A Catechin‐rich Beverage Improves Obesity and Blood Glucose Control in Patients With Type 2 Diabetes

We investigated the effects of continuous ingestion of a catechin‐rich beverage in patients with type 2 diabetes who were not receiving insulin (Ins) therapy in a double‐blind controlled study. The participants ingested green tea containing either 582.8 mg of catechins (catechin group; n = 23) or 96.3 mg of catechins (control group; n = 20) per day for 12 weeks. At week 12, the decrease in waist circumference was significantly greater in the catechin group than in the control group. Adiponectin, which is negatively correlated with visceral adiposity, increased significantly only in the catechin group. Although the increase in Ins at week 12 was significantly greater in the catechin group than in the control group, no apparent difference was noted between the two groups in glucose and hemoglobin A_1c. In patients treated with insulinotropic agents, the increase in Ins at week 12 was significantly greater in the catechin group than in the control group. This significant increase in Ins levels was observed only in the catechin group. In the catechin group receiving other treatments, Ins levels remained unchanged. In addition, in patients treated with insulinotropic agents, the decrease in hemoglobin A_1c at week 12 was significantly greater in the catechin group than in the control group. These results suggest that a catechin‐rich beverage might have several therapeutic uses: in the prevention of obesity; in the recovery of Ins‐secretory ability; and, as a way to maintain low hemoglobin A_1c levels in type 2 diabetic patients who do not yet require Ins therapy.     

儿茶素对棉枯萎病菌胞壁降解酶的抑制及在棉花抗病性中的作用

在含有儿茶素的培养液中棉枯萎病菌(Fusarium oxysporum f. sp. vasinfectum)的多聚半乳糖醛酸酶(PG)和果胶裂解酶(PL)活性明显降低。儿茶素可明显抑制初步纯化的PG和PL活性以及它们对棉苗组织的浸软作用。对棉苗组织中儿茶素含量的测定结果表明:抗病品种棉苗组织中儿茶素含量较高;氟乐灵处理可诱发棉苗产生对枯萎病的诱导抗性,同时也提高棉苗组织中的儿茶素的含量;枯萎病菌侵染后棉苗组织中儿茶素含量明显升高,以抗病品种棉苗和氟乐灵诱发处理棉苗组织中儿茶素含量的增加更为明显。棉苗组织提取液中的酚类物质可抑制PG和PL的活性,且证明这种抑制作用主要是由儿茶素引起。提取液对PG和PL活性的抑制作用与棉苗组织中儿茶素的含量呈直接的正相关关系。因此,作者认为棉苗组织中的儿茶素可能通过对病菌PG和PL等胞壁降解酶的抑制而与棉花对枯萎病的抗病性及氟乐灵诱发的诱导抗性有关。     

Amplification of antioxidant activity of catechin by polycondensation with acetaldehyde

Catechin exhibits numerous biological and pharmacological effects attributed to antioxidant action. The synthetic poly(catechin)s condensed through acetaldehyde with different molecular weights were assessed in terms of antioxidant activity and enzyme inhibitory activity on the basis of a catechin repeating unit and compared with monomeric catechin. The poly(catechin)s showed great amplification of superoxide scavenging activity, xanthine oxidase (XO) inhibitory activity, and inhibition effects on human low-density lipoprotein oxidation initiated by 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH) as a radical generator on the catechin unit level, compared to monomeric catechin: these activities were proportional to their molecular weights. The reducing power of the polymer was lower than that of monomeric catechin, which decreased with increasing the molecular weight. The polymer also protected endothelial cells from oxidative injury induced by AAPH, with a greater effect expressed on a catechin unit basis than that of the monomer. These results demonstrate that the poly(catechin)s are more potent antioxidant agents and enzyme inhibitors.     

The binding of palmitoyl-CoA to bovine serum albumin

Bovine serum albumin (BSA) is routinely utilized in vitro to prevent the adverse detergent effects of long-chain acyl-CoA esters (i.e., palmitoyl-CoA) in enzyme assays. Determination of substrate saturation kinetics in the presence of albumin would only be valid if the relationship between bound and free substrate concentrations was known. To elucidate the relationship between bound and free palmitoyl-CoA concentrations in the presence of BSA, several different techniques including equilibrium dialysis, equilibrium partitioning, fluorescence polarization and direct fluorescence enhancement were investigated. Direct fluorescence enhancement using a custom synthesized fluorescent probe, 16-(9-anthroyloxy)palmitoyl-CoA (AP-CoA), was the best approach to this question. Measurement of the relationship between mol of palmitoyl-CoA bound per mol of BSA (nu) versus -log[free palmitoyl-CoA] revealed that the binding of palmitoyl-CoA to BSA, like palmitate was nonlinear, suggesting the presence of more than one class of acyl-CoA binding sites. Computer analyses of the binding data gave a best fit to the 2,4 two-class Scatchard model, suggesting the presence of two high-affinity primary binding sites (k1 = (1.55 +/- 0.46) x 10(-6) M-1) and four lower affinity secondary binding sites (k2 = (1.90 +/- 0.09) x 10(-8) M-1). Further analyses using the six parameter stoichiometric (stepwise) ligand binding model supports the existence of six binding sites with the higher affinities associated with the binding of the first mole of palmitoyl-CoA and weaker binding occurring after the first two sites are occupied. The association constants from this model of multiple binding diminish sequentially (i.e., K1 greater than K2 greater than K3 greater than...greater than or equal to K6), suggesting that each mol of long-chain acyl-CoA binds to BSA with decreasing affinities.     

Association of the radiosensitizers metronidazole and misonidazole (RO-07-0582) with bovine serum albumin. Effect of urea and ionic strength

The stability of association of nitroimidazole radiosensitizers (metronidazole and misonidazole) with bovine serum albumin (BSA) was examined in aqueous solutions by 1H n.m.r. spectroscopy in the presence of urea (0-8M) as denaturant, or high salt concentration (NaCl0-5M). A broadening of n.m.r. lines of the two radiosensitizers observed in the presence of BSA disappeared with increasing urea concentration. An especially large narrowing effect was observed for the lines attributed to the methylene group near to the hydroxyl in the side chain of misonidazole. The results suggest a release of both radiosensitizers from their binding sites on unfolding by urea of the polypeptide chain of BSA. The increase of ionic strength I caused a monotonic enhancement of broadening by BSA of the metronidazole lines. For misonidazole, the enhancement of broadening was observed at values of I greater than 1, but at low (less than 1 M) concentrations of NaCl the broadening disappeared. Thus, the results obtained in the systems with salt reflect quantitative changes in hydrophobic and hydrogen-bonded contributions to binding of aliphatic moieties of radiosensitizers to BSA.     

Enhancement of antibody production by growth factor addition in perfusion and hollow-fiber culture systems

The effects of the high-molecular-weight growth factors, transferrin and bovine serum albumin (BSA), on antibody production were analyzed quantitatively in continuous hollow-fiber cultivation over a period of 60 days. Transferrin enhanced cell growth but had no significant effect on the specific antibody production rate, whereas BSA significantly enhanced antibody production. The antibody production rate was increased 4- and 14-fold respectively by feeding BSA at 2 and 5 g L(-1) into the EC side of the system (the side connected to the cell-containing outer part of the hollow-fiber unit) compared with the production achieved without BSA. Addition of 5 g L(1) BSA into the IC side of the system (the side connected to the inner part of the hollow-fiber unit) resulted in a 2.5-fold increase in the antibody production rate. The effect of BSA was also analyzed using the perfusion culture system with a separation unit. When fresh medium containing either 2 or 5 g L(-1) BSA was fed into the reactor, both the specific growth rate and specific death rate increased, while the specific antibody production rate was increased 2- and 25-fold, respectively, by feeding BSA at these two concentrations compared with no addition. Comparing the two systems, the increase in the antibody production rate achieved with the hollow-fiber system was threefold greater than that in the perfusion culture system with the same concentration of BSA feeding. (c) 1995 John Wiley & Sons, Inc.     

HepG2 cell LDL receptor activity and the accumulation of apolipoprotein B and E in response to docosahexaenoic acid and cholesterol.

In the present study, the accumulation of apolipoproteins (apo) A-I, B, and E in culture medium was measured after 0, 3, 6, 12, and 24 h of incubation with 150 microM docosahexaenoic acid complexed to 75 microM bovine serum albumin (BSA-22:6), either in the presence or absence of 50 micrograms/ml cholesterol and 4 micrograms/ml 25-hydroxycholesterol (C/25-OH). HepG2 cells incubated with BSA + C/25-OH for 24 h accumulated approximately 2.0-fold greater apoE and B as compared to BSA-treated cells. Moreover, HepG2 cell apoB accumulation after 24 h of BSA-22:6 treatment was approximately 2.0-fold greater than apoB accumulation from cells treated with BSA alone. When BSA-22:6 and C/25-OH were both included in the incubation, apoB accumulation was approximately 5.0-fold greater than BSA-treated cells. Comparative studies using BSA-18:1 were carried out for 24 h and showed similar levels of apoA-I, B, and E accumulation in culture medium as compared to BSA-22:6-treated cells. In addition, apoA-I, B, and E mRNA abundance were found to be unaffected by type of fatty acid treatment or length of incubation, averaging 48.2 +/- 7.5, 222 +/- 33.6, and 17.1 +/- 0.7 pg mRNA/micrograms RNA (mean +/- SEM), respectively. As the accumulation of apoB and apoE in culture medium may be modified by HepG2 cell LDL receptor expression, LDL receptor mRNA abundance and LDL receptor activity were quantified at various times over the course of the study. By 6 h of BSA + C/25-OH treatment, LDL receptor mRNA was reduced approximately 2.3-fold, while receptor activity was reduced approximately 1.5-fold, as compared to BSA controls. In an experiment designed to determine uptake of HepG2 cell lipoproteins, 3H-labeled apoB-containing lipoproteins derived from HepG2 cells were prepared. The 3H-labeled lipoproteins were 1.25-fold more likely to be removed from the media of HepG2 cells treated with BSA than from cells treated with BSA + C/25-OH. From these results, we postulate that HepG2 cell LDL receptor activity mediates the removal of apoB, E-containing lipoproteins from culture medium and contributes to the lower accumulation of apoB and E observed in culture medium from cells treated with BSA as compared to cells treated with C/25-OH.     

Carbon 13 NMR studies of saturated fatty acids bound to bovine serum albumin. I. The filling of individual fatty acid binding sites

13C NMR chemical shift and intensity results for a series of carboxyl 13C-enriched saturated fatty acids (8-18 carbons) bound to bovine serum albumin (BSA) are presented as a function of increasing fatty acid (FA)/BSA mole ratio. Spectra for long-chain (greater than or equal to 12 carbons) FA X BSA complexes exhibited up to five FA carboxyl resonances, designated a, b, b', c, and d. Only three resonances (peaks b, b', and d) were observed below 3:1 FA X BSA mole ratio, and at greater than or equal to 3:1 mole ratio, two additional resonances were observed (peaks c and a). In a spectrum of 5:1 stearic acid X BSA complexes, peaks b, b', and d each represented approximately one-fifth, and peak c approximately two-fifths, of the total FA carboxyl intensity. Plots of total carboxyl/carbonyl intensity ratio as a function of FA X BSA mole ratio were linear up to 7-9 mole ratio. Deviation from linearity at mole ratios greater than or equal to 7 was accompanied by the detection of crystalline unbound FA (as 1:1 acid/soap) by X-ray diffraction. In contrast to long-chain FA X BSA complexes, 13C NMR spectra of octanoic acid X BSA complexes yielded only one FA carboxyl resonance (peak c) at FA X BSA mole ratios between 1 and 20. We conclude: peaks b, b', and d represent FA bound to three individual high affinity (primary) long-chain FA binding sites on BSA; peak c represents FA bound to several secondary long-chain (or primary short-chain) FA binding sites on BSA; peak a represents long-chain FA bound to an additional lower affinity binding site. We present a model that correlates the observed 13C NMR resonances with individual binding site locations predicted by a recent three-dimensional model of BSA.     

Screening of Grassland Plants for Restoration after Spotted Knapweed Invasion

Invasions of North American grasslands by Spotted knapweed (Centaurea maculosa Lam.) are mediated in part by Spotted knapweed root exudation of (±)‐catechin, a potent phytotoxin. Residual soil (±)‐catechin may interfere with reestablishment of native grassland species even after Spotted knapweed populations are controlled. Grassland species that are resistant to (±)‐catechin may be more successful for restoration of areas infested by Spotted knapweed. We evaluated the (±)‐catechin resistance of 23 grassland species by measuring the effects of seven (±)‐catechin concentrations (0–4.0 mg/mL) on seed germination, seedling root and shoot elongation, and seedling mortality. (±)‐Catechin treatments were chosen to reflect the range of observed Spotted knapweed field soil (±)‐catechin concentrations. Inhibition of root elongation was the strongest and most common effect of (±)‐catechin treatment. High (±)‐catechin concentrations reduced mean root lengths of 5 of the species by more than 75% and another 10 species by more than 55%. Experimentally derived concentrations needed to reduce root length by 50% (EC50), an indicator of (±)‐catechin resistance, ranged from 0.43 mg/mL ± 0.30 SE to greater than 4.0 mg/mL among species. Eight species with EC50s greater than 3.0 mg/mL were identified as resistant to (±)‐catechin and are likely suitable for revegetation of Spotted knapweed–infested areas. (±)‐Catechin resistance was positively correlated with mean seed mass, suggesting that seed carbohydrate reserves may allow seedlings to detoxify (±)‐catechin, develop barriers to (±)‐catechin exposure, or sustain a positive growth rate, despite (±)‐catechin‐induced cell death. Future efforts to identify allelochemical‐resistant grassland species should focus on large‐seeded species.     

Molecular characteristics of bovine serum albumin-dextran conjugates

Bovine serum albumin (BSA)-dextran conjugates were prepared by using the Maillard reaction; depending on the ratio of dextran to BSA used, about 0.5-1 mol of dextran could be bound to 1 mol of native BSA. SDS-PAGE patterns revealed that BSA and dextran had been covalently bonded. Structural analyses by fluorescence spectroscopy and circular dichroism indicated that the BSA surface in each conjugate was covered with dextran without any great disruption of the native conformation. The conjugates could be grouped into two fractions on the basis of the weight-average molecular mass measured: the main fraction at 1.95-2.35 x 10(5) g/mol and a less-abundant fraction with aggregates greater than 1.50 x 10(6) g/mol. High-performance size-exclusion chromatography in conjunction with multi-angle laser light scattering detection revealed that the BSA-dextran conjugates prepared by using the Maillard reaction had various molar masses and radii.     

Comparison of the bioavailability of quercetin and catechin in rats

Quercetin and catechin are present in noticeable amounts in human diet and these polyphenolic compounds are supposed to exert beneficial effects on human health. However, their metabolic fates in the organism have never been compared. In the present study, rats were fed a 0.25% quercetin or a 0.25% catechin diet. Quercetin and catechin metabolites were analyzed in plasma and liver samples by high-performance liquid chromatography coupled to an ultraviolet or a multielectrode coulometric detection. All plasma metabolites were present as conjugated forms, but catechin metabolites were mainly constituted by glucuronidated derivatives, whereas quercetin metabolites were sulfo- and glucurono-sulfo conjugates. Quercetin was more intensively methylated than catechin in plasma. The plasma quercetin metabolites are well maintained during the postabsorptive period (approximately 50 microM), whereas the concentration of catechin metabolites dropped dramatically between 12- and 24-h after an experimental meal (from 38.0 to 4.5 microM). In the liver, the concentrations of quercetin and catechin derivatives were lower than in plasma, and no accumulation was observed when the rats were adapted for 14 d to the supplemented diets. The hepatic metabolites were intensively methylated (90-95%), but in contrast to plasma, some free aglycones could be detected. Thus, it clearly appears that studies dealing with the biological impact of these polyphenols should take into account the feature of their bioavailability, particularly the fact that their circulating metabolites are conjugated derivatives.     

Influence of albumin on granulocyte and macrophage colony-forming efficiency

Mouse granulocyte and macrophage precursors were assayed in plasma clot and fibrin clot cultures, and the effect of bovine serum albumin (BSA) on colony formation was investigated. The number of granulocyte colonies (CFU-g) and clusters increased as the albumin concentration was increased and the number of macrophage colonies (CFU-m) and clusters concomitantly decreased. The albumin-mediated suppression of macrophage colony formation was overcome by the addition of more than 10% fetal bovine serum (FBS) to the plasma clot culture. The effect of BSA and fatty-acid-free BSA on colony-forming efficiency was also tested in fibrin clot cultures containing 10% FBS. Both BSA and fatty-acid-free BSA at a final concentration of 0.5-2% enhanced CFU-g colony formation, while both forms of BSA reduced the number of CFU-m colonies. However, neither BSA nor fatty-acid-free BSA had any effect on colony formation in FBS-free fibrin clot cultures, and only BSA enhanced colony formation when transferrin, linoleic acid, alpha-thioglycerol and dextran were added to the culture. The number of CFU-g (15.6 +/- 3.1) was higher in cultures containing BSA, transferrin, etc., than the number (9.8 +/- 2.5) in cultures without BSA and including transferrin, etc., than the number (9.8 +/- 2.5) in cultures without BSA and including transferrin, etc. (p less than 0.01). The number of CFU-m (32.0 +/- 6.8) in cultures containing BSA and the other four factors was lower than the number (72.2 +/- 5.6) in the culture without BSA (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Optimization and validation of analytical conditions for bovine serum albumin using capillary electrophoresis.

A quick and reproducible capillary electrophoresis method was optimized and validated for the assay of bovine serum albumin (BSA). The effects of various parameters such as pH of buffer, concentration of buffer, capillary dimensions, use of coated capillaries, and additives such as surfactants and protein solubilizers were evaluated. The capillary coatings or additives did not give any advantage in reducing the surface adsorption of BSA on the capillary walls. The optimized conditions include use of borate buffer, pH 8.5 having a concentration of 150 mM in a 27 cm capillary with an aperture window of 100 x 200 microns for detection. The optimized method for the detection of BSA was validated. The interday and intraday coefficient of variation was not greater than 7.59% at BSA concentrations of 25-1000 micrograms/ml. The method developed was reproducible and accurate.     

Relationship between the anti-hemolysin activity and the structure of catechins and theaflavins

We examined the corresponding isomers of catechins and theaflavins for anti-hemolysin activities against Staphylococcus aureus alpha-toxin and Vibrio cholerae O1 hemolysin. Catechins and theaflavins showed anti-hemolysin activities in a dose-dependent manner. Among the catechins tested, (-)catechin gallate, (-)epicatechin gallate and (-)epigallocatechin gallate having galloyl groups in their molecules showed more potent anti-hemolysin activities against both toxins. On the other hand, free catechins, i. e. (-)catechin, (-)gallocatechin, (-) epicatechin and (-)epigallocatechin had low anti-hemolysin activities against alpha-toxin. Although (-)catechin or (-)gallocatechin had no effect on cholera hemolysin, (-) epicatechin and (-)epigallocatechin were slightly inhibitory. Among dextrocatechins, (+) epicatechin and (+)epigallocatechin proved to be more effective than (+)catechin and (+) gallocatechin. The anti-hemolysin activities of theaflavins against alpha-toxin and cholera hemolysin were dependent on the number of the galloyl group in their structure. These results suggest that the tertiary structure of the catechin or theaflavin and the active site of hemolysin, that affects the interaction between them, plays an important role in the anti-hemolysin activity.     

Exploring the differences and similarities between urea and thermally driven denaturation of bovine serum albumin: intermolecular forces and solvation preferences

The interactions of bovine serum albumin (BSA) with urea/water were investigated by computer simulation. It was revealed that the BSA-hydrophobic residues in urea solutions favored contact with urea more than with water. Energy decomposition analysis showed that van der Waals energy was the dominant driving force behind urea affinity for hydrophobic residues, whereas coulombic attraction was largely responsible for water affinity for these residues. Meanwhile, urea–BSA hydrogen bond energies were found to be weaker than water–BSA hydrogen bond energies. The greater strength of water–BSA hydrogen bonds than urea–BSA hydrogen bonds, and the opposing preferential interaction between the BSA and urea suggest that disruption of hydrophobic interaction predominates urea–protein denaturation. In pure water, hydrophobic residues showed aggregation tendencies at 323 K, suggesting an increase in hydrophobicity, while at 353 K the residues were partly denatured due to loss of hydrogen bonds; thus, disruption of hydrophobic interactions appeared to contribute less to thermal denaturation.     

Co-administration of quercetin and catechin in rats alters their absorption but not their metabolism

Quercetin and catechin are among the major flavonoids in plant foods and their intake has been associated to a risk reduction in several degenerative diseases. The aim of the present study was to bring data on the bioavailability of quercetin and catechin when administered simultaneously. The study was performed on rats adapted to diets containing (i) 0.25% quercetin, or (ii) 0.25% catechin, or (iii) 0.25% quercetin+0.25% catechin. Quercetin, catechin and their metabolites were determined in plasma, urine and liver by HPLC with UV or coulometric detection. When quercetin and catechin were fed in association, their respective plasma concentration significantly decreased (-35% and -28% respectively), whereas the urinary and hepatic concentrations were only affected for quercetin (-36%). These data may be explained by a competitive interaction between quercetin and catechin at the digestive level, leading to a reduction of the intestinal absorption of quercetin and a possible delaying of catechin absorption over time. The simultaneous administration of quercetin and catechin had no effect on the formation of their glucurono and sulfo conjugates, indicating the absence of competition between quercetin and catechin for the corresponding conjugative enzymes.     

Preferential interaction of albumin-binding proteins, gp30 and gp18, with conformationally modified albumins. Presence in many cells and tissues with a possible role in catabolism.

Albumin binding to the endothelial surface apparently initiates its transcytosis via plasmalemmal vesicles and also increases capillary permselectivity. Several albumin-binding proteins, which, we call gp60, gp30, and gp18, have been identified; however, their functional relationship to each other is unclear. In this study, we show that gp30 and gp18 are both variably expressed by cultured rat fibroblasts, smooth muscle cells, and endothelial cells and are present in all tissues examined (heart, lung, skeletal muscle, diaphragm, duodenum, kidney, fat, brain, adrenal, pancreas, and liver). The binding of albumin-gold complexes (A-Au) to gp30 and gp18 was compared with that of native and modified albumins. Monomeric native bovine serum albumin (BSA) interacted much less avidly than A-Au and BSA that was chemically modified by formaldehyde (Fm-BSA) or maleic anhydride (Mal-BSA). Mal-BSA and A-Au have similar affinity constants for gp30 and gp18 (KD approximately 3-7 micrograms/ml (50-100 nM)), which is 1000-fold greater than BSA. These interactions were Ca(2+)-independent but sensitive to pH (< 6.0) and high salt concentrations (> or = 1.0 M). Comparative biochemical characterization provided evidence of conformational changes for Mal-BSA, Fm-BSA, and A-Au. Anti-native BSA serum recognizes BSA much more avidly than modified BSA. Mal-BSA, Fm-BSA, and A-Au are much more sensitive to trypsin digestion than BSA. Cellular processing was also examined. A-Au and Mal-BSA bound at the endothelial cell surface were degraded, whereas BSA was not. Our results indicate that: (i) gp30 and gp18, unlike gp60, are expressed in all tissues tested regardless of the type of endothelia lining the microvasculature and the local mechanism of transendothelial albumin transport; (ii) BSA conformationally modified by either surface adsorption or chemical means not only interacts more avidly with gp30 and gp18 than native albumin but also is preferentially degraded by the cells; (iii) A-Au and native albumin are not equivalent probes for detecting albumin interaction sites; and (iv) gp30 and gp18 exhibit binding behavior resembling scavenger receptors. The possible roles of gp30 and gp18 in albumin binding, transcytosis, endocytosis, and even protein catabolism are discussed.     

Ganglioside-specific binding protein on rat brain membranes

A derivative of ganglioside GT1b (IV3NeuAc,II3(NeuAc)2-GgOse4) with an active ester in its lipid portion was synthesized and covalently attached to bovine serum albumin (BSA). The conjugate, having four GT1b molecules per albumin molecule [GT1b)4BSA) was radioiodinated and used to probe rat brain membranes for ganglioside binding proteins. A ganglioside-specific, high affinity (KD = 2-4 nM), saturable (Bmax = 13-20 pmol/mg membrane protein) binding site for 125I-(GT1b)4BSA was demonstrated on detergent-solubilized rat brain membranes adsorbed to filters. 125I-(GT1b)4BSA binding was tissue-specific (more than 35-fold greater to brain than to liver membranes) and was nearly eliminated by pretreatment of brain membrane-adsorbed filters with trypsin (1 microgram/ml). Underivatized gangliosides added as mixed detergent-lipid micelles blocked 125I-(GT1b)4BSA binding to brain membranes; structurally related GQ1b, GT1b, and GD1b were the most potent (half-maximal inhibition at 70-110 nM), while half-maximal inhibition by other gangliosides (GD3, GD1a, GM3, GM2, and GM1) required 5-20-fold higher concentrations. Other sphingolipids, neutral glycosphingolipids, and glycoproteins were poor inhibitors, and treatment of (GT1b)4BSA with neuraminidase attenuated its binding. Although most phospholipids were noninhibitory, phosphatidylinositol and phosphatidylglycerol inhibited half-maximally at 400-600 nM. However, inhibition of 125I-(GT1b)4BSA binding by gangliosides was competitive and reversible while that by phosphatidylinositol and phosphatidylglycerol was not. Ganglioside-protein conjugate binding reveals ganglioside-specific brain membrane receptors.     

A green tea extract high in catechins reduces body fat and cardiovascular risks in humans

Objective: The body fat reducing effect and reduction of risks for cardiovascular disease by a green tea extract (GTE) high in catechins was investigated in humans with typical lifestyles. Research Methods and Procedures: Japanese women and men with visceral fat‐type obesity were recruited for the trial. After a 2‐week diet run‐in period, a 12‐week double‐blind parallel multicenter trial was performed, in which the subjects ingested green tea containing 583 mg of catechins (catechin group) or 96 mg of catechins (control group) per day. Randomization was stratified by gender and body mass index at each medical institution. The subjects were instructed to maintain their usual dietary intake and normal physical activity. Results: Data were analyzed using per‐protocol samples of 240 subjects (catechin group; n = 123, control group; n = 117). Decreases in body weight, body mass index, body fat ratio, body fat mass, waist circumference, hip circumference, visceral fat area, and subcutaneous fat area were found to be greater in the catechin group than in the control group. A greater decrease in systolic blood pressure (SBP) was found in the catechin group compared with the control group for subjects whose initial SBP was 130 mm Hg or higher. Low‐density lipoprotein (LDL) cholesterol was also decreased to a greater extent in the catechin group. No adverse effect was found. Discussion: The continuous ingestion of a GTE high in catechins led to a reduction in body fat, SBP, and LDL cholesterol, suggesting that the ingestion of such an extract contributes to a decrease in obesity and cardiovascular disease risks.