Oxidized plant sterols in human serum and lipid infusions as measured by combined gas-liquid chromatography-mass spectrometry

Abstract

Some oxidized forms of cholesterol (oxysterols) are thought to be atherogenic and cytotoxic. Because plant sterols are structurally related to cholesterol, we examined whether oxidized plant sterols (oxyphytosterols) could be identified in human serum and soy-based lipid emulsions. We first prepared both deuterated and nondeuterated reference compounds. We then analyzed by gas-liquid chromatographymass spectrometry the oxyphytosterol concentrations in serum from patients with phytosterolemia or cerebrotendinous xanthomatosis, in a pool serum and in two lipid emulsions. 7-Ketositosterol, 7 ␤ -hydroxysitosterol, 5 ␣ , 6 ␣ -epoxysitosterol, 3 ␤ ,5 ␣ ,6 ␤ -sitostanetriol, and probably also 7 ␣ -hydroxysitosterol were present in markedly elevated concentrations in serum from phytosterolemic patients only. Also, campesterol oxidation products such as 7 ␣ -hydroxycampesterol and 7 ␤ -hydroxycampesterol were found. Interestingly, sitosterol was oxidized for approximately 1.4% in phytosterolemic serum, which is rather high compared with the approximate 0.01% oxidatively modified cholesterol normally seen in human serum. The same oxyphytosterols were also found in two lipid emulsions in which the ratio of oxidized sitosterol to sitosterol varied between 0.038 and 0.041. In conclusion, we have shown that oxidized forms of plant sterols are present in serum from phytosterolemic patients and two frequently used soy-based lipid emulsions. Currently, it is unknown whether oxyphytosterols affect health, as has been suggested for oxysterols. However, 7 ␤ -hydroxycholesterol may be one of the more harmful oxysterols, and both sitosterol and campesterol were oxidized into 7 ␤ -hydroxysitosterol and 7 ␤ -hydroxycampesterol. The relevance of these findings therefore deserves further exploration. -Plat, J., H. Brzezinka, D. Lütjohann, R. P. Mensink, and K. von Bergmann. Oxidized plant sterols in human serum and lipid infusions as measured by combined gas-liquid chromatographymass spectrometry.

Dietary plant stanol ester supplementation reduces peripheral symptoms in a mouse model of Niemann-Pick type C1 disease

“…If so, this would further enhance the application of plant stanol supplementation as an additional therapeutic tool in NPC1 disease. Of note, unlike stanols, phytosterol molecules are prone to oxidation (49,50) and may therefore have pro-inflammatory effects if consumed in high amounts. Given the importance of inflammation in NPC1 disease burden (30,51,52), phytosterol supplementation should thus be regarded with caution. )…”

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

“…However, advancements in the purification or synthesis of POPs have made it possible to generate suitable standards, ensuring accurate quantification. For example, both deuterated and non-deuterated reference POPs with the desired stereochemistry have been chemically synthesized [39][40][41]. Reference POPs via purification from thermally oxidized phytosterols by reversed-or normal-phase liquid chromatography have been reported, although chemical synthesis is sometimes incorporated due to the inability of one approach to prepare all desired POPs [19,42].…”

“…The procedure involved a conditioning process with n-hexane, a washing step with 0.5% 2-propanol in n-hexane, and elution with 30% 2-propanol in n-hexane. In another study, POPs were purified from serum where cyclohexane was employed for conditioning, a washing step with 0.5% ethyl acetate in cyclohexane, and elution with ethyl acetate [41]. In effect, the extraction solvent mixture should possess medium polarity, allowing for efficient extraction.…”

“…Although the above-discussed GC methods utilized COPs as reference standards, few studies have been reported where POP reference standards were used. Through the synthesis of both POP reference standards and deuterated internal standards, POPs were analyzed using GC-SIM-MS in human serum [41]. Using POP standards instead of COPs resulted in improved sensitivity in the determination of POPs in serum, with detection limits in the range of 7-243 pg/mL [39,40].…”

Pflanzliche Sterole als Nahrungsmitteladditiva zur Prävention kardiovaskulärer Erkrankungen

“…Glueck In einer klinischen Untersuchung zeigte sich darüber hinaus, dass Patienten, die regelmäßig Sterolester-angereicherte "Functional Foods" zu sich nehmen vermehrt Phytosterole im kardiovaskulären Gewebe einlagern [28]. Weitere mechanistische Daten lassen vermuten, dass eine vaskuläre Disposition von Sterolen anstelle von Cholesterin zu einer erhöhten Oxidierung und Freisetzung von Sauerstoffradikalen führt [17].…”