7 research outputs found
Food Polyphenol Apigenin Inhibits the Cytochrome P450 Monoxygenase Branch of the Arachidonic Acid Cascade
The product of cytochrome P450 monooxygenase
(P450) ω-hydroxylation
of arachidonic acid (AA), 20- hydroxyeicosatetraenoic acid (HETE),
is a potent vasoconstrictor. Utilizing microsomes as well as individual
CYP4 isoforms we demonstrate here that flavonoids can block 20-HETE
formation. Apigenin inhibits CYP4F2 with an IC<sub>50</sub> value
of 4.6 μM and 20-HETE formation in human liver and kidney microsomes
at 2.4–9.8 μM. Interestingly, the structurally similar
naringenin shows no relevant effect on the formation of 20-HETE. Based
on these in vitro data, it is impossible to evaluate if a relevant
blockade of 20-HETE formation can result in humans from intake of
polyphenols with the diet. However, the potency of apigenin is comparable
to those of P450 inhibitors such as ketoconazole. Moreover, an IC<sub>50</sub> value in the micromolar range is also described for the
inhibition of CYP-mediated drug metabolism leading to food–drug
interactions. The modulation of the arachidonic acid cascade by food
polyphenols therefore warrants further investigation
Comparison of derivatization/ionization techniques for liquid chromatography tandem mass spectrometry analysis of oxylipins
The performance of two derivatization and ionization techniques for the quantitative reversed phase liquid chromatography (LC)- mass spectrometry (MS) analysis of hydroxy fatty acids (OH-PUFA) in plasma was evaluated: One used AMPP (N-(4-aminomethylphenyl)pyridinium chloride) leading to a positive charged amid-derivate which can be detected by electrospray ionization (ESI)-MS. Second yielded penta fluorobenzyl bromide (PFB) ester derivates allowing detection in electron capture atmospheric pressure chemical ionization (ecAPCI)-MS. The sensitivity of detection of a comprehensive set of hydroxy fatty acids of n6- and n3- poly unsaturated fatty acids was investigated. On the SCIEX3200 MS the applied PFB derivatization led to poor limits of detection (LOD) of 10–100 nM (0.1–1 pmol/0.03–0.3 ng on column). By contrast, AMPP derivatization led to a similar sensitivity compared to the standard ESI(-) of non derivatized analytes (LOD about 1 nM (10 fmol/3 pg on column)). For several analytes, including 9-HETE, 11-HETE and 17-HDHA the AMPP derivatization improved sensitivity enabling their detection in human plasma. However, precision was reduced by AMPP derivatization and variation in IS recovery indicated a strong matrix influence on the MS-signal. In sum, with the instrumentation used, neither of these derivatization methods improves in our hands the LC–MS based quantification of oxylipins
Comparison of derivatization/ionization techniques for liquid chromatography tandem mass spectrometry analysis of oxylipins
The performance of two derivatization and ionization techniques for the quantitative reversed phase liquid chromatography (LC)- mass spectrometry (MS) analysis of hydroxy fatty acids (OH-PUFA) in plasma was evaluated: One used AMPP (N-(4-aminomethylphenyl)pyridinium chloride) leading to a positive charged amid-derivate which can be detected by electrospray ionization (ESI)-MS. Second yielded penta fluorobenzyl bromide (PFB) ester derivates allowing detection in electron capture atmospheric pressure chemical ionization (ecAPCI)-MS. The sensitivity of detection of a comprehensive set of hydroxy fatty acids of n6- and n3- poly unsaturated fatty acids was investigated. On the SCIEX3200 MS the applied PFB derivatization led to poor limits of detection (LOD) of 10–100 nM (0.1–1 pmol/0.03–0.3 ng on column). By contrast, AMPP derivatization led to a similar sensitivity compared to the standard ESI(-) of non derivatized analytes (LOD about 1 nM (10 fmol/3 pg on column)). For several analytes, including 9-HETE, 11-HETE and 17-HDHA the AMPP derivatization improved sensitivity enabling their detection in human plasma. However, precision was reduced by AMPP derivatization and variation in IS recovery indicated a strong matrix influence on the MS-signal. In sum, with the instrumentation used, neither of these derivatization methods improves in our hands the LC–MS based quantification of oxylipins
Lipid Class Specific Quantitative Analysis of n‑3 Polyunsaturated Fatty Acids in Food Supplements
Supplementation
products containing n-3 PUFA from marine sources
serve a large market. Although the amount of eicosapentaenoic acid
and docosahexaenoic acid in the products is provided by the manufacturer,
no or little information is available on their lipid pattern. Therefore,
we quantitatively analyzed the fatty acid pattern in the lipid fractions
triglycerides, phospholipids, ethyl esters, and free fatty acids in
supplementation products by means of solid phase extraction and gas
chromatography. Twelve products from the European and U.S. markets
containing fish, krill, algal, or plant oil were analyzed. Total n-3
PUFA content ranged from 68 g/100 g fat (fish oil) to 42 g/100
g
fat (algal oil) to 17 g/100 g fat (krill oil). On the basis of the
n-3 PUFA containing lipid class, the supplements can be separated
dominantly in ethyl ester, re-esterified triglyceride, triglyceride,
and phospholipid containing products. Algae-based products contained
natural triglycerides, krill oils a complex mixture of phospholipids,
triglycerides, and free fatty acids, and fish oil products either
ethyl esters, re-esterified triglycerides, or triglycerides. Even
products of the same class and source showed distinct differences
in their lipid pattern. A specification of the lipid composition of
n-3 PUFA products would allow distinguishing the different (qualities
of) supplements