Browsing by Subject "Tocochromanol"

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LC‐Orbitrap‐HRMS determination of two novel plastochromanol homologues
(2023) Hammerschick, Tim; Graf, Jana; Vetter, Walter
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.
Quantification of tocochromanols in vitamin E dietary supplements by instrumental thin-layer chromatography
(2022) Kröpfl, Alexander; Schweizer, Sina; Vetter, Walter
A variety of vitamin E dietary supplement capsules (DSC) based on different natural oils or synthesis products are currently found on the market whose vitamin contents need to be controlled before and after marketing. Here, we present an instrumental thin-layer chromatography (TLC) method which allows a direct determination of all tocopherols (T) and tocotrienols (T3) as well as α-tocopherol acetate simultaneously in one run with short analysis time. For this purpose, contents of the DSC were extracted, applied on silica gel 60 plates, and developed with n-hexane/ethyl acetate/acetic acid, 90:10:2 (v/v/v) as mobile phase. The UV scan of the plate at 293 nm was used for quantification based on the peak height. Following the scan, the plate was treated with 10% sulphuric acid in methanol which led to characteristic yellow-to-brown colouring of the tocochromanol spots which allowed to distinguish tocochromanols from matrix components with similar Rf values. In most cases, determined vitamin E contents matched well with the information listed on the label of the investigated DSC samples. The method is fast, easy to perform and gently treats the analytes as it requires no thermal treatment prior to quantification, which makes it suitable as a screening method.
The influence of phosphate-availability and phytic acid on the profiles of fatty acids, (poly)phenols, carotenoids, and tocochromanols in maize (Zea mays L.) grains – from field experiments to human in vitro digestion studies
(2022) Lux, Peter Erwin; Frank, Jan
Phosphorus (P) is an essential element for living organisms and involved in phosphorylation reactions, including the biosynthesis of several organic micronutrients. Since P is taken up by plants from soil as phosphates, phosphate fertilizers are applied on fields to support the P-supply for crops. Today, shrinking global P-resources demand a reduction in the application of P-containing fertilizers, but knowledge about possible effects of a reduced phosphate-availability in soils on the quality of maize grains is lacking. Thus, it was hypothesized that a reduced phosphate-availability in soil influences the concentrations of dietary organic compounds (phenolics, fatty acids, carotenoids, and tocochromanols) in grains of maize during cultivation. Moreover, concentration differences in the P-storage form phytic acid in maize grains may impact the oxidative stability of these organic compounds during processing and digestion. Fertilizer experiments with maize hybrids were conducted at study sites with low to high phosphate concentrations in soil (1.6 to 20.6 mg CAL-P/100 g soil) in Germany. GC-MS or HPLC-(MS) analyses of the ground maize grains revealed the identity of fatty acids, insoluble (mostly diferulic and triferulic acids) and soluble (poly)phenols, carotenoids, and tocochromanols. The concentrations of these (poly)phenols, carotenoids, and tocochromanols as well as the fatty acid composition in the grains of the maize plants grown with or without phosphate fertilizer were not significantly (p < 0.05) different. Interaction effects between phosphate application and the locations on the fatty acid composition as well as on carotenoids and tocochromanols were considered as insignificant, concluding that a reduction in phosphate fertilization could be implemented on most fields in Germany when only considering these dietary compounds. Lastly, the influence of phytic acid on oxidation processes in maize during processing of porridge and in vitro digestion was examined. Porridges were prepared from maize flour containing either high phytic acid concentration or low phytic acid concentration supplemented with or without phytate. The porridges were digested using a human in vitro digestion model, resulting in a decrease in tocochromanols, carotenoids and unsaturated fatty acids. Oxidation products (alpha-tocopherylquinone, malondialdehyde) were formed in all samples, implying that phytic acid addition did not show the expected protective effect. The addition of phytate evoked a significant reduction in the micellarization efficiency of most carotenoids. Thus, the knowledge about phytic acid as antinutrient was extended.