The simultaneous quantification of phytosterols and tocopherols in liposomal formulations using validated atmospheric pressure chemical ionization- liquid chromatography -tandem mass spectrometry

Liposomal Phytosterols as LDL-Cholesterol-Lowering Agents in Diet-Induced Hyperlipidemia

The high blood level of low-density lipoprotein cholesterol (LDL-C) is a primary risk factor for cardiovascular disease. Plant sterols, known as phytosterols (PSs), can reduce LDL-C in a range of 8-14%. The extent of LDL-C reduction depends on its formulation. Encapsulation into liposomes is one formulation strategy to enhance the efficiency of PSs. PSs (campesterol, stigmasterol, and β-sitosterol) have frequently been assessed alone or in combination for their LDL-C-lowering ability. However, one naturally abundant PS, brassicasterol, has not yet been tested for its efficacy. We have previously developed a novel liposomal formulation containing the PS mixture present naturally in canola that is composed of brassicasterol, campesterol, and β-sitosterol. In this work, the efficacy of our novel liposomal PS formulation that includes brassicasterol was assessed in a hamster model. Animals were divided into five groups: (i) liposomal PS in orange juice, (ii) liposomal PS in water, (iii) marketed PS in orange juice, (iv) control orange juice, and (v) control water. The animals were fed a high-fat, cholesterol-supplemented (0.5%) diet to induce hypercholesterolemia. The treatment was administered orally once daily for 4 weeks. Fasting blood samples were collected at baseline, week 2, and week 4. The extent of the reduction of total cholesterol, LDL-C, high-density lipoprotein cholesterol (HDL-C), and triglycerides was compared among the groups. Liposomal PSs in both orange juice and water significantly reduced LDL-C compared to their controls. Furthermore, the liposomal PS was as effective as a marketed PS-containing product in reducing LDL-C. Liposomal PSs in both orange juice and water showed similar efficacy in LDL-C reduction, highlighting that these vehicles/food matrices do not affect the efficacy of PSs. The liposomal formulation of a natural PS mixture extracted from canola oil, with brassicasterol as a major component, exhibited a significant LDL-C reduction in a hamster model.

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.

Differences in lipid composition of Bigeye tuna (Thunnus obesus) during storage at 0 °C and 4 °C

This study aimed to investigate the lipid oxidation and distribution in Bigeye tuna stored at 0 °C and 4 °C for 6 days. Tuna were evaluated by determining the peroxide value (POV), acid value (AV), anisidine value (AnV), polyene index, fluorescence ratio (FR), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) content, and major glycerophospholipid molecular species. The value of lipid oxidation indexes (POV, AV, AnV, FR, PC, PE and PI) increased as the storage time increased. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) results indicated that the major types of lipids included diacylglycerol (DAG), monoacylglycerol (MAG), phospholipid (PL), and triacylglycerol (TAG). At least 136 PC and 64 PE molecular species were identified in Bigeye tuna. The results of the confocal laser scanning microscope analysis indicated the distribution of TAG and PL particles. In addition, principal component analysis showed that the contents of PI and TAG were positively correlated with PC, polyene index and lipid content but negatively correlated with PI, POV, FR, AOV, AnV, MAG, and DAG, which might be explained by distinguishing the lipid parameters affecting lipid oxidation. Therefore, this study may provide a novel method to evaluate lipid changes and contribute to the balanced nutritional value of aquatic foods during cold storage.

Novel Fast Chromatography-Tandem Mass Spectrometric Quantitative Approach for the Determination of Plant-Extracted Phytosterols and Tocopherols

Phytosterols and tocopherols are commonly used in food and pharmaceutical industries for their health benefits. Current analysis methods rely on conventional liquid chromatography, using an analytical column, which can be tedious and time consuming. However, simple, and fast analytical methods can facilitate their qualitative and quantitative analysis. In this study, a fast chromatography-tandem mass spectrometric (FC-MS/MS) method was developed and validated for the quantitative analysis of phytosterols and tocopherols. Omitting chromatography by employing flow injection analysis—mass spectrometry (FIA-MS) failed in the quantification of target analytes due to analyte-to-analyte interferences from phytosterols. These interferences arise from their ambiguous MS fingerprints that would lead to false identification and inaccurate quantification. Therefore, a C18 guard column with a 1.9 µm particle size was employed for FC-MS/MS under isocratic elution using acetonitrile/methanol (99:1 v/v) at a flow rate of 600 µL/min. Analyte-to-analyte interferences were identified and eliminated. The false peaks could then be easily identified due to chromatographic separation. In addition, two internal standards were evaluated, namely cholestanol and deuterated cholesterol. Both internal standards contributed to the observed analyte-to-analyte interferences; however, adequate shift in the retention time for deuterated cholesterol eliminated its interferences and allowed for an accurate quantification. The method is fast (1.3 min) compared to published methods and can distinguish false peaks observed in FIA-MS. Seven analytes were quantified simultaneously, namely brassicasterol, campesterol, stigmasterol, β-sitosterol, α-tocopherol, δ-tocopherol, and γ-tocopherol. The method was successfully applied in the quantitative analysis of phytosterols and tocopherols present in the unsaponifiable matter of canola oil deodorizer distillate (CODD). β-sitosterol and γ-tocopherol were the most abundant phytosterols and tocopherols, respectively.

Analytical Strategies to Analyze the Oxidation Products of Phytosterols, and Formulation-Based Approaches to Reduce Their Generation

Phytosterols are a class of lipid molecules present in plants that are structurally similar to cholesterol and have been widely utilized as cholesterol-lowering agents. However, the susceptibility of phytosterols to oxidation has led to concerns regarding their safety and tolerability. Phytosterol oxidation products (POPs) present in a variety of enriched and non-enriched foods can show pro-atherogenic and pro-inflammatory properties. Therefore, it is crucial to screen and analyze various phytosterol-containing products for the presence of POPs and ultimately design or modify phytosterols in such a way that prevents the generation of POPs and yet maintains their pharmacological activity. The main approaches for the analysis of POPs include the use of mass spectrometry (MS) linked to a suitable separation technique, notably gas chromatography (GC). However, liquid chromatography (LC)-MS has the potential to simplify the analysis due to the elimination of any derivatization step, usually required for GC-MS. To reduce the transformation of phytosterols to their oxidized counterparts, formulation strategies can theoretically be adopted, including the use of microemulsions, microcapsules, micelles, nanoparticles, and liposomes. In addition, co-formulation with antioxidants, such as tocopherols, may prove useful in substantially preventing POP generation. The main objectives of this review article are to evaluate the various analytical strategies that have been adopted for analyzing them. In addition, formulation approaches that can prevent the generation of these oxidation products are proposed.

Dispersive solid phase extraction combined with solidification of floating organic drop-liquid-liquid microextraction using in situ formation of deep eutectic solvent for extraction of phytosterols from edible oil samples

In this study, a dispersive solid phase extraction method was combined with solidification of floating organic drop-liquid-liquid microextraction based on in situ synthesis of deep eutectic solvent. It was used for the extraction of some phytosterols from edible oil samples. The extracted analytes were quantified by gas chromatography-mass spectrometry. In this procedure, the sample lipids are saponified with sodium hydroxide and then the analytes are adsorbed onto an octadecylsilane sorbent. After that the analytes are desorbed from the sorbent with ethanol as an elution solvent and the eluant is diluted with deionized water to obtain a homogenous solution. Then, a few amounts of choline chloride and n-butyric acid are dissolved in the solution and transferred into a water batch adjusted at 75 ⁰C for 5 min. During this period Choline chloride and n-butyric acid form a deep eutectic solvent (extraction solvent) dispersed in whole parts of the solution. The obtained cloudy solution is placed into an ice bath. The extraction solvent is collected and solidified on the top of the solution. Finally, it is removed and allows melted at room temperature and an aliquat of the solution is injected into the separation system. Validation of the method showed that limits of detection and quantification were in the ranges of 0.52-1.6 and 1.7-5.6 ng mL-1, respectively. Enrichment factors and extraction recoveries of the analytes ranged from 312 to 375 and 75-90%, respectively. The method had a proper percision with relative standard deviations less than ≤8.2% for intra- (n = 6) and inter-day (n = 6) precisions at a concentration of 15 ng mL-1 of each analyte. Finally the method was successfully used for determination of the analytes in some edible oil samples.

Fast Quantification Without Conventional Chromatography, The Growing Power of Mass Spectrometry

Mass spectrometry (MS) in hyphenated techniques is widely accepted as the gold standard quantitative tool in life sciences. However, MS possesses intrinsic analytical capabilities that allow it to be a stand-alone quantitative technique, particularly with current technological advancements. MS has a great potential for simplifying quantitative analysis without the need for tedious chromatographic separation. Its selectivity relies on multistage MS analysis (MSⁿ), including tandem mass spectrometry (MS/MS), as well as the ever-growing advancements of high-resolution MS instruments. This perspective describes various analytical platforms that utilize MS as a stand-alone quantitative technique, namely, flow injection analysis (FIA), matrix assisted laser desorption ionization (MALDI), including MALDI-MS imaging and ion mobility, particularly high-field asymmetric waveform ion mobility spectrometry (FAIMS). When MS alone is not capable of providing reliable quantitative data, instead of conventional liquid chromatography (LC)-MS, the use of a guard column (i.e., fast chromatography) may be sufficient for quantification. Although the omission of chromatographic separation simplifies the analytical process, extra procedures may be needed during sample preparation and clean-up to address the issue of matrix effects. The discussion of this manuscript focuses on key parameters underlying the uniqueness of each technique for its application in quantitative analysis without the need for a chromatographic separation. In addition, the potential for each analytical strategy and its challenges are discussed as well as improvements needed to render them as mainstream quantitative analytical tools. Overcoming the hurdles for fully validating a quantitative method will allow MS alone to eventually become an indispensable quantitative tool for clinical and toxicological studies.