Stability of a type 2 diabetes rat model induced by high-fat diet feeding with low-dose streptozotocin injection

OBJECTIVE

The present study aims at determining the stability of a popular type 2 diabetes rat model induced by a high-fat diet combined with a low-dose streptozotocin injection.

METHODS

Wistar rats were fed with a high-fat diet for 8 weeks followed by a one-time injection of 25 or 35 mg/kg streptozotocin to induce type 2 diabetes. Then the diabetic rats were fed with regular diet/high-fat diet for 4 weeks. Changes in biochemical parameters were monitored during the 4 weeks.

RESULTS

All the rats developed more severe dyslipidemia and hepatic dysfunction after streptozotocin injection. The features of 35 mg/kg streptozotocin rats more resembled type 1 diabetes with decreased body weight and blood insulin. Rats with 25 mg/kg streptozotocin followed by normal diet feeding showed normalized blood glucose level and pancreatic structure, indicating that normal diet might help recovery from certain symptoms of type 2 diabetes. In comparison, diabetic rats fed with high-fat diet presented decreased but relatively stable blood glucose level, and this was significantly higher than that of the control group (P<0.05).

CONCLUSIONS

This model easily recovers with normal diet feeding. A high-fat diet is suggested as the background diet in future pharmacological studies using this model.

Antioxidant capacity and amino acid profile of millet bran wine and the synergistic interaction between major polyphenols

Millet bran, the by-product of millet processing industry, contains an abundance of phytochemicals, especially polyphenols. The main objective of this study was brewing antioxidant wine from millet bran, as well as the nutritional evaluation. The total polyphenol content of wine samples was determined by Folin-Ciocalteu colorimetric method, and the antioxidant capacity was evaluated by DPPH radical-scavenging capacity, Trolox equivalent antioxidant capacity (TEAC), and ferric reducing antioxidant power (FRAP). Results showed that millet bran wine (MBW) contained as much as six times of total polyphenols compared with millet wine (MW), and performed considerably stronger antioxidant activity in DPPH, TEAC and FRAP assays. More than sixfold of total amino acids (AA) were found in MBW than in MW. Moreover, the indispensable AA and functional AA were also abundant in MBW. The major polyphenol compounds in MBW were identified using HPLC, including vanillic acid, syringic acid (SA), p-coumaric acid (CA) and ferulic acid (FA). They exhibited synergism in the antioxidant assays, especially the combinations of SA and CA, SA and FA. This study not only provides evidence for MBW as a nutraceutical with antioxidant activity, but also opens new avenues in the area of making comprehensive utilization of agricultural by-products.

Note. Microbial Changes During the Salting Process of Traditional Pickled Chinese Cabbage

Changes in microflora during salting Chinese cabbage were studied, with special attention given to the effects of salt concentration, time and temperature of the process. Total mesophilic aerobic bacteria (TMAB), bacterial endospores (B. endospores), lactic acid bacteria (LAB), Enterobacteriaceae and fungi were used as control parameters. LAB accounted for 0.1-1% of total bacteria. Best process conditions for highest undesirable microbial inhibition were: salt 8% (w/v), temperature 15°C, and salting time 8h. High levels (>105 cfu/g) of TMAB and Enterobacteriaceae were found in the whole salting time, and 90% of TMAB was identified as Gram negative. The levels of fungi, LAB and B. endospores after 12h of the salting process were lower than 104, 103 and 102 cfu/g, respectively.

Synergistic interactions of apigenin, naringin, quercetin and emodin on inhibition of 3T3-L1 preadipocyte differentiation and pancreas lipase activity

The interactions of four natural compounds including apigenin, naringin, emodin and quercetin were investigated on inhibiting 3T3-L1 preadipocyte differentiation and pancreas lipase activity. Oil Red O staining was conducted to visualise and quantify lipid accumulation. The difference between experimental and calculated results was utilised for determining the interaction types. Interestingly, emodin synergistically interacted with the other three compounds, and the combination of emodin and apigenin exhibited the strongest synergistic effect in both differentiation and pancreas lipase assays. Results implied that the combination of apigenin and emodin may be regarded as a promising complementary therapy for management of overweight or obesity.

The protective effects of berry-derived anthocyanins against visible light-induced damage in human retinal pigment epithelial cells

BACKGROUND

Studies have shown that anthocyanins (ACNs) in berries contribute to eye health. However, information on the relationship between the chemical structures and visual functions of ACNs is scarce. This study investigated the protection effects of ACNs with different structures against visible light-induced damage in human retinal pigment epithelial (RPE) cells.

RESULTS

Four ACNs with different aglycones, namely, pelargonidin-3-glucoside (Pg-3-glu), cyanidin-3-glucoside (Cy-3-glu), delphinidin-3-glucoside, and malvidin-3-glucoside (Mv-3-glu), were isolated from three berries (blueberry, blackberry and strawberry). Of these ACNs, Cy-3-glu exhibited the highest reactive oxygen species inhibitory capacity in RPE cells, with 40 µg mL(-1) Cy-3-glu showing a ROS clearance of 57.5% ± 4.2%. The expression of vascular endothelial growth factor levels were significantly (P < 0.05) down-regulated by Cy-3-glu and Mv-3-glu in a visible light-induced damage RPE cell model. Cy-3-glu and Pg-3-glu treatments significantly (P < 0.05) inhibited the increase in β-galactosidase during the RPE cell ageing caused by visible light exposure.

CONCLUSION

Our findings suggest that the biological properties of different ACNs significantly vary. Cy-3-glu, which contains an ortho hydroxyl group in its B ring, possibly exerts multiple protective effects (antioxidant, anti-angiogenic and anti-ageing) in RPE cells. Therefore, Cy-3-glu may prove useful as a prophylactic health food for the prevention of retinal diseases.

A diet formula of Puerariae radix, Lycium barbarum, Crataegus pinnatifida, and Polygonati rhizoma alleviates insulin resistance and hepatic steatosis in CD-1 mice and HepG2 cells

According to the principles of traditional Chinese medicine, medicinal and edible herbs exhibit holistic effects through their actions on multiple target organs.

Antioxidant activity of protein hydrolysates from aqueous extract of velvet antler (Cervus elaphus) as influenced by molecular weight and enzymes

The crude protein hydrolysates from aqueous extract of velvet antler (AEVA) were prepared by simulated gastrointestinal digestion (SGI, pepsin-pancreatin) using pancreatin-pepsin, alcalase and neutrase. The resulting hydrolysates were separated by sequential ultrafiltration into four fractions. The antioxidant activities of peptide fractions were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging and Fe(2+)-chelating assays. Results showed that the hydrolysate prepared by SGI had a low degree of hydrolysis, which was significantly improved with altered proteases, such as pancreatin-pepsin and alcalase. Antioxidant activities of peptide fractions varied with molecular weight (MW) and the enzyme used. Generally, low-MW peptide fractions had higher ABTS radical scavenging activity and Fe(2+)-chelating ability, and high-MW peptide fractions were more effective in DPPH radical scavenging activity and reducing power.

Antioxidant Activity of Protein Hydrolysates from Aqueous Extract of Velvet Antler (Cervus elaphus) as Influenced by Molecular Weight and Enzymes

The crude protein hydrolysates from aqueous extract of velvet antler (AEVA) were prepared by simulated gastrointestinal digestion (SGI, pepsin-pancreatin) using pancreatin-pepsin, alcalase and neutrase. The resulting hydrolysates were separated by sequential ultrafiltration into four fractions. The antioxidant activities of peptide fractions were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging and Fe2+-chelating assays. Results showed that the hydrolysate prepared by SGI had a low degree of hydrolysis, which was significantly improved with altered proteases, such as pancreatin-pepsin and alcalase. Antioxidant activities of peptide fractions varied with molecular weight (MW) and the enzyme used. Generally, low-MW peptide fractions had higher ABTS radical scavenging activity and Fe2+-chelating ability, and high-MW peptide fractions were more effective in DPPH radical scavenging activity and reducing power.

Hypocholesterolemic effects of Auricularia auricula ethanol extract in ICR mice fed a cholesterol-enriched diet

The cholesterol-lowering properties of Auricularia auricula are commonly attributed to the presence of polysaccharides based on previous research. The present study was designed to investigate the effects of ethanol extract of A. auricula (AAE) on hypercholesterolemia in ICR mice. AAE contained more than 16% (g/g) polyphenolic compounds, excluding other interfering factors such as polysaccharides, water-soluble fibre and protein. Thirty-six mice were randomly assigned to three groups (n = 12). The experimental group was fed cholesterol-enriched diet (CED) with oral administration of AAE (150 mg/kg/d b.w.) for 8-week, normal control group and CED control group received either a regular diet (RD) or CED along with oral administration of equal volume distilled water. Serum lipid profiles and antioxidant status were measured in addition to fecal neutral cholesterol and bile acids. AAE showed a remarkable hypocholesterolemic effect, improving antioxidant status, decreasing the level of total cholesterol and atherosclerosis index, increasing the level of high-density lipoprotein cholesterol and fecal excretion of bile acids. No apparent effects on serum triglycerides, low-density lipoprotein cholesterol, fecal excretion of neutral cholesterol and feeding efficiency were observed among all groups. These results indicated that A. auricula functional components, which prevented hypercholesterolemia contained polyphenolic compounds, in addition to polysaccharides.

[Possibilities of near-infrared spectroscopy for the assessment of principle components in honey]

The potential of near infrared spectroscopy (NIR) as a nondestructive method for determining the principle components of honeys was studied for 153 unifloral honeys and multifloral honey samples. Fourier transform near-infrared spectroscopy (FT-NIR), CCD near-infrared spectroscopy and PDA near-infrared spectroscopy were evaluated to quantitatively determine water content, fructose content and glucose content in honey. On the basis of partial-least square (PLS) regression, the models of honey were compared. The best calibration model gives the correlation coefficients of 0.978 5, 0.931 1 and 0.90 7 for water, fructose and glucose, respectively, with the root mean square error of prediction (RMSEP) of 0.410 8(%), 1.914 48(%) and 2.531 9(%) respectively. The results demonstrated that near-infrared spectrometry is a valuable, rapid and nondestructive tool for the quantitative analysis of the principle components in honey.

[Analysis of NIR characteristic wavelengths for apple flesh firmness based on GA and iPLS]

In the present study, the fruit flesh firmness of apple was analyzed by near infrared (NIR) spectroscopy using an FT-NIR spectrometer. The sensitive spectral regions that provide the lowest prediction error were analyzed by different well-known variable selection methods, including dynamic backward interval partial least-squares (dynamic biPLS), sequential application of backward interval partial least-squares and genetic algorithm(dynamic biPLS & GA-PLS), and iterative genetic algorithm partial least-squares (iterative GA-PLS). Iterative GA-PLS, dynamic biPLS & GA-PLS led to a distinct reduction in the number of spectral data points with better predictive quality. Furthermore, the majority of selected wavelengths were content with the characteristic of the sorption bands of fruit flesh firmness. Pectin constituents, complex non-starch polysaccharides, which are related to texture change in apple, play an important role in their harvest maturity, ripening and storage. Comparing NIR characteristic wavelengths of apple flesh firmness and typical absorption bands for pectin, it was found that characteristic wavelengths of apple flesh firmness were consistent with the pectins relevant spectral regions. Therefore, the NIR characteristic wavelengths of apple firmness based on GA and iPLS reflected the chemical component of apple and the results were reasonable.

[Using GA-dOSC method to eliminate interference of peel with prediction of apple firmness based on near infrared diffuse reflection spectra]

In the present work, "Fuji" apples from Shandong Yantai were used to take the diffuse reflection spectra by FT-NIR PLS components (i.e., factors) were computed by nonlinear iterative partial least squares (NIPALS) and the number of latent factors (LV) was optimized by a leave-one-out cross-validation procedure on the calibration set. On the basis of partial least square (PLS) regression, the models for apples' firmness before and after peeling were compared. In order to eliminate the effect of apple peel on prediction, spectral pretreatments such as multiplicative scatter correction (MSC), derivative, direct orthogonal signal correction (DOSC) and wavelengths selection based on genetic algorithms (GA) were used. Finally, the results of different spectral treatments were compared. In conclusion, the RSDp of models for apples before and after peeling was 16.71% and 12.36%, respectively, suggesting that the apple peel played a negative role in constructing good predictive models. Moreover, the traditional spectral pretreatments (such as MSC, derivative) can hardly resolve the problem. In this research, GA-DOSC played an important role in reducing the interference of apple peel. It not only reduced the wavelength variables from 1480 to 36, but also reduced the latent variables from 5 to 1. The correlation coefficient (r) was improved from 0.753 to 0.805, and the RMSECV and RMESP were reduced from 1.019 kgf x cm(-2) and 1.197 kgf x cm(-2) to 0.919 kgf x cm(-2) and 0.924 kgf x cm(-2), respectively. Especially, the RSDp was decreased remarkably from 16.71% to 12.89%. The performance of the model after GA-DOSC treatment was similar to the model using spectra of apple flesh (12.36%). It was concluded that the prediction precision based on GA-DOSC satisfied the requirement of NIR non-destruction determination of apples firmness.

Effects of fructose and/or fat in the diet on developing the type 2 diabetic-like syndrome in CD-1 mice

The aim of the present study was to examine the interactions of fructose and fat on glucose regulation and lipid metabolism in CD-1 mice. Mice were assigned in five groups. The control group was provided with tap water and a gavage of vehicle; four experimental groups were treated with 150 g/l fructose solution (FS1), fat emulsion (FE), 150 g/l fructose solution and fat emulsion (FS1+FE), or 70 g/l fructose solution and fat emulsion (FS2+FE) for 12 weeks. At the end of the 8th week, both oral glucose tolerance test and insulin tolerance test were conducted. Lipid profiles in serum, liver, and red gastrocnemius muscle, and serum insulin and glucose concentrations were assessed. The FS1+FE group showed combined glucose intolerance (CGI) and decrease of insulin sensitivity. The low-density lipoprotein cholesterol (LDL-C) concentrations were elevated in all experimental groups (p<0.05). The combined diet groups showed statistically significant (p<0.01) increase in total cholesterol (TC) level in comparison with the control FE (p<0.05), or FS1 (p<0.05) group. Triglyceride levels in liver and red gastrocnemius muscle were significantly increased in FE and combined groups. In conclusion, combination of FE and 150 g/l fructose solution for 8 weeks led to CGI. Fructose enhanced the adverse effect of FE on glucose regulation with increasing percentage in the diet. Furthermore, there was a synergistic effect of fructose and fat on elevating the serum TC level.