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BACKGROUND: Recent studies indicate that the bioavailability of anthocyanins is extremely low. One of the possible reasons could be their binding to proteins. Therefore, the binding affinity of cyanidin-3-glucoside (Cy3glc) to HSA and alpha-amylase was investigated by the quenching of protein tryptophan fluorescence. From data obtained, the binding constants and the free Gibbs energy were calculated. The changes in conformation of the proteins tested were studied with circular dichroism and the influence of binding on alpha-amylase activity determined. RESULTS: Cy3glc quenched the tryptophan fluorescence and upon ligand binding a change in protein structure was observed related to the corresponding decrease in the et-amylase activity. The association constants of 25 to 77 x 10(3) L mol(-1) were calculated for different proteins, indicating weak interactions of non-covalent nature. Competitive binding with HSA in the presence of 8-anilino-1-naphthalene sulfonic acid suggest involvement of hydrophobic interactions, in the case of HSA the possible site being subdomain IIA. CONCLUSION: The strongest affinity of Cy3glc for HSA being at pH 7 underlines its potential in transport and distribution of the phenolic compounds in organisms. An influence on salivary amylase activity is possible when drinking berry juices with high anthocyanins content.
Energy balance is maintained by controlling both energy intake and energy expenditure. Thyroid hormones play a crucial role in regulating energy expenditure. Their levels are adjusted by a tight feed back-control led regulation of thyroid hormone production/incretion and by their hepatic metabolism. Thyroid hormone degradation has previously been shown to be enhanced by treatment with phenobarbital or other antiepileptic drugs due to a CAR-dependent induction of phase 11 enzymes of xenobiotic metabolism. We have recently shown, that PPAR alpha agonists synergize with phenobarbital to induce another prototypical CAR target gene, CYP2B1. Therefore, it was tested whether a PPAR alpha agonist could enhance the phenobarbital-dependent acceleration of thyroid hormone elimination. In primary cultures of rat hepatocytes the apparent half-life of T3 was reduced after induction with a combination of phenobarbital and the PPARa agonist WY14643 to a larger extent than after induction with either Compound alone. The synergistic reduction of the half-life could be attributed to a synergistic induction of CAR and the CAR target genes that code for enzymes and transporters involved in the hepatic elimination of T3, such as OATP1A1, OATP1A3, UGT1A3 and UCT1A10. The PPAR alpha-dependent CAR induction and the subsequent induction of T3-eliminating enzymes might be of physiological significance for the fasting- incluced reduction in energy expenditure by fatty acids as natural PPARa ligands. The synergism of the PPAR alpha agonist WY14643 and phenobarbital in inducing thyroid hormone breakdown might serve as a paradigm for the synergistic disruption of endocrine control by other combinations of xenobiotics.
Isoflavone intake is associated with various properties beneficial to human health which are related to their antioxidant activity, for example, to their ability to increase LDL oxidation resistance. However, the distribution of isoflavones among plasma lipoproteins has not yet been elucidated in vivo. Therefore, the objective of the present study was to investigate the association between daidzein (DAI) and lipoproteins in human plasma upon administration of the aglycone and glucoside form. Five men aged 22-30 years participated in a randomised, double-blind study in cross-over design. After ingestion of DAI and daidzein-7-O-beta-D-glucoside (DG) (1 mg DAI aglycone equivalents/kg body weight) blood samples were drawn before isoflavone administration as well as 1, 2, 3, 4.5, 6, 8, 10, 12, 24 and 48 h post-dose. Concentrations of DAI in the different lipoprotein fractions (chylomicrons, VLDL, LDL, HDL) and in the non-lipoprotein fraction were analysed using isotope dilution capillary GUMS. The lipoprotein fraction profiles were similar for all subjects and resembled those obtained for plasma in our previously published study. The lipoprotein distribution based on the area under the concentration-time profiles from 0 h to infinity in the different fractions were irrespective of the administered form: non-lipoprotein fraction (53%) > LDL (20%) > HDL (14%) > VLDL (9-5%) > chylomicrons (2-5%). Of DAI present in plasma, 47% was associated to lipoproteins. Concentrations in the different lipoprotein fractions as well as in the non-lipoprotein fraction were always higher after the ingestion of DG than of DAI. Taken together, these results demonstrate an association between isoflavones and plasma lipoproteins in vivo.
Vitamin A (VA) deficiency in very low birth weight (VLBW) infants is associated with an increased risk for disorders related to kidney and lung maturation and function. VA losses through increased urinary retinol (ROH) excretion might contribute to this deficiency risk. The mechanism accounting for ROH loss in the urine has not yet been clarified. The aim of this study was to assess the excretion of ROH, retinol-binding protein 4 (RBP4) and transthyretin (TTR) in urine from VLBW infants in comparison with that in term infants in relation to kidney function. Urine specimens were collected from 15 VLBW infants (birth weight < 1,500 g) as well as from 20 term infants during the first 2 days after birth. ROH in urine was detectable in 14 of the 15 VLBW infants at a median concentration of 234 nmol/g creatinine. In the group of term infants, 17 of the 20 excreted ROH, but at an approximately five-times lower concentration (P<0.001). Excretion of RBP4 and TTR was also much higher in VLBW infants (both P<0.001). The urinary ROH excretion in VLBW infants may be related to the impaired tubular handling of its carrier proteins RBP4 and TTR. Thus, ROH excretion might contribute to an increased risk of VA deficiency, especially in VLBW infants.
The health promoting effects of a grapevine-shoot extract named Vineatrol (R) 30, which contains resveratrol (Resv) as well as considerable amounts of Resv oligomers, have recently been investigated. In the present study, we analyzed the free radical scavenging capacity, the ability to inhibit lipid peroxidation, and the capacity to enhance the human glutathione peroxidase 1 (GPx) and the human superoxide dismutase 1 (SOD) gene promoter activities of Vineatrol (R) 30. Vineatrol (R) 30 was able to scavenge the 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid radical cation and led to concentration-dependent inhibition of lipid peroxidation, Vineatrol (R) 30 not being superior to Resv alone in both cases. Vineatrol (R) 30 also enhanced the gene promoter activities of human GPx and SOD expressed in V79 cells, whereas this effect could not be demonstrated for Resv. In summary, the results presented in this study show that the Vineatrol (R) 30 grapevine-shoot extract is a free radical scavenger and potent antioxidant at non- eytotoxic concentrations.
This paper provides an overview of analytical techniques used to determine isoflavones (IFs) in foods and biological fluids with main emphasis on sample preparation methods. Factors influencing the content of IFs in food including processing and natural variability are summarized and an insight into IF databases is given. Comparisons of dietary intake of IFs in Asian and Western populations, in special subgroups like vegetarians, vegans, and infants are made and our knowledge on their absorption, distribution, metabolism, and excretion by the human body is presented. The influences of the gut microflora, age, gender, background diet, food matrix, and the chemical nature of the IFs on the metabolism of IFs are described. Potential mechanisms by which IFs may exert their actions are reviewed, and genetic polymorphism as determinants of biological response to soy IFs is discussed. The effects of IFs on a range of health outcomes including atherosclerosis, breast, intestinal, and prostate cancers, menopausal symptoms, bone health, and cognition are reviewed on the basis of the available in vitro, in vivo animal and human data.
The influence of a commercial production process for dehydrated potato flakes on the content of free phenolic compounds, total phenolics, and glycoalkaloids in potatoes during the subsequent processing steps was determined. Processing byproducts, such as potato peel (steam peeling), mashed potato residues, and side streams (blanching and cooking waters), have also been investigated. A high-performance liquid chromatography (HPLC) method was developed to separate and quantify caffeic acid, gallic acid, ferulic acid, p-coumaric acid, p-hydoxybenzoic acid, protocatechuic acid, vanillic acid, catechin, and three isomers of caffeoylquinic acid: chlorogenic, neochlorogenic and cryptochlorogenic acid. Determination of the glycoalkaloids a-solanine and alpha-chaconine was performed by using a high- performance thin-layer chromatography (HPTLC) method. The deliverables reveal that processing potatoes to potato flakes remarkably diminishes the content of the analyzed compounds, mainly due to peeling and leaching. The influence of thermal exposure is less significant. About 43% of the initial phenolic acids and 10% of the glycoalkaloids remain after processing. The results of the total phenolic content assay by Folin-Ciocalteu reagent are proportional to the content of phenolic compounds determined by HPLC. Steam peeling has a higher influence on glycoalkaloid losses compared to that on phenolics. The highest amounts of phenolic compounds and glycoalkaloids were found in peeling byproduct. During processing, the amount of chlorogenic acid decreased, whereas the concentration of neochlorogenic acid increased due to isomerization. The impact of the results on potato processing technology is discussed.
beta-Carotene functions independently of vitamin A in the reproductive performance of dairy cows. The concentrations of beta-carotene in plasma decrease during the dry period, and reach a nadir in about the first week postpartum. This coincides with a negative energy balance, which affects the onset of the first ovulation in early postpartum cows. Thus, we hypothesised that plasma beta-carotene concentrations during the peripartum period may affect ovulation in the first follicular wave postpartum in dairy cows. The aim of the present study was to investigate changes in the profiles of plasma beta-carotene concentrations during the peripartum period in ovulatory and anovulatory cows during the first follicular wave postpartum. We used 22 multiparous Holstein cows, which were fed a total mixed ration consisting of grass, corn silage and concentrate, and collected blood samples for beta-carotene and progesterone analysis from week 3 prepartum to week 3 postpartum when the period of day 0-6 after parturition was regarded as the parturient week (week 0). The first ovulation was confirmed using the profile of plasma progesterone concentrations and colour Doppler ultrasound. Thirteen cows ovulated during the first postpartum follicular wave. Parity, the dry-off period, calving interval, mastitis episodes, and actual 305 days' milk yield during the previous lactation, and milk composition in the last month during the previous lactation in this study did not differ between ovulatory and anovulatory cows. Differences in the plasma beta-carotene profile were observed between ovulatory and anovulatory cows. Plasma P-carotene concentrations at week 3 prepartum were greater in ovulatory cows (2.97 +/- 0.24mg/L) than in anovulatory cows (1.53 +/- 0.14mg/L; P < 0.001), after that its concentrations in ovulatory cows decreased and reached the lowest level at week I postpartum, although its concentrations in anovulatory cows remained unchanged. No differences in plasma P-carotene concentrations between the two groups were observed postpartum. The present study indicates for the first time that the lower P-carotene concentrations in plasma during the prepartum period is associated with anovulation during the first follicular wave postpartum.