Linking phytosterols and oxyphytosterols from food to brain health: origins, effects, and underlying mechanisms

Molecular dynamics simulations of the interfacial behaviors and photo-oxidation of phytosterol under different emulsion oil content

Phytosterol, recognized for its health benefits, is predominantly extracted from plants and exhibits significantly reduced stability under varying light conditions. Their photooxidation is significantly influenced by emulsion interfaces. This study examined the mechanism of interface structure on phytosterol photooxidation with unparalleled molecular precision, utilizing molecular dynamics simulations and experimental procedures. Hydrogen bonding between the hydroxyl group at the C3 position of phytosterols and water molecules, coupled with van der Waals forces between the hydrophobic regions and the oil phase, induced phytosterol molecules to disperse toward the interface. The elevated polarity of the oil phase, specifically in tributyrin, facilitated the permeation of water molecules into the oil phase. This was achieved by diminishing the emulsion's interfacial tension, thereby fostering the development of more interface or micelles, and accelerating the photooxidation process of phytosterols. These simulations unraveled that the preponderance of phytosterol distribution is localized and oxidized at the oil-water interface.

Encapsulation of antioxidants with colloidal lipid particles for enhancing the photooxidation stability of phytosterol in Pickering emulsions

In order to prevent the photooxidation of phytosterols, a new type of Pickering emulsion was developed by regulating the oriented distribution of antioxidants in colloidal lipid particles (CLPs) at the oil-water interface. High-melting-point and low-melting-point lipids were tested to modulate their protective effect against phytosterols photooxidation. Results showed that CLPs could stabilize Pickering emulsion and encapsulate antioxidants, providing a dual functional delivery system for phytosterols protection. The Pickering emulsion formed had a particle size of around 350-820 nm, and the crystallization and melting temperatures of tripalmitin particles were approximately 32 °C and 63.8 °C, respectively. The addition of tributyrin or tricaprylin reduced the crystallization and melting temperatures of Pal CLPs and improved the photooxidation emulsion stability. The prepared Pickering emulsion remained stable for a maximum of 12 days under accelerated light-induced oxidation. Among all formulations, the emulsion primarily composed of tripalmitin CLPs, with added tributyrin and resveratrol, exhibited the highest photooxidation stability.

Phytosterols in human serum as measured using a liquid chromatography tandem mass spectrometry

Phytosterols are lipophilic compounds found in plants with structural similarity to mammalian cholesterol. They cannot be endogenously produced by mammals and therefore always originate from diet. There has been increased interest in dietary phytosterols over the last few decades due to their association with a variety of beneficial health effects including low-density lipoprotein cholesterol lowering, anti-inflammatory and anti-cancerous effects. They are proposed as potential moderators for diseases associated with the central nervous system where cholesterol homeostasis is found to be imperative (multiple sclerosis, dementia, etc.) due to their ability to reach the brain. Here we utilised an enzyme-assisted derivatisation for sterol analysis (EADSA) in combination with a liquid chromatography tandem mass spectrometry (LC-MSn) to characterise phytosterol content in human serum. As little as 100 fg of plant sterol was injected on a reversed phase LC column. The method allows semi-quantitative measurements of phytosterols and their derivatives simultaneously with measurement of cholesterol metabolites. The identification of phytosterols in human serum was based on comparison of their LC retention times and MS2, MS3 spectra with a library of authentic standards. Free campesterol serum concentration was in the range from 0.30-4.10 µg/mL, β-sitosterol 0.16-3.37 µg/mL and fucosterol was at lowest concentration range from 0.05-0.38 µg/mL in ten individuals. This analytical methodology could be applied to the analysis of other biological fluids and tissues.

Deciphering the effect of phytosterols on Alzheimer's disease and Parkinson's disease: the mediating role of lipid profiles

BACKGROUND

Studies have suggested that blood circulating phytosterols, plant-derived sterols analogous to cholesterol, were associated with blood lipid levels and the risk of Alzheimer's disease (AD) and Parkinson's disease (PD). This Mendelian randomization (MR) study is performed to determine the causal effect of circulating phytosterols on AD and PD and evaluate the mediation effect of blood lipids.

METHODS

Leveraging genome-wide association studies summary-level data for phytosterols, blood lipids, AD, and PD, univariable and multivariable MR (MVMR) analyses were conducted. Four types of phytosterols (brassicasterol, campesterol, sitosterol, and stigmasterol), three blood lipids parameters (high-density lipoprotein cholesterol [HDL-C], non-HDL-C, and triglyceride), two datasets for AD and PD were used. Inverse-variance weighted method was applied as the primary analysis, and false discovery rate method was used for adjustment of multiple comparisons.

RESULTS

Using the largest AD dataset, genetically proxied higher levels of stigmasterol (OR = 0.593, 95%CI = 0.431-0.817, P = 0.004) and sitosterol (OR = 0.864, 95%CI = 0.791-0.943, P = 0.004) significantly correlated with a lower risk of AD. No significant associations were observed between all four types of phytosterols levels and PD. MVMR estimates showed that the above causal associations were missing after integrating the blood lipids as exposures. Sensitivity analyses confirmed the robustness of these associations, with no evidence of pleiotropy and heterogeneity.

CONCLUSION

The study supports a potential beneficial role of blood stigmasterol and sitosterol in reducing the risk of AD, but not PD, which is dependent on modulating blood lipids. These insights highlight circulating stigmasterol and sitosterol as possible biomarkers and therapeutic targets for AD.

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.

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.

Stigmasterol regulates microglial M1/M2 polarization via the TLR4/NF-κB pathway to alleviate neuropathic pain

(Switching from the microglial M1 phenotype to the M2 phenotype is a promising therapeutic strategy for neuropathic pain (NP). This study aimed to investigate the potential use of stigmasterol for treating NP. In animal experiments, 32 male Sprague-Dawley rats were randomly divided into the sham operation group, chronic constriction injury (CCI) group, CCI + ibuprofen group, and CCI + stigmasterol group. We performed behavioral tests, enzyme-linked immunosorbent assay, hematoxylin-esoin staining (H&E) staining and immunohistochemistry, immunofluorescence, and Western blotting. In cell experiments, we performed flow cytometry, immunofluorescence, Western blotting, and qRT-PCR. Stigmasterol reduced thermal and mechanical hyperalgesia and serum IL-1β and IL-8 levels and increased serum IL-4 and TGF-β levels in CCI rats. Stigmasterol reduced IL-1β, COX-2, and TLR4 expression in the right sciatic nerve and IL-1β expression in the spinal cord. Stigmasterol reduced the expression of Iba-1, TLR4, MyD88, pNF-κB, pP38 MAPK, pJNK, pERK, COX-2, IL-1β, and CD32 in the spinal cord of CCI rats while increasing the expression of IL-10 and CD206. Stigmasterol decreased M1 polarization markers and increased M2 polarization markers in lipopolysaccharide (LPS)-induced microglia and decreased the expression of Iba-1, TLR4, MyD88, pNF-κB, pP38 MAPK, pJNK, pERK, iNOS, COX-2, and IL-1β in LPS-treated microglia while increasing the expression of Arg-1 and IL-10. Stigmasterol regulates microglial M1/M2 polarization via the TLR4/NF-κB pathway to alleviate NP.

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.

A fast ultra performance supercritical fluid chromatography-tandem mass spectrometric method for profiling of targeted phytosterols

Phytosterols are essential structural components of plant cell membranes and possess health-related benefits, including lowering blood cholesterol levels in humans. Numerous analytical methods are being used to profile plant and animal sterols. Chromatography hyphenated to tandem mass spectrometry, is a better option due to its specificity, selectivity, and sensitivity. An ultra-performance supercritical fluid chromatography hyphenated with atmospheric pressure chemical ionization (APCI) tandem mass spectrometric method was developed and evaluated for fingerprint analysis of seven phytosterols. Mass spectrometry fragmentation behavior was used for phytosterol identification, and multiple reaction monitoring scanning was utilized for phytosterol confirmation, where APCI outperformed superiority in terms of ion intensity, particularly in the production of [M + H-H₂O]⁺ ions rather than [M + H]⁺ ions. The chromatographic conditions were thoroughly evaluated, and the ionization parameters were optimized as well. In a 3 min. run, the seven phytosterols were separated concurrently. The calibration and repeatability tests were conducted to check the instrument's performance, and the results indicated that all of the phytosterols tested had correlation coefficients (r²) greater than 0.9911 over the concentration range of 5-5000 ng/mL. The limit of quantification was below 20 ng/mL for all the tested analytes except for stigmasterol and campesterol. The partially validated method was applied for the evaluation of phytosterols in pure coconut oil and palm oil in order to demonstrate its applicability. Total sterols in coconut and palm oils were 126.77 ng/mL and 101.73 ng/mL, respectively. In comparison to earlier methods of phytosterol analysis, the novel method offers a far faster, more sensitive, and more selective analytical process.

Mechanistic Insights into the Neuroprotective Potential of Sacred Ficus Trees

Ficus religiosa (Bo tree or sacred fig) and Ficus benghalensis (Indian banyan) are of immense spiritual and therapeutic importance. Various parts of these trees have been investigated for their antioxidant, antimicrobial, anticonvulsant, antidiabetic, anti-inflammatory, analgesic, hepatoprotective, dermoprotective, and nephroprotective properties. Previous reviews of Ficus mostly discussed traditional usages, photochemistry, and pharmacological activities, though comprehensive reviews of the neuroprotective potential of these Ficus species extracts and/or their important phytocompounds are lacking. The interesting phytocompounds from these trees include many bengalenosides, carotenoids, flavonoids (leucopelargonidin-3-O-β-d-glucopyranoside, leucopelargonidin-3-O-α-l-rhamnopyranoside, lupeol, cetyl behenate, and α-amyrin acetate), flavonols (kaempferol, quercetin, myricetin), leucocyanidin, phytosterols (bergapten, bergaptol, lanosterol, β-sitosterol, stigmasterol), terpenes (α-thujene, α-pinene, β-pinene, α-terpinene, limonene, β-ocimene, β-bourbonene, β-caryophyllene, α-trans-bergamotene, α-copaene, aromadendrene, α-humulene, alloaromadendrene, germacrene, γ-cadinene, and δ-cadinene), and diverse polyphenols (tannin, wax, saponin, leucoanthocyanin), contributing significantly to their pharmacological effects, ranging from antimicrobial action to neuroprotection. This review presents extensive mechanistic insights into the neuroprotective potential, especially important phytochemicals from F. religiosa and F. benghalensis. Owing to the complex pathophysiology of neurodegenerative disorders (NDDs), the currently existing drugs merely alleviate the symptoms. Hence, bioactive compounds with potent neuroprotective effects through a multitarget approach would be of great interest in developing pharmacophores for the treatment of NDDs.

Simultaneous Analysis of Free/Combined Phytosterols in Rapeseed and Their Dynamic Changes during Microwave Pretreatment and Oil Processing

Here, a simple, efficient, and rapid solid phase extraction-gas chromatography (SPE–GC) method was developed for the simultaneous analysis of free/combined phytosterols in rapeseed and their dynamic changes during microwave pretreatment and oil processing. First, by comparing different methods for extracting free/combined phytosterols from rapeseed and rapeseed cake, the Folch method was considered to be the optimal method and was selected in subsequent experiments. Subsequently, the extraction method was validated by determining the recoveries of standards (brassinosterol, campesterol, β-sitosterol and cholesteryl oleate) spiked in rapeseed and rapeseed oil samples, and the recoveries were in the range from 82.7% to 104.5% and 83.8% to 116.3%, respectively. The established method was applied to study the dynamic changes of the form and content of phytosterols in rapeseed and its products (rapeseed oil and cake) during rapeseed microwave pretreatment and the oil production process. Additionally, the results showed that more than 55% of the free/combined phytosterols in rapeseed were transferred to rapeseed oil during the oil processing, and this proportion will increase after microwave pretreatment of rapeseed. This work will provide analytical methods and data support for a comprehensive understanding of phytosterols in rapeseed and its products during oil processing.

Ecological lipidology

Dietary lipids (DLs), particularly sterols and fatty acids, are precursors for endogenous lipids that, unusually for macronutrients, shape cellular and organismal function long after ingestion. These functions – cell membrane structure, intracellular signalling, and hormonal activity – vary with the identity of DLs, and scale up to influence health, survival, and reproductive fitness, thereby affecting evolutionary change. Our Ecological Lipidology approach integrates biochemical mechanisms and molecular cell biology into evolution and nutritional ecology. It exposes our need to understand environmental impacts on lipidomes, the lipid specificity of cell functions, and predicts the evolution of lipid-based diet choices. Broad interdisciplinary implications of Ecological Lipidology include food web alterations, species responses to environmental change, as well as sex differences and lifestyle impacts on human nutrition, and opportunities for DL-based therapies.

The dopaminergic neuroprotective effects of different phytosterols identified in rice bran and rice bran oil

Phytosterols are important bioactive compounds in rice bran and rice bran oil, and the compositions of different phytosterols in rice bran and rice bran oil were investigated in our previous research. In this study, the dopaminergic neuroprotective effects and the underlying mechanisms of sitosterol, cycloartenyl ferulate, 24-methylenecycloartanyl ferulate and campesteryl ferulate identified in rice bran and rice bran oil were investigated in a rotenone-treated C. elegans model. The results indicated that the increased oxidative stress resistance induced by the activation of the DAF-16/FOXO pathway and the inhibition of the apoptotic protein CED-3 overexpression might play an important role in protecting the dopaminergic neurons. The results of this research reveal a new bioactivity of different phytosterols and are helpful for the further nutritional evaluation of rice bran and rice bran oil.

Sterols and Sterol Oxidation Products: Effect of Dietary Intake on Tissue Distribution in ApoE-Deficient Mice

Sterols and sterol oxidation products (SOPs) are well-known dietary factors influencing atherosclerosis; however, their distribution in vivo after dietary sterol/SOP intake is still unclear. Here, we investigated the tissue distribution of sterols and SOPs in ApoE^-/- mice after dietary exposure to diets supplemented with phytosterols (PS), phytosterol oxidation products (POPs), or cholesterol oxidation products (COPs). The results showed that PS intake reduced cholesterol in serum and the liver but increased cholesterol in the brain. PS intake increased the levels of PS in vivo and the levels of 7-keto- and triol-POPs in serum and the liver. COP intake elevated the level of all COPs in serum but did not change the 7-keto-cholesterol level in the liver and brain. All POPs in serum and parts of POPs in the liver and brain increased after dietary POP exposure. Our study indicated that dietary PS and SOPs accumulated in vivo with varying degrees and influenced cerebral cholesterol metabolism.