Total Sterol Content Research Articles

Virgin Olive oil Authenticity Assays in a Single Run Using Two-Dimensional Liquid Chromatography-High Resolution Mass Spectrometry.

Sterols and triterpenic alcohol analyses are one of the officially established parameters for assessing the authenticity of virgin olive oil (VOO). Most of the applications described for sterol analysis, including the official method, only allow the determination of the total sterol content but not its distribution in free or esterified form. This work proposes a two-dimensional liquid chromatography/high-resolution mass spectrometry (2D-LC-HRMS) method for the simultaneous analysis of triterpenic alcohols, free sterols and steryl esters. A reversed phase liquid chromatography (RPLC)-RPLC coupling was performed through a multiple heart-cutting interface equipped with an active solvent modulation (ASM) valve. Additionally, a selection valve was coupled to the 2D-LC system, allowing the simultaneous data acquisition from both dimensions in a single analysis. A simplified sample treatment based on solid phase extraction was also proposed to avoid tedious steps such as saponification or derivatization before gas chromatography analysis. To evaluate the content of these compounds in different olive oil categories, the proposed 2D-LC-HRMS system was applied to a set of samples from different commercial olive oil categories (extra virgin olive oil, virgin olive oil, olive oil, pomace olive oil) and sunflower oil. The results revealed significant differences in the distribution of free and esterified sterols of the analyzed samples, highlighting the free/esterified sterol ratio as a powerful tool to unveil olive oil fraud practices and fat manipulation.

Phytosterol Depletion in Soybean Oil Using a Synthetic Silica Adsorbent

Phytosterols in vegetable oils have gained attention for their nutritional benefits in foods and food supplements. However, the use of vegetable oils in emulsions for infant formulas and parenteral nutrition has raised some concerns, as phytosterols may contribute to phytosterolemia in the case of infant formulas and, in a second scenario, to parenteral nutrition-associated liver disease. The present study proposes removing phytosterols from soybean oil using a synthetic amorphous silica Trisyl® (E551) as an adsorbent material. The process is simple and involves stirring the oil at a high temperature under vacuum conditions followed by filtration to remove the adsorbent. A rotational factorial design of experiments, considering the adsorbent/oil ratio, temperature, and time was carried out to determine the optimal conditions. Additionally, the effects on tocopherols levels and formation of trans fatty acids were explored. The total sterol content in the initial refined soybean oil was 2540 mg/kg, with 32% in ester form (813 mg/kg). The treatments effectively reduced the sterol concentration, achieving a reduction of nearly 70% when 10% Trisyl®, 140 °C, and a 90-min treatment were applied. Under these conditions, nearly 80% of the oil was recovered. Campesterol and stigmasterol levels were almost halved. Tocopherol losses were found to be below 20%. Thermal degradation, as analyzed by triacylglycerol polymers and trans fatty acids, was not observed in the treatments.

Effect of Andean Lupin (Lupinus mutabilis) genotype and harvest altitude on the chemical composition and nutritional quality of flours

Andean Lupin (Lupinus mutabilis S.) or tarwi, a legume cultivated in the Andean region of South America, is considered a protein source. In this work, flours were prepared from different Andean Lupin genotypes, namely Cholo Fuerte (CHF), Común (CM), or Altagracia (ALT), grown at 2700 (1) or 3300 (2) meters above sea level. The effect of genotype and growth altitude on the chemical composition, color, phytochemical (alkaloids, free phenolics, fatty acids, and sterols) content, antioxidant activity, and microbiological quality of the flours was evaluated. CM-1 flour had higher protein, polyunsaturated fatty acid (PUFA), and Δ5-avenasterol content. CHF-1 flour had higher crude fiber, Δ7-campesterol, clerosterol, and saturated fatty acid (SFA) content and higher antioxidant activity. ALT-2 flour had the highest total sterol content, particularly stigmasterol and β-sitosterol. None of the flours contained alkaloids or microorganisms, confirming that the preparation process was efficient. Andean Lupin cultivated at high and low altitude provides flour with high phytosterol and PUFA content, respectively. CM-1 flour has potential use in the food and nutraceutical industry due to its higher protein, essential fatty acid or PUFA, and total sterol content as well as low SFA content.

Integrating QTL mapping and transcriptomics to decipher the genetic architecture of sterol metabolism in Brassica napus L.

Sterols are secondary metabolites commonly found in rapeseed that play crucial physiological roles in plants and also benefit human health. Consequently, unraveling the genetic basis of sterol synthesis in rapeseed is highly important. In this study, 21 individual sterols as well as total sterol (TS) content were detected in a double haploid (DH) population of Brassica napus, and a total of 24 quantitative trait loci (QTL) and 157 mQTL were identified that were associated with TS and different individual sterols. Time-series transcriptomic analysis showed that the differentially expressed genes (DEGs) involved in sterol and lipid biosynthesis pathways were enriched. Additionally, a regulatory network between sterol-related DEGs and transcription factors (TFs) was established using coexpression analysis. Some candidate genes were identified with the integration of transcriptomic analysis and QTL mapping, and the key candidate gene BnSQS1.C03 was selected for further functional analysis. BnSQS1.C03 demonstrated squalene synthase activity in vitro and increased the TS by 3.8% when overexpressed in Arabidopsis. The present results provide new insights into sterol regulatory pathways and a valuable genetic basis for breeding rapeseed varieties with high sterol content in the future.

Effect of Pulsed Electric Field Pretreatment on the Concentration of Lipophilic and Hydrophilic Compounds in Cold-Pressed Grape Seed Oil Produced from Wine Waste.

Pretreatment of grape pomace seeds with a pulsed electric field (PEF) was applied to improve the extraction yield of cold-pressed grape seed oil. The effects of different PEF conditions, electric field intensities (12.5, 14.0 and 15.6 kV/cm), and durations (15 and 30 min) on the oil chemical composition were also studied. All PEF pretreatments significantly increased the oil yield, flow rate and concentration of total sterols (p < 0.05). In addition, similar trends were observed for total tocochromanols and phenolic compounds, except for PEF pretreatment under the mildest conditions (12.5 kV/cm, 15 min) (p < 0.05). Notably, the application of 15.6 kV/cm for 30 min resulted in the highest relative increase in oil yield and flow rate (29.6% and 56.5%, respectively) and in the concentrations of total tocochromanols, nonflavonoids, and flavonoids (22.1%, 60.2% and 81.5%, respectively). In addition, the highest relative increase in the concentration of total sterols (25.4%) was achieved by applying 12.5 kV/cm for 30 min. The fatty acid composition of the grape seed oil remained largely unaffected by the PEF pretreatments. These results show that PEF pretreatment effectively improves both the yield and the bioactive properties of cold-pressed grape seed oil.

Valorization of waste seashells for neutralization of sunflower oil

In this study, an investigation was conducted to explore the potential of utilizing calcium oxide (CaO) derived from carbonized seashells for the purpose of acid removal. Consequently, the objective of this research is to develop an alternative bio-material to be employed in the neutralization process. The CaO produced was compared to the conventional utilization of caustic (NaOH) based on various parameters related to oil quality. It was observed that the removal rates of free fatty acid content using CaO and NaOH were 61% and 85% respectively. Furthermore, it was determined that the use of CaO did not result any adverse effects on the composition of sterols and fatty acids during the neutralization process. On the contrary, the preservation of total sterol content was superior in comparison to NaOH. The neutralization loss observed with CaO was comparable to that of NaOH. Consequently, CaO demonstrates promise as an alkaline substitute for acid removal in vegetable oils. Additionally, it is well-suited for implementation under minimal process conditions, which have become increasingly popular in recent years.

Chemical Profile of Cold-Pressed Beech Nut (Fagus sylvatica L.) Oil

The objective of this study was to assess the chemical characteristics of cold-pressed beech nut oil. The nuts, gathered from the forest, comprised 25.35% water, 13.19% oil, and 19.40% protein. The predominant fatty acid was linoleic acid (40.5%), followed by oleic acid (35.0%) and gondoic acid (7.7%). All four tocopherols were present in the oil, with γ-tocopherol being the dominant form at 99.38 mg per 100 g of oil. The total sterol content was 2708.73 mg per kg of oil, with β-sitosterol constituting 80.5% of all sterols. The main characteristics of the oil included its relatively high tocopherol and gondoic acid content, a dominant oleic–linoleic fatty acid profile, and elevated levels of carotenoids.

Flavor enhancement of strong fragrant rapeseed oils by enzymatic treatment

Fragrant rapeseed oils with the sensory characteristics attract increasing market in China. The unique flavor of strong fragrant rapeseed oil (SFRO) is the first choice to attract the consumers’ preference. Thus, enzymatic treatments of rapeseeds were used to enhance the flavor properties of SFROs in the present study. Results showed that SFRO produced from neutral protease and α-amylase-treated rapeseeds (NRO+ARO) had the highest percentages of unsaturated fatty acid (USFA), monounsaturated fatty acid (MUSFA) and oleic acid (C18:1) of 93.30%, 65.90% and 65.22%, respectively, with the highest tocopherol content of 577.35 mg/kg and total sterol content of 4523.46 mg/kg. The NRO+ARO showed a strong nutty and rich roasted fragrance and distinguishing sweet flavor with the highest overall sensory evaluation score. Majority of volatile compounds in NRO+ARO belonged to pyrazines and furans originated from Maillard reactions with the highest contents. The highest decrease trends of monosaccharide and amino acid contents from 8.42 g/kg to 2.04 g/kg and from 128.91 mg/kg to 47.39 mg/kg, respectively, were observed in the neutral protease and α-amylase-treated rapeseeds after roasting. Glucose/xylose-lysine reaction products contained the high contents of pyrazines, suggesting enhancement of supply of glucose/xylose and lysine in rapeseeds would significantly improve the fragrance of SFROs. The outputs of present study would provide a clue to understand the formation of unique flavor of SFROs and a reference to develop series of SFRO products.

Lipid composition and physicochemical parameters of unrefined sunflower oil

Unrefined sunflower oil is obtained by pressing of the sunflower seeds and subsequent fine filtration. It contains more biologically active substances compared to the refined one, it is more stable to oxidation processes, for that reason it is widely used in the composition of the various food products. The main acids in the oil are oleic (56.5%), linoleic (31.7%), palmitic (6.4%), and stearic acid (3.2%). Total sterol content is 0.7%, with ß-sitosterol as a main component (84.0%). The quantity of tocopherol is 188 mg/kg and it consists of one compound α-tocopherol (100%). Different physicochemical parameters were obtained at temperature ranges (from 20 to 80°C). The values of these parameters decrease with an increase in temperature, density (from 0.938 to 0.901 g/ml), surface tension (from 44.124 to 31.787 mN/m), dynamic viscosity (from 29.195 to 14.913 mPa.s), and kinematic viscosity (from 31.125 to 16.552 mm2/s). All these changes are in confirmation of the data from the literature and are relevant in our next studies.

Effect of enzymatic Maillard reaction conditions on physicochemical properties, nutrition, fatty acids composition and key aroma compounds of fragrant rapeseed oil.

A new enzymatic hydrolysis-based process inspired by the Maillard reaction can produce strong flavored, high-value rapeseed oil that meets safety requirements. In the present study, the effect of reaction time (10-30 min) and temperature (130-160 °C) on the physicochemical properties, nutritional status, fatty acids composition and key aroma compounds of fragrant rapeseed oil (FRO) was investigated. An increasing reaction time and temperature substantially decreased the total tocopherol, polyphenol and sterol contents of FRO, but increased benzo[a]pyrene content, as well as the acid and peroxide values, which did not exceed the European Union legislation limit. Among the volatile components, 2,5-dimethyl was the main substance contributing to the barbecue flavor of FRO. The 150 °C for 30 min reaction conditions produced a FRO with a strong, fragrant flavor, with high total tocopherol (560.15 mg kg-1 ), polyphenol (6.82 mg kg-1 ) and sterol (790.65 mg kg-1 ) contents; acceptable acid (1.60 mg g-1 ) and peroxide values (4.78 mg g-1 ); and low benzo[a]pyrene (1.39 mg g-1 ) content. These were the optimal conditions for the enzymatic Maillard reaction, according to the principal component analysis. Furthermore, hierarchical cluster analysis showed that reaction temperature had a stronger effect on FRO than reaction time. The optimal enzymatic Maillard reaction conditions for the production of FRO are heating at 150 °C for 30 min. These findings provide new foundations for better understanding the composition and flavor profile of FRO, toward guiding its industrial production. © 2023 Society of Chemical Industry.

Enzymatic methods for the preparation of fragrant rapeseed oil: Effect of reducing sugars on flavor production using the Maillard reaction

This study investigated the effects of different reducing sugars (glucose, fructose, and maltose) on quality and flavor during the enzymatic preparation of fragrant rapeseed oils (FROs) through Maillard reaction. The FROs was determined using sensory and physiochemical analyses. The fructose group had a reasonable fatty acid composition, lower acid value (1.28 mg/g), peroxide value (0.12 g/100g), moisture (0.08%), and benzo(a)pyrene content (1.43 μg/kg); higher total tocopherol content (597.78 mg/kg), sterol content (790.00 mg/kg), and sensory evaluation score (3.81 score); a sweeter nutty/toasted flavor and a weaker spicy flavor. The flavor was attributed to the presence of furfural, a sweet-tasting compound, and the nitrile content, which was responsible for the spicy flavor, was lower than that of traditional FROs, resulting in weaker spiciness. Overall, the results suggest that fructose is the best reducing sugar for enzymatic preparation of FROs, providing key directives for the industrial production of FROs.

Lipid Composition and Physicochemical Parameters of Flaxseed Oil (Linum usitatissimum L.) from Bulgaria

Flaxseed oil is a prevalent food supplement. On one hand, vegetable oil is used in the food industry and pharmacy due to its health benefits; on the other hand, it has an application as a lubricant oil. The fatty acid composition of the investigated oil was determined as follows: the main fatty acids were α-linolenic (57.5%), oleic (17.5%), linoleic (12.5%), palmitic (6.0%), and stearic acid (4.3%). The content of unsaponifiable matter was 1.4%. The total sterol content was determined (0.5%), with identified β-sitosterol (79.7%) as a main component, followed by stigmasterol. The content of tocopherols was found to be 243 mg/kg. The compound γ-tocopherol predominated (68%) in the tocopherol fraction, followed by γ-tocotrienol (32%). Some physicochemical indicators were also determined—density, surface tension, and dynamic and kinematic viscosity—at the following temperatures: 20, 30, 40, 50, 60, 70, and 80 °C. The increase in temperature led to a decrease in all indexes and good linear dependence was observed. The determined physicochemical indicators provided information about the stability of flaxseed oil, which is very important considering its use in food and technical products.

Maturity impact on physicochemical composition and polyphenol properties of extra virgin olive oils obtained from Manzanilla, Arbequina, and Koroneiki varieties in Iran.

This study investigated the physicochemical properties and polyphenol composition of extra virgin olive oils (EVOOs) extracted from three olive cultivars. The investigated cultivars were Arbequina, Koroneiki, and Manzanilla, grown in Olive Research Station in Rudbar county, Gilan province, Iran, at three ripening stages. Several parameters were analyzed, including peroxide and acidity values, unsaponifiable matter, oxidative stability, total aliphatic alcohols, fatty acids (FAs), sterols, and triacylglycerol composition. The results showed that as maturity increased, parameters such as oil content, acidity value, and iodine value, rise, while parameters including peroxide value, oxidative stability, aliphatic alcohols, and unsaponifiable matter decreased (p < .05). The saponification value was slightly reduced in the developing ripening process (p > .05). The MUFA/PUFA ratio and total sterol content declined during the olive ripening stages (p < .05). The triterpenes decreased in Arbequina and Koroneiki cultivars but increased in Manzanilla cultivar during the maturity stages. According to the data, oleuropein decreased while oleuropein aglycone, oxidized aldehyde, and hydroxylic form of oleuropein increased for all EVOOs during maturation. Apigenin, quercetin, ligstroside aglycone, aldehyde and hydroxylic form, ferulic acid, caffeic acid, and catechin decreased during the ripening of fruits (p < .05). The main triglycerides were triolein (OOO), palmitodiolein (POO), dioleolinolein (OOL), and palmitooleolinolein (PLO) in all EVOOs. In addition, the olive cultivar and harvesting date influence the physicochemical properties and polyphenol composition of EVOOs extracted from olive varieties grown in one region. In conclusion, the results can present helpful information to determine the optimum maturity stage for the investigated olive cultivars.

The Impact of Growth Years on the Medicinal Material Characteristics and Metabolites of Stellaria dichotoma L. var. lanceolata Bge. Reveals the Optimal Harvest Age.

The original plant of Chinese medicine Stellariae Radix (Yin Chai Hu) is Stellaria dichotoma L. var. lanceolata Bge (abbreviated as SDL). SDL is a perennial herbaceous plant and a characteristic crop in Ningxia. Growth years are vital factors that affect the quality of perennial medicinal materials. This study aims to investigate the impact of growth years on SDL and screen for the optimal harvest age by comparing the medicinal material characteristics of SDL with different growth years. Additionally, metabolomics analysis using UHPLC-Q-TOF MS was employed to investigate the impact of growth years on the accumulation of metabolites in SDL. The results show that the characteristics of medicinal materials and the drying rate of SDL gradually increase with the increase in growth years. The fastest development period of SDL occurred during the first 3 years, after which the development slowed down. Medicinal materials characteristics of 3-year-old SDL exhibited mature qualities with a high drying rate, methanol extract content, and the highest content of total sterols and total flavonoids. A total of 1586 metabolites were identified, which were classified into 13 major classes with more than 50 sub-classes. Multivariate statistical analysis indicated significant differences in the diversity of metabolites of SDL in different growth years, with greater differences observed in metabolites as the growth years increased. Moreover, different highly expressed metabolites in SDL at different growth years were observed: 1-2 years old was beneficial to the accumulation of more lipids, while 3-5 years old was conducive to accumulating more alkaloids, benzenoids, etc. Furthermore, 12 metabolites accumulating with growth years and 20 metabolites decreasing with growth years were screened, and 17 significantly different metabolites were noted in 3-year-old SDL. In conclusion, growth years not only influenced medicinal material characteristics, drying rate, content of methanol extract, and total sterol and flavonoid contents, but also had a considerable effect on SDL metabolites and metabolic pathways. SDL planted for 3 years presented the optimum harvest time. The screened significantly different metabolites with biological activity, such as rutin, cucurbitacin e, isorhamnetin-3-o-glucoside, etc., can be utilized as potential quality markers of SDL. This research provides references for studying the growth and development of SDL medicinal materials, the accumulation of metabolites, and the selection of optimal harvest time.

Evaluation of Selected Medicinal, Timber and Ornamental Legume Species' Seed Oils as Sources of Bioactive Lipophilic Compounds.

Bioactive lipophilic compounds were investigated in 14 leguminous tree species of timber, agroforestry, medicinal or ornamental use but little industrial significance to elucidate their potential in food additive and supplement production. The tree species investigated were: Acacia auriculiformis, Acacia concinna, Albizia lebbeck, Albizia odoratissima, Bauhinia racemosa, Cassia fistula, Dalbergia latifolia, Delonix regia, Entada phaseoloides, Hardwickia binata, Peltophorum pterocarpum, Senegalia catechu, Sesbania sesban and Vachellia nilotica. The hexane-extracted oils of ripe seeds were chromatographically analysed for their fatty acid composition (GC-MS), tocochromanol (RP-HPLC/FLD), squalene and sterol (GC-FID) content. A spectrophotometrical method was used to determine total carotenoid content. The results showed generally low oil yield (1.75-17.53%); the highest was from H. binata. Linoleic acid constituted the largest proportion in all samples (40.78 to 62.28% of total fatty acids), followed by oleic (14.57-34.30%) and palmitic (5.14-23.04%) acid. The total tocochromanol content ranged from 100.3 to 367.6 mg 100 g-1 oil. D. regia was the richest and the only to contain significant amount of tocotrienols while other oils contained almost exclusively tocopherols, dominated by either α-tocopherol or γ-tocopherol. The total carotenoid content was highest in A. auriculiformis (23.77 mg 100 g-1), S. sesban (23.57 mg 100 g-1) and A. odoratissima (20.37 mg 100 g-1), and ranged from 0.7 to 23.7 mg 100 g-1 oil. The total sterol content ranged from 240.84 to 2543 mg 100 g-1; A. concinna seed oil was the richest by a wide margin; however, its oil yield was very low (1.75%). Either β-sitosterol or Δ5-stigmasterol dominated the sterol fraction. Only C. fistula oil contained a significant amount of squalene (303.1 mg 100 g-1) but was limited by the low oil yield as an industrial source of squalene. In conclusion, A. auriculiformis seeds may hold potential for the production of carotenoid-rich oil, and H. binata seed oil has relatively high yield and tocopherol content, marking it as a potential source of these compounds.

Effects of Trace Elements on Traits and Functional Active Compounds of Camellia oleifera in Nutrient-Poor Forests

Camellia oleifera is a major woody oilseed species in China, but it is typically cultivated in nutrient-poor soils and may be affected by various trace elements. This study examined how spraying selenium, boron, and zinc trace elements affected the traits and functional active compounds of C. oleifera under nutrient deficiency. The results revealed significant variations in the effects of different trace element combinations on C. oleifera. Optimal concentrations of zinc and selenium are critical for promoting the growth and development of C. oleifera fruit. The transverse diameter of the fruit, the single fruit weight, the number of seeds per fruit, the single fresh seed weight, the oil content in the fruit, and the oil yield per plant of other treatments can be increased by up to 3.07%, 10.57%, 23.66%, 30.23%, 7.94%, and 21.95%, respectively, at most, compared to the control group. Diluting zinc from 1000 to 1500 times and maintaining a selenium concentration from 100 to 200 mg/L has been found to be beneficial for fruit growth. While low concentrations of selenium may promote an increase in fruit transverse diameter, high concentrations of selenium, along with high dilutions of zinc, can have the opposite effect, leading to a reduction in fruit diameter. However, a high concentration of selenium can positively impact the number of seeds per fruit. The most effective combination was found to be a selenium concentration of 0 mg/L, a boron concentration of 4 mg/L, and a zinc dilution of 1500. Interestingly, lower concentrations of selenium and boron, as well as lower dilutions of zinc, were found to increase the oil yield per plant. This suggests that a careful balance of trace elements is required to promote both fruit growth and oil content. The total sterol, squalene, total flavonoid, and polyphenol content of other treatments can be increased by up to 28.81%, 32.07%, 188.04%, and 92.61%, respectively, at most, compared to the control group. Selenium fertilizer and boron fertilizer increased the total sterol content in Camellia oil and had a significant positive correlation at the 0.01 level, but zinc fertilizer had little influence on it. High concentration selenium fertilizer generally increased the squalene, total flavonoid, and polyphenol content in Camellia oil, but boron and zinc fertilizers had little effect on these components. The results suggested that choosing appropriate fertilizer combinations could improve nutrient deficiency in C. oleifera and enhance the functional active compounds of its oil, thereby enhancing its value.

Wild nettle (Urtica dioica L.) root: Composition of phytosterols and pentacyclic triterpenes upon habitat diversity

Nettle (Urtica dioica L.) root is a well-known source of valuable phytosterols, however scientific data regarding their composition are scarce. Therefore, this study aimed to examine the profile of phytosterols and triterpenes in nettle root (12 samples) harvested in three different climate regions and to provide more detailed information on the profile of nettle root lipophilic extract. Nettle root samples were extracted using n-hexane, while detection and quantification of phytosterols and triterpenes was achieved by GC–MS. Average content of total sterols was 0.80–0.86 g kg−1 dry weight and total pentacyclic triterpenes (PT) of 0.0048–0.0070 g kg−1. A total of 10 sterols and 3 PT were detected. The dominant sterol in all samples was β-sitosterol, followed by campesterol and stigmasterol. Lower quantities of Δ7 sterol - citrostadienol were detected. The dominant PT in root samples from warmer regions was β-amyrin acetate, while samples from the colder region showed the predominance of β-amyrin.

Characterization of Non-Cholesterol Sterols in Microglia Cell Membranes Using Targeted Mass Spectrometry.

Non-cholesterol sterols, as well as plant sterols, cross the blood-brain barrier and, thus, can be incorporated into cell membranes, affecting the cell's inflammatory response. The aim of our work was to develop an analytical protocol for a quantitative assessment of the sterol composition within the membrane microdomains of microglia. A protocol for cell membrane isolation using OptiPrepTM gradient ultracentrifugation, in combination with a targeted mass spectrometry (LC-MS/MS)-based assay, was developed and validated for the quantitative analysis of free sterols in microglia cell membranes. Utilizing an established LC-MS/MS assay, cholesterol and seven non-cholesterol sterols were analyzed with a limit of detection from 0.001 to 0.05 mg/L. Applying the detergent-free isolation of SIM-A9 microglia cell membranes, cholesterol (CH), desmosterol (DE), lanosterol (LA) stigmasterol (ST), beta-sitosterol (SI) and campesterol (CA) were quantified with coefficients of variations between 6 and 29% (fractions 4-6, n = 5). The highest concentrations of non-CH sterols within the microglia plasma membranes were found in the microdomain region (DE>LA>SI>ST>CA), with ratios to CH ranging from 2.3 to 435 lower abundancies. By applying our newly developed and validated analytical protocol, we show that the non-CH sterol concentration is about 38% of the total sterol content in microglia membrane microdomains. Further investigations must clarify how changes in the non-sterol composition influence membrane fluidity and cell signaling.

3-Hydroxy-3-methylglutaryl coenzyme A reductase genes from Glycine max regulate plant growth and isoprenoid biosynthesis

Isoprenoids, a large kind of plant natural products, are synthesized by the mevalonate (MVA) pathway in the cytoplasm and the 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway in plastids. As one of the rate-limiting enzymes in the MVA pathway of soybean (Glycine max), 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is encoded by eight isogenes (GmHMGR1–GmHMGR8). To begin, we used lovastatin (LOV), a specific inhibitor of GmHMGR, to investigate their role in soybean development. To further investigate, we overexpressed the GmHMGR4 and GmHMGR6 genes in Arabidopsis thaliana. The growth of soybean seedlings, especially the development of lateral roots, was inhibited after LOV treatment, accompanied by a decrease in sterols content and GmHMGR gene expression. After the overexpression of GmHMGR4 and GmHMGR6 in A. thaliana, the primary root length was higher than the wild type, and total sterol and squalene contents were significantly increased. In addition, we detected a significant increase in the product tocopherol from the MEP pathway. These results further support the fact that GmHMGR1–GmHMGR8 play a key role in soybean development and isoprenoid biosynthesis.

Effects of Replacement of Fish Oil with Microbial Oil (Schizochytrium sp. T18) on Membrane Lipid Composition of Atlantic Salmon Parr Muscle and Liver Tissues

A 16-week feeding trial was conducted to investigate effects of replacing dietary fish oil (FO) with docosahexaenoic acid (DHA)-rich microbial oil (MO) from Schizochytrium sp. (T18) on membrane lipid composition of Atlantic salmon parr liver and muscle tissues. Four nutritionally balanced diets were formulated with varying levels of FO, MO, and canola oil (CO), including a control diet with 20% FO, a secondary control diet with 10% FO and 10% CO, and two experimental diets that completely replaced FO with a low (5%) and high (10%) proportion of MO. No significant differences were observed in growth parameters (81–98 g; weight gain), total lipid class composition, and total sterol content among the dietary treatments. However, there were significant differences in the proportions of individual ꞷ3 and ꞷ6 fatty acids in both liver and muscle tissues, reflecting the different dietary treatments. Notably, the presence of low eicosapentaenoic acid (EPA) in the MO diets did not affect the growth performance of the fish, suggesting a lower requirement for EPA in the diet and a greater necessity for DHA. The results also showed that DHA was present in very high proportions in the cellular membrane, particularly in muscle tissue, with low levels of linoleic acid and alpha-linolenic acid. Overall, the findings suggest that MO derived from Schizochytrium sp. (T18) could be a potential substitute for FO in the diet of farmed Atlantic salmon.