Hypocholesterolaemic effect of Bifidobacterium animalis subsp. lactis (Bb12) and trypsin casein hydrolysate

Hypercholesterolaemia is one of the most important risk factors in the development of cardiovascular disease. In this study, we report the in vitro potential of Bifidobacterium animalis subsp. lactis (Bb12) cultures and bovine casein hydrolysates formed by trypsin and Bb12 culture to reduce cholesterols levels. Cholesterol levels in vitro were reduced by up to 48% after incubation with Bb12 and up to 87% after incubation with trypsin hydrolysates, whereas unhydrolysed bovine casein did not affect cholesterol levels. Individual peptide fractions, obtained from size-exclusion chromatography, from casein hydrolysates formed by trypsin after a 48 h hydrolysis, reduced cholesterol levels by 2.7–50%. The molecular masses of these fractions, containing hypocholesterolaemic peptides, were below 1200 Da, as determined by LC-MS.     

Lipid components prepared from a freshwater Clam (Corbicula fluminea) extract ameliorate hypercholesterolaemia in rats fed high-cholesterol diet

To explore the hypocholesterolaemic components in the fat fraction of freshwater clam extract (FCE), we further fractionated the fat fraction by silica gel column chromatography into nine fat subfractions. In the present study, we used exogenous hypercholesterolaemic rats induced by feeding a high-cholesterol diet; the doses of the added fat subfractions were equivalent to those in 30% FCE. Two (FF1, FF2) out of the nine fat subfractions strongly reduced serum cholesterol levels in the rats fed a high-cholesterol diet. Both FF1 and FF2 up-regulated the hepatic gene expression of cholesterol 7α-hydroxylase, a rate-limiting enzyme of bile acid biosynthesis. Thin-layer chromatography showed that FF1 primarily contained sphingolipids, while FF2 mainly contained triacylglycerols and sterol esters. These results indicate that fractions containing sphingolipids, triacylglycerols, and sterol esters are possibly responsible for the hypocholesterolaemic action in a novel manner through the up-regulation of the hepatic biosynthesis of bile acids.     

Selective in vivo effect of chitosan on fatty acid,neutral sterol and bile acid excretion: A longitudinal study

Chitosan, a deacetylated form of chitin, is a dietary fibre known for its hypolipidemic properties, which are mainly attributed to its unique cationic characteristics. We studied the selective in vivo effect of chitosan on fat excretion in order to elucidate its hypolipidemic mechanism. A 4-week longitudinal study was conducted in guinea pigs and the effect of chitosan on fat-absorption was compared to that of a soluble fibre: digestion-resistant maltodextrin. Animals were fed with high-fat isocaloric diets containing 12/100 g of cellulose, digestion-resistant maltodextrin or chitosan. Subsequently, the excretion of fatty acids, neutral sterols and bile acids was determined. Chitosan selectively reduced fat absorption in comparison to digestion-resistant maltodextrin. The excretion of lauric, myristic and palmitic fatty acids of animals fed with chitosan was more than 10-, 5- and 2-fold higher, respectively, than in the cellulose group, whereas stearic acid excretion was not significantly altered. Oleic, linoleic and α-linolenic acid excretion were also significantly higher (P < 0.001). The n−6/n−3 ratio in faeces of the chitosan group was 23.68, compared to 13.95 in the cellulose group. Total neutral sterol excretion was increased by both dietary fibres, whereas bile acid excretion was only increased by chitosan. Nevertheless, chitosan inhibited the intestinal bioconversion of cholesterol and primary bile acids to secondary metabolites. Hence, these results reveal that chitosan and digestion resistant maltodextrin exert their hypolipidemic activity by different mechanisms.     

不同脱乙酰度蚕蛹壳聚糖抑菌性能的比较

研究了3种不同脱乙酰度蚕蛹壳聚糖对9种供试菌的抑菌效果。结果表明:3种壳聚糖对蜡状芽孢杆菌、鼠伤寒杆菌、枯草芽孢杆菌、白色念珠球菌、绿脓假单胞菌、大肠杆菌和金黄色葡萄球菌有明显的抑制作用,对巨大芽孢杆菌和嗜热脂肪芽孢杆菌的抑制作用不明显。随着壳聚糖溶液浓度的增大,其抑菌能力也增强。3种壳聚糖的抑菌活性为:脱乙酰度为95.96%的壳聚糖>脱乙酰度为86.45%的壳聚糖>脱乙酰度为78.12%的壳聚糖。壳聚糖的抑菌活性呈现随pH降低而增加的趋势,当pH值在pH 4.0～5.0,壳聚糖对所有供试菌均能完全抑制。高脱乙酰度蚕蛹壳聚糖作为热加工食品的防腐剂,可稳定保持其抑菌防腐性能。     

Cholesterol-lowering effect of whole lupin (Lupinus albus) seed and its protein isolate

This study describes the hypocholesterolaemic effect of whole lupin and its protein in hamsters. The diets were: casein (control group HC), lupin protein isolate (group HPI) and whole lupin seed (group HWS). Diets from HPI and HWS promoted a significant reduction of total cholesterol and non-HDL cholesterol in the hamsters’ plasma as compared with HC. The true digestibility of HPI and HC groups were similar and differed significantly from the HWS one, which in turn showed a significant difference in total sterol excretion as compared to the former groups. Histological analysis of the liver revealed that animals fed on HPI and HWS diets presented a low level of steatosis (level 1) as compared to the ones fed on HC diet (level 4). Our findings demonstrate that protein isolate from Lupinus albus from Brazil has a metabolic effect on endogenous cholesterol metabolism and a protector effect on development of hepatic steatosis.     

Hypocholesterolaemic action of Lactobacillus casei F0822 in rats fed a cholesterol-enriched diet

Elevated serum cholesterol is a major risk factor for coronary artery disease. Probiotics may manage elevated cholesterol. The hypocholesterolaemic effects of Lactobacillus casei F0822 and its functional mechanisms were investigated in rats. The serum total cholesterol, low-density lipoprotein cholesterol and liver total cholesterol levels significantly decreased in rats fed a high-cholesterol diet plus drinking water supplemented with viable cells of strain F0822; however, there was no significant difference in the serum high-density lipoprotein cholesterol levels among the treatment groups. The hypocholesterolaemic mechanisms of strain F0822 were attributed to its ability to suppress the reabsorption of bile acids into the enterohepatic circulation though hydrolysis of conjugated bile acids in the small intestine, binding of deoxycholic acid and hyodeoxycholic acid in the large intestine, and increase in propionate:acetate ratio in the large intestine in rats. Strain F0822 may be a promising probiotic culture with potential hypocholesterolaemic action in human.     

Promising interaction between nanoencapsulated lutein with low molecular weight chitosan: Characterization and bioavailability of lutein in vitro and in vivo

This study aims to develop water-soluble low molecular weight chitosan (LMWC) nanoencapsules with lutein to improve its bioavailability. Lutein-LMWC nanoencapsules were prepared, characterized and bioavailability was studied in vitro and in vivo with lutein in mixed micelles (control). The particle size ranged between 80–600 nm, which was confirmed by Atomic Force Microscope. The interaction between LMWC and lutein in nanocencapsules by ¹H and ¹³C NMR showed the essentiality of water molecules to hold the lutein between LMWC chains of nanoparticle with a reversible weak bond. Bioavailability of lutein (200 μM) in vitro showed that lutein-LMWC nanoencapsules was significantly higher (27.7%) than control. Postprandial lutein level in the plasma (54.5%), liver (53.9%) and eyes (62.8%) of mice fed on nanoencapsulated lutein were higher than the control. LMWC may serve as novel carrier for enhancing the lutein bioavailability and can be suggested as the better dietary compound in food and pharmaceutical applications.     

Separation and purification of hypocholesterolaemic peptides from whey protein and their stability under simulated gastrointestinal digestion

In this study, hypocholesterolaemic peptides were separated from whey protein trypsin hydrolysates (WPTHs) and the inhibition of cholesterol micellar solubility (ICMS) and the stability of hypocholesterolaemic peptides after exposure to simulated gastrointestinal conditions were evaluated. Whey protein trypsin hydrolysates were concentrated by ultrafiltration and then desalted through macroporous adsorption resin DA201‐C. Sephadex G‐50 gel filtration chromatography was used to separate the hypocholesterolaemic peptides from the fraction eluted with 75% ethanol. The results suggested that the fraction obtained by gel filtration with a molecular weight (MW) ranging from 1900 Da to 3100 Da exhibited the highest hypocholesterolaemic activity. This fraction was further separated by reversed‐phase high‐performance liquid chromatography into 14 fractions; the peptides with the highest activities were obtained from the fifth peak with a MW of 2454 Da and 58.77% ICMS. The hypocholesterolaemic peptides were relatively stable when exposed to simulated gastrointestinal digestion.     

离子交换层析色谱法分离壳聚糖

用CMsepharoseCL 6B离子交换剂,使用不同的柱尺寸,采用离子强度线性梯度洗脱,对脱乙酰度80%,90%的壳聚糖样品进行分离。从脱乙酰度80%的壳聚糖样品分离得到3个组分实验结果表明,采用线性梯度洗脱时,直径相同的柱子,长的离子交换柱有利于壳聚糖的分离;对同一根离子交换柱,线性梯度洗脱体积的增加有利于壳聚糖的分离.分离不同脱乙酰度壳聚糖时,高脱乙酰度壳聚糖较低脱乙酰度壳聚糖在起始缓冲液洗脱时,洗脱出的壳聚糖含量较低,在高离子强度处洗脱出的壳聚糖含量较高.     

Concentration-dependent displacement of cholesterol in micelles by hydrophobic rice bran protein hydrolysates

BACKGROUND: Rice bran, containing about 100–150 g kg^?1 protein, is a by‐product of rice milling that has only become an available ingredient in recent years owing to the centralisation of rice milling. Rice bran, but not its protein fraction or hydrolysates, has been shown to have a hypocholesterolaemic effect. Peptides from soy, milk and other foods have been proposed to have hypocholesterolaemic effects based on their ability to lower cholesterol solubility in bile acid/phosphotidyl choline micelles. RESULTS: Rice bran protein hydrolysates (RBPHs) were prepared and investigated for their potential to lower cholesterol concentration in micelles. The RBPHs were produced by digestion using four different peptidases, alcalase 2.4L^®, neutrase 0.8L^®, papaya latex papain and porcine pancreas trypsin, and then fractionated by hydrophobicity using styrene/divinylbeneze resins. Alcalase 2.4L^® produced the highest degree of hydrolysis, and the resulting hydrolysates had the highest micellar cholesterol inhibition ability in an in vitro hypocholesterolaemic test. The adsorption dynamics of four different macroporous resins, DA201‐C, Sepabeads SP207 and SP825 and Diaion HP20, were determined using the Langmuir isotherm model. DA201‐C had the highest adsorption capacity with an equilibrium concentration of 220 mg g^?1. The hydrolysates eluted with 25, 50, 75 and 95% (v/v) ethanol lowered the micellar cholesterol concentration by 11.88, 14.76, 19.37 and 7.56% respectively. CONCLUSION: A hydrophobic fraction of RBPH had the highest inhibitory activity on micellar cholesterol, which suggests that it may have hypocholesterolaemic properties. Copyright © 2011 Society of Chemical Industry