A RP-HPLC method for the simultaneous analysis of tocotrienol isoforms (TRF) and simvastatin (SIM) in SIM-TRF nanoparticles (NPs) was developed. Analytes were monitored by UV detection at 238 and 295 nm for SIM and TRF, respectively, using a gradient methanol/water elution. Calibration curves for TRF and SIM were linear over concentration range of 20-80 microg/mL and 1-10 microg/mL with correlation coefficients 0.9990 and 0.9991, respectively. The recovery of TRF and SIM from the NPs was in the range from 97.35 to 102.19% and from 92.71 to 104.35%, respectively. This developed method was successfully employed in quantifying both drugs in NPs for future use in cancer therapy.

The metabolism of gamma-tocotrienol (gamma-TE) and gamma-tocopherol (gamma-T) was investigated in human A549 cells and in rats. Similar to gamma-T, A549 cells metabolized gamma-TE to sulfated 9′-, 11′-, and 13′-carboxychromanol and their unconjugated counterparts. After 72-h incubation with the cells, 90% of long-chain carboxychromanols in the culture media from gamma-TE, but <45% from gamma-T, were in the sulfated form. The formation of these metabolites was further investigated in rats gavaged by gamma-TE at 10 or 50 mg/kg, gamma-T at 10 mg/kg, or tocopherol-stripped corn oil in controls. Six hours after a single dosing, the supplemented rats had increased plasma concentrations of 13′-carboxychromanol and sulfated 9′-, 11′-, 13′-carboxychromanol, whereas none of these metabolites were detectable in the controls. Sulfated 11′-carboxychromanol was the most abundant long-chain metabolite in gamma-TE-supplemented rats. Sulfatase/glucuronidase hydrolysis revealed for the first time that >88% 2-(beta-carboxyethyl)-6-hydroxychroman (gamma-CEHC), the terminal beta-oxidation metabolite, was in the conjugated form in the plasma. In all groups, conjugated gamma-CEHC accounted for >75% of total metabolites, whereas free CEHC was a minor metabolite. At 10 mg/kg, the plasma concentrations of total metabolites from gamma-TE-supplemented rats were higher (P < 0.05) than those from gamma-T-fed rats. These results demonstrate that in rats, conjugation such as sulfation occurs parallel to beta-oxidation in the liver and is quantitatively important to vitamin E metabolism. Conjugated long-chain carboxychromanols may be novel excreted metabolites during supplementation. Our data also provide in vivo evidence that gamma-TE is more extensively metabolized than gamma-T.

Tocopherols and tocotrienols have been simultaneously determined in food samples using a rapid and simple analytical method including pressurized liquid extraction (PLE) and LC with electrochemical detection. Separation was carried out on a Phenomenex Synergi 4 microm Hydro-RP 80A column, using a solution of 2.5 mM acetic acid/sodium acetate in methanol/water (99:1, v/v) as mobile phase at a flow rate of 1.0 mL/min. Column temperature was maintained at 30 degrees C. Detection was performed by coulometric detection at 500 mV except for (beta+gamma)-tocotrienol, in wheat and rye samples, which was at +350 mV. A palm oil containing a relatively large amount of gamma-tocotrienol and lower concentrations of alpha- and delta-tocotrienols and alpha- and gamma-tocopherols was used to provide reference retention times for the tocotrienols. Analyte quantification was performed using the external standard method. The calibration equations of tocopherols were used to quantify both tocopherols and their corresponding tocotrienols. The extraction recoveries obtained using the optimized PLE conditions were in the 80-114% range, with RSDs lower than 15%. The method was successfully applied to the determination of tocotrienols and tocopherols in cereal (wheat, rye, barley, maize and oat) and palm oil samples.

Owing to the increasing interest in the health effects of antioxidant micronutrients on chronic diseases, a robust and rapid HPLC method for simultaneous measurement of coenzyme Q(10) (ubiquinone and ubiquinol), vitamin A (all-trans-retinol), vitamin E (tocopherols and tocotrienols) and carotenoids (lutein, zeaxanthin, beta-cryptoxanthin, lycopene and beta-carotene) was developed. Sample preparation and analytical conditions that would affect solubility and stability of these antioxidants were investigated and optimized. The mobile phase used was made up of acetonitrile, methanol, ethanol and tert-butanol without corrosive additives such as ammonium perchlorate and perchloric acid. Our results show that using two C(18) columns coupled with photodiode array, fluorescence and electrochemical detection, a comprehensive spectrum of 16 lipid-soluble antioxidants in 30 microL of plasma could be separated and quantified within 30 min. The chromatographic run time was about 3-fold faster and the sample size was about 5-fold smaller than when assays were performed separately using existing methods. The present method will be useful for dietary habit studies and for antioxidant status investigations.