Two-dimensional high performance liquid chromatography for determination of homocysteine, methionine and cysteine enantiomers in human serum.

A two-dimensional HPLC system with electrochemical detection was used for determination of homocysteine, methionine and cysteine enantiomers in biological samples. The amino acid separations were not possible only by using a chiral column. The compounds were separated from each other on an achiral column (Purospher RP-18 endcapped 250-4mm, 5µm) and their enantiomers were separated on Chirobiotic TAG (250-4.6mm, 5µm) column in an on-line system. The mobile phase composition and a choice of electrode potentials for detection were investigated. The l-enantiomers always eluted before the d-enantiomers. The proposed method was applied to the analysis of human serum of healthy volunteers and patients with multiple sclerosis. The limit of detection (LOD) and quantitation (LOQ) were defined as the concentration that produced a signal-to-noise ratio (S/N) of 3 and 10. The method LOD values were found to be between 0.05 and 0.50µgmL(-1). The range of LOQ values were between 0.17 and 1.67µgmL(-1), respectively.

Influence of oak wood polyphenols on cysteine, homocysteine and glutathione total levels and PON1 activities in human adult volunteers - a pilot study.

Oxidative stress reflects an imbalance between antioxidants and pro-oxidants. Many diseases like atherosclerosis or heart failure are involved in oxidative stress. Increased oxidative stress is one of the potential contributing factors to aging. The aim of this study was to monitor the total thiol levels as markers of oxidative stress in 20 healthy volunteers after polyphenols intake (extract from the French oak wood Quercus robur - Robuvit® (300 mg/day)). Polyphenols are known as biomodulators with antioxidant activities. Homocysteine, cysteine and glutathione total levels were determined by using HPLC with electrochemical detection. The activity of the antioxidant enzyme paraoxonase-1 toward two substrates was determined by spectrophotometry. The level of thiol compounds and paraoxonase-1 activities were controlled after run-in (week 0), intervention (week 4) and washout (week 6) period. After the intervention period the results showed that Robuvit® had no significant influence on glutathione level (p = 0.382) and paraoxonase activities towards both, arylester and lactone substrates. On the other hand, homocysteine and cysteine levels decreased significantly (p = 0.029; p < 0.001, respectively). The negative correlation between paraoxonase lactonase activity and homocysteine level was noticed. This confirms that paraoxonase might play an important role in homocysteine-thiolactone metabolism.

Effect of PUFA-rich plant oil on risk factors of STZ-induced diabetes in Wistar rats.

OBJECTIVE: This study has been focused on the effect of an n-6 polyunsaturated fatty acid (PUFA) rich plant oil on oxidation and glycooxidation stress markers as well as on antioxidant enzyme activities in male Wistar rats with streptozotocin-induced diabetes. METHODS: The non-diabetic and diabetic groups of Wistar rats were administered plant oil at concentrations of 100 and 500 mg/kg body weight and controls without plant oil. The parameters of glycaemic control, lipid profile, total antioxidant status, antioxidant enzyme activities, together with oxidative and glycooxidative stress markers were measured in the blood. RESULTS: The intake of the plant oil did not significantly influence the parameters of glycaemic control and significantly increased the levels of all lipid profile parameters in the diabetic rats. Plant oil administration significantly decreased the total antioxidant status and glutathione peroxidase activity and the activity of Cu/Zn superoxide dismutase was significantly increased. The plant oil also increased the levels of lipoperoxides and advanced the glycation end products. DISCUSSION: These results suggest that the plant oil with high concentrations of n-6 PUFA - linoleic acid, acts prooxidatively when administered to the rats.