Mangiferin has an additive effect on the apoptotic properties of hesperidin in Cyclopia sp. tea extracts.

A variety of biological pro-health activities have been reported for mangiferin and hesperidin, two major phenolic compounds of Honeybush (Cyclopia sp.) tea extracts. Given their increasing popularity, there is a need for understanding the mechanisms underlying the biological effects of these compounds. In this study, we used real-time cytotoxicity cellular analysis of the Cyclopia sp. extracts on HeLa cells and found that the higher hesperidin content in non-fermented "green" extracts correlated with their higher cytotoxicity compared to the fermented extracts. We also found that mangiferin had a modulatory effect on the apoptotic effects of hesperidin. Quantitative PCR analysis of hesperidin-induced changes in apoptotic gene expression profile indicated that two death receptor pathway members, TRADD and TRAMP, were up regulated. The results of this study suggest that hesperidin mediates apoptosis in HeLa cells through extrinsic pathway for programmed cell death.

Vitamin B6 and the immunity in kidney transplant recipients.

OBJECTIVE: The study aimed to determine vitamin B6 status in elderly (age ≥ 60 years) and younger (age <60 years) recipients of allogeneic kidney graft and to investigate associations between vitamin B6 status and immunity markers. DESIGN: A retrospective observational study. SETTING: The study was conducted at the Medical University of Gdansk, Poland. SUBJECTS: We recruited 34 kidney allograft recipients (17 males and 17 females) and allocated them into 2 groups: patients aged ≥ 60 years (18 patients) and those aged <60 years (16 patients). Exclusion criteria included patients receiving vitamin B6 supplementation or drugs known to influence vitamin B6 metabolism. MAIN OUTCOME MEASURE: Plasma levels of pyridoxal 5'-phosphate (PLP), pyridoxal, pyridoxine, pyridoxamine, pyridoxamine 5'-phosphate, and 4 pyridoxic acid were determined by high-performance liquid chromatography. Measured immunity markers were serum cytokines (interleukin-6, interleukin-10, and transforming growth factor-ß), levels of T-lymphocyte subsets, and the proliferative ability of peripheral blood mononuclear cells. RESULTS: Concentrations of all vitamin B6 vitamers in plasma (PLP, pyridoxal, pyridoxamine 5'-phosphate, pyridoxamine, pyridoxine, 4 pyridoxic acid) were comparable in the 2 studied groups. There were no cases of PLP deficiency in the study population, but 29% of patients had PLP concentrations more than the upper reference limit. Vitamin B6 vitamer concentrations were not influenced by gender, estimated glomerular filtration rate, and circulating phosphate concentration. There was no difference in immunity markers according to age. However, the plasma concentrations of vitamin B6 vitamers were inversely associated with levels of CD28(+) lymphocyte subsets, as well as with the proliferative response of peripheral blood mononuclear cells in both groups. CONCLUSIONS: No cases of vitamin B6 deficiency were found among kidney allograft recipients, and we report inverse links between vitamin B6 vitamer concentrations and markers of cellular immunity, suggesting that bioactive vitamin B6 concentration in kidney allograft recipients merits further investigation.

Evaluation for magnesium and vitamin B6 supplementation among Polish elite athletes.

Contemporary sport requires a lot of effort from sportsmen, frequently exceeding their maximum physical and mental efficiency. Athletes often report poor dietary habits and reach for magnesium and vitamin B supplements to avoid dietary deficiencies. The aim of this study was to determine magnesium and vitamin B6 content in daily food rations of Polish athletes and to verify the justification of diet supplementation. Magnesium and vitamin B6 concentrations were determined in 62 collected and 12 reconstructed daily food rations of elite Polish runners. Flame atomic absorption spectrometry and HPLC methods were used for quantification of magnesium and vitamin B6, respectively. The analyzed female diets provided daily 256 +/- 111 mg of magnesium and 2.04 +/- 0.63 mg of vitamin B6 whereas male diets provided 284 +/- 58 mg of magnesium and 2.12 +/- 0.68 mg of vitamin B6. Computer analysis calculated 159-181% higher content o magnesium and vitamin B6 comparing to determined laboratory values. The results of this study indicate that in the analyzed daily food rations of athletes low magnesium intake was observed, thus diet supplementation with this mineral may be justified. Daily food rations fulfilled RDA for vitamin B6, thus supplementation with this vitamin was not justified.

Application of the high-performance liquid chromatography method with coulometric detection for determination of vitamin B(6) in human plasma and serum.

A reversed-phase high-performance liquid chromatography method (HPLC) with coulometric electrochemical detection has been developed and validated for the simultaneous analysis of pyridoxamine-5'-phosphate (PMP), pyridoxamine (PM), pyridoxal 5'-phosphate (PLP), pyridoxal (PL), pyridoxine (PN) and 4-pyridoxic acid (4-PA) in human plasma and serum. The isocratic separation was achieved on C(18) column (250mmx4.6mm, I.D., 5microm) with a mobile phase consisted of 35mM sodium phosphate containing 2.5mM heptanesulfonic acid, adjusted to pH 3.2 with 85% orthophosphoric acid and 12% methanol (v/v). Within-run and between-run precisions expressed by the relative standard deviations were less than 2.7% and 7.7% for all the analysed vitamins and 4-PA, respectively. The limits of detection (LOD) and quantification (LOQ) were: 0.8 and 2.6nM, 1.1 and 3.8nM, 1.5 and 4.5nM, 1.3 and 4.2nM, 1.1 and 3.7nM, 2.1 and 6.3nM for PMP, PM, PLP, PL, PN and 4-PA, respectively. The recoveries ranged from 90.4% to 98.4%. Stability of vitamins was checked under a variety of storage conditions. The developed application demonstrated acceptable sensitivity, precision, accuracy, stability, and linearity over the physiological concentration range. The major advantage of the proposed method is its great simplicity.

[Hiperhomocysteinemia in active and passive smokers and the levels of folate and vitamin B6 in plasma]. / Hiperhomocysteinemia u osób palqcych oraz biernie narazonych na dym tytoniowy a stezenia kwasu foliowego i witaminy B6 w osoczu.

The increased plasma level of homocysteine have been shown to be the sensitive marker for the folate, vitamin B6 and cobalamins deficiency and an independent risk factor for the cardiovascular disease, neutral tube defects and a potential causal risk factor for neuropsychiatric disorders. The blood and plasma homocysteine levels except for genetic defects are influenced by age, gender, efficiency of detoxication systems, one or more unhealthy lifestyle factors, such as high alcohol consumption, low nutritional intake of vitamins, high coffee consumption, acquired disorders and lack of physical exercise. Many studies confirm that active tobacco smoking and environmental tobacco smoke (ETS) have been significantly associated with hiperhomocysteinemia. In metabolic pathway of homocysteine the important role played folic acid, as a donor of methyl group in re-methylated reaction to methionine and vitamin B6. It acts as the cofactor in transsuphuration reactions of homocysteine to cystathionine and cysteine. Hence, the aim of this work was to compare the plasma folate and vitamin B6 concentrations in smokers and passive smokers with a hiperhomocysteinemia (> 15 micromol/L). It was observed that the plasma folate levels in active (n = 30) and passive smokers (n = 29) groups decrease statistically significant (P < 0.001) in comparison to non-smokers (n = 37). The calculated Spaermann's correlations coefficient of total plasma homocysteine level and plasma folate concentrations in the non-smoker group indicated a weak, statistically insignificant correlation (r = -0.103, P = 0.542). However, the above relationship in passive and active smokers were statistically significant (r = -0.495, P 0 0.01; r = -0.672, P < 0.001, respectively). The decrease of vitamin in B6 plasma was observed in all active smokers group (P < 0.01) and men smokers comparing to non-smokers (P < 0.001). There was no observed significant correlations between hiperhomocysteinemia and vitamin B6 in all studied groups. The results indicated that hiperhomocysteinemia have strong negative impact on folate levels in active and passive smokers. The tobacco smoke exposure have negative influence on the status of vitamin B6. The lack of significant correlation between increased homocysteine levels and vitamin B6 status confirmed hypothesis that hiperhomocysteinemia is not depended on vitamin B6 concentrations in plasma.

Reversed-phase high-performance liquid chromatography method with coulometric electrochemical and ultraviolet detection for the quantification of vitamins B(1) (thiamine), B(6) (pyridoxamine, pyridoxal and pyridoxine) and B(12) in animal and plant foods.

A rapid and sensitive high-performance liquid chromatography (HPLC) method with coulometric electrochemical and ultraviolet detections for analysis of vitamin B (B(1), B(6) and B(12)) in animal and plant foods has been developed. A combination of acid digestion and enzymatic extraction to release protein bound and phosphorylated vitamins followed by HPLC analysis was applied. The analyses were carried out on a LC18 column 5 microm (25 cm x 4.6 mm), using the mobile phase consisting of methanol-phosphate buffer (10:90) and 0.018 M trimethylamine, pH 3.55, following at 1.0 ml min(-1). The method offers excellent linearity with regression coefficient r>0.998, good repeatability and reproducibility and relatively short analysis time (17 min). The relative standard deviation (RSD) of the intermediate precision was satisfactory for all the vitamins studied and amounted to <7.3%. The repeatability of the method was <4.7%. The limits of quantification (LOQ) for pyridoxamine, pyridoxal, pyridoxine, vitamins B(1) and B(12) in seafood products were as follows: 2.1, 2.01, 0.99, 62.0 and 0.11 ng ml(-1), respectively. The mean recovery values from a food products spiked with all five vitamins ranged from 92.3 to 101.3%, with a relative standard deviation less than 3.4%. The proposed separation and detection procedures were successfully applied for the simultaneous determination of vitamins B(1), B(6) and B(12) in fruit juices and vitamins B(6) and B(12) in seafood.

[Smoking influence on the level of homocysteine and 5-methyltetrahydrofolic acid in active and non smokers]. / Ekspozycja na dym tytoniowy a poziom homocysteiny i kwasu 5-metylotetrahydrofoliowego u osób palacych i niepalacych.

Cigarette smoking is associated with oxidative stress and increased risk of many chronic diseased. Smoking inducts depletion of cellular antioxidant and is also known to be associated with an increased homocysteine level. Exposure to tobacco smoke has negative impact on the folic acid level. Folic acid is cofactor by demethyla-tion of homocysteine to non toxic methionine. The aim of this study was to determine the concentration of total plasma homocysteine and 5-methyltetrahydrofolic acid in active and non smokers and to evaluate the influence of the tobacco smoke exposure on urinary cotinine levels. The results indicated significant increase of total plasma homocysteine in smokers, than non smokers. We also investigated the negative influence of tobacco smoke on the level of folic acid in plasma and it suggests, that additional supplementation of folic acid in smokers is necessary.

[The influence of tobacco smoking on homocysteine and glutathione levels in biological samples]. / Wplyw palenia tytoniu na poziom homocysteiny i glutationu w materiale biologicznym.

The aim of this paper was to examine the effect of tobacco smoking on the level of homocysteine and glutathione in biological samples. The study comprised 30 people, who qualified into two groups--subjects who never smoke the cigarettes (n = 10) and currently smoking (n = 20). Smoking habit were assessed by questionnaire. Cotinine (major metabolite of nicotine) was determined in urine using high-performance liquid chromatography method (HPLC) with ultraviolet detection. The biothiols: glutathione in reduced and oxidized forms and homocysteine were determined by HPLC method using coulometric electrochemical detection. The concentrations of total and free plasma homocysteine were higher in active smoker. Glutathione levels in both groups were comparable. Observed differences should be explained in the further experiment.

High-performance liquid chromatography method for the simultaneous determination of thiamine hydrochloride, pyridoxine hydrochloride and cyanocobalamin in pharmaceutical formulations using coulometric electrochemical and ultraviolet detection.

The method for the simultaneous determination of thiamine hydrochloride, pyridoxine hydrochloride and cyanocobalamin by high-performance liquid chromatography (HPLC) with coulometric electrochemical and UV detections is presented. The retention time of vitamins was repeatedly determined by isocratic elution using 0.05 M phosphate buffer-10% methanol and 0.018 M trimethylamine (1 ml min(-1), pH 3.55) as mobile phase with the Supelco LC 18 column 5 microm (25 cm x 4.6 mm). The specificity of the method was demonstrated by the retention characteristics, coulometric electrochemical and UV detection. The limits of detection of thiamine, pyridoxine and cyanocobalamin were: 9.2, 2.7 and 0.08 ng/ml, respectively. The method was characterized also by wide concentration range, high sensitivity and good accuracy (99.6-102.7%). The repeatability of the method was evaluated at different level of concentration of vitamins and the relative standard deviation was below 4.5%. The method was successfully applied for the quantification of Vitamins B1, B6 and B12 in pharmaceutical preparations and dietary supplements.