Rapid measurement of phytosterols in fortified food using gas chromatography with flame ionization detection

Lipidomics in food quality and authentication: A comprehensive review of novel trends and applications using chromatographic and spectroscopic techniques

Lipid analysis is an integral part of food authentication and quality control which provides consumers with the necessary information to make an informed decision about their lipid intake. Recent advancement in lipid analysis and lipidome scope represents great opportunities for food science. In this review we provide a comprehensive overview of available tools for extraction, analysis and interpretation of data related to dietary fats analyses. Different analytical platforms are discussed including GC, MS, NMR, IR and UV with emphasis on their merits and limitations alongside complementary tools such as chemometric models and lipid-targeted online databases. Applications presented here include quality control, authentication of organic and delicacy food, tracing dietary fat source and investigating the effect of heat/storage on lipids. A multitude of analytical methods with different sensitivity, affordability, reproducibility and ease of operation are now available to comprehensively analyze dietary fats. Application of these methods range from studies which favor the use of large data generating platforms such as MS-based methods, to routine quality control which demands easy to use affordable equipment as TLC and IR. Hence, this review provides a navigation tool for food scientists to help develop an optimal protocol for their future lipid analysis quest.

The Lack of Standardization and Pharmacological Effect Limits the Potential Clinical Usefulness of Phytosterols in Benign Prostatic Hyperplasia

The prevalence of benign prostatic hyperplasia (BPH) markedly increases with age. Phytotherapeutic approaches have been developed over time owing to the adverse side effects of conventional medications such as 5-reductase inhibitors and α1-adrenergic receptor antagonists. Therefore, dietary supplements (DS) containing active compounds that benefit BPH are widely available. Phytosterols (PSs) are well recognized for their role in maintaining blood cholesterol levels; however, their potential in BPH treatment remains unexplored. This review aims to provide a general overview of the available data regarding the clinical evidence and a good understanding of the detailed pharmacological roles of PSs-induced activities at a molecular level in BPH. Furthermore, we will explore the authenticity of PSs content in DS used by patients with BPH compared to the current legislation and appropriate analytical methods for tracking DS containing PSs. The results showed that PSs might be a useful pharmacological treatment option for men with mild to moderate BPH, but the lack of standardized extracts linked with the regulation of DS containing PSs and experimental evidence to elucidate the mechanisms of action limit the use of PSs in BPH. Moreover, the results suggest multiple research directions in this field.

Extraction and Quantitation of Phytosterols from Edible Brown Seaweeds: Optimization, Validation, and Application

Brown seaweeds are known as important marine food sources, from which phytosterols have been recognized as functional food components with multiple health-beneficial effects. However, studies on phytosterol extraction and quantitation from edible brown seaweeds are limited. In the present work, extraction methods for seaweed phytosterols were compared and optimized by one-factor-at-one-time method and response surface methodology. Moreover, the quantitation method of total sterols and major sterol components, including fucosterol, saringosterol, and ostreasterol, was established and validated using 1H NMR. Furthermore, the developed extraction and determination methods were applied to investigate three common edible seaweeds from Japan (Hijiki, Wakame, and Kombu). As a result, the finally optimized conditions were ultrasound-assisted extraction with CHCl3-MeOH 2:3 for 15 min followed by saponification with 1.65 mL of 1.85 M KOH for 14.5 h. Based on the developed methods, phytosterols in three seaweeds were compared, and Hijiki showed an abundant total sterol amount (2.601 ± 0.171 mg/g DW), significantly higher than Wakame (1.845 ± 0.137 mg/g DW) and Kombu (1.171 ± 0.243 mg/g DW). Notably, the composition of the sterol components varied in different seaweeds. These findings might help the nutritional investigation and functional food development concerning phytosterols from seaweeds.

Characterization of seven sterols in five different types of cattle feedstuffs

This paper provides a method for the quantification of sterols in different types of calf feedstuffs based on soy, sunflower, hay, calf feed and a mixture of all of them. The free fraction and the total sterolic fraction, after saponification and acidic hydrolysis of the samples, are extracted by solvent and the sterols are identified/quantified by reversed phase HPLC coupled to tandem mass spectrometry by atmospheric pressure chemical ionization. After the recovery evaluation, the method is validated in terms of linearity (coefficient of determination R2), repeatability (coefficient of variation RSD), limit of detection and quantification. In most of the cases, the most representative phytosterol is β-sitosterol, followed by campesterol or stigmasterol and by other minor sterols such as fucosterol, and Δ-5-avenasterol. In addition, also cholesterol and ergosterol, if present, are evaluated in all the samples. As far as we know, very little information is available on the investigated feeds, which are commonly used on farms. The results of this survey were compared to other studies, if present in literature, showing good agreement. The proposed method resulted to be simple, fast and suitable for application to other sterols, feedstuffs and derived foods. The knowledge of the sterolic content and composition is getting more and more important, both in terms of comprehension of the vegetal biochemistry and as basis for sterolomic studies.

Microencapsulation as a Tool for the Formulation of Functional Foods: The Phytosterols' Case Study

Hypercholesterolemia, which is an increase in total and low-density lipoprotein (LDL) serum cholesterol, is an important risk factor for the development of cardiovascular diseases. Lifestyle modifications underpin any action plan for reducing serum cholesterol. Phytosterols are natural compounds belonging to the triterpenes family. Thanks to their structural analogy with cholesterol, phytosterols have the ability to reduce serum LDL-cholesterol levels. Phytosterols are used to enrich or fortify a broad spectrum of food products. Like unsaturated fatty acids and cholesterol, phytosterols are easily oxidized. Microencapsulation could be a useful tool to overcome this and other drawbacks linked to the use of phytosterols in food fortification. In this review, in addition to explaining the phytosterols’ mechanisms of action, a focus on the use of free and encapsulated phytosterols for the formulation of functional foods, taking also into account both technological and legislative issues, is given.

Development of an innovative phytosterol derivatization method to improve the HPLC-DAD analysis and the ESI-MS detection of plant sterols/stanols

HPLC analyses of phytosterols are associated with the issues of sensitivity due to their high lipophilicity and their lack of chromophore. These problems could be solved through chemical modifications of plant sterols/stanols structures. Therefore, the present study aims to develop a new method for phytosterols derivatization. This method was performed using dansyl chloride (4 mg ml^-1) as derivatizing agent and different reaction parameters have been optimized. The highest yields of phytosterol derivatization were obtained with 4-dimethylaminopyridine (DMAP) as catalyst at a concentration of 8 mg ml^-1 and dichloromethane as reaction solvent. In addition, 40 ˚C was the best reaction temperature for 30 min as the best reaction time. This derivatization method presented a high reproducibility (%RSD = 1.2-2.7%) and a good linearity (R² = 0.9982-0.9999). The UV absorption intensities after derivatization showed a 23-fold increment for plant sterols and a 400-fold increment for plant stanols. Moreover, this derivatization method allowed the use of high and more selective wavelengths of detection and improved the chromatographic separation of phytosterols. Furthermore, the developed method allowed the ESI-MS ionization and analysis of phytosterols. This method can therefore contribute to the improvement of the HPLC analyses of plant sterols/stanols.

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

A novel liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated to simultaneously quantify phytosterols (brassicasterol, campesterol, stigmasterol and β-sitosterol) and tocopherols (alpha, beta, gamma and delta) entrapped in the lipid bilayer of a liposomal formulation. Apart from liposomes (a pharmaceutical product), the developed method was able to quantify target analytes in agricultural products, thus showing wide applications. Atmospheric pressure chemical ionization (APCI) was employed due to the enhanced ionization of phytosterols and tocopherols in comparison to electrospray ionization. Unlike published work, the chromatographic conditions were modified to simplify the analytical approach. For the first time, a simple isocratic elution (acetonitrile:methanol 99:1 v/v) was utilized for the separation of four phytosterols and four tocopherols in a single run. A substantially better baseline separation of phytosterols were obtained in comparison to reported methods by using poroshell C18 column. The method has a total run time of 7 min, which is the shortest run time among all reported quantitative methods for the simultaneous determination of four phytosterols and four tocopherols. Calibration curves for all phytosterols were linear in the range of 0.05-10 μg/mL. In the case of tocopherols, alpha tocopherol showed linear response in the range of 0.25-10 μg/mL. However, gamma and delta tocopherols exhibited quadratic relationship in the same concentration range (0.25-10 μg/mL). Validation parameters met the International Conference on Harmonization (ICH) guidelines in terms of selectivity, accuracy, precision, repeatability, sensitivity, matrix effects, dilution integrity and stability. The method was, for the first time, successfully applied for the quantifying phytosterols and tocopherols entrapped inside liposomes. An interesting chromatographic phenomenon was observed during sample analysis. Alpha tocopherol (entrapped in the liposomal lipid bilayer) was found to elute at two retention times, 2.53 min and 3.60 min. Such dual separation was not observed in calibration standards and quality controls. It was concluded that the chiral recognition ability of liposomes made up of phosphatidylcholine separated the enantiomers of alpha tocopherol, giving rise to two peaks at two different retention time. To sum, the reported novel LC-MS/MS method addresses three major analytical shortcomings, namely i)longer run time, ii)complex gradient elution and iii)poor baseline separation of phytosterols and tocopherols.

Intracellular Environment Improvement of Mycobacterium neoaurum for Enhancing Androst-1,4-Diene-3,17-Dione Production by Manipulating NADH and Reactive Oxygen Species Levels

As one of the most significant steroid hormone precursors, androst-1,4-diene-3,17-dione (ADD) could be used to synthesize many valuable hormone drugs. The microbial transformation of sterols to ADD has received extensive attention in recent years. In a previous study, Mycobacterium neoaurum JC-12 was isolated and converted sterols to the major product, ADD. In this work, we enhanced ADD yield by improving the cell intracellular environment. First, we introduced a nicotinamide adenine dinucleotide (NADH) oxidase from Bacillus subtilis to balance the intracellular NAD+ availability in order to strengthen the ADD yield. Then, the catalase gene from M. neoaurum was also over-expressed to simultaneously scavenge the generated H2O2 and eliminate its toxic effects on cell growth and sterol transformation. Finally, using a 5 L fermentor, the recombinant strain JC-12yodC-katA produced 9.66 g/L ADD, which increased by 80% when compared with the parent strain. This work shows a promising way to increase the sterol transformation efficiency by regulating the intracellular environment.

Performance and selectivity of lower-rim substituted calix[4]arene as a stationary phase for capillary gas chromatography

This work presents the investigation of p-tert-butyl(tetradecyloxy)calix[4]arene (C4A-C10) as stationary phase for capillary gas chromatographic (GC) separations. The statically-coated C4A-C10 capillary column showed weak polarity and column efficiency of 2566 plates per m determined by n-dodecane at 120 °C. Impressively, the C4A-C10 column exhibited extremely high resolving capability for a wide range of analytes from nonpolar to polar, including n-alkanes, esters, ketones, aldehydes, alcohols and bromoalkanes. Most importantly, the C4A-C10 column exhibited an excellent separation performance for positional, structural and cis-/trans-isomers. Among them, the column displayed advantageous resolving capability over the commercial polysiloxane stationary phase for aromatic amine isomers. Moreover, the C4A-C10 column showed good column repeatability with RSD values below 0.06% for run-to-run, 0.12–0.27% for day-to-day and 2.8–5.3% for column-to-column.

This work presents the investigation of p-tert-butyl(tetradecyloxy)calix[4]arene (C4A-C10) as stationary phase for capillary gas chromatographic (GC) separations.

Neuroprotective effects of Moringa oleifera: Bio-guided GC-MS identification of active compounds in diabetic neuropathic pain model

OBJECTIVES

To explore the phytotherapeutic-activities of Moringa oleifera (MO) seeds on painful diabetic neuropathy in alloxan-induced diabetic mice.

METHODS

The bio-guided fractionation of MO utilizing column chromatography aided with GC-MS was used to detect the most active constituent of MO. Hyperalgesia, using tail-flick and hot-plate latency experiments, and mechanical-allodynia, utilizing von-Frey filaments, were evaluated before and after 8 weeks of intraperitoneal alloxan administration (180 mg/kg). Serum catalase and insulin levels, body weight and blood glucose levels (BGL), alpha-glucosidase inhibition, lipid peroxidation and glycated hemoglobin (HbA1c) were measured to evaluate both alloxan-induced diabetes mellitus and diabetic painful neuropathy (DPN).

RESULTS

Beta-sitosterol (BSL) was proved to be the most active constituent of MO. The administration of MO (40, 60 and 80 mg/kg) or BSL (18, 25 and 35 mg/kg) significantly attenuated hyperalgesia and tactile allodynia (P⩽0.05), compared with tramadol (10 mg/kg) acting as a positive control, in alloxan-treated animals (n=7 per group). Moreover, MO and BSL have improved insulin secretion, in vivo antioxidant catalase, lipid peroxidation, acute and subchronic BGL, and normalized alpha-glucosidase and HbA1c levels.

CONCLUSIONS

The observed insulin secretagogue, alpha-glucosidase inhibition, hypoglycemic and antioxidant potentials might be responsible for MO and BSL antinociception and neuroprotective mechanism. MO and BSL have shown good glycemic-control and powerful neuroprotective properties which might serve as potential lead-compounds for further analysis.