Antidiabetic Effect of Collagen Peptides from Harpadon nehereus Bones in Streptozotocin-Induced Diabetes Mice by Regulating Oxidative Stress and Glucose Metabolism

Oxidative stress and abnormal glucose metabolism are the important physiological mechanisms in the occurrence and development of diabetes. Antioxidant peptides have been reported to attenuate diabetes complications by regulating levels of oxidative stress, but few studies have focused on peptides from marine bone collagen. In this study, we prepared the peptides with a molecular weight of less than 1 kD (HNCP) by enzymolysis and ultrafiltration derived from Harpadon nehereus bone collagen. Furthermore, the effects of HNCP on blood glucose, blood lipid, liver structure and function, oxidative stress, and glucose metabolism were studied using HE staining, kit detection, and Western blotting experiment in streptozocin-induced type 1 diabetes mice. After the 240 mg/kg HNCP treatment, the levels of blood glucose, triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) in streptozotocin-induced diabetes mice decreased by 32.8%, 42.2%, and 43.2%, respectively, while the levels of serum insulin and hepatic glycogen increased by 142.0% and 96.4%, respectively. The antioxidant enzymes levels and liver function in the diabetic mice were markedly improved after HNCP intervention. In addition, the levels of nuclear factor E2-related factor 2 (Nrf2), glucokinase (GK), and phosphorylation of glycogen synthase kinase-3 (p-GSK3β) in the liver were markedly up-regulated after HNCP treatment, but the glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase1 (PEPCK1) were down-regulated. In conclusion, HNCP could attenuate oxidative stress, reduce blood glucose, and improve glycolipid metabolism in streptozocin-induced type 1 diabetes mice.

The Research Progress of Bioactive Peptides Derived from Traditional Natural Products in China

Traditional natural products in China have a long history and a vast pharmacological repertoire that has garnered significant attention due to their safety and efficacy in disease prevention and treatment. Among the bioactive components of traditional natural products in China, bioactive peptides (BPs) are specific protein fragments that have beneficial effects on human health. Despite many of the traditional natural products in China ingredients being rich in protein, BPs have not received sufficient attention as a critical factor influencing overall therapeutic efficacy. Therefore, the purpose of this review is to provide a comprehensive summary of the current methodologies for the preparation, isolation, and identification of BPs from traditional natural products in China and to classify the functions of discovered BPs. Insights from this review are expected to facilitate the development of targeted drugs and functional foods derived from traditional natural products in China in the future.

Yao-Shan of traditional Chinese medicine: an old story for metabolic health

Type 2 diabetes mellitus, nonalcoholic fatty liver disease (NAFLD), cardio-cerebrovascular diseases (CCVDs), hyperuricemia and gout, and metabolic-related sexual dysfunction are metabolic diseases that affect human health in modern society. Scientists have made great efforts to investigate metabolic diseases using cell models in vitro or animal models in the past. However, the findings from cells or animals are difficult to translate into clinical applications due to factors such as the in vitro and in vivo differences; the differences in anatomy, physiology, and genetics between humans and animals; and the differences in microbiome-host interaction. The Chinese have extensively used the medicated diet of traditional Chinese medicine (TCM) (also named as Yao-Shan of TCM, Chinese Yao-Shan et al.) to maintain or improve cardiometabolic health for more than 2,200 years. These ancient classic diets of TCM are essential summaries of long-term life and clinical practices. Over the past 5 years, our group has made every effort to collect and sort out the classic Yao-Shan of TCM from the ancient TCM literature since Spring and Autumn and Warring States Period, especially these are involved in the prevention and treatment of metabolic diseases, such as diabetes, NAFLD, CCVDs, hyperuricemia and gout, and sexual dysfunction. Here, we summarized and discussed the classic Yao-Shan of TCM for metabolic diseases according to the time recorded in the ancient literature, and revised the Latin names of the raw materials in these Yao-Shan of TCM. Moreover, the modern medicine evidences of some Yao-Shan of TCM on metabolic diseases have also been summarized and emphasized in here. However, the exact composition (in terms of ratios), preparation process, and dosage of many Yao-Shan are not standardized, and their main active ingredients are vague. Uncovering the mystery of Yao-Shan of TCM through modern biological and chemical strategies will help us open a door, which is ancient but now looks new, to modulate metabolic homeostasis and diseases.

Amelioration of exosome and mesenchymal stem cells in rats infected with diabetic nephropathy by attenuating early markers and aquaporin-1 expression

Diabetic nephropathy (DN) is a prevalent diabetic microvascular condition. It is the leading cause of kidney disease in the advanced stages. There is no currently effective treatment available. This research aimed to investigate the curative potentials of exosomes isolated from mesenchymal stem cells affecting DN. This study was performed on 70 male adult albino rats. Adult rats were randomized into seven groups: Group I: Negative control group, Group II: DN group, Group III: Balanites treated group, Group IV: MSCs treated group, Group V: Exosome treated group, Group VI: Balanites + MSCs treated group and Group VII: Balanites + exosome treated group. Following the trial period, blood and renal tissues were subjected to biochemical, gene expression analyses, and histopathological examinations. Results showed that MDA was substantially increased, whereas TAC was significantly decreased in the kidney in the DN group compared to normal health rats. Undesired elevated values of MDA levels and a decrease in TAC were substantially ameliorated in groups co-administered Balanites aegyptiacae with MSCs or exosomes compared to the DN group. A substantial elevation in TNF-α and substantially diminished concentration of IGF-1 were noticed in DN rats compared to normal health rats. Compared to the DN group, the co-administration of Balanites aegyptiacae with MSCs or exosomes substantially improved the undesirable elevated values of TNF-α and IGF-1. Furthermore, in the DN group, the mRNA expression of Vanin-1, Nephrin, and collagen IV was significantly higher than in normal healthy rats. Compared with DN rats, Vanin-1, Nephrin, and collagen IV Upregulation were substantially reduced in groups co-administered Balanites aegyptiacae with MSCs or exosomes. In DN rats, AQP1 expression was significantly lower than in normal healthy rats. Furthermore, the groups co-administered Balanites aegyptiacae with MSCs or exosomes demonstrated a substantial increase in AQP1 mRNA expression compared to DN rats.

Nature-Inspired Bioactive Compounds: A Promising Approach for Ferroptosis-Linked Human Diseases?

Ferroptosis is a type of cell death driven by iron overload and lipid peroxidation. It is considered a key mechanism in the development of various diseases such as atherosclerosis, Alzheimer, diabetes, cancer, and renal failure. The redox status of cells, such as the balance between intracellular oxidants (lipid peroxides, reactive oxygen species, free iron ions) and antioxidants (glutathione, glutathione Peroxidase 4), plays a major role in ferroptosis regulation and constitutes its principal biomarkers. Therefore, the induction and inhibition of ferroptosis are promising strategies for disease treatments such as cancer or neurodegenerative and cardiovascular diseases, respectively. Many drugs have been developed to exert ferroptosis-inducing and/or inhibiting reactions, such as erastin and iron-chelating compounds, respectively. In addition, many natural bioactive compounds have significantly contributed to regulating ferroptosis and ferroptosis-induced oxidative stress. Natural bioactive compounds are largely abundant in food and plants and have been for a long time, inspiring the development of various low-toxic therapeutic drugs. Currently, functional bioactive peptides are widely reported for their antioxidant properties and application in human disease treatment. The scientific evidence from biochemical and in vitro tests of these peptides strongly supports the existence of a relationship between their antioxidant properties (such as iron chelation) and ferroptosis regulation. In this review, we answer questions concerning ferroptosis milestones, its importance in physiopathology mechanisms, and its downstream regulatory mechanisms. We also address ferroptosis regulatory natural compounds as well as provide promising thoughts about bioactive peptides.

Health Effects of Peptides Extracted from Deer Antler

Deer antler is widely used as a nutraceutical in Asian countries. In the past decades, deer antler peptides (DAPs) have received considerable attention because of their various biological properties such as antioxidant, anti-inflammatory, anti-bone damage, anti-neurological disease, anti-tumor and immunomodulatory properties. This review describes the production methods of DAPs and the recent progress of research on DAPs, focusing on the physiological functions and their regulatory mechanisms.

Dietary-Nutraceutical Properties of Oat Protein and Peptides

Oats are considered the healthiest grain due to their high content of phytochemicals, dietary fibers, and protein. In recent years, oat protein and peptides have gained popularity as possible therapeutic or nutraceutical candidates. Generally, oat peptides with bioactive properties can be obtained by the enzymatic hydrolysis of proteins and are known to have a variety of regulatory functions. This review article focused on the nutraceutical worth of oat proteins and peptides and also describes the application of oat protein as a functional ingredient. Outcomes of this study indicated that oat protein and peptides present various therapeutical properties, including antidiabetic, antioxidant, antihypoxic, antihypertensive, antithrombotic, antifatigue, immunomodulatory, and hypocholestrolaemic. However, most of the conducted studies are limited to in vitro conditions and less data is available on assessing the effectiveness of the oat peptides in vivo. Future efforts should be directed at performing systematic animal studies; in addition, clinical trials also need to be conducted to fully support the development of functional food products, nutraceutical, and therapeutical applications.

Characterization of a thermostable, protease-tolerant inhibitor of α-glycosidase from carrot: A potential oral additive for treatment of diabetes

Inhibiting α-glucosidase activity is important in controlling postprandial hyperglycemia and, thus, helping to manage type-2 diabetes mellitus (T2DM). In the present study, we purified a hypothetical protein of carrots called DCHP (Daucus Carrot hypoglycemic peptide), and their inhibitory effects on α-glucosidase, as well as related mechanisms, were investigated. The recombinant DCHP protein with a molecular weight of 8 kDa showed strong inhibitory activity against α-glycosidase and maintained good stability in solution. DCHP exhibited no inhibitory activity but was tolerant to trypsin and chymotrypsin. Cellular experiments demonstrated that glucose consumption and lactic acid production increased rapidly when treated with DCHP in Caco-2 and HepG2 cells. DCHP crystal was generated, and the crystal structure, which was similar to that of rBTI and consisted of a central α-helix and a two-stranded β-sheet with a unique loop region. The interaction between DCHP and α-glycosidase was investigated by molecular docking and site-directed mutation, which revealed that Glu43, Pro46, Thr47 Thr48 and Gln49 are the key residues in DCHP that inhibit α-glycosidase activity. This work provides potential bioactive peptides as functional foods or nutraceutical supplements in preventing and managing T2DM.

Protective effects of di- and tri-peptides containing proline, glycine, and leucine on liver enzymology and histopathology of diabetic mice

CONTEXT

Small peptides as multifunctional biomolecules can prevent the metabolic disorders such as diabetes.

OBJECTIVE

The purpose of this study was to investigate the effects of small peptides on the enzymes and histopathology of the liver in mice exposed to diabetes.

METHODS

Di- and tri-peptides containing proline, glycine, and leucine were produced by solid phase peptide synthesis (SPPS) protocol. The effects of produced peptides as well as carnosine (Ala-His) and glutathione (Glu-Cys-Gly) were evaluated on hepatic enzymes activity by enzymatic method and histopathology of liver using hematoxylin and eosin and TUNEL staining to assess histologic changes and apoptosis in diabetes induced by multiple low doses of streptozotocin (MLDS).

RESULTS

The Ala-His, Leu-Gly and Pro-Gly-Pro peptides had the higher protective effects against the effects of diabetes on the enzymes and histologic changes of liver in mice.

CONCLUSION

These peptides can be raised as considerable pharmaceutical preventive agent against diabetes development.

Neurotherapeutic Potential of Cervus elaphus Sibericus on Axon Regeneration and Growth Cone Reformation after H2O2-Induced Injury in Rat Primary Cortical Neurons

Cervus elaphus sibericus (CES), commonly known as deer antler, has been used as a medicinal herb because of its various pharmacological activities, including its anti-infective, anti-arthritic, anti-allergic, and anti-oxidative properties. However, the precise mechanisms by which CES functions as a potent anti-oxidative agent remain unknown; particularly, the effects of CES on cortical neurons and its neurobiological mechanism have not been examined. We used primary cortical neurons from the embryonic rat cerebral cortex and hydrogen peroxide to induce oxidative stress and damage in neurons. After post-treatment of CES at three concentrations (10, 50, and 200 µg/mL), the influence of CES on the neurobiological mechanism was assessed by immunocytochemistry, flow cytometry, and real-time PCR. CES effectively prevented neuronal death caused by hydrogen peroxide-induced damage by regulating oxidative signaling. In addition, CES significantly induced the expression of brain-derived neurotrophic factor and neurotrophin nerve growth factor, as well as regeneration-associated genes. We also observed newly processing elongated axons after CES treatment under oxidative conditions. In addition, filopodia tips generally do not form a retraction bulb, called swollen endings. Thus, CES shows therapeutic potential for treating neurological diseases by stimulating neuron repair and regeneration.

Effect of natural extract eye drops in dry eye disease rats

AIM

To investigate the therapeutic effect of natural extract eye drops containing bee venom, musk, and deer antlers in dry eye disease (DED) animal models.

METHODS

Scopolamine-injected DED rats and lacrimal gland-excised rats were allocated into control, saline, and natural extract groups respectively and a normal group (lacrimal gland excision was not performed) in lacrimal gland-excised rats. After eye drop instillation 4 times a day for 5d, corneal fluorescein staining (CFS) scores, tear MUC5AC levels, and tear lactic dehydrogenase (LDH) levels were measured.

RESULTS

In scopolamine-injected rats, the natural extract-treated group had significantly lower CFS scores (1.7±0.5, 4.7±1.4, 3.8±1.9, P=0.006) and tear LDH levels (0.10±0.01, 0.19±0.01, 0.16±0.08 OD, P=0.014) but higher tear MUC5AC levels (12.9±3.7, 7.9±2.0, 9.7±3.6 ng/mL, P=0.041) compared with the control and saline-treated groups. There were no significant differences between the control and saline-treated groups. In lacrimal gland-excised rats, the natural extract-treated group also had lower CFS scores (4.3±1.2, 11.5±2.3, 9.0±1.9, P<0.001, P=0.001) and tear LDH levels (0.30±0.08, 0.48±0.12, 0.39±0.05 OD, P<0.05) but higher tear volume (4.3±0.9, 1.9±0.7, 2.8±1.1 mm, P=0.005, P=0.124) and tear MUC5AC levels (8.2±2.0, 2.9±1.2, 5.4±2.2 ng/mL, P<0.001, P=0.047) compared with the control and saline-treated groups. There were no significant differences in the CFS scores, tear MUC5AC level, and tear LDH level between the normal and natural extract-treated groups.

CONCLUSION

The natural extract consisting of bee venom, musk, and deer antlers may have effectiveness in DED treatment by restoring the damaged ocular surface, increasing tear volume, and recovering the tear mucin layer in DED rats.

Obesity-associated insulin resistance adversely affects skin function

The aim of this study was to identify changes in skin function associated with obesity and the mechanisms underlying these changes. Functional changes and gene expression in skin were investigated in C57BL/6J mice fed either a control or high-fat diet (HFD). The insulin responsiveness of the skin and skeletal muscle was also evaluated. The effects of inhibiting insulin signaling and altered glucose concentration on skin function-associated molecules and barrier function were analyzed in keratinocytes. HFD-fed mice were not only severely obese, but also exhibited impaired skin barrier function and diminished levels of glycerol transporter aquaporin-3, keratins, and desmosomal proteins involved in maintaining skin structure. Moreover, the expression of cell cycle regulatory molecules was altered. Insulin signaling was attenuated in the skin and skeletal muscle of HFD-fed mice. In keratinocytes, inhibition of insulin signaling leads to decreased keratin expression and diminished barrier function, and higher glucose concentrations increased the expression of CDK inhibitor 1A and 1C, which are associated with cell-cycle arrest. Obesity-associated impairment of skin function can be attributed to structural fragility, abnormal glycerol transport, and dysregulated proliferation of epidermal cells. These alterations are at least partly due to cutaneous insulin resistance and hyperglycemia.

Hypoglycemic Effects of Oat Oligopeptides in High-Calorie Diet/STZ-Induced Diabetic Rats

The study was aimed to determine whether treatment with oat oligopeptides (OOPs) could modulate hyperglycemia related to type 2 diabetes mellitus (T2DM) in Sprague–Dawley (SD) rats. Diabetic SD rats modeling by a joint effect of high-calorie diet for 45 days and twice intraperitoneal injection of 30 mg/kg streptozotocin at one-week interval were observed with or without OOPs administration (0.25, 0.50, 1.00, and 2.00 g/kg Body Weight) for 12 weeks. Fasting blood glucose (FBG), oral glucose test tolerance (OGTT), serum insulin, level of antioxidant, and hepatic enzymes were measured. In addition, frequency of micturition was recorded in this study for the first time. It was observed that the administration of OOPs (2.00 g/kg Body Weight) resulted in a significant decrease (p < 0.05) in FBG since 6th week and a significant decrease (p < 0.05) in the OGTT-AUC on 6th and 10th week. In addition, the administration of OOPs (2.00 g/kg Body Weight) reduced HOMA-IR index and 24-h urine volume significantly (p < 0.05) whereas increased SOD activity significantly (p < 0.05). These results suggested that OOPs may have a hypoglycemic effect in diabetic rats.

Anti-diabetic potential of peptides: Future prospects as therapeutic agents

Diabetes mellitus is a metabolic disorder in which the glucose level in blood exceeds beyond the normal level. Persistent hyperglycemia leads to diabetes late complication and obviously account for a large number of morbidity and mortality worldwide. Numerous therapeutic options are available for the treatment of diabetes including insulin for type I and oral tablets for type II, but its effective management is still a dream. To date, several options are under investigation in various research laboratories for efficacious and safer agents. Of them, peptides are currently amongst the most widely investigated potential therapeutic agents whose design and optimal uses are under development. A number of natural and synthetic peptides have so far been found with outstanding antidiabetic effect mediated through diverse mechanisms. The applications of new emerging techniques and drug delivery systems further offer opportunities to achieve the desired target outcomes. Some outstanding peptides in preclinical and clinical studies with better efficacy and safety profile have already been identified. Further detail studies on these peptides may therefore lead to significant clinically useful antidiabetic agents.

Antidiabetic and Antioxidant Impacts of Desert Date (Balanites aegyptiaca) and Parsley (Petroselinum sativum) Aqueous Extracts: Lessons from Experimental Rats

Medicinal plants are effective in controlling plasma glucose level with minimal side effects and are commonly used in developing countries as an alternative therapy for the treatment of type 1 diabetes mellitus. The aim of this study is to evaluate the potential antidiabetic and antioxidant impacts of Balanites aegyptiaca and Petroselinum sativum extracts on streptozotocin-induced diabetic and normal rats. The influences of these extracts on body weight, plasma glucose, insulin, total antioxidant capacity (TAC), malondialdehyde (MDA) levels, and liver-pyruvate kinase (L-PK) levels were assessed. Furthermore, the weight and histomorphological changes of the pancreas were studied in the different experimental groups. The herbal preparations significantly reduced the mean plasma glucose and MDA levels and significantly increased the mean plasma insulin, L-PK, and TAC levels in the treated diabetic groups compared to the diabetic control group. An obvious increase in the weight of the pancreas and the size of the islets of Langerhans and improvement in the histoarchitecture were evident in the treated groups compared to untreated ones. In conclusion, the present study provides a scientific evidence for the traditional use of these extracts as antidiabetic and antioxidant agents in type 1 diabetes mellitus.