Effects of a Lysine-Involved Maillard Reaction on the Structure and In Vitro Activities of Polysaccharides from Longan Pulp.

The effects of amino acid-involved Maillard reactions (MRs) on the structure and activities of longan pulp polysaccharides (LPs), which were heteropolysaccharides mainly composed of glucose, galactose, mannose, rhamnose, glucuronic acid, ribose, and galacturonic acid, were investigated. The changes of browning degree and molecular weight (Mw) distribution in the MR systems containing LPs and amino acids (lysine, proline, or glycine) indicated that lysine was more active in conjugating with LPs. The MR-modified LPs (MLPs) obtained via a 4 h MR between LPs and lysine showed obvious structural differences from LPs. Specifically, particle-like LPs contained 94% fractions with a Mw less than 7.07 kDa, by contrast, network-like MLPs contained 45% fractions with a Mw larger than 264.1 kDa. Moreover, MLPs showed stronger radical scavenging abilities and macrophage immunostimulating effects, but weaker cancer cell growth-inhibitory abilities. The results indicate that the amino acid-involved MR is a promising method to modify native polysaccharides for better biological properties.

Investigation of the Maillard Reaction between Polysaccharides and Proteins from Longan Pulp and the Improvement in Activities.

The purpose of this study was to investigate the Maillard reaction between polysaccharides and proteins from longan pulp and the effects of reaction on their in vitro activities. The polysaccharide-protein mixtures of fresh longan pulp (LPPMs) were co-prepared by an alkali extraction-acid precipitation method. They were then dry-heated under controlled conditions for monitoring the characterization of the Maillard reaction by the measurement of the free amino group content, ultraviolet-visible spectrum, Fourier transform infrared spectrum and molecular weight distribution. All the physicochemical analyses indicated the development of the Maillard reaction between polysaccharides and proteins. The in vitro activity evaluation indicated that the Maillard reaction could effectively enhance the antioxidant, antitumor and immunostimulating activities of LPPMs. The enhancement of 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and ferric reducing antioxidant power displayed both a positive correlation with the reaction time (p < 0.05). LPPMs dry-heated for three days obtained relatively strong inhibitory activity against HepG2 cells and SGC7901 cells, as well as strong immunostimulating effects on the nitric oxide production and tumor necrosis factor α secretion of macrophages. Maillard-type intermacromolecular interaction is suggested to be an effective and controllable method for improving the functional activities of polysaccharides and proteins from longan pulp.

Phenolic Profiles and Antioxidant Activity of Lotus Root Varieties.

Lotus root attracts increasing attention mainly because of its phenolic compounds known as natural antioxidants. Its thirteen varieties were systematically analyzed on the content, distribution, composition and antioxidant activity of phenolic compounds for a better understanding of this aquatic vegetable. The respective mean contents of total phenolics in their flesh, peel and nodes were 1.81, 4.30 and 7.35 mg gallic acid equivalents (GAE)/g fresh weight (FW), and those of total flavonoids were 3.35, 7.69 and 15.58 mg rutin equivalents/g FW. The phenolic composition determined by a high-performance liquid chromatography method varied significantly among varieties and parts. The phenolics of flesh were mainly composed of gallocatechin and catechin; those of peel and node were mainly composed of gallocatechin, gallic acid, catechin and epicatechin. The antioxidant activities of phenolic extracts in increasing order were flesh, peel and node; their mean concentrations for 50% inhibition of 2,2-diphenyl-1-picrylhydrazyl radical were 46.00, 26.43 and 21.72 µg GAE/mL, and their mean values representing ferric reducing antioxidant power were 75.91, 87.66 and 100.43 µg Trolox equivalents/100 µg GAE, respectively. "Zoumayang", "Baheou", "No. 5 elian" and "Guixi Fuou" were the hierarchically clustered varieties with relatively higher phenolic content and stronger antioxidant activity as compared with the others. Especially, their nodes and peels are promising sources of antioxidants for human nutrition.

Microanalysis, Pharmacokinetics and Tissue Distribution of Polysaccharide-Protein Complexes from Longan Pulp in Mice.

A high performance size exclusion-fluorescence detection (HPSEC-FD) method combined with fluorescein isothiocyanate (FITC) prelabeling was established for the microanalysis of polysaccharide-protein complexes from longan pulp (LPP). FITC-labeled LPP (LPPF) was fractionated by gel filtration chromatography. The weight-average molecular weight and FITC substitution degree of LPPF were 39.01 kDa and 0.20%, respectively. The HPSEC-FD calibration curves linear over the range of 1-200 µg/mL in mouse plasma, spleen and lung samples with correlation coefficients greater than 0.995. The inter-day and intra-day precisions of the method were not more than 6.9%, and the relative recovery ranged from 93.7% to 106.4%. The concentration-time curve of LPPF in plasma following intravenous (i.v.) administration at 40 mg/kg body weight well fitted to a two-compartment model. LPPF rapidly eliminated from plasma according to the short half-lives (t1/2α=2.23 min, t1/2ß=39.11 min) and mean retention times (MRT0-t=1.15 h, MRT0-∞=1.39 h). After administration over 5 to 360 min, the concentration of LPPF in spleen homogenate decreased from 7.41 to 3.68 µg/mL; the concentration in lung homogenate decreased from 9.08 to 3.40 µg/mL. On the other hand, the increasing concentration of LPPF fraction with low molecular weight in heart homogenate was observed.

[Research progresses of pharmacokinetics of polysaccharides].

Pharmacokinetic analysis has attracted more and more attentions in the research field of bioactive natural product. However, there is limited study on the pharmacokinetics of polysaccharides. This paper focused on the research progresses of pharmacokinetics of polysaccharide, summarized the applications of chromatography, isotope labeling method, spectrophotometry, fluorospectrophotometry and biological assay in the analysis of polysaccharide pharmacokinetics, elucidated the behaviors of absorption, distribution, degradation and excretion of polysaccharide in experimental animals, and revealed the effects of physicochemical characteristic, administration dose and route on the pharmacokinetic properties of polysaccharide, which could be served as a reference for the related works.

In vitro anti-hepatocellular carcinogenesis of 1,2,3,4,6-Penta-O-galloyl-ß-D-glucose.

Background: 1,2,3,4,6-Penta-O-galloyl-ß-D-glucose (ß-PGG) is a polyphenol ellagic compound with a variety of pharmacological effects and has an inhibitory effect on lots of cancers. Objective: To explore the antitumor effects and mechanism of 1,2,3,4,6-Penta-O-galloyl-ß-D-glucose on human hepatocellular carcinoma HepG2 cells. Design: A network pharmacology method was first used to predict the possible inhibition of hepatocellular carcinoma growth by 1,2,3,4,6-Penta-O-galloyl-ß-D-glucose (ß-PGG) through the p53 signaling pathway. Next, the Cell Counting Kit (CCK-8) assay was performed to evaluate changes in the survival rate of human hepatocellular carcinoma HepG2 cells treated with different concentrations of the drug; flow cytometry was used to detect changes in cell cycle, apoptosis, mitochondrial membrane potential (MMP) and intracellular Ca2+ concentration; real-time fluorescence quantification and immunoblotting showed that the expression of P53 genes and proteins associated with the p53 signaling pathway was significantly increased by ß-PGG treatment. Reasult: It was found that ß-PGG significantly inhibited survival of HepG2 cells, promoted apoptosis, decreased MMP and intracellular Ca2+ concentration, upregulated P53 gene and protein expression, increased CASP3 expression, and induced apoptosis in HepG2 cells. Conclusion: This study has shown that network pharmacology can accurately predict the target of ß-PGG's anti-hepatocellular carcinoma action. Moreover, it was evident that ß-PGG can induce apoptosis in HepG2 cells by activating the p53 signaling pathway to achieve its anti-hepatocellular carcinoma effect in vitro.

Comprehensive characterization of lotus root polysaccharide-phenol complexes.

To explore the effects of phenolic binding on the structure and activity of lotus root polysaccharides (LRPs), five LRP-phenol complexes containing catechin (61.22 mg/g), gallic acid (9.37 mg/g), ferulic acid (29.28 mg/g), chlorogenic acid (83.80 mg/g) or caffeic acid (14.80 mg/g) were prepared via noncovalent intermolecular interaction, respectively. The interaction was confirmed by the differences among LRPs, phenols and their complexes in ultraviolet-visible and Fourier-transform infrared spectra. The phenolic binding caused significant changes in the molecular weight (MW) distribution and aggregation behavior of LRPs, particularly their average MW (34.49 kDa) increased by 3.73-8.30 times. Compared to LRPs, the complexes all showed stronger antioxidant activities. Notably, the binding of catechin improved the macrophage-stimulating effect of LRPs, specifically promoting the NO production at normal condition and inhibiting the NO overproduction induced by lipopolysaccharide. The noncovalent interaction with phenolic compounds is a promising method for the structural and functional improvement of LRPs.

Integrative Analysis of the Transcriptome and Metabolome Reveals Genes Involved in Phenylpropanoid and Flavonoid Biosynthesis in the Trapa bispinosa Roxb.

Background: Trapa bispinosa Roxb. is grown worldwide as an important aquatic cash crop. Current research on Trapa bispinosa primarily focuses on the separation and identification of active ingredients, as well as the inhibitory effect on tumors; however, research on the molecular mechanism of secondary metabolite accumulation is rather limited. Consequently, an integrative analysis of transcriptome and metabolome is required to identify the key metabolic pathways, and key genes, and to explain the molecular mechanism of Trapa bispinosa. Results: The biosynthesis pathways of phenolics in Trapa bispinosa were examined through transcriptome and metabolome analyses. Transcriptome analysis yielded 42.76 million clean reads representing 81,417 unigenes with an average length of 1,752 bp. KEGG pathway analysis revealed that 1,623 unigenes, including 88 candidate unigenes related to phenolics biosynthesis, were up-regulated in Trapa bispinosa shell (FR) when compared to leaves (LF), root (RT), and stem (ST). The FR vs. LF group had the highest number of specific genes involved in phenylpropanoid, flavonoid, flavone, and flavonol biosynthesis pathways compared to all other comparison groups. In addition, RNA sequencing revealed 18,709 SSRs spanning 14,820 unigenes and 4,387 unigenes encoding transcription factors. Metabolome analysis identified 793 metabolites, including 136 flavonoids and 31 phenylpropane compounds. In the FR group compared to the LF group, there were 202 differentially accumulated metabolites (DAMs). The combined transcriptome and metabolome analyses indicated a significant correlation between 1,050 differentially expressed genes (DEGs) and 62 DAMs. This view proposes a schematic of flavonoid biosynthesis in the FR vs. LF group, providing evidence for the differences in genes and metabolites between FR and LF. Conclusion: In this study, through de novo transcriptome assembly and metabolome analysis, several DEGs and DAMs were identified, which were subsequently used to build flavonoid biosynthesis pathways and a correlation network. The findings pave the way for future research into the molecular mechanisms and functional characterization of Trapa bispinosa candidate genes for phenolics biosynthesis.

Investigation of the inhibition effect of 1,2,3,4,6-pentagalloyl-ß-D-glucose on gastric cancer cells based on a network pharmacology approach and experimental validation.

Background: Gastric cancer (GC) is ranked as the third leading cause of cancer-related mortality worldwide. 1,2,3,4,6-Pentagalloyl-ß-D-glucose (ß-PGG) has various pharmacological activities and has been shown to suppress cancer development. However, the mechanism by which ß-PGG inhibits gastric cancer has not been elucidated. Objective: This study explored the potential targets and mechanism of ß-PGG in GC using the network pharmacology approach combined with in-vitro experiments. Methods: The PharmMapper software was used to predict the potential targets of ß-PGG, and GC-related genes were identified on the GeneCards database. PPI analysis of common genes was performed using the STRING database. The potential regulatory mechanism of ß-PGG in GC was explored through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. The binding ability of key genes and target proteins was verified by molecular docking. The effects of ß-PGG on genes and proteins were evaluated using the CCK-8 assay, cell cycle analysis, apoptosis assay, real-time fluorescence quantification polymerase chain reaction (qRT-PCR), and Western blotting. Results: Eight hub genes involved in cell cycle progression and apoptosis were identified. Cancer-related signaling pathways were identified using the Cytoscape tool. Some of those genes were significantly enriched in the p53 signaling pathway. The CCK-8 assay showed that ß-PGG inhibited the proliferation of GC cells. Cell cycle and apoptosis experiments revealed that ß-PGG induced cell cycle arrest and apoptosis of gastric cancer cells. qRT-PCR and Western blot analysis showed that ß-PGG inhibited ß-PGG cells by modulating the p53 signaling pathway. Conclusion: In the present study, the targets and mechanism of ß-PGG in gastric cancer were explored. The results indicate that ß-PGG can be used to develop treatments for GC.

Drosophila as an emerging model organism for studies of food-derived antioxidants.

Dietary supplementation with antioxidants provides health benefits by preventing diseases caused by oxidative stress and damage. Consequently, there has been growing interest in the study of antioxidative foods and their active ingredients. Oxidative stress and antioxidative responses are mechanistically conserved from Drosophila to mammals. Therefore, as a well-established model organism with a short life cycle and advantages of genetic manipulation, the fruit fly has been increasingly employed to assess functions of antioxidants in vivo. In this review, the antioxidative defense mechanisms, methods used and assays developed in Drosophila to evaluate antioxidant supplementation, are highlighted. The main manifestations of antioxidation include reduction of reactive species, up-regulation of endogenous antioxidants, inhibition on oxidative damage to biomacromolecules, enhanced resistance against oxidative stress and extension of lifespan, which are related to the activations of nuclear factor erythroid 2-related factor 2-antioxidant response element pathway and other adaptive responses. Moreover, the key considerations and future perspectives for the application of Drosophila models in the studies of food-derived antioxidants are discussed.

The effects of different temperatures on the storage characteristics of lotus (Nelumbo nucifera G.) root.

Lotus root (Nelumbo nucifera G.) is a high economic value crop in the world. In this study, the storage characteristics (color, sensory, texture, and fatty acids) of lotus root ("Elian No.5″) were evaluated at different harvest periods (September 2018, October 2018, November 2018, December 2018, and January 2019). Moreover, the storage characteristics were evaluated after the short- term and long-term storage of lotus root at 4 °C and 20 °C. The hardness of lotus root significantly decreased at both temperatures (4 °C and 20 °C) during the first 3 days of storage. In contrast, the decrease in hardness delayed at 4 °C (beyond 3 days of storage). Further, genes related to hardness at different storage temperatures were identified using the RNA-seq and qRT-PCR. The results of this study provide a reference for lotus root storage and a basis for the molecular breeding of longterm-storable lotus root.

Natural polysaccharides experience physiochemical and functional changes during preparation: A review.

The preparation mainly composed of extraction, pre-purification and dehydration is essential for the research and development of natural polysaccharides. The methods or conditions used in the three procedures had significant effects on the composition, structure and function of the polysaccharides obtained. Temperature, pH, enzyme, ultrasound and microwave were the important factors associated with their physicochemical changes. Molecular degradation and intermolecular interaction were two of the main mechanisms responsible for the changes. The degradations of polysaccharides responding to hydrothermal and ultrasonic conditions could be partly descripted by multiple linear regression model, implying the possibility for the prediction and control of polysaccharide degradation. Moreover, the interactions between polysaccharide and other compounds, forming complexes natively or conditionally, could be selectively triggered or eliminated to obtain polysaccharides under certain functions. This work shows new insights into the preparation of polysaccharides, which could benefit the efficient utilization of their natural and modified properties.

Polysaccharides from Pyracantha fortuneana and its biological activity.

This study used response surface methodology to determine the optimal conditions for extraction of polysaccharides from Pyracantha. fortuneana (PSPF), and studied the mechanism of PSPF-inducing apoptosis in human ovarian carcinoma Skov3 cells. Response surface methodology (RSM) were adopted to extract PSPF. The maximum value of polysaccharide yield was obtained under these optimal conditions. PSPF had good potential as an antioxidant. Exposure of cells to PSPF resulted in cytotoxicity through the induction of apoptosis, and the reactive oxygen species were increased, mitochondrial membrane potential decreased, DNA damage (detected as γ- H2AX and RAD51 foci) was observed in Skov3 cells. In addition, PSPF could induce apoptosis of cancer cells. Therefore, PSPF should be explored as novel potential antioxidants and an anti-tumor drug in a clinical setting.

Investigation on the quality diversity and quality-FTIR characteristic relationship of sunflower seed oils.

Forty-one sunflower seed oil (SSO) products were collected to investigate their quality parameters before and after high-temperature and short-time (HTST) cooking, including peroxide value (PV), acid value (AV) and fatty acid (FA) composition. Their Fourier-transform infrared (FTIR) spectra were then scanned to explore the parameter-FTIR characteristic relationship using chemometrics with multiple linear regression (MLR) analysis. The PV and AV of uncooked products were in the range of 1.49-6.29 mmol kg-1 and 0.04-0.31 mg g-1, with the variation coefficient of 36.47% and 146.82%, respectively. They were mainly composed of palmitic acid (2.39-3.33%), stearic acid (1.76-2.54%), oleic acid (10.02-24.77%) and linoleic acid (66.42-83.62%). The parameter changes caused by HTST cooking were slight. SSO products from different countries might have significantly different FA composition, especially linoleic acid content (P < 0.05), and those with different shelf times might differ in PV (P < 0.05). In addition, the FTIR spectra of cooked and uncooked SSO showed the similarity degree values ranging from 0.67 to 0.97 and 0.72 to 0.97, respectively. All the spectra exhibited the characteristic bands of -C-H, -C[double bond, length as m-dash]O, -C-O- and [double bond, length as m-dash]CH2, in which 11 common bands as independent variables were selected to establish various FTIR characteristic-quality relationship models. The models of palmitic acid, oleic acid and linoleic acid were acceptable for their content predictions. Moreover, the cooked oils and uncooked oils could be completely distinguished by orthogonal partial least squares discriminant analysis due to the cooking-caused changes in FTIR spectrum. Production place and shelf time were the important factors related to the quality diversity of SSO, and FTIR spectroscopy combined with chemometrics was feasible for the simultaneous determination of various quality parameters.

Effects of storage condition on the physicochemical characteristics of sunflower seed oil.

The effects of storage condition on the physicochemical characteristics of sunflower seed oil (SSO) were investigated, to understand the required conditions and the typical indicators for its quality control. The changes of SSO in peroxide value (PV), acid value (AV), fatty acid (FA) composition, Fourier transform infrared (FTIR) spectrum and volatile compound (VC) during 11 month storage under seven different conditions, were analyzed. The PVs and AVs of the seven groups all increased with time, but the PVs fluctuated strongly during the last 4 months. The between-group differences in PV and AV indicated that light-exposure and high-temperature (≥40 °C) both accelerated the production and degradation of primary oxidation products of FA. However, the FA composition of SSO did not obviously change regardless of storage condition and time, as well as its FTIR characteristics. By contrast, its VC composition was significantly changed by light-exposure and high-temperature (≥55 °C). 3-Methyl-2,5-furandione, acetic acid/1-phenylethyl ester, 2-pentyl-furan and limonene might be the main VCs related to the desirable flavor, in which 3-methyl-2,5-furandione in all the groups showed a significantly decreased percentage of VC composition during storage. Light-exposure and high-temperature enhanced the accumulation of aldehydes, especially hexanal and (E)-2-heptenal, which principally contributed to the undesirable flavor of SSO. 3-Methyl-2,5-furandione, hexanal and (E)-2-heptenal were proposed to be marker compounds for its quality control. A low-temperature and dark condition is necessary for SSO to remain a desirable flavor.

Walnut oil improves spatial memory in rats and increases the expression of acid-sensing ion channel genes Asic2a and Asic4.

Although Walnut oil (WO) has been reported to enhance cognitive function, the underlying molecular mechanisms are not well understood. This study was designed to assess the effects of WO on spatial memory in rats through modulation of the expression of acid-sensing ion channel genes, Asic2a and Asic4. To investigate the effect of WO on cognitive performance, we supplemented the diet of female rats with WO. The results showed that supplementation with WO at doses of 2.2 and 11 g kg-1 day-1 significantly improved learning and memory. In vitro treatment of rat hippocampal neuronal cells with appropriate doses of WO revealed a significant increase in the expression of Asic2a and Asic4 in a dose-dependent manner at both the mRNA and protein levels. We conclude that WO intake might help to prevent cognitive decline, particularly in the elderly, and that ASIC genes in neurons can be the targets of compounds contained in the oil.

Structural and biological properties of polysaccharides from lotus root.

To investigate the structure, in vitro digestibility and activity of polysaccharides from lotus root, their main fractions named LRPs were isolated and purified by gel filtration chromatography. Structural analyses indicated that: LRPs were α­(1 → 6)­d­heteroglucans mainly composed of Glc-(1→, →6)-Glc-(1→, →6)-Gal-(1→, →4,6)-Gal-(1→ and →3,6)-Glc-(1→ at a molar ratio of 1.00: 4.33: 0.83: 0.13: 1.14; the total molar percentage of other monosaccharides in LRPs, including Man, Rha, GalA and Ara, was 8.10%; the molecular weights of LRPs was in the range of 1.33 kDa to 5.30 kDa. According to the change of molecular weight and the productions of reducing sugar and free monosaccharide, the simulated experiments of salivary, gastric and intestinal digestion confirmed that LRPs were almost undigestible. Moreover, LRPs showed the scavenging ability against DPPH and hydroxyl radicals, the growth inhibition ability against SGC7901 and HepG2 cancer cells in vitro, and the immunostimulating effect on the NO and TNF-α productions of macrophages in vitro. LRPs nearly remain their initial structure and activities in upper gastrointestinal tract and have health-improving potentials.

Fingerprint profiling of polysaccharides from different parts of lotus root varieties.

Thirty-nine polysaccharides isolated from different parts of 13 lotus root varieties were characterized with fingerprint and chemometrics analyses to explore their similarity and diversity. The physicochemical features of lotus root polysaccharides (LRPs) were found to be the following: LRPs contained mainly polysaccharides (5.94 kDa) and polysaccharide-protein complexes (11.57 kDa and 5.30 kDa); their carbohydrates were composed of mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose and arabinose approximately in the molar ratio of 0.19 : 0.14 : 0.08 : 0.17 : 6.49 : 1.00 : 0.16; and node LRPs possessed more binding proteins and uronic acids than both flesh and peel LRPs. Their fingerprints based on Fourier-transform infrared spectroscopy, pre-column derivatization high-performance liquid chromatography and high performance size-exclusion chromatography all exhibited relatively high similarities, contributing to the common figerprint models which could be utilized as references for the identification of LPRs. In addition, the fingerprint characteristics associated with the between-group variability of LRPs in the score plots derived from multivariate analytical models might indicate which variety or part of lotus root they were isolated from. Therefore, multi-fingerprinting techniques have the potential to be applied to the identification and quality control of LRPs.

Activity diversity structure-activity relationship of polysaccharides from lotus root varieties.

The in vitro activities of 39 polysaccharides from different parts of 13 lotus root varieties were evaluated and introduced into multiple linear regression analysis to explore the structure-activity relationships using their chromatographic fingerprint features as independent variables. Their 2,2-diphenyl-1-picrylhydrazyl/hydroxyl radical scavenging abilities, ferric reducing antioxidant powers and growth-inhibitory effects against HepG2 and SGC7901 cancer cells were all diverse, with the variable-coefficients ranging from 24.49% to 87.76%, while their macrophage immunostimulatory activities evaluated by nitric oxide production and tumor necrosis factor-alpha secretion showed relatively low variations. Lotus root polysaccharides (LRPs) from the peels and nodes possessed stronger activities than those from the fleshes. Their fingerprint-activity relationship models indicated that monosaccharide composition was closely related to the activities, but not molecular weight. LRPs have health-improving potentials, and their activities can be partly predicted by the quantitative fingerprint-activity relationship model.