Analytical scale supercritical fluid chromatography for the analysis of nine tocochromanols in 24 different cold-pressed plant oils: Method development, validation, and isolation of tocotrienols and plastochromanol-8

Reversed phase HPLC with UHPLC benefits for the determination of tocochromanols in the seeds of edible fruits in the Rosaceae family

Rosaceae family includes several edible fruit species processed in vast quantities and generates large amounts of seeds valuable in tocopherols. In the present study, the composition of tocochromanols in the seeds of 141 samples was determined by reversed phase high-performance liquid chromatography (RPLC) with diode array detector (DAD), fluorescence detector (FLD) and confirmed by mass detector (MS). The thirteen species belonging to the Rosaceae family were classified by multivariate statistical analysis, hierarchical cluster analysis (HCA) and principal component analysis (PCA) into two groups based on tocochromanols content. Group 'A' includes pears (Pyrus communis), sweet cherry (Prunus avium), sour cherry (Prunus cerasus), apricots (Prunus armeniaca), hexaploid plums (Prunus domestica), diploid plums (Prunus cerasifera), raspberry (Rubus idaeus), and rose hip (Rosa rugosa); while group 'B' quince (Cydonia oblonga), Japanese quince (Chaenomeles japonica), strawberry (Fragaria × ananassa), dessert apples (Malus domestica), and crab apples (Malus spp.). Two rapid (6-7 min) and low pressure (7.2-8.1 MPa) separation methods were developed and validated using two core-shell columns (i) C18 and (ii) F5. The F5 achieved a separation of β and γ isomers while the C18 column did not.

Evaluation of RPLC stationary phases for tocopherol and tocotrienol positional isomer separation: Method development and profiling

Reversed-phase separation of tocopherols (Ts) and tocotrienols (Ts) using C18 stationary phases results in the coelution of β and γ positional isomers, leading to identification errors. This study investigates the potential of alternative stationary phase chemistries to effectively resolve tocochromanols, specifically focusing on the critical pair of β and γ positional isomers. Initial screening of seven different stationary phases (C18, C18-PFP, C30, PFP, 5PYE, πNAP, and RP-Amide) was conducted. Linear solvent strength (LSS) studies were performed to assess the impact of the organic modifier (methanol) and temperature on the chromatographic performance parameters. Five columns were found to be suitable for the tocochromanol separation and two different chromatographical conditions per column were proposed. Elution order of tocochromanols was unique for 5PYE, πNAP and C30 columns in comparison to RP-Amide and PFP. Method development for the quantitative analysis of four tocopherol and four tocotrienol homologues was performed. The optimised method employed the RP-Amide (150 × 4.6 mm, 2.6 μm dp) superficially porous particle column, mobile phase of methanol:water of 92:8, v/v, with a flow rate of 1.0 mL/min, column oven temperature of 40 °C and fluorescence detection (λex 295 nm, λem 330 nm). The analysis run time was 10.5 min with 13.6 MPa back pressure. The method was validated and the obtained LOQs were found to be 1.30-3.13 μg/mL. The method developed was successfully applied for the determination of tocochromanols in twenty samples with unique tocochromanol profiles. Principal component analysis illustrated three distinct groups based on the tocochromanol profile.

LC-Orbitrap-HRMS Determination of Two Novel Plastochromanol Homologues

SCOPE

The antioxidant plastochromanol-8 (PC-8) is a tocochromanol which differs from γ-tocotrienol in having an unsaturated side chain of eight instead of three isoprene units. The recent isolation of PC-8 from flaxseed oil indicates the additional presence of lower shares of two previously unknown homologues, plastochromanol-7 (PC-7) and plastochromanol-9 (PC-9), which feature seven and nine isoprenoid units respectively on the γ-chromanol backbone. Here, a fast LC-Orbitrap-HRMS method is applied for the determination of PC-7 and PC-9 in seven plant oils and a plant extract.

METHODS AND RESULTS

The presence of PC-7, PC-8, and PC-9 is confirmed in all eight investigated samples by LC-Orbitrap-HRMS analysis after saponification. PC-8 amounts of ≈315-350 mg kg-1 in two flaxseed oils, ≈75 mg kg-1 in rapeseed oil, ≈38 mg kg-1 in camelina oil, ≈80-120 mg kg-1 in two mustard oils, ≈90 mg kg-1 in candle nut oil, and ≈900 mg kg-1 dry weight in Cecropia leaves are determined by quantification. Semi-quantification of PC-7 and PC-9 indicated the presence of ≈0.1-1% of PC-7 and PC-9 in varied relative ratios.

CONCLUSION

The novel plastochromanol homologues are of particular interest to researchers with focus on vitamin E and other tocochromanols because of their unexplored bioactivity.

Comprehensive Characterization of Oils and Fats of Six Species from the Colombian Amazon Region with Industrial Potential

The Colombian Amazon is a megadiverse region with high potential for commercial use in the pharmaceutical, food, and cosmetic industries, constantly expanding and looking for new alternatives from natural resources; unfortunately, few characterization reports of its profitable non-timber species in Colombia have been conducted. This work aimed to perform a comprehensive analysis of traditionally used species: Carapa guianensis (Andiroba), Euterpe precatoria (Asai), Mauritia flexuosa (Miriti), Astrocaryum murumuru (Murumuru), Plukenetia volubilis (Sacha Inchi), and Caryodendron orinocense H.Karst (Cacay). For this purpose, oil and fat quality indices, phytosterol, carotenoid, tocopherol, and tocotrienol content, as well as density and refractive index, were measured to establish their quality level. Multivariate analysis showed four groups of samples; such differences were mainly due to the composition rather than quality indices and physical properties, especially the content of saturated and unsaturated fatty acids. All species reported a precise composition, which makes them noninterchangeable, and Miriti oil arose as the most versatile ingredient for the industry. The Colombian Amazon region is a promising source of quality raw material, especially for oils/fats and unsaturated fatty acids; this resulted in the most interest for pharmaceutical, food, and cosmetic purposes.

Isolation of plastochromanol-8 from flaxseed oil by countercurrent separation methods

The naturally occurring antioxidant plastochromanol-8 (PC-8) is a member of the tocochromanol (vitamin E) family which features eight unsaturated isoprene units in the side chain compared to three in the case of γ-tocotrienol. Due to the lack of a commercially available PC-8 standard, we developed a route to gain relevant amounts of highly pure PC-8. Specifically, ∼320 g flaxseed oil was saponified and the bulky PC-8 was enriched by gel permeation chromatography. It followed countercurrent chromatography using the solvent system n-hexane/benzotrifluoride/acetonitrile (20:7:13, v/v/v). The final purification was achieved by centrifugal partition chromatography using the novel solvent system hexamethyldisiloxane/acetonitrile (1:1, v/v). This step provided ∼26 mg PC-8 (>99.5 %, according to HPLC, GC and NMR analysis). Two further, hitherto unknown minor tocochromanols (<1 % of PC-8) were detected and could be identified to be plastochromanol-7 (PC-7) and plastochromanol-9 (PC-9), i.e. tocochromanols with seven and nine unsaturated isoprene units, respectively, in the side chain.

Free and Esterified Tocopherols, Tocotrienols and Other Extractable and Non-Extractable Tocochromanol-Related Molecules: Compendium of Knowledge, Future Perspectives and Recommendations for Chromatographic Techniques, Tools, and Approaches Used for Tocochromanol Determination

Free and esterified (bound) tocopherols, tocotrienols and other tocochromanol-related compounds, often referred to "tocols", are lipophilic antioxidants of great importance for health. For instance, α-tocopherol is the only tocochromanol with vitamin E activity, while tocotrienols have a positive impact on health and are proposed in the prevention and therapy of so-called modern diseases. Tocopherols, tocotrienols and plastochromanol-8 are the most well-known tocochromanols; in turn, knowledge about tocodienols, tocomonoenols, and other rare tocochromanol-related compounds is limited due to several challenges in analytical chemistry and/or low concentration in plant material. The presence of free, esterified, and non-extractable tocochromanols in plant material as well as their biological function, which may be of great scientific, agricultural and medicinal importance, is also poorly studied. Due to the lack of modern protocols as well as equipment and tools, for instance, techniques suitable for the efficient and simultaneous chromatographical separation of major and minor tocochromanols, the topic requires attention and new solutions, and/or standardization, and proper terminology. This review discusses the advantages and disadvantages of different chromatographic techniques, tools and approaches used for the separation and detection of different tocochromanols in plant material and foodstuffs. Sources of tocochromanols and procedures for obtaining different tocochromanol analytical standards are also described. Finally, future challenges are discussed and perspective green techniques for tocochromanol determination are proposed along with best practice recommendations. The present manuscript aims to present key aspects and protocols related to tocochromanol determination, correct identification, and the interpretation of obtained results.

The potential of wild olive leaves (Olea europaea L. subsp. oleaster) addition as a functional additive in olive oil production: the effects on bioactive and nutraceutical compounds using LC-ESI-QTOF/MS

This study aims to investigate the influence of traditional maceration upon the enrichment of olive oil with oleaster leaves. The phenolic and tocopherolic compositions of control olive oil and enriched olive oils were determined. The influence of these oil preparation procedures on oil quality indicators was also investigated through spectrophotometric indices and fatty acid profiles. The total contents of bioactive compounds and pigments improved in oils obtained by maceration of fresh wild olive leaves, and were in statistically significant correlation with leaves proportions additions. The obtained results revealed that 15 phenolic compounds belonging to different phenolic types were characterized and quantified by an effective HPLC-DAD-ESI-MS/MS method. In all expected olive oils, the oleuropein aglycon (3,4-DHPEA-EA), and ligstroside aglycon (p-HPEAEA) derivatives were the most abundant compounds. Similarly, to phenolic compounds, tocopherols strongly increased with leaves addition during maceration process. The data obtained from this study suggested that the addition of olive leaf to oils allowed more functional olive oils with higher antioxidant contents. Thus, Extra Virgin Olive Oil (EVOO) extracted with 10% of olive leaves presented the highest amount of phenolic and tocopherol compounds.