell membranes, and their chemical structure is comparable to cholesterol found in mammalian cells. They are widely distributed in plant foods like olive oil, nuts, seeds, and legumes. Amongst the variety of phytosterols, stigmasterol is the vital compound found abundantly in plants. Numerous hormones, including estrogen, progesterone, corticoids and androgen, are synthesized by stigmasterol. Multiple in-vitro and in-vivo investigations have shown that stigmasterol has various biological effects, including antioxidant, anticancer, antidiabetic, respiratory diseases, and lipid-lowering effects. Experimental research on stigmasterol provides indisputable proof that this phytosterol has the potential to be employed in supplements used to treat the illnesses mentioned above. This substance has a high potential, making it a noteworthy medication in the future. Although several researchers have investigated this phytosterol to assess its prospective qualities, it has not yet attained therapeutic levels, necessitating additional clinical studies. This review offers a comprehensive update on stigmasterol, including chemical framework, biosynthesis, synthetic derivatives, extraction and isolation, analytical aspects, pharmacological profile, patent status, clinical trials, stability and specifications as per regulatory bodies.

Characterization of the cholesterol biosynthetic pathway in Dioscorea transversa.

Cholesterol is the precursor of bioactive plant metabolites such as steroidal saponins. An Australian plant, Dioscorea transversa, produces only two steroidal saponins: 1ß-hydroxyprotoneogracillin and protoneogracillin. Here, we used D. transversa as a model in which to elucidate the biosynthetic pathway to cholesterol, a precursor to these compounds. Preliminary transcriptomes of D. transversa rhizome and leaves were constructed, annotated, and analyzed. We identified a novel sterol side-chain reductase as a key initiator of cholesterol biosynthesis in this plant. By complementation in yeast, we determine that this sterol side-chain reductase reduces Δ24,28 double bonds required for phytosterol biogenesis as well as Δ24,25 double bonds. The latter function is believed to initiate cholesterogenesis by reducing cycloartenol to cycloartanol. Through heterologous expression, purification, and enzymatic reconstitution, we also demonstrate that the D. transversa sterol demethylase (CYP51) effectively demethylates obtusifoliol, an intermediate of phytosterol biosynthesis and 4-desmethyl-24,25-dihydrolanosterol, a postulated downstream intermediate of cholesterol biosynthesis. In summary, we investigated specific steps of the cholesterol biosynthetic pathway, providing further insight into the downstream production of bioactive steroidal saponin metabolites.

Impact of molecular interactions between hydrophilic phytosterol glycosyl derivatives and bile salts on the micellar solubility of cholesterol.

Hydrophilic phytosterol glycosyl derivatives are synthetic phytosterol analogues by coupling with the glycosyl moiety to improve the water solubility and bioaccessibility of free phytosterols. The aim of this study is to clarify the molecular interaction of phytosterol glycosyl derivatives with bile salts and the consequent impact on cholesterol solubilization. Sharp nonlinear decrease in the micellar solubility of cholesterol and accompanying changes in particle size, zeta potential and microtopography of mixed micelles were observed when phytosterol glycosyl derivatives were introduced in cholesterol-loaded bile salt micelles. These results suggested that ß-sitosterol glycosyl derivatives molecules indeed participated in the formation of mixed micelles. Further, nuclear magnetic resonance showed that the structural change of mixed micelles was caused by the insertion of ß-sitosterol glycosyl derivatives via hydrogen bonds with sodium taurocholate, which resulted in the low cholesterol solubilization. Moreover, the hydrogen-bond interactions were apparently influenced by the glycosyl moiety of ß-sitosterol glycosyl derivatives. These molecular mechanisms may contribute to the development of cholesterol-absorption inhibitors.

Soy proteins as vehicles for enhanced bioaccessibility and cholesterol-lowering activity of phytosterols.

BACKGROUND: The formulation of phytosterol (PS)-enriched functional foods has attracted increasing interest in the recent years, owing to its potential health effects. However, the poor solubility and bioavailability greatly limit PS application in this regard. This study investigated whether soy protein isolate (SPI) could effectively perform as a nanocarrier for improving the water solubility, bioaccessibility, and cholesterol-lowering activity of PSs. RESULTS: In this work, we fabricated SPI-PS nanocomplexes, which not only can enhance the stability and bioaccessibility of PS, but also improve the cholesterol-lowering ability of SPI. This improvement was mainly due to the formation of protein-active substance complexes, through hydrophobic interactions. The complexation with PSs resulted in formation of nanosized particles with greater sizes, lower ζ-potential, and higher surface hydrophobicity. The encapsulation efficiency, loading amount, and solubility of PS were closely related to the applied PS concentration in the mixed dispersions, and the maximal PS solubility in the aqueous phase reached about 1.63 mg mL-1 at the highest PS concentration (2.0 mg mL-1 ). The PS molecules in the nanocomplexes were mainly present in the amorphous form. The enhanced in vitro cholesterol-lowering activity of PS nanocomplexes relative to free PS seemed to be closely related to its higher bioaccessibility. CONCLUSION: The findings are of relevance for the development of food-grade PS ingredients suitable for the formulations of PS-enriched functional foods. © 2022 Society of Chemical Industry.

Protective effect of surfactant modified phytosterol oleogels on loaded curcumin.

BACKGROUND: Oleogels represent one of the most important carriers for the delivery of lipophilic nutraceuticals. Phytosterols (PS), plant-derived natural sterol compounds, are preferred for oleogel preparation due to their self-assembly properties and health function. However, the relationship between the physical properties of PS-based oleogels and the chemical stability of loaded bioactive compounds is still unclear. RESULTS: The influence of lecithin (LC) and glycerol monostearate (GMS) on the physical properties of PS-based oleogels made of liquid coconut oil and the stability of curcumin as a model bioactive loaded in the oleogels was investigated. Results showed that the flow consistency index was much higher for GMS-containing oleogels than that for LC-containing oleogels. The optical microscopy and X-ray scattering analysis showed that the addition of GMS in the PS oleogels promoted the formation of a crystal mixture with different crystal polymorph structures, whereas LC addition promoted the formation of needle-like crystals of PS. Using curcumin as a model lipophilic nutraceutical, the GMS-enriched PS oleogels with high crystallinity and flow consistency index exhibited a good retention ratio and scavenging activity of the loaded curcumin when stored at room temperature. CONCLUSION: This study shows that enhancing the firmness of oleogels made from PS and liquid coconut oil is beneficial to the retention and chemical stability of a loaded bioactive (curcumin). The findings of the study will boost the development of PS-based oleogel formulations for lipophilic nutraceutical delivery. © 2022 Society of Chemical Industry.

Controlled flavor release from high internal phase emulsions as fat mimetics based on glycyrrhizic acid and phytosterol.

Animal fat as the key component of sensory experience impacts texture, juiciness, and aroma pleasantness of meat, which indicates the necessity of designing fat mimetics in meat alternatives. In this study, high internal phase emulsions (HIPE) with tunable flavor release as fat mimetics based on glycyrrhizic acid (GA) and phytosterol were prepared, and the effects of GA and phytosterol concentrations on the microstructural, rheological, and flavor release properties of HIPE were evaluated. Phytosterol crystals-enriched oil droplets were trapped inside the GA fibrillar matrix as stabilizers. HIPE containing higher GA and phytosterol concentrations exhibited smaller droplet size and better viscoelastic attributes. Additionally, phytosterol played a synergistic role with GA to form a double-fiber microstructure at the oil-water interface. This hierarchical microstructure of oil phase, interface and aqueous phase in the HIPE could regulate the release of hydrophilic and lipophilic meat volatiles. HIPE as fat mimetics with unique microstructure have potential applications in meat alternatives.

Quantitation of 20 Phytosterols in 34 Different Accessions of Quinoa (Chenopodium quinoa).

Phytosterols were analyzed in 34 different quinoa accessions, which were obtained from the same field trial. Twenty different sterols were detected, and 17 could be structurally assigned by means of gas chromatography with mass spectrometry. Sterols were quantitated in selected ion monitoring mode (GC/MS-SIM) with the novel internal standard 3-O-tert-butyldimethylsilyl-cholestanol (cholestanyl-TBDMS). GC/MS-SIM response factors of minor sterols were determined after enrichment by countercurrent chromatography. The total sterol contents varied from 120 to 180 mg/100 g of seeds, which is higher than has been described in quinoa before. This was due to the fact that Δ7-sterols (e.g., Δ7-sitosterol, spinasterol, and Δ7-avenasterol) were quantitated for the first time in quinoa and contributed ∼64% to the total sterol content. Clustering allowed distributing of the 34 different quinoa accessions into four distinct groups on the basis of the different sterol patterns.

Impact of photosensitizers and light wavelength on photooxidation of phytosterols in soymilk emulsions.

The impact of photosensitizer and wavelength on photooxidation of phytosterols (PS) in soymilk and the oxidative stability of lipid and protein was determined. The oxidation of lipid and the consumption of dissolved oxygen showed a close relationship with PS oxidation. Riboflavin (Rb) leads to extra oxidation of both lipid and protein, and chlorophyll (Chl) prefer to absorb to and change the structure of protein. The influence of Rb and Chl on PS degradation under different wavelengths of light in the range of 365-665 nm was measured. Original soymilk emulsion placed under UVA (365-375 nm) and violet (400-410 nm) light underwent the most PS deterioration, whereas riboflavin was responsible for oxidation around blue (465-475 nm) region and extra formation of 6ß-OH sterols, and chlorophyll enriched emulsion was vulnerable under red (645-665 nm) light. The wavelength of light (UVA > violet > blue > green > red > yellow) showed a great different effect in oxidation of PS and formation of phytosterol oxidation products (POPs). The UVA, violet, blue and red light gives rise to the prior five kind oxides of phytosterol: 6α-OH, 7α-OH, 7ß-OH, 5,6ß-epoxy and 7-keto.