[Protective effect of corn peptide on nonalcoholic fatty liver disease in rats induced by high fat diet].

OBJECTIVE: To explore the dose-effect and mechanism of the protective effect of corn peptide(CP) on nonalcoholic fatty liver disease(NAFLD). METHODS: Seventy male SD rats were randomly divided into control group, model group, CP group, puerarin positive control group, low-, medium-, high-dose corn peptide group, the experiment started after 1 week of adaptive feeding. The control group and CP group were fed with ordinary feed and others were fed with high-fat feed, while the control group was given intragastric administration of purified water, the CP group and the low-, medium-, high-dose corn peptide group were given intragastric administration of corn peptide(800, 400, 600 and 800 mg/(kg·d), respectively), and the puerarin positive control group was given intragastric administration of 300 mg/(kg·d) of puerarin, for 10 weeks. The body weight and general condition of rats were recorded every week, after 10 weeks, the indexes of 7 groups were compared. RESULTS: Compared with the model group, the liver index(3.67, 3.29, 3.19 and 3.04, P<0.05) of the rats in the three doses of corn peptide groups decreased. The homeostasis model assessment of insulin resistance(13.66, 11.82, 11.55 and 10.53, P<0.05) decreased. The serum triglyceride(TG)(0.59, 0.42, 0.34 and 0.28, P<0.05), total cholesterol(TC)(2.57, 2.10, 1.67 and 1.46, P<0.05), free fatty acid(FFA)(0.66, 0.44, 0.40 and 0.36, P<0.05), and leptin(10.64, 9.87, 9.43 and 9.05, P<0.05) decreased. The serum interleukin-6(74.61, 61.66, 51.12 and 35.68, P<0.05) and tumor necrosis factor-α(100.18, 74.13, 67.44 and 48.46, P<0.05) decreased. The serum aspartate aminotransferase(41.38, 19.41, 14.98 and 8.44, P<0.05) and alanine aminotransferase(25.14, 13.10, 11.57 and 7.48, P<0.05) activity decreased. The liver TG(9.89, 5.55, 4.73 and 3.13, P<0.05), TC(1.73, 0.97, 0.80 and 0.50, P<0.05) and FFA(1.81, 1.11, 0.77 and 0.70, P<0.05) decreased. The serum malondialdehyde(MDA)(21.36, 15.24, 12.75 and 10.87, P<0.05) level and liver MDA(11.87, 8.27, 6.33 and 4.98, P<0.05) level decreased. The serum and liver superoxide dismutase and glutathione peroxidase activity increased(P<0.05), and the effect is related to the intervention dose of corn peptide. The size of the liver became smaller, the liver color gradually changed from light yellow to light red. CONCLUSION: Corn peptide has a certain preventive effect on NAFLD in rats, and the preventive effect of corn peptide is related to its intervention dose.

Anti-obesity effects of corn peptide on 3T3-L1 preadipocytes and C57BL/6J obese mice.

Corn peptide (CP) is a small, natural, biologically active peptide obtained by protease-catalysed hydrolysis of corn. CP exerts antihypertensive, hypoglycaemic, antihyperlipidemic, antioxidant, and antitumor effects, as well as prevents cardiovascular and cerebrovascular diseases. Although CP plays a role in preventing obesity-related diseases, its role in reducing obesity has not yet been determined. In this study, we analysed the inhibitory effects of CP on lipid droplet accumulation in 3T3-L1 preadipocytes and high-fat diet (HFD)-induced C57BL/6J Obese Mice. The results show that CP could inhibit preadipocyte differentiation and oil accumulation in 3T3-L1 preadipocytes. Oral CP administration reduced serum triglyceride (TG) content, epididymal fat weight, abnormal liver fat droplet accumulation, and C/EBPα expression. Furthermore, combination of CP administration and exercise reduced body, liver, and adipose tissue weights; decreased serum total cholesterol (TC), triglyceride and low-density lipoprotein (LDL) levels; and inhibited hepatic lipid droplet accumulations and epididymal fat cell hypertrophy. Additionally, this combination inhibited the expression of transcription factors, C/EBPα, C/EBPß, and PPARγ, and adipogenic factors, FABP4 in mice. In conclusion, oral administration of CP inhibited lipid droplet accumulation and counteracted HFD-induced obesity in mice.

Preparation, structural and functional characterization of corn peptide-chelated calcium microcapsules using synchronous dual frequency ultrasound.

The utilization of peptide-chelated calcium is low due to the influence of factors such as solubility, heat and digestive environmental conditions; therefore, it is crucial to protect, prolong and stabilize this nutrient in order to enhance its efficacy. This study was conducted to prepare corn peptide-chelated calcium microcapsules using ß-cyclodextrin (ß-CD) as the wall material through an improved ultrasonic-assisted method. The structure, solubility, thermal stability, and in vitro gastrointestinal digestion of these microcapsules were thoroughly investigated and analyzed. The microcapsules were prepared using the following recommended conditions: a chelate concentration of 5 mg/mL, a mass ratio of chelate to ß-CD of 1:8 g/g, and a synchronous dual-frequency ultrasound (20/28 kHz) at a power of 75 W, a duty ratio of 20/5 s/s, and a time of 20 min. These specific parameters were carefully selected to ensure the optimal fabrication of the microcapsules. The results showed that the utilization of dual-frequency ultrasound resulted in a significant increase in both the encapsulation rate and yield, which were enhanced by 15.84 % and 15.68 %, respectively, reaching impressive values of 79.17 % and 90.60 %. Moreover, the results of the structure index analysis provided further confirmation that ultrasonic treatment had a significant impact on the structure of the microcapsules, leading to a noticeable reduction in particle size and transformation into nanoparticles. Furthermore, the microcapsules demonstrated excellent solubility within a wide pH range of 2 to 10, with solubility ranging from 93.54 % to 88.68 %. Additionally, these microcapsules exhibited remarkable thermal stability, retaining a minimum of 84.8 % of their stability when exposed to temperatures ranging from 40 to 80 °C. Moreover, during gastric and intestinal digestion, these microcapsules exhibited a high slow-release rate of 44.66 % and 51.6 %, indicating their ability to gradually release calcium contents. The inclusion of dual-frequency ultrasound in the preparation of high calcium microcapsules yielded promising outcomes. Overall, our work presents a novel method for synthesizing corn peptide-chelated calcium microcapsules with desirable properties such as good solubility, excellent thermal stability, and a significant slow-release effect. These microcapsules have the potential to serve as fortified high calcium supplements.

Effect of Different Cereal Peptides on the Development of Type 1 Diabetes is Associated with Their Anti-inflammatory Ability: In Vitro and In Vivo Studies.

SCOPE: The aim of the study is to explore which properties of selected peptides will positively predict their antidiabetic activity in vitro and in vivo. METHODS AND RESULTS: Streptozotocin-induced diabetic C57BL/6J mice are administered with soybean peptide (SP), mung bean peptide (MP), corn peptide (CP), and wheat peptide (WP) (500 mg kg-1  d-1 ) for 10 weeks. CP and WP improve hyperglycemia homeostasis in streptozotocin-induced diabetic mice. Female nonobese diabetic (NOD) mice are treated with CP, WP, fractions C1 and C2 (isolated from CP), and W1 and W2 (isolated from WP) beginning at 3 weeks of age. CP, C2, and W2 delay the initiation of diabetes and decrease serum IL-6 levels in NOD mice. CP also reduces insulitis and increases the ß-cell area in NOD mice. MIN-6 cells are incubated with the selected peptides. CP, C2, and W2 result in the reduced expression of LPS-induced IL-6 mRNA in MIN-6 cells. CP inhibits signaling pathways related to apoptosis and inflammation. The antioxidative, hydrophobic, and proliferative properties of the selected peptides are analyzed. The hypoglycemic effects of cereal peptides are not associated with their antioxidant activity, hydrophobicity, or proliferative ability. CONCLUSION: Findings suggest that the effect of cereal peptides on the development of T1D is associated with their anti-inflammatory ability.

[Effects of dietary corn peptide and exercise on hepatic ATGL and TNF-α in obese rats].

OBJECTIVE: To determine whether dietary corn peptides supplementation with or without exercise on body composition and fac-tors related to hepatic lipid metabolism in obese rats induced by a high fat diet. METHODS: Male SD rats were fed a high-fat diet (40% calorie as fat) for 8 weeks as a dietary induced obesity model (DIO, n=32). They were then randomly divided into four groups, control, corn pip-tide(CP) group, exercise group and CP + exercise group (n=8). Supplement (CP:200 g/kg) and exercise(tread mill Ex was performed 15 m/min for 60 min/d, 5 days a week) protocol for 4 weeks. Body weight and dietary levels of rats were monitored during the experimental peri-od. At the end of the 4th weeks, rats of all groups were sacrificed. Perirenal fat and liver were harvested, and hepatic adipose triglyceride li-pase(ATGL) and TNF-α were analyzed via Western blot. RESULTS: After 4 weeks, compared with DIO control group, body weight and perire-nal fat mass index in CP + exercise group were significantly decreased (P < 0.05). Hepatic ATGL was significantly higher in corn peptides supplementation, especially in combination with exercise (P < 0.05). At the same time, the values of TNF-α expression were decreased signif-icantly in exercise groups compared with DIO group (P < 0.05). CONCLUSIONS: Corn peptides combined with aerobic exercise has a weight re-duction by lowering adipose tissue in experimental animals, it may be related to the expression of ATGL and TNF-α in the liver, and promote lipid metabolism.