Galactooligosaccharides in infant formulas: Maillard reaction characteristics and influence on formation of advanced glycation end products.

As prebiotics supplemented in infant formulas (IFs), galactooligosaccharides (GOSs) also have many other biological activities; however, their Maillard reaction characteristics are still unclear. We investigated the Maillard reactivity of GOSs and their effects on advanced glycation end product (AGE) formation during IF processing. The results showed that AGE and HMF formation was temperature-dependent and reached the maximum at pH 9.0 in the Maillard reaction system of GOSs and Nα-acetyl-L-lysine. Acidic conditions accelerated HMF formation; however, protein cross-linking was more likely to occur under alkaline conditions. The degree of polymerization (DP) of GOSs had no significant effect on AGEs formation (except pyrraline); however, the greater the DP, the higher the concentration of HMF and pyrraline. Besides, compared with arginine and casein, lysine and whey protein were more prone to Maillard reaction with GOSs. GOSs promoted AGEs formation in a dose-dependent manner during the processing of IFs. These results provide a reliable theoretical basis for application of GOSs in IFs.

Effect of pectin oligosaccharides supplementation on infant formulas: The storage stability, formation and intestinal absorption of advanced glycation end products.

Pectin oligosaccharides with a molecular weight greater than 700 Da was obtained from the pomace of kiwi (Actinidia arguta). Based on characteristics analysis and inhibitory activity of advanced glycation end products (AGEs) formation in vitro, the target pectin oligosaccharides was added to infant formulas and then subjected to accelerated storage. Results showed that pectin oligosaccharides supplementation inhibited the browning of infant formulas and glassy transition of lactose, and slowed down the increase of water activity under accelerated storage conditions. Pectin oligosaccharides also inhibited the formation of AGEs in infant formulas, such as 5-(hydroxymethyl)furfural, Nε-carboxymethyl-lysine, Nε-carboxyethyl-lysine, methylglyoxal hydromidazolones, glyoxal hydromidazolones, glyoxal-lysine dimer, methylglyoxal-lysine dimer and pyrraline. Besides, permeability studies using Caco-2 cell monolayer also showed that pectin oligosaccharides supplementation inhibited the intestinal absorption of AGEs, especially 5-(hydroxymethyl)furfural, Nε-carboxymethyl-lysine, Nε-carboxyethyl-lysine and glyoxal hydromidazolones. These results provide a reliable theoretical basis for the application of pectin oligosaccharides in infant formulas.

Pectin oligosaccharides from hawthorn (Crataegus pinnatifida Bunge. Var. major) inhibit the formation of advanced glycation end products in infant formula milk powder.

Pectin oligosaccharides (POSs) can not only be used as prebiotics to promote the growth of beneficial bacteria in the intestine but also can be used as natural food-borne antiglycation agents to inhibit the formation of advanced glycation end products (AGEs) in vitro, which is related to their structure, including molecular weight and galacturonic acid content. In this study, haw polysaccharides (HPSs) were isolated and purified, and POSs with high antiglycation activity in vitro were prepared. On this basis, the inhibitory effect of POSs on the formation of AGEs in infant formula milk powder was investigated. The results showed that no obvious inhibitory effect of POSs was found on the formation of AGEs in infant formula milk powder under accelerated storage at 25 °C and 45 °C. But, POSs showed a strong inhibitory effect on the formation of furosine, Nε-carboxymethyllysine (CML), Nε-carboxyethyllysine (CEL) and the total AGEs in infant formula milk powder under accelerated storage at 65 °C. In addition, POSs also had a strong inhibitory effect on the formation of lipid oxidation products but did not affect the formation of protein degradation products. Simultaneously, the cytotoxicity experiments using human umbilical vein endothelial cells showed that the infant formula milk powder supplemented with POSs had the lowest cytotoxicity compared to the blank control (BC) and GOS/FOS supplementation milk powder under accelerated storage at 65 °C, which may be related to the inhibitory effect of POSs on the formation of AGEs in infant formula milk powder. Furthermore, the in vitro fermentation experiments showed that the antiglycation process did not affect the prebiotic activity of POSs in infant formula milk powder.

Pectin oligosaccharides from fruit of Actinidia arguta: Structure-activity relationship of prebiotic and antiglycation potentials.

Pectin oligosaccharides (POSs) have prebiotic and antiglycation activities in vitro, but the specific structure-activity relationship is unclear. In this study, POSs were obtained by enzymatic and ultrasound-assisted enzymatic degradation of pectin polysaccharide (PPS), respectively. Based on the chemical characterization, the antiglycation in vitro and prebiotic activities of POSs were compared and the structure-activity relationship was studied. The results showed that the antiglycation activity of POSs in vitro was proportional to the galacturonic acid content and GalA:Rha molar ratios except for the low molecular weight POSs (LM-POSs), and inversely proportional to its branching degree, such as Ara:Rha and Gal:Rha molar ratios. In addition, it was also found that the prebiotic activity of POSs was positively correlated with Ara:Rha and Gal:Rha molar ratios in molecule composition and the neutral sugar content, especially galactose and arabinose. The degree of esterification (DE) was less important for both antiglycation and prebiotic activity of POSs. These results provided an important theoretical basis for POSs application in food.

Pectin oligosaccharides from hawthorn (Crataegus pinnatifida Bunge. Var. major): Molecular characterization and potential antiglycation activities.

The crude polysaccharide was extracted from hawthorn (Crataegus pinnatifida Bunge. Var. major) and a salt-eluted polysaccharide (SPS-2) was fractionated by DEAE cellulose-52 chromatography. Monosaccharide composition and Fourier-transform infrared (FT-IR) analysis indicated that the SPS-2 contained 72.3% galacturonic acid and may be pectin. The results of antiglycation activity in vitro showed that the medium molecular weight pectin oligosaccharide (MM-POS) had the highest antiglycation activity among SPS-2 degradation products. Moreover, the MM-POS obtained by enzymatic degradation had stronger antiglycation activity than that by ultrasonic assisted enzymatic degradation. Composition analysis of MM-POS obtained from ultrasound-assisted enzymatic degradation showed that polygalacturonans content decreased from 85.1% to 61.9% but the arabinan and rhamnogalacturonans increased from 10.6% to 22.7% and from 3.5% to 13.2%, respectively, compared to the MM-POS obtained from enzymatic degradation. This study will provide a theoretical basis for the application of POSs in the food field, especially the exploitation of antiglycation agents.

Pectin penta-oligogalacturonide reduces cholesterol accumulation by promoting bile acid biosynthesis and excretion in high-cholesterol-fed mice.

Haw pectin penta-oligogalacturonide (HPPS) has important role in improving cholesterol metabolism and promoting the conversion of cholesterol to bile acids (BA) in mice fed high-cholesterol diet (HCD). However, the mechanism is not clear. This study aims to investigate the effects of HPPS on cholesterol accumulation and the regulation of hepatic BA synthesis and transport in HCD-fed mice. Results showed that HPPS significantly decreased plasma and hepatic TC levels but increased plasma high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (apoA-I) levels, compared to HCD. BA analysis showed that HPPS markedly decreased hepatic and small intestine BA levels but increased the gallbladder BA levels, and finally decreased the total BA pool size, compared to HCD. Studies of molecular mechanism revealed that HPPS promoted hepatic ATP-binding cassette transporter A1 (ABCA1), ATP-binding cassette transporter G1 (ABCG1), and scavenger receptor BI (SR-BI) expression but did not affect ATB binding cassette transporter G5/G8 (ABCG5/8) expression. HPPS inactivated hepatic farnesoid X receptor (FXR) and target genes expression, which resulted in significant increase of cholesterol 7α-hydroxylase 1 (CYP7A1) and sterol 12α-hydroxylase (CYP8B1) expression, with up-regulations of 204.2% and 33.5% for mRNA levels, respectively, compared with HCD. In addition, HPPS markedly enhanced bile salt export pump (BSEP) expression but didn't affect the sodium/taurocholate co-transporting polypeptide (NTCP) expression. In conclusion, the study revealed that HPPS reduced cholesterol accumulation by promoting BA synthesis in the liver and excretion in the feces, and might promote macrophage-to-liver reverse cholesterol transport (RCT) but did not liver-to-fecal RCT.

Pectin Penta-Oligogalacturonide Suppresses Intestinal Bile Acids Absorption and Downregulates the FXR-FGF15 Axis in High-Cholesterol Fed Mice.

Haw pectin penta-oligogalacturonide (HPPS), purified from the hydrolysates of haw pectin, has important role in decreasing hepatic cholesterol accumulation and promoting bile acids (BA) excretion in the feces of mice fed a high-cholesterol diet (HCD). However, the mechanism is not clear. This study aims to investigate the effects of HPPS on BA reabsorption in ileum and biosynthesis in liver of mice. Results showed that HPPS increased fecal BA output by approximately 110%, but decreased ileal BA and the total BA pool size by approximately 47 and 36%, respectively, compared to HCD. Studies of molecular mechanism revealed that HPPS significantly decreased the mRNA and protein levels of farnesoid X receptor (FXR) in the small intestine of mice and inactivated the fibroblast growth factor 15 (FXR-FGF15) axis, which increased the mRNA and protein levels of CYP7A1 by approximately 204 and 104%, respectively, compared to HCD. Interestingly, the mRNA and protein levels of apical sodium-dependent bile acid transporter (ASBT) in the small intestine were approximately 128 and 73% higher in HPPS-fed mice than those in HCD-fed mice, respectively. However, no significant difference was detected for ASBT expression between HCD group and BA sequestrant cholestyramine group. These findings indicate that HPPS can suppress intestinal BA reabsorption and promoting hepatic BA biosynthesis. We speculated that HPPS could be ASBT competitive inhibitor rather than BA sequestrant in inhibiting BA reabsorption in ileum and improving cholesterol metabolism.

Comparative effects of hawthorn (Crataegus pinnatifida Bunge) pectin and pectin hydrolyzates on the cholesterol homeostasis of hamsters fed high-cholesterol diets.

This study aims to compare the effects of feeding haw pectin (HP), haw pectin hydrolyzates (HPH), and haw pectin pentasaccharide (HPPS) on the cholesterol metabolism of hypercholesterolemic hamsters induced by high-cholesterol diets. The animals were fed a standard diet (SD), high-cholesterol diet (HCD), or HCD plus HP, HPH, or HPPS at a dose of 300mg/kg body weight for 4weeks. Results showed that HPPS was more effective than HP and HPH in decreasing the body weight gain (by 38.2%), liver weight (by 16.4%), and plasma and hepatic total cholesterol (TC; by 23.6% and 27.3%, respectively) of hamsters. In addition, the bile acid levels in the feces were significantly higher by 39.8% and 132.8% in the HPH and HPPS groups than in the HCD group. Such changes were not noted in the HP group. However, the HP group had higher cholesterol excretion capacities than the HPH and HPPS groups by inhibiting cholesterol absorption in the diet, with a 21.7% increase in TC excretion and a 31.1% decrease in TC absorption. Thus, HPPS could be a promising anti-atherogenic dietary ingredient for the development of functional food to improve cholesterol metabolism.

Antioxidant activity of penta-oligogalacturonide, isolated from haw pectin, suppresses triglyceride synthesis in mice fed with a high-fat diet.

To expand application of hawthorn (Crataegus pinnatifida Bge) fruit, the antioxidant and anti-lipidemic effects of haw pectin penta-oligogalacturonide (HPPS) prepared from hawthorn fruit were investigated in vitro and in mice. HPPS exhibited concentration-dependent scavenging activities against superoxide anion, hydroxyl and DPPH radicals. Additionally, HPPS supplementation significantly enhanced the antioxidant enzyme activities of superoxide dismutase, catalase, glutathione peroxidase, increased the total antioxidant capacity and the levels of glutathione, but lowered the malondialdehyde content in the liver of high-fat fed mice. Furthermore, HPPS significantly decreased the TG levels, the activity and the mRNA and protein levels of glycerol 3-phosphate acyltransferase (GPAT) and phosphatidate phosphohydrolase (PAP) in mice livers. Moreover, liver steatosis of mice associated with diffuse hepatocyte ballooning induced by a high-fat diet was markedly improved by a dose of 300 mg/kg HPPS-consumption. The results revealed that HPPS might be applicable as a dietary supplement for the prevention of fatty liver and oxidative damage.

Effects of pectin pentaoligosaccharide from Hawthorn ( Crataegus pinnatifida Bunge. var. Major) on the activity and mRNA levels of enzymes involved in fatty acid oxidation in the liver of mice fed a high-fat diet.

The regulatory effects of haw pectin pentaoligosaccharide (HPPS) on fatty acid oxidation-related enzyme activities and mRNA levels were investigated in the liver of high fat diet induced hyperlipidemic mice. Results showed that HPPS (150 mg/kg for 10 weeks) significantly suppresses weight gain (32.3 ± 0.26 and 21.1 ± 0.14 g for high-fat diet and HPPS groups, respectively), decreases serum triacylglycerol levels (1.64 ± 0.09 and 0.91 ± 0.02 mmol/L, respectively), and increases lipid excretion in feces (55.7 ± 0.38 and 106.4 ± 0.57 mg/g for total lipid, respectively), compared to high-fat diet as control. HPPS significantly increased the hepatic fatty acid oxidation-related enzyme activities of acyl-CoA oxidase, carnitine palmitoyltransferase I, 3-ketoacyl-CoA thiolase, and 2,4-dienoyl-CoA reductase by 53.8, 74.2, 47.1, and 24.2%, respectively. Meanwhile, the corresponding mRNAs were up-regulated by 89.6, 85.8, 82.9, and 30.9%, respectively. Moreover, HPPS was able to up-regulate the gene and protein expressions of peroxisome proliferator-activated receptor α. Results suggest that continuous HPPS ingestion may be used as dietary therapy to prevent obesity and cardiovascular diseases.