Astaxanthin is responsible for antiglycoxidative properties of microalga Chlorella zofingiensis

The antiglycoxidative properties of microalga Chlorella zofingiensis were investigated for the first time in this study. Algal extracts containing different contents of astaxanthin were prepared. Through the comparison, it was shown that the extract rich in astaxanthin exhibited higher antioxidant abilities as well as stronger antiglycative capacities, including the inhibition of advanced glycation endproducts (AGEs) formation, glucose autoxidation as well as glycation-induced protein oxidation. The extract was further fractionated using TLC. Among all fractions obtained, the fraction of astaxanthin in diester form was found to contain the strongest inhibitory effects on the glycation cascade. Its tentative structure was subsequently identified by LC–MS analysis. These results clearly ascertained the antiglycoxidative properties of astaxanthin derived from C. zofingiensis and supported the possibility of using natural antioxidants as glycation inhibitors. The microalga C. zofingiensis, therefore, might be the beneficial food and preventive agent choice for diabetic patients.     

Angelica acutiloba root alleviates advanced glycation end-product-mediated renal injury in streptozotocin-diabetic rats

Angelica acutiloba root, a Japanese species of Dong quai being cultivated in Hualien County in eastern Taiwan, is used primarily for gynecological disorders in women. Increasing evidence indicates that advanced glycation end-products (AGEs) contribute to the pathogenesis of diabetic nephropathy. We investigated whether A. acutiloba root is beneficial in the amelioration of AGE-mediated renal injury in a diabetic rat model. Streptozotocin (STZ)-diabetic rats were treated orally with A. acutiloba root extract (AARE) [50, 100, 200 mg/(kg × day)] for 8 wk. Changes in renal function-related parameters in plasma and urine were analyzed at the end of the study. Kidneys were isolated for enzyme immunoassay, pathology histology, immunohistochemistry, and Western blot analyses. Polyphenolic compounds and flavonoids were abundant in AARE. AARE [200 mg/(kg × day)] partially decreased the high plasma glucose level in diabetic rats. Diabetic-dependent alterations in urinary albumin, 24-h urinary albumin excretion rate, creatinine clearance, and glomerular mesangial matrix expansion were ameliorated by AARE treatment. The increased expression of nuclear factor-κB, transforming growth factor-β(1), and the progressive accumulation of fibronectin in kidney of diabetic rats were attenuated by AARE treatment. AARE treatment ameliorated the elevated levels of advanced glycation end products (AGEs) and mitochondrial thiobarbituric acid-reactive substance, as well as the elevated levels of Nε-(carboxymethyl)lysine and receptors for AGEs in kidneys of diabetic rats. The results show that A. acutiloba root has an anti-diabetic property that involves antihyperglycemia accompanied by amelioration of glycation-mediated renal damage.     

Dietary advanced glycation endproducts (AGEs) and their health effects--PRO

Thermal processing of food results in the formation of various novel compounds, among others advanced glycation endproducts (AGEs). AGEs result from nonenzymatic glycation reactions between reducing sugars and free amino groups of proteins, peptides, or amino acids. Due to their potential noxious effects, alimentary AGEs are also called glycotoxins. This review provides a summary of the available evidence on the health effects of exaggerated intake of thermally treated food. Data from experimental studies in rodents and from clinical studies in healthy volunteers and in patients suffering from selected diseases in which AGEs are of pathogenetic importance (diabetes, chronic renal failure) are summarized. It is concluded that, an exaggerated intake of thermally processed foods may exert in vivo diabetogenic and nephrotoxic effects, induce low-grade inflammation, enhance oxidative stress, and promote atherosclerosis.     

New molecular and field evidences for the implication of mycotoxins but not aristolochic acid in human nephropathy and urinary tract tumor

To find out whether ochratoxin A (OTA), citrinin (CIT), aristolochic acids (AA) are etiologic agents of Balkan endemic nephropathy (BEN) or Chinese herbal nephrotoxicity, and associated urinary tract tumor (UTT), we have compared (i) in human kidney cell culture, the DNA adduct formation and persistence of OTA/CIT and AA adducts (ii) analyzed DNA adduct in several tumors from human kidney suspected to be exposed to either OTA and CIT, or AAs (iii) analyzed OTA, CIT, and AA in food. In kidney cell cultures, formation of specific OTA-DNA adduct and AA-DNA adduct were detected in the same range (around 10 adducts/10(9) nucleotides) and were time- and dose-dependent. After 2 days all disappeared. DNA adduct related to OTA and CIT are found in human kidney tissues from Balkans, France, and Belgium whereas no DNA adducts related to AA could be found in any tumors of BEN patients from Croatia, Bulgaria, or Serbia. No DNA adduct was found in kidney biopsy or necropsy of the French women suspected to be exposed to AA. OTA and CIT are more frequently found in rural area. AA was never detected. All these plead for implication of mycotoxins, especially OTA, in BEN and UTT.     

Ochratoxin A: An overview on toxicity and carcinogenicity in animals and humans

Ochratoxin A (OTA) is a ubiquitous mycotoxin produced by fungi of improperly stored food products. OTA is nephrotoxic and is suspected of being the main etiological agent responsible for human Balkan endemic nephropathy (BEN) and associated urinary tract tumours. Striking similarities between OTA-induced porcine nephropathy in pigs and BEN in humans are observed. International Agency for Research on Cancer (IARC) has classified OTA as a possible human carcinogen (group 2B). Currently, the mode of carcinogenic action by OTA is unknown. OTA is genotoxic following oxidative metabolism. This activity is thought to play a central role in OTA-mediated carcinogenesis and may be divided into direct (covalent DNA adduction) and indirect (oxidative DNA damage) mechanisms of action. Evidence for a direct mode of genotoxicity has been derived from the sensitive 32P-postlabelling assay. OTA facilitates guanine-specific DNA adducts in vitro and in rat and pig kidney orally dosed, one adduct comigrates with a synthetic carbon (C)-bonded C8-dG OTA adduct standard. In this paper, our current understanding of OTA toxicity and carcinogenicity are reviewed. The available evidence suggests that OTA is a genotoxic carcinogen by induction of oxidative DNA lesions coupled with direct DNA adducts via quinone formation. This mechanism of action should be used to establish acceptable intake levels of OTA from human food sources.     

Dietary AGEs and ALEs and risk to human health by their interaction with the receptor for advanced glycation endproducts (RAGE)--an introduction

The receptor for advanced glycation endproducts (RAGE) has a well-substantiated role in cell dysfunction and mechanisms of inflammatory disease. The physiological agonists of RAGE are less certain: S100/calgranulin proteins, high mobility group-1 protein HMGB1 and other proteins are candidate agonists. It increasingly appears unlikely proteins modified by advanced glycation endproducts are effective agonists in vivo. In the following debate, Professors Ann Marie Schmidt and Claus Heizmann gave arguments and evidences for and against the motion. Recent evidence suggesting the activation of RAGE impairs the enzymatic defence against glycation provided by glyoxalase 1 (Glo 1) suggests that studies of RAGE will continue to be of importance to our understanding of the physiological significance of protein glycation.     

Evidence against dietary advanced glycation endproducts being a risk to human health

In vivo, advanced glycation endproducts (AGEs) are linked to various diseases, particularly those associated with diabetes. AGEs are also formed when many foods are thermally processed. The extent to which dietary AGEs are absorbed by the gastrointestinal (GI) tract and their possible role in the onset and promotion of disease are currently of considerable interest. This paper reviews information that supports the argument that dietary AGEs are not a risk to human health.     

Quality analysis,classification, and authentication of liquid foods by near-infrared spectroscopy: A review of recent research developments

Nowadays, near-infrared spectroscopy (NIR) has become one of the most efficient and advanced techniques for analysis of food products. Many relevant researches have been conducted in this regard. However, no reviews about the applications of NIR for liquid food analysis are reported. Therefore, this review summarizes the recent research developments of NIR technology in the field of liquid foods, focusing on the detection of quality attributes of various liquid foods, including alcoholic beverages (red wines, rice wines, and beer), nonalcoholic beverages (juice, fruit vinegars, coffee beverages, and cola beverages), dairy products (milk and yogurt), and oils (vegetable, camellia, peanut, and virgin olive oils and frying oil). In addition, the classification and authentication detection of adulteration are also covered. It is hoped that the current paper can serve as a reference source for the future liquid food analysis by NIR techniques.     

Biological effects of acrylamide after daily ingestion of various foods in comparison to water: a study in rats

Scope: Acrylamide (AA), classified as a genotoxic carcinogen, is generated by heating foods. We studied whether the food matrix modulates bioavailability and/or biotransformation and investigated kinetics and biological effectiveness of AA in rats. Methods and results: AA was given to the animals at a daily intake level of AA containing foods for up to 9 days, resulting in an exposure of 50 or 100 μg AA/kg body weight (b.w.)/day. Positive controls received the same dosages of AA in water, negative controls just water. As biomarkers urinary mercapturic acids, hemoglobin adducts, plasma levels of AA and glycidamide (GA) and DNA integrity in white blood cells and hepatocytes were measured. Altogether, no significant differences in bioavailability of AA from water and the different food matrices were observed. Only with bread crust, biomarkers indicated a slightly reduced bioavailability. Monitoring glycidamide valine adduct adducts did not provide evidence for treatment‐related significantly enhanced GA‐haemoglobin adduct formation in blood although glycidamide mercapturic acid excretion in urine indicated significant GA formation. Conclusions: The results suggest AA at dietary intake levels, exceeding estimated human mean intake by a factor of at least 100 to become detoxified in Sprague–Dawley rats to a major extent through glutathione coupling.     

Polyphenols of Hibiscus sabdariffa improved diabetic nephropathy via regulating the pathogenic markers and kidney functions of type 2 diabetic rats

We recently demonstrated the chemical composition of Hibiscus sabdariffa polyphenol extracts (HPE), and its anti-insulin resistance property using a type 2 diabetic rat model. In the present study, we examined whether HPE prevents diabetic nephropathy, and its putative regulations of the pathogenic markers. HPE significantly inhibited albuminuria and the elevation of clearance of creatinine (CCr) caused by early diabetic nephropathy. Histological findings revealed that HPE inhibited fat deposition and advanced glycation end-products (AGE) expression in kidneys of type 2 diabetic rats. The increase of tubular connective tissue growth factors (CTGFs) and glomerular cluster of differentiation 31 (CD31) were also ameliorated by HPE. HPE reversed collagen accumulation, decreased angiotensin II type 1 receptor (AT-1) elevation, and improved oxidative stress. In conclusion, using the type 2 diabetic model, we have successfully shown that HPE not only has a benefit in reducing hyperglycaemia and hyperinsulinaemia, but can also prevent diabetic nephropathy. HPE has the potential to act as an adjuvant for diabetic therapy, and deserves further investigation.     

Inhibition of advanced glycation endproduct formation by foodstuffs

The Maillard reaction, which is generally termed nonenzymatic browning or glycation, has been implicated in accelerated aging and diabetic complications in vivo. Although the molecular basis of glycation-induced pathogenesis is not well understood, the following have been noted: (1) protein glycation leads to the formation and accumulation of toxic advanced glycation endproducts (AGEs); (2) AGEs can permanently alter the structure and function of body proteins; and (3) the interaction between AGE-modified proteins and AGE-specific receptors (RAGEs) on the cell surface induces the overproduction of reactive oxygen species (ROSs) and inflammatory mediators, which leads to cellular disorders in biological systems. To date, studies that have examined the contribution of protein glycation to disease-states have primarily focused on the deleterious effects and related mechanisms of these glycotoxins. However, it remains unknown whether phytochemicals exert protective effects against glycotoxin-induced damage. Thus, the development and investigation of AGE inhibitors, especially the natural anti-AGE agents without adverse effects, may provide a therapeutic approach for delaying and preventing premature aging and diabetic complications. In this review, we provide an outline of anti-glycation properties of foodstuffs and/or their active components, and discuss their mechanisms of action.     

Protective actions of microalgae against endogenous and exogenous advanced glycation endproducts (AGEs) in human retinal pigment epithelial cells

The formation and accumulation of advanced glycation endproducts (AGEs) is a key pathophysiological process involved in various diabetic complications such as diabetic retinopathy. In the present study, for the first time, protective effects of three microalgal strains, including their extracts and active compounds, against both endogenous and exogenous AGEs in cell-based models were investigated. Results showed that in cultured human-derived retinal pigment epithelial ARPE-19 cells, the extract of Chlorella zofingiensis and its nutritional ingredient astaxanthin exhibited significant inhibitory effects on the formation of endogenous N(ε)-carboxymethyllysine (CML), a key AGE representative, through the suppression of intracellular oxidative stress. On the other hand, extracts of Chlorella zofingiensis, Chlorella protothecoides and Nitzschia laevis as well as their nutritional ingredients, namely astaxanthin, lutein and eicosapentaenoic acid (EPA), attenuated the deleterious effects induced by exogenous AGEs, such as cell proliferation and mRNA upregulation of vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMP)-2, which are critical steps involved in the pathogenesis of diabetic retinopathy. These results suggested the positive roles of astaxanthin, lutein and EPA in controlling the development of diabetes. These microalgae, therefore, might be regarded as beneficial foods and preventive agent choices for patients with diabetic retinopathy.     

Changes in measures of biotin status do not reflect milk yield responses when dairy cows are fed supplemental biotin

A sensitive indicator of biotin status for lactating dairy cows is necessary to understand factors that affect milk yield responses to biotin supplementation. 3-Hydroxyisovaleric acid (3HIA) is an alternative metabolite in the pathway of Leu catabolism when the biotin-dependent enzyme methylcrotonyl-coenzyme A carboxylase is limiting. We evaluated urinary excretion of 3HIA as a determinant of biotin status in lactating dairy cows. We hypothesized that high-producing cows would have a greater biotin requirement and excrete more 3HIA than low-producing cows and that biotin supplementation would decrease 3HIA excretion. Twenty high-producing and 20 low-producing Holstein cows (43 ± 5 and 23 ± 4 kg/d of milk, respectively) were fed diets that contained either 0 or 0.96 mg/kg of supplemental biotin. On d 16 cows were given an intraruminal infusion of 1.4 mol of isovaleric acid and urine was sampled. Biotin supplementation did not affect basal urinary excretion of 3HIA. The infusion of isovaleric acid increased urinary excretion of 3HIA (maximum at 8 h after infusion), but biotin supplementation did not attenuate this increase. The increase in urinary 3HIA excretion was less for low-producing cows than for high-producing cows. Biotin increased yields of milk and milk components in high-producing cows but had no effect in low-producing cows. However, potential measures of biotin status (concentrations of avidin-binding substances in the plasma, milk, and urine, and urinary 3HIA excretion) responded similarly to biotin supplementation for both high- and low-producing cows. A sensitive indicator of biotin status for lactating dairy cows is still needed.     

Steady and dynamic rheological properties of thickened beverages used for dysphagia diets

Thickened beverages prepared with commercial food thickeners are widely used to promote safer and more successful swallowing in patients with dysphagia. In this study, the rheological properties of cold thickened beverages (bottled water, orange juice, apple juice, and whole milk) prepared with a commercially available gum-based food thickener (xanthan-guar gum mixture) marketed in Korea were investigated at 3 different thickener concentrations (2, 3, and 4%, w/w). Thickened beverages showed high shearthinning (n=0.12–0.21) behavior with Casson yield stress at all concentrations. Their apparent viscosity (η_a,50), consistency index (K), Casson yield stress (σ_oc), storage modulus (G′), and loss modulus (G″) increased with an increase in thickener concentration. Steady and dynamic rheological parameters also demonstrated greater differences in rheological behaviors between thickened beverages with different thickener concentrations. These results suggest that rheological properties of thickened beverages are strongly affected by thickener concentration and the type of beverage prepared.     

末端糖基化产物抑制剂的研究进展

目前研究表明人体的衰老和糖尿病的一些并发症,都与体内的糖基化反应(美拉德反应)所产生的末端糖基化产物有关。为了延迟体内的糖基化反应,末端糖基化产物抑制剂成为了相关研究领域的热点。为此,从末端糖基化产物的形成原理、病理学危害、抑制机理及天然产物中的抑制剂方面做阐述,并对未来研究领域进行展望。     

Invited review: Microfiltration-derived casein and whey proteins from milk

Milk, a rich source of nutrients, can be fractionated into a wide range of components for use in foods and beverages. With advancements in filtration technologies, micellar caseins and milk-derived whey proteins are now produced from skim milk using microfiltration. Microfiltered ingredients offer unique functional and nutritional benefits that can be exploited in new product development. Microfiltration offers promise in cheesemaking, where microfiltered milk can be used for protein standardization to improve the yield and consistency of cheese and help with operation throughputs. Micellar casein concentrates and milk whey proteins could offer unique functional and flavor properties in various food applications. Consumer desires for safe, nutritious, and clean-label foods could be potential growth opportunities for these new ingredients. The application of micellar casein concentrates in protein standardization could offer a window of opportunity to US cheese makers by improving yields and throughputs in manufacturing plants.     

Fate of the glucose degradation products 3-deoxyglucosone and glyoxal during peritoneal dialysis

Conventional fluids for peritoneal dialysis (PD) contain reactive glucose degradation products (GDPs) as a result of glucose breakdown during heat-sterilization. GDPs in PD fluids (PDFs) have been associated with the progressive alteration of the peritoneal membrane during long-term PD by cytotoxic effects and formation of advanced glycation endproducts (AGEs). In this study, we investigated the possible fate of two characteristic GDPs, 3-deoxyglucosone (3-DG) and glyoxal, during PD. In vivo, 3-DG and glyoxal concentrations, which were analyzed by high-performance liquid chromatography (HPLC), decreased in PDFs by 78% and 88% during 4 h of dwell time. The PDFs were then incubated in vitro in the presence of the most important reaction partners of GDPs in the peritoneal cavity. Neither human peritoneal mesothelial cells, human peritoneal fibroblasts, soluble protein, an insoluble collagen surface, nor components of spent dialysate led to a significant reduction of 3-DG or glyoxal after 6 h. Only after long-term incubation, a noticeable decrease of 3-DG was observed (-37% after three weeks), more likely due to spontaneous degradation reaction than formation of advanced glycation endproducts. These results suggest that in the course of PD, 3-DG, and glyoxal are absorbed into the organism and thus might contribute to the systemic pool of reactive carbonyl compounds.     

苹果多酚提取物对体外蛋白质非酶糖化的抑制作用

采用牛血清白蛋白-葡萄糖非酶糖化反应体系,研究苹果多酚提取物对体外蛋白质非酶糖化反应进程的影响。结果表明,苹果多酚提取物对蛋白质非酶糖化反应中间产物Amadori和高级糖化终末产物(AGEs)的形成均具有较强的抑制作用并呈明显的量效关系;在试验条件下,苹果多酚提取物对蛋白质非酶糖化反应中间产物Amadori和AGEs形成的最大抑制率分别可达80.85%和98.36%,IC50分别为0.40 g/L和0.28 g/L。说明苹果多酚提取物可能对糖尿病并发症具有一定的防治作用。     

Anti-glycation and inhibition of starch hydrolyzing enzymes by enzymatically hydrolysed djulis (Chenopodium formosanum Koidz.) hull,leaf and seedling

Glycation is the reaction of the carbonyl group of the reducing sugars to form advanced glycation end products (AGEs), which are major contributors to glycation-related diabetes. Hence, it is necessary to find an alternative approach in management of diabetes that can reduce the formation of AGEs. Therefore, we investigated the anti-glycation and starch hydrolysing enzymes inhibition by djulis (Chenopodium formosanum Koidz.) hull, leaf and seedling treated with enzymatic hydrolysis (EH) and studied the possible phenolic compounds responsible for the anti-glycation efficacy. Djulis samples treated with EH showed a high inhibitory effect on AGEs (65.04–72.77%), methylglyoxal (80.01–90.70%), α-amylase (86.37–93.50%) and α-glucosidase (35.50–38.16%). Bioactive compounds were significantly contributed to the anti-glycation potential of djulis samples. Therefore, djulis hull, leaf and seedling treated with EH could be used as a natural potential source in the prevention of glycation-associated diabetes, health risks and to increase food productivity.