Silk protein hydrolysate increases glucose uptake through up-regulation of GLUT 4 and reduces the expression of leptin in 3T3-L1 fibroblast

Boosting resistant starch in rice: Bacterial inulin as a metabolic and glucose uptake modulator

Bacillus stercoris PSSR12 (B. stercoris PE), an isolate from rice field soils, was identified via 16s rRNA sequencing. The synthesis of the inulin and inulin producing enzyme (IPE) in B. stercoris PE was verified using SDS-PAGE and FTIR. This study aimed to assess the impact of B. stercoris PE treatment on in vitro inhibition of α-amylase and α-glucosidase from traditional and commercial rice varieties of South India. Additionally, the study investigated enzymatic inhibition and mRNA expression of starch synthesis genes (RAmy1a, GBSSIa, SBEIIa, and SBEIIb). Glucose transporter gene expression (GLUT1 and GLUT4) patterns were analyzed in 3T3-L1 adipocytes to evaluate glucose uptake in B. stercoris PE treated rice varieties. The application of B. stercoris PE enhanced grain quality by imparting starch ultra-structural rigidity, inhibiting starch metabolizing enzymes, and inducing molecular changes in starch synthesis genes. This approach holds promise for managing type II diabetes mellitus and potentially reducing insulin dependence.

Nutritional Composition, Health Benefits, and Application Value of Edible Insects: A Review

For thousands of years, edible insects have been used as food to alleviate hunger and improve malnutrition. Some insects have also been used as medicines because of their therapeutic properties. This is not only due to the high nutritional value of edible insects, but more importantly, the active substances from edible insects have a variety of biofunctional activities. In this paper, we described and summarized the nutritional composition of edible insects and discussed the biological functions of edible insects and their potential benefits for human health. A summary analysis of the findings for each active function confirms that edible insects have the potential to develop functional foods and medicines that are beneficial to humans. In addition, we analyzed the issues that need to be considered in the application of edible insects and the current status of edible insects in food and pharmaceutical applications. We concluded with a discussion of regulations related to edible insects and an outlook on future research and applications of edible insects. By analyzing the current state of research on edible insects, we aim to raise awareness of the use of edible insects to improve human health and thus promote their better use and development.

Silkworm Pupae: A Functional Food with Health Benefits for Humans

Silkworm pupae are insects that are beneficial to human health, not only for their high nutritional value but, more importantly, for the variety of pharmacological functions they can perform when consumed. Currently, there is a lot of interest in the pharmaceutical applications of silkworm pupae. In recent years, the biological functions of domestic silkworm pupae have gradually been identified and confirmed, especially for their beneficial effects on human health. Studies have found that silkworm pupae have positive effects on liver protection, immune enhancement, antiapoptosis, antitumour, antibacterial, regulation of blood glucose and blood lipids, and lowering of blood pressure. However, the pharmacological mechanisms and systemic safety of silkworm pupae have not been systematically evaluated. In this paper, the nutritional composition of the pupae of the domestic silkworm is first summarised. The pharmacological functions of silkworm pupae and their components are then classified, and their mechanisms of occurrence are described. In addition, we provide a preliminary evaluation of the safety of silkworm pupae, analyse their application prospects, and suggest future directions for further pharmacological function studies. The aim is to generate interest in the promotion of human health through the use of silkworm pupae.

Nutritional, functional, and allergenic properties of silkworm pupae

Edible insects are a food source that has high nutritional value. Domestic silkworm pupae are an important by-product of sericulture and have a long history as food and feed ingredients in East Asia. Silkworm pupae are a good source of protein, lipids, minerals, and vitamins and are considered a good source of nutrients for humans. Silkworm pupae are a valuable insect source of substances used in healthcare products, medicines, food additives, and animal feed. Because silkworm pupae are being increasingly used in the human diet, potential allergic reactions to the substances they contain must be elucidated. Here, we present an overview of the benefits of silkworm pupae. First, we describe their nutritional value. Second, we report their functional properties and applications, focusing on their potential use in the food and pharmaceutical industries. Finally, we consider the current state of research regarding silkworm pupae-induced allergies.

Lactococcus chungangensis CAU 28 alleviates diet-induced obesity and adipose tissue metabolism in vitro and in mice fed a high-fat diet

Obesity, which has become a major public health problem, can arise from complex dyslipidemia, insulin resistance, and immune responses, among other mechanisms. Some Lactobacillus strains effectively ameliorate obesity; however, the beneficial effects of Lactococcus spp., which are often used as dairy starters, remain unclear. In the present study, we evaluated the efficacy of Lactococcus chungangensis CAU 28 using the 3T3-L1 cell line and obese mice fed a high-fat diet. Overall, administration of Lc. chungangensis CAU 28 effectively resolved obesity associated with weight gain and lipid accumulation. In differentiated 3T3-L1 cells, Lc. chungangensis CAU 28 treatment significantly diminished the total lipid quantity, inhibited triglyceride formation, and prevented the proliferation of adipogenic transcription factors (fatty acid synthase, adiponectin, peroxisome proliferator-activated receptor-gamma, and CCAAT-enhancer-binding protein-α) associated with lipid accumulation. In the obesity mouse model, wherein the intake of Lc. chungangensis CAU 28 effectively reduced body weight gain, along with fat differentiation and accumulation (white fat; abdominal and subcutaneous). Furthermore, Lc. chungangensis CAU 28 increased serum adiponectin levels, decreased serum leptin levels, and effectively regulated adipokine secretion. It also increased the high-density lipoprotein:cholesterol ratio, reduced total cholesterol and triglyceride levels, reduced the low-density lipoprotein:cholesterol ratio, and affected obesity-regulated inflammatory cytokines IL-6, tumor necrosis factor-α, IFN-γ, and IL-1β. Additionally, Lc. chungangensis CAU 28 was associated with an increase in the CD3⁺CD4⁺CD8^- phenotype among obese mice. Thus, the administration of Lc. chungangensis CAU 28 induced antiobesity effects, suggesting potential applications of this species as a supplement for obesity mitigation.

Effect of Dietary Silk Peptide on Obesity, Hyperglycemia, and Skeletal Muscle Regeneration in High-Fat Diet-Fed Mice

Obesity is associated with excess body fat accumulation that can cause hyperglycemia and reduce skeletal muscle function and strength, which characterize the development of sarcopenic obesity. In this study, we aimed to determine the mechanism whereby acid-hydrolyzed silk peptide (SP) prevents high-fat diet (HFD)-induced obesity and whether it regulates glucose uptake and muscle differentiation using in vivo and in vitro approaches. Our findings demonstrate that SP inhibits body mass gain and the expression of adipogenic transcription factors in visceral adipose tissue (VAT). SP also had an anti-diabetic effect in VAT and skeletal muscle because it upregulated glucose transporter type 4 (GLUT4) and uncoupling protein 3 (UCP3) expression. Furthermore, SP reduced ubiquitin proteasome and promoted myoblast determination protein 1 (MyoD)/myogenic factor 4 (myogenin) expression, implying that it may have potential for the treatment of obesity-induced hyperglycemia and obesity-associated sarcopenia.

Dietary Silk Peptide Prevents High-Fat Diet-Induced Obesity and Promotes Adipose Browning by Activating AMP-Activated Protein Kinase in Mice

Obesity is associated with metabolic syndrome and other chronic diseases, and is caused when the energy intake is greater than the energy expenditure. We aimed to determine the mechanism whereby acid-hydrolyzed silk peptide (SP) prevents high-fat diet-induced obesity, and whether it induces browning and fatty acid oxidation (FAO) in white adipose tissue (WAT), using in vivo and ex vivo approaches. We determined the effects of dietary SP in high-fat diet-fed obese mice. The expression of adipose tissue-specific genes was quantified by western blotting, qRT-PCR, and immunofluorescence analysis. We also investigated whether SP directly induces browning in primarily subcutaneous WAT-derived adipocytes. Our findings demonstrate that SP has a browning effect in WAT by upregulating AMP-activated Protein Kinase (AMPK) phosphorylation and uncoupling protein 1 (UCP1) expression. SP also suppresses adipogenesis and promotes FAO, implying that it may have potential as an anti-obesity drug.

Antioxidative and antidiabetic effects of germinated rough rice extract in 3T3-L1 adipocytes and C57BLKS/J-db/db mice

Background

To overcome disadvantages of germinated brown rice, we germinated rough rice and tested effects of its useful ingredients on prevention of diabetes.

Objective

This study investigated the in vitro antioxidant and in vivo antidiabetic effects of rough rice (Oryza sativa L.) with hulls, before and after germination. Rough rice was germinated for 4 days and extracted with water at 120°C.

Design

This study measured antioxidants and antioxidative effects and inhibitory activities against α-amylase and α-glucosidase of rough rice before and after germination and investigated antidiabetic effects of rough rice through animal experiments.

Results

All these factors increased after germination. Also, α-amylase and α-glucosidase inhibition and glucose uptake by 3T3-L1 adipocytes were significantly increased after germination. Oral administration of the germinated rough rice extract for 8 weeks significantly increased insulin levels and decreased blood glucose levels in a C57BLKS/J-db/db mice model. Immunohistochemical analysis showed that germinated rough rice effectively protected against liver, kidney, and pancreatic tissue damage.

Discussion

Useful ingredients in germinated rough rice could be used to prevent diabetes.

Conclusions

These results suggest that germinated rough rice extract had a beneficial effect on diabetes by increasing the antioxidant activity and further purification studies are necessary to elucidate the mechanism of the extract’s antidiabetic activity.

Multiple antidiabetic effects of three α-glucosidase inhibitory peptides, PFP, YPL and YPG: Dipeptidyl peptidase-IV inhibition, suppression of lipid accumulation in differentiated 3T3-L1 adipocytes and scavenging activity on methylglyoxal

Antidiabetic agents with multiple targets have the greatest pharmaceutical potential. In this study, three α-glucosidase inhibitory peptides, PFP, YPL and YPG, were investigated for additional antidiabetic targets viz.; dipeptidyl peptidase-IV inhibition (DPP-IV), lipid accumulation and the differentiation of 3T3-L1 adipocytes, and scavenging of methylglyoxal (MGO), reactive oxygen species (ROS) and nitric oxide (NO). The peptides were subjected to molecular docking on human DPP-IV where the binding free energies were PFP < YPG < YPL < diprotin A while hydrogen bond interactions were critical in the binding of YPL and YPG. Moreover, YPG demonstrated significantly higher (p < 0.05) in vitro DPP-IV inhibition than PFP and YPL. Kinetic analysis revealed that all three peptides are uncompetitive inhibitors of DPP-IV while YPG had the lowest inhibition binding constant. PFP and YPG prevented lipid accumulation in 3T3-L1 differentiated adipocytes but may be due to cytotoxicity for PFP. The peptides scavenged MGO, ROS and NO but only the ROS and NO scavenging activities of YPG were comparable to glutathione. In conclusion, PFP, YPL and YPG exhibited DPP-IV inhibitory activity, reduced adipocyte differentiation and lipid accumulation as well as scavenged MGO, ROS and NO. However, YPG had the best potential as a possible multifunctional antidiabetic agent.

The kinetics and mechanism of α-glucosidase inhibition by F5-SP, a novel compound derived from sericin peptides

The inhibition of α-glucosidase decreases postprandial blood glucose and therefore plays an important role in the treatment of type 2 diabetes mellitus. The present study investigated and characterized a peptide fraction of sericin hydrolysate, the kinetics of peptide-induced inhibition of α-glucosidase, and the interaction mechanism between the peptides and α-glucosidase. The fraction that eluted with 0.4 M NaCl (F5-SPs) on a DEAE-cellulose column exhibited significant inhibitory activity with an IC₅₀ of 41 ± 1.94 μg mL^-1. A kinetics analysis revealed that the F5-SP-induced inhibition was a reversible and parabolic mixed-type inhibition with a K_i value of 86.63 ± 0.014 μg mL^-1. F5-SPs can bind to α-glucosidase at multiple sites to alter the conformation of α-glucosidase. F5-SPs were found to be rich in Gly, Ser, Glu, Tyr, Arg, and Pro, and had a sericin-conserved sequence SEDSSEVDIDLGNLG, as analyzed by Nano LC-MS/MS. Fluorescence spectra analysis showed that F5-SPs quenched the intrinsic fluorescence of α-glucosidase by a static quenching mechanism, and circular dichroism analysis suggested that the binding of F5-SPs to α-glucosidase resulted in the alteration of the secondary structure of an enzyme. The results of this study support the dietary recommendation of F5-SPs for the treatment of type 2 diabetes.

Processing and characterization of silk sericin from Bombyx mori and its application in biomaterials and biomedicines

Bombyx mori silk is composed of 60-80% fibroin, 15-35% sericin and 1-5% non-sericin component including wax, pigments, sugars and other impurities. For two decades, the protein-based silk fibroin was extensively used in the research and development of medical biomaterials and biomedicines. Sericin is frequently ignored and abandoned as a byproduct or waste in the processing of traditional silk fabrics, silk floss or modern silk biomaterials. However, similar to fibroin, sericin is not only a highly useful biological material, but also a lot of biological activity. Moreover, the non-sericin component present with sericin in the cocoon shell also has a strong biological activity. In this review, the extraction and recovery methods of sericin and the non-sericin component from the cocoon layer are reported, and their composition, properties and biological activity are described to produce a comprehensive report on biomedical materials and biological drugs. In addition, related problems or concerns present in the research and development of sericin are discussed, and a potential application of sericin in sustainable development is also presented.

GC/MS-based metabolomic studies reveal key roles of glycine in regulating silk synthesis in silkworm, Bombyx mori

Metabolic profiling of silkworm, especially the factors that affect silk synthesis at the metabolic level, is little known. Herein, metabolomic method based on gas chromatography-mass spectrometry was applied to identify key metabolic changes in silk synthesis deficient silkworms. Forty-six differential metabolites were identified in Nd group with the defect of silk synthesis. Significant changes in the levels of glycine and uric acid (up-regulation), carbohydrates and free fatty acids (down-regulation) were observed. The further metabolomics of silk synthesis deficient silkworms by decreasing silk proteins synthesis using knocking out fibroin heavy chain gene or extirpating silk glands operation showed that the changes of the metabolites were almost consistent with those of the Nd group. Furthermore, the increased silk yields by supplying more glycine or its related metabolite confirmed that glycine is a key metabolite to regulate silk synthesis. These findings provide important insights into the regulation between metabolic profiling and silk synthesis.

Importance of pH homeostasis in metabolic health and diseases: crucial role of membrane proton transport

Protons dissociated from organic acids in cells are partly buffered. If not, they are transported to the extracellular fluid through the plasma membrane and buffered in circulation or excreted in urine and expiration gas. Several transporters including monocarboxylate transporters and Na(+)/H(+) exchanger play an important role in uptake and output of protons across plasma membranes in cells of metabolic tissues including skeletal muscle and the liver. They also contribute to maintenance of the physiological pH of body fluid. Therefore, impairment of these transporters causes dysfunction of cells, diseases, and a decrease in physical performance associated with abnormal pH. Additionally, it is known that fluid pH in the interstitial space of metabolic tissues is easily changed due to little pH buffering capacitance in interstitial fluids and a reduction in the interstitial fluid pH may mediate the onset of insulin resistance unlike blood containing pH buffers such as Hb (hemoglobin) and albumin. In contrast, habitual exercise and dietary intervention regulate expression/activity of transporters and maintain body fluid pH, which could partly explain the positive effect of healthy lifestyle on disease prognosis.

Silk peptide treatment can improve the exercise performance of mice

BACKGROUND

We previously reported that silk peptide (SP) treatment led to increased resting fat oxidation in exercised mice. However, it was not known whether SP treatment could effectively increase exercise capacity. Accordingly, this study aimed to examine whether SP treatment affected energy metabolism during exercise in addition to exercise performance.

METHODS

We randomized 36 7-week-old male ICR mice into 2 groups: the control (n = 18) and SP (n = 18) groups. All mice were trained by treadmill running 5 times per week for 2 weeks. SP was dissolved in distilled water and daily 800-mg/kg body weight doses before the running exercise were oral administered intraperitoneally to the SP group for 2 weeks. [Formula: see text] was measured before and after the 2 weeks training period. We also assessed energy metabolism during exercise for 1 h after the 2 week training period. In addition to blood samples, liver glycogen and gastrocnemius-white and gastrocnemius-red muscle was obtained at the following 3 time points: at rest, immediately after exercise, and 1-hour post exercise.

RESULTS

The [Formula: see text] max after 2 weeks of training was significantly increased (8%) in the SP group compared to the baseline; a similar result was not observed in the CON group. The sum of fat oxidation during a 1-h period tended to be 13% higher in the SP group than in the CON group (P < 0.077). In particular, the sum of fat oxidation was significantly higher in the SP group during the initial 20-min phase than that in the CON group (P < 0.05). The glycogen concentration in the white gastrocnemius muscle did not differ between the groups either rest or after 1 h of exercise but was significantly higher in the SP group than in the CON group during the recovery period (1 h post-exercise completion).

CONCLUSIONS

These results suggest that SP treatment can improve the exercise performance. Therefore, SP is considered to confer beneficial effects upon athletes, in whom exercise abilities are required.

Silkworm pupae powder ingestion increases fat metabolism in swim-trained rats

[Purpose]

Many researchers are trying to solve the metabolic syndrome by utilizing a variety of nutritional control and exercise. Of those, silkworm pupae peptides are known to inhibit the synthesis of fat. Therefore, we examine the effect of fat metabolism by supplying silkworm pupae (SP) for 5-week in swim-trained rats.

[Methods]

Animals were divided into four groups as a group (n = 32) fed a normal diet (CO) with exercise training (CE); a group fed a silkworm pupa diet (SPC) with an exercise training (SPE), respectively.

[Results]

Abdominal fat pads (abdominal and epididymal) weight were lowest in SPE. The serum triglyceride, total cholesterol concentrations were lower in the SP and the SPE. HDL-cholesterol, however, was not different between groups. Liver AMPK (AMP-activated protein kinase) was increased in the CE and the SPE. Liver PPAR-α (Peroxisome proliferator-activated receptor alpha) was increased in the SPC and SPE. L-FABP (liver fatty acids binding protein) was increased by SP ingestion. Liver CPT-1 (carnitine palmitoyltransferase-1) protein expression was increased by exercise training only.

[Conclusion]

In the present study showed that the silkworm pupae intake and/or swimming exercise training activates fat metabolism to reduce the concentration of serum lipids. Thus, the silkworm pupae intake leads to a reduction in fat storage, this is considered to be effective in the inhibition of the metabolic syndrome.

Silk peptide intake increases fat oxidation at rest in exercised mice

Silk peptides (SP) have been reported to decrease body weight and accumulate fat. We investigated the effects of SP administration by using an open circuit calorimetry system on resting energy expenditure and substrate utilization in resting mice for the duration of 24 h. Seven-week-old male ICR-mice were orally administered SP (800 mg/kg) for 2 wk and were subjected to endurance training. The results indicated that not only was oxygen uptake higher in the SP group than in the CON group (*p<0.05), but also the respiratory exchange rate was lower than that in the CON group for the duration of 24 h (**p<0.01). Moreover, fat oxidation was increased in the SP group. Body weight of the SP group was significantly decreased compared to that of the CON group (*p<0.05). These results suggest that intake of silk peptides increases fat oxidation during rest in exercised mice. Intake of silk peptides is considered to be a favorable supplement for athletes in training. In particular, it would be an effective supplement for athletes who require weight loss along with an increase in muscle mass.