Modulation effect of black rice dietary fiber on the metabolism and fermentation of cyanidin-3-glucoside in an in vitro human colonic model.

Black rice (Oryza sativa L.) is a great source of anthocyanins and dietary fiber and possesses various health-promoting properties. The modulating effect of insoluble dietary fiber (IDF) from black rice on the fermentation of cyanidin-3-O-glucoside (Cy3G) in an in vitro human colonic model, together with the possible microbiota-mediated mechanisms, was investigated. The combined Cy3G and IDF fermentation can promote the biotransformation of Cy3G into phenolic compounds such as cyanidin and protocatechuic acid with stronger antioxidant activities and increase the total production of SCFAs during the fermentation of Cy3G. 16S rRNA sequencing analysis revealed that the addition of IDF modulated the microbiota structure and bloomed Bacteroidota and Prevotellaceae-related genera, which were positively correlated with metabolites of Cy3G, thus potentially regulating the microbial metabolism of Cy3G. The work is of great significance for elucidating the material basis of the health benefits of black rice.

Shatianyu (Citrus grandis L. Osbeck) Flavonoids and Dietary Fiber in Combination Are More Effective Than Individually in Alleviating High-Fat-Diet-Induced Hyperlipidemia in Mice by Altering Gut Microbiota.

This study was aimed at exploring the separate and combined anti-hyperlipidemic effect of Shatianyu (Citrus grandis L. Osbeck) flavonoids (SPFEs) and DF (SPDF) on HFD-fed mice after 14-week administration in diet, together with the possible microbiota-mediated mechanisms. SPFEs and SPDF were more effective together than separately in improving serum lipid profiles, decreasing hepatic lipid accumulation, and upregulating the expression of hepatic CPT1a, CYP7A1, ABCG5, and ABCG8. Butyrate has been previously proved to have an anti-hyperlipidemic effect. The fecal butyrate contents were negatively correlative with serum/liver lipid but positively correlated with fecal total bile acids levels, and SPDF + SPFEs had the most fecal butyrate in this study. SPDF or SPFEs enriched microbiota related to acetic and propionic acids production, while SPDF + SPFEs also bloomed norank_f_Muribaculaceae, Dubosiella, Lachnoclostridium, and norank_f_Eubacterium_coprostanoligenes_group, which were positively correlated to fecal butyrate contents. Thus, SPFEs and SPDF might alleviate hyperlipidemia synergistically by regulating microbiota to produce butyrate, thereby regulating lipid metabolism.

Physicochemical properties and prebiotic activities of polysaccharides from Zizyphus jujube based on different extraction techniques.

Zizyphus jujube polysaccharide was extracted with hot water, ultrahigh pressure, deep eutectic solvent (DES) and ultrahigh pressure-assisted DES. Comparative analyses were conducted on the yield, physicochemical properties and prebiotic activity of four polysaccharides (JP-H, JP-U, JP-D and JP-UD). The yield of JP-UD (10.42 %) was 3.3 times that of JP-H (3.12 %), and its sugar content was the highest. JP-UD possessed the lowest Mw, while JP-H possessed the highest. Four JPs were acidic pyranose and mainly composed of galacturonic acid, arabinose and galactose. NMR results demonstrated that they contained not only similar glycosidic linkage but also the specific glycosidic linkage of →4)-α-D-Glcp-(l→ appeared in JP-U and JP-UD, the esterified units of GalA and CONH2 group appeared in JP-D and JP-UD, and the Terminal ß-D-Galp and →4)-α-GalpA-(1→ appeared in JP-UD. JPs showed different proliferation effects on four lactobacillus strains, among which JP-UD exhibited the strongest prebiotic activity. Zizyphus jujube polysaccharides have great potential for application in the functional food and medical industry.

The flavonoid profiles in the pulp of different pomelo (Citrus grandis L. Osbeck) and grapefruit (Citrus paradisi Mcfad) cultivars and their in vitro bioactivity.

Previous results indicated that the flavonoid profiles might have varietal differences in pomelo, but detailed information is unknown. We previously isolated 4 new flavonoids, cigranoside C, D, E, F, in Citrus grandis Shatianyu pulp. However, their distribution in different pomelo cultivars remains to be explored. Therefore, the flavonoid profiles and in vitro bioactivity of the pulp from 5 pomelo and 1 grapefruit cultivars commonly consumed in China were investigated. Fourteen flavonoids were identified, cigranoside C, D, E were detected in these pomelo and grapefruit. Naringin and cigranoside C were the major flavonoids in grapefruit, Guanximiyu-W, Guanximiyu-R and Liangpingyu, while melitidin and rhoifolin was the predominant flavonoid in Shatianyu and Yuhuanyu, respectively. Pomelo and grapefruit showed strong antioxidant activity, and were potent inhibitors of pancreatic lipase with IC50 values of 11.4-72.6 mg fruit/mL except Shatianyu. Thus, pomelo and grapefruit are natural antioxidants and possess anti-obesity potential.

Hydrolyzed Bound Phenolics from Rice Bran Alleviate Hyperlipidemia and Improve Gut Microbiota Dysbiosis in High-Fat-Diet Fed Mice.

It has been confirmed the lipid-lowering effect of rice bran free phenolics, but it is unknown whether rice bran bound phenolics, the phenolic profile of which differs from the free ones, have a similar effect. Thus, the hypolipidemic effect and potential mechanism of hydrolyzed bound phenolics (HBP) from rice bran was investigated in this study. The results showed that HBP supplementation significantly improved serum lipid profiles of high-fat-diet fed mice. HBP inhibited the activation of nuclear receptors liver X receptor-α (LXRα), sterol regulatory element binding protein 1c (SREBP-1c), and peroxisome proliferators-activated receptors-γ (PPARγ), and, therefore, changed the expressions of their downstream genes, including LDLR, CD36, ACC1, FAS, and DGAT2 in the liver. Moreover, HBP supplementation reversed the high-fat-diet induced gut microbiota dysbiosis. These findings suggest that HBP might alleviate the hyperlipidemia via inhibiting the hepatic de novolipogenesis, regulating the uptake of cholesterol and fatty acid in the liver and their absorption in the gut. The attenuation of microbiota dysbiosis might contribute to the above effects.

Phenolic profiles and bioactivities of different milling fractions of rice bran from black rice.

Phytochemicals are unevenly distributed in grain kernels and concentrated in bran fractions. However, their specific distribution in the grain bran, especially colored grains, is not clarified. This study divided rice bran from black rice into five fractions by stepwise milling to obtain BF1(outermost layer) to BF5 (the innermost layer). Each fraction accounted for approximately 2% of the whole kernel. The total content of phenolics (TPC), flavonoids (TFC), and anthocyanins (TAC) of five fractions significantly decreased from BF1 to BF5. The TPC, TFC and TAC of BF1 contribute 25.7%, 28.2%, 28.4% to the total of five fractions, respectively. HPLC analysis showed that the contents of most anthocyanin and phenolic acids compounds decreased from BF1 to BF5. Together with α-glucosidase and α-amylase inhibitory activities of BF1, the antioxidant activity was higher than those of other fractions. These results can guide the moderate processing of black rice and the utilization of its bran.

α-Glucosidase inhibitors from brown rice bound phenolics extracts (BRBPE): Identification and mechanism.

Brown rice bound phenolics extracts (BRBPE) have been reported to possess α-glucosidase inhibitory effects, the specific enzyme inhibitors involved in this process were unknown. Here, α-glucosidase inhibitors in BRBPE were screened using bioaffinity ultrafiltration methods, and seven phenolic compounds - three monomers (p-coumaric acid, ferulic acid and methyl ferulate), three dimers (8-5', 5-5' and 8-O-4' diferulic acid) and a trimer (5-5'/8-O-4″ dehydrotriferulic acid) were identified as exact inhibitors, among which 5-5'/8-O-4″ dehydrotriferulic acid and 5-5'diferulic acid exhibited the best inhibitory activity. Enzyme kinetic analysis suggested that the inhibitory mechanism of these seven inhibitors including competitive, noncompetitive, uncompetitive and mixed manner. Molecular docking analysis revealed that the seven inhibitors bind with α-glucosidase mainly by hydrogen bonding interaction, hydrophobic force and ionic bond. Molecular dynamics simulation further explored the structure and molecular property of phenolic-glucosidase complex. This work provided a deep insight into brown rice bound phenolics acting as potent α-glucosidase inhibitors.

Structural elucidation of flavonoids from Shatianyu (Citrus grandis L. Osbeck) pulp and screening of key antioxidant components.

The Citrus genus is a good source of dietary flavonoids, which have many health benefits. As a representative citrus fruit, the flavonoids composition in Shatianyu (Citrus grandis L. Osbeck) pulp remains to be investigated. In the present study, 11 flavonoids were isolated and identified from Shatianyu pulp flavonoid extracts (SPFEs). Among them, 4 flavonoids were previously undescribed and 2 flavonoids were firstly isolated from pummelo. The cellular antioxidant activity (CAA) and oxygen radical absorbance capacity (ORAC) of isolated compounds were evaluated. Naringin and rhoifolin showed the highest ORAC activity, and the presence of a 3-hydroxy-3-methylglutaryl or a 4'-glucose decreased the ORAC activity of flavonoids. The contribution of isolated flavonoids to the holistic antioxidant activity of SPFEs was determined by an online knockout method. Melitidin, bergamjuicin and naringin contributed most to ORAC activity, while bergamjuicin, melitidin and apigenin-4'-O-ß-d-glucopyranosyl-7-O-α-l-rhamnopyranosyl-(1 â†’ 2)-[6″-O-(3- hydroxy-3-methylgltaryl)]-ß-d-glucopyranoside contributed most to CAA activity.

Structural elucidation, distribution and antioxidant activity of bound phenolics from whole grain brown rice.

Chemical profiles, distribution, and antioxidant activity of bound phenolics from brown rice were investigated. Four new dehydrodiferulic acid dimers (DFA) along with eighteen known phenolics were isolated from brown rice bound phenolic extracts and their structures were determined by multiple spectroscopic methods. Among them, ferulic acid and 8-5' DFA were the most abundant monomeric and dimeric bound phenolics in brown rice, rice bran and polished rice. In whole brown rice, polished rice contributed more than 50% of three phenolic monomers and six phenolic dimers, while rice bran contributed more than half of the other thirteen phenolics including eight monomers, four dimers, and one trimer. All the isolated compounds exhibited oxygen radical absorbance capacity. Thomasidioic acid, caffeic acid, methyl caffeate, and 8-5' DC DFA displayed potent peroxyl radical scavenging capacity, and the last three compounds also showed moderate cellular antioxidant activity.

Co-culture submerged fermentation by lactobacillus and yeast more effectively improved the profiles and bioaccessibility of phenolics in extruded brown rice than single-culture fermentation.

This study aims to investigate the effects of fermentation on the phenolic components and their bioaccessibility in extruded brown rice (EBR). The saccharified solution of EBR (SS-EBR) depicted higher phenolics when fermented by single or co-culture of Lactobacillusplantarum, Lactobacillus fermentum and Saccharomyces cerevisiae for 24 h at 37 °C. The co-culture fermented SS-EBR more significantly enhanced free, conjugated and bound phenolics and flavonoids with total increment of 93.3% and 61.3%, respectively. Fermentation changed the contents and compositions of phenolics in each fraction with more than 10-fold increase in vanillic acid and quercetin contents. Ferulic, p-cumaric and chlorogenic acids were increased by 83.5%, 52.2% and 113.4%, respectively, while kaempferol and cinnamic acid were found only in fermented SS-EBR. Fermentation also improved the oxygen radical absorption capacity (ORAC) and the bioaccessible phenolics in SS-EBR. Hence, the co-culture fermented SS-EBR, can be utilized as a functional supplement to provide more bioaccessible antioxidants.

Bound Phenolics Ensure the Antihyperglycemic Effect of Rice Bran Dietary Fiber in db/db Mice via Activating the Insulin Signaling Pathway in Skeletal Muscle and Altering Gut Microbiota.

Whole-grain dietary fiber intake is beneficial in the prevention of metabolic syndrome. Considering rich in bound phenolics being a special characteristic of whole-grain dietary fiber, the aim of this study was to evaluate the effects of the presence or absence of bound phenolics in rice bran dietary fiber (RBDF) on regulating glucose metabolism in diabetic db/db mice. In comparison to phenolics-removed RBDF (PR-RBDF) intervention without an antihyperglycemic effect, RBDF and formulated RBDF (F-RBDF, obtained by mixing PR-RBDF and hydrolyzed-bound phenolics) significantly reduced fasting blood glucose levels after 1 and 5 weeks of interventions, respectively. The presence of bound phenolics interventions could activate the IRS1/AKT/GLUT4 insulin signaling pathway in skeletal muscle and alter gut microbiota by modulating gut microbiota dysbiosis and enriching the butyric-acid-producing bacteria genera of the families Lachnospiraceae and Ruminococcaceae, thus leading to the reduction of blood glucose levels. These findings indicate that bound phenolics ensure the antihyperglycemic effect of RBDF.

Longan pulp polysaccharide protects against cyclophosphamide-induced immunosuppression in mice by promoting intestinal secretory IgA synthesis.

This study aimed to explore the effect of longan pulp polysaccharide (LP) on the systemic immunity and intestinal mucosal immunity of immunosuppressive mice. The synthesis process and secretion of intestinal secretory IgA (SIgA) were investigated. Results showed that LP increased the thymus index, spleen index, and serum IgA level in cyclophosphamide (CTX)-treated mice. SIgA secretion in the intestinal lumen was increased by LP as well. The underlying mechanism comes down to the facts as follow: LP increased intestinal cytokines expression and TGFßRII that is associated with pathways of IgA class switch recombination (CSR). By improving protein expression of mucosal addressin cell-adhesion molecule-1 (MAdCAM-1) and integrin α4ß7, LP was beneficial to gut homing of IgA+ plasma cells. LP increased IgA, polymeric immunoglobulin receptor (pIgR), and secretory component (SC) to fortify the SIgA secretion. This study suggested that moderate consumption of LP is helpful for improving systemic immunity and intestinal mucosal immunity via promotion of intestinal SIgA to strengthen the mucosal barrier.

Characterization of saponins and phenolic compounds: antioxidant activity and inhibitory effects on α-glucosidase in different varieties of colored quinoa (Chenopodium quinoa Willd).

This study investigated the contents of saponins and phenolic compounds in relation to their antioxidant activity and α-glucosidase inhibition activity of 7 colored quinoa varieties. The total saponin content was significantly different among 7 varieties and ranged from 7.51 to 12.12 mg OAE/g DW. Darker quinoa had a higher content of phenolic compounds, as well as higher flavonoids and antioxidant activity than that of light varieties. Nine individual phenolic compounds were detected in free and bound form, with gallic acid and ferulic acid representing the major compounds. The free and bound phenolic compounds (gallic acid and ferulic acid in particular) exhibited high linear correlation with their corresponding antioxidant values. In addition, the free phenolic extracts from colored quinoa exhibited higher inhibitory activity against α-glucosidase than the bound phenolic extracts. These findings imply that colored quinoa with abundant bioactive phytochemicals could be an important natural source for preparing functional food.

Lychee pulp phenolics ameliorate hepatic lipid accumulation by reducing miR-33 and miR-122 expression in mice fed a high-fat diet.

Dietary phenolics exhibit hypolipidemic activity by changing lipid metabolism-related microRNA (miRNA) expression. Quercetin 3-O-rutinoside-7-O-α-l-rhamnosidase (quercetin 3-rut-7-rha), rutin and (-)-epicatechin are the main phenolics in lychee (Litchi chinensis Sonn.) pulp. A previous study reported that quercetin 3-rut-7-rha and rutin had hypolipidemic effects. To elucidate these effects and the underlying molecular mechanisms of lychee pulp phenolics (LPPs), the hepatic mRNA and protein expression of lipid metabolism-related genes and their associated miRNAs were measured after ten weeks of treatment with a high-fat diet (HFD) alone or in combination with LPPs. The administration of LPPs significantly reduced the HFD-induced increase in serum total cholesterol and triglyceride levels but increased the HDL-c content. The mRNA and protein expression levels of hepatic adenosine triphosphate-binding cassette transporter A1 (ABCA1) and carnitine palmitoyltransferase 1a (CPT1a) were upregulated, while fatty acid synthase (FAS) mRNA and the corresponding protein expression levels were downregulated by LPPs. Furthermore, the expression levels of miR-33, which directly modulates ABCA1 and CPT1a, and miR-122, which indirectly regulates FAS, were downregulated in mouse hepatocytes. The repression of miR-33 and miR-122 is a possible molecular mechanism of the hypolipidemic effects of LPPs in the liver. Our results suggest a novel hypolipidemic mechanism of LPPs.

[Physico-chemical Characteristics of Individual Aerosol Particles in Marine Atmosphere on South Hemisphere].

During the 29th Chinese National Antarctic Research Expedition (CHIANRE), individual particle samples were collected from South China to Antarctic during November 2012 to April 2013. A transmission electron microscopy with energy-dispersive X-ray spectrometry (TEM-EDS) was employed to analyze the morphology, mixing state, composition, and relative abundances of individual aerosol particles. Atmospheric particles were classified into four types:sea salt, mineral, S-rich and C-rich. Sea salt aerosols (SSA) were dominant in the marine particles from South China to Antarctic, and they were further divided into three sub-types:fresh SSA, partially aged SSA, and fully aged SSA. Partially and fully aged SSA accounted for 86% of total SSA number. Interestingly, surface of partially aged SSA and fully aged SSA contained abundant rod-like Na2SO4. Mineral dust particles increased in the coastal areas which were influenced by continental air. In addition, we found that S-rich particles were abundant at two sampling sites (the middle eastern of Indian Ocean and Antarctic inland). The back trajectories of air masses indicated that these S-rich particles were mainly formed via the oxidation of dimethyl sulfide (DMS) emitted from the marine phytoplanktons. Our study suggests that the SSA aging process in the South Hemisphere atmosphere was controlled by the DMS which is different from the SSA aging under the influence of anthropogenic pollutants in the North Hemisphere.

Characteristics of carbonaceous aerosols: Impact of biomass burning and secondary formation in summertime in a rural area of the North China Plain.

To determine the characteristics of carbonaceous aerosols in rural areas of the North China Plain, field measurements were conducted at Yucheng (YC) in the summers of 2013 and 2014. The concentrations of carbonaceous aerosols at YC exhibited clear diurnal variation, with higher concentrations in the early morning and at night and lower concentrations during the afternoon hours. The mass-balance method designed for particulate matter smaller than 2.5µm (PM2.5) was used to calculate the organic matter (OM)/organic carbon (OC) ratio. The value obtained, 2.07±0.05, was suggested as a reference to estimate organics in PM2.5 in rural areas of the North China Plain. Biomass burning was identified to be a significant source of carbonaceous aerosols; approximately half of the samples obtained at YC were affected by biomass burning during summer 2013. Case studies revealed that biomass burning accounted for up to 52.6% of the OC and 51.1% of the elemental carbon in PM2.5 samples. The organic coatings observed on sulphur-rich and potassium-rich particles indicated the formation of secondary organic aerosols (SOA) from the oxidation of precursor volatile organic compounds (VOCs) during the aging of smoke released from biomass burning. Based on the evolution of the VOCs, the contribution of VOCs oxidation to SOA concentration was 3.21 and 1.07µgm(-3)ppm(-1) CO under conditions of low nitrogen oxide (NOx) and high NOx, respectively. Aromatics (e.g. benzene, toluene, xylene and ethylbenzene) made the greatest contribution to SOA concentration (88.4% in low-NOx conditions and 80.6% in high-NOx conditions). The results of the study offer novel insights into the effects of biomass burning on the carbonaceous aerosols and SOA formation in polluted rural areas.

Phenolic-rich lychee (Litchi chinensis Sonn.) pulp extracts offer hepatoprotection against restraint stress-induced liver injury in mice by modulating mitochondrial dysfunction.

The pulp from lychee, a tropical to subtropical fruit, contains large quantities of phenolic compounds and exhibits antioxidant activities both in vitro and in vivo. In the present study, we investigated the mechanisms underlying the hepatoprotective effects of lychee pulp phenolics (LPPs) against restraint stress-induced liver injury in mice. After 18 h of restraint stress, increased levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were observed. High levels of thiobarbituric acid reactive substances (TBARS) were also found. Restraint stress causes liver damage, which was protected against by LPP pretreatment at a dosage of 200 mg (kg d)(-1) for 21 consecutive days. This treatment remarkably decreased the serum ALT, AST and TBARS levels, elevated the liver glutathione (GSH) content, and the activities of glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT). Furthermore, respiratory chain complex and Na(+)-K(+)-ATPase activities were enhanced in liver mitochondria, while mitochondrial membrane potential levels and reactive oxygen species (ROS) production decreased. Thus, treatment with LPPs ameliorated restraint stress-induced liver mitochondrial dysfunction. These results suggest that LPPs protect the liver against restraint stress-induced damage by scavenging free radicals and modulating mitochondrial dysfunction. Thus, lychee pulp may be a functional biofactor to mitigate oxidative stress.

Effect of extrusion on phytochemical profiles in milled fractions of black rice.

The phytochemical profile and antioxidant activities of unprocessed and extruded milled fractions of black rice were investigated. Extrusion increased the free phenolics, anthocyanins and oxygen radical absorbance capacity (ORAC) and decreased the bound forms. The total phenolics, anthocyanins and ORAC increased by 12.6%, 5.4% and 19.7%, respectively, in bran. Extrusion decreased both free and bound phenolics and anthocyanins while ORAC values decreased by 46.5%, 88.4% and 33.1%, respectively, in polished rice and by 71.2%, 87.9% and 14.7%, respectively, in brown rice. A total of seven phenolics, gallic, chlorogenic, vanillic, caffeic, syringic, p-coumaric and ferulic acids, were detected in both forms. Cyanidin 3-glucoside (Cy-3-G), cyanidin 3-rutinoside and peonidin 3-glucoside were also detected with Cy-3-G found in the highest amounts in unprocessed and extruded rice bran. These results provide the basis for the development of different milled fractions of extruded black rice with balanced nutritional characteristics for today's functional food markets.

Free and bound phenolic profiles and antioxidant activity of milled fractions of different indica rice varieties cultivated in southern China.

This study quantified free and bound phytochemicals and their antioxidant activity in the endosperm and bran/embryo of different indica rice varieties. Phytochemicals mainly existed as free form in the bran/embryo and as both free and bound forms in the endosperm. The average values of total phenolic content, flavonoid content, FRAP, ABTS and ORAC values in the bran/embryo were 3.1, 10.4, 8.2, 11.2 and 11.4 times higher than those in the endosperm, respectively. In whole brown rice, the bran contributed 59.2%, 53.7%, 47.7%, 55.5% and 56.9% of total phenolics, flavonoids, FRAP, ABTS and ORAC values, respectively. Seven individual phenolics (gallic, protocatechuic, chlorogenic, caffeic, syringic, coumaric and ferulic acids) were detected with most coumaric and ferulic acids in the bran. All measurements exhibited varietal differences. These findings provide important information for improving human health by encouraging the consumption of whole brown rice and its use in food product development.

Antioxidant activity of polysaccharide-enriched fractions extracted from pulp tissue of Litchi Chinensis sonn.

Natural antioxidants such as polysaccharides with strong antioxidant activities are used to protect against oxidative damage, yet little is known so far about the antioxidant effects of litchi fruit polysaccharides. In the present study, four different polysaccharide-enriched fractions were isolated from litchi pulp tissue and partially purified by a stepwise method of ethyl alcohol (EtOH) precipitation. Their chemical and physical characteristics were determined by chemical methods, gas chromatography and IR spectrophotometry. Antioxidant activities of these fractions were investigated using various in vitro assay systems. These four polysaccharide-enriched fractions exhibited a dose-dependent free radical scavenging activity as shown by their DPPH radical, superoxide anion and hydroxyl radical inhibition, chelating ability and reducing power. Among the different fractions, LFP-III showed the strongest scavenging activity against DPPH radical, superoxide and hydroxyl radicals and chelating ability. These findings suggest litchi polysaccharides from pulp tissue have potential as functional foods with enhanced antioxidant activity.