Corn gluten hydrolysate and capsaicin have complimentary actions on body weight reduction and lipid-related genes in diet-induced obese rats. Nutr Res. 2014;34:458-465. [PMID: 24916560 DOI: 10.1016/j.nutres.2014.04.009]

Protaetia brevitarsis Hydrolysate Mitigates Muscle Dysfunction and Ectopic Fat Deposition Triggered by a High-Fat Diet in Mice

BACKGROUND/OBJECTIVES

Obesity is a key factor in metabolic syndrome (MetS) development. Consumption of a high-fat diet (HFD) accelerates the onset of obesity and associated metabolic complications. Protaetia brevitarsis (PB) has been traditionally utilized in Korean medicine for its antioxidant, anti-diabetic, anticancer, and hepatoprotective effects. However, specific effects of PB hydrolysate on skeletal muscles have not been fully elucidated. Therefore, this study sought to assess the influence of PB on HFD-induced MetS, focusing on the lipid metabolism and inflammatory responses mediated by AMP-activated protein kinase activation.

METHODS

To induce obesity, 6-week-old C57BL/6J mice were maintained on an HFD for 8 weeks, after which PB hydrolysate was orally administered for 16 weeks while the HFD regimen was sustained. A glucose tolerance test was conducted orally to evaluate glucose regulation, and forelimb grip strength was assessed upon completion of the experimental period. Histological assessments, serum biochemical analysis, lipid extraction, Western blot analysis, and quantitative reverse-transcription polymerase chain reaction (qRT-PCR) were performed following euthanasia.

RESULTS

PB significantly reduced ectopic lipid deposition in skeletal muscles, enhanced muscle strength, and improved insulin sensitivity by increasing fatty acid oxidation via AMP-activated protein kinase/carnitine palmitoyltransferase 1 activation and inhibiting lipogenesis via stearoyl-CoA desaturase 1 gene downregulation. Furthermore, PB alleviated HFD-induced low-grade chronic inflammation by decreasing systemic monocyte chemoattractant protein 1 levels, thereby reducing ectopic fat deposition.

CONCLUSIONS

This study highlights the potential of PB as a nutraceutical to mitigate MetS in HFD-fed mice.

Dietary Capsaicin: A Spicy Way to Improve Cardio-Metabolic Health?

Today's sedentary lifestyle with too much food and too little exercise has made metabolic syndrome a pandemic. Metabolic syndrome is a major risk factor for type-2 diabetes and cardiovascular disease. New knowledge of medical and nutraceutical intervention in the early stages of metabolic syndrome is central to prevent these deadly complications. People who eat chili pepper on a regular basis seem to stay healthier and live longer than those who do not. Animal experiments suggest a therapeutic potential for dietary capsaicin, the active principle in hot chili pepper, to reduce the risk of developing metabolic syndrome. This is an attractive theory since capsaicin has been a culinary staple for thousands of years, and is generally deemed safe when consumed in hedonically acceptable doses. The broad expression of the capsaicin receptor TRPV1 in metabolically active tissues lends experimental support to this theory. This review critically evaluates the available experimental and clinical evidence for and against dietary capsaicin being an effective dietary means to improve cardio-metabolic health. It comes to the conclusion that although a chili pepper-rich diet is associated with a reduced risk of dying due to cardiovascular disease, dietary capsaicin has no clear effect on blood glucose or lipid profiles. Therefore, the reduced mortality risk may reflect the beneficial action of digested capsaicin on gut microbiota.

Plant extracts in prevention of obesity

Obesity has become a worldwide issue and is accompanied by serious complications. Western high energy diet has been identified to be a major factor contributing to the current obesity pandemic. Thus, it is important to optimize dietary composition, bioactive substances, and agents to prevent and treat obesity. To date, extracts from plants, such as vegetables, tea, fruits, and Chinese herbal medicine, have been showed to have the abilities of regulating adipogenesis and attenuating obesity. These plant extracts mainly contain polyphenols, alkaloids, and terpenoids, which could play a significant role in anti-obesity through various signaling pathways and gut microbiota. Those reported anti-obesity mechanisms mainly include inhibiting white adipose tissue growth and lipogenesis, promoting lipolysis, brown/beige adipose tissue development, and muscle thermogenesis. In this review, we summarize the plant extracts and their possible mechanisms responsible for their anti-obesity effects. Based on the current findings, dietary plant extracts and foods containing these bioactive compounds can be potential preventive or therapeutic agents for obesity and its related metabolic diseases.

Anti-obesity effects of capsaicin and the underlying mechanisms: a review

Obesity and overweight have become serious health problems in the world and are linked to a variety of metabolic disorders. Phytochemicals with a weight-loss effect have been widely studied for the past few decades. Capsaicin is the major bioactive component in red chili peppers with many beneficial functions. Its anti-obesity effects have been evaluated extensively using different model systems, including cell models, animal models and human subjects. In this paper, anti-obesity effects of capsaicin are reviewed and the underlying mechanisms are characterized.

Fish protein hydrolysate exhibits anti-obesity activity and reduces hypothalamic neuropeptide Y and agouti-related protein mRNA expressions in rats

Fish protein is a source of animal protein that is consumed worldwide. Although it has been reported that the intake of Alaska pollack protein (APP) reduces body fat accumulation and increases muscle weight in rats, the mechanisms underlying these effects are poorly understood. As a possibility, peptides released from APP in the gastrointestinal tract are important to the functions of APP. In the present study, we examined the effects of APP hydrolysate digested artificially with pepsin and pancreatin on white adipose tissue and skeletal muscle. We found that APP hydrolysate group shows significantly lower weight of white adipose tissue and higher weight of soleus muscle than the control group. We also found that APP hydrolysate group reduces food intake and mRNA expressions of neuropeptide Y and agouti-related protein in the hypothalamus compared with the control group. These results may imply that APP hydrolysate exhibits anti-obesity activity by the reduction of appetite and the enhancement of basal energy expenditure by skeletal muscle hypertrophy in rats. The downregulation of orexigenic gene by APP hydrolysate in the hypothalamus may contribute to the reduction of appetite. These results suggest that the effect of APP on anti-obesity and muscle hypertrophy may be induced by peptides released from APP in the gastrointestinal tract.

Capsaicin in Metabolic Syndrome

Capsaicin, the major active constituent of chilli, is an agonist on transient receptor potential vanilloid channel 1 (TRPV1). TRPV1 is present on many metabolically active tissues, making it a potentially relevant target for metabolic interventions. Insulin resistance and obesity, being the major components of metabolic syndrome, increase the risk for the development of cardiovascular disease, type 2 diabetes, and non-alcoholic fatty liver disease. In vitro and pre-clinical studies have established the effectiveness of low-dose dietary capsaicin in attenuating metabolic disorders. These responses of capsaicin are mediated through activation of TRPV1, which can then modulate processes such as browning of adipocytes, and activation of metabolic modulators including AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor α (PPARα), uncoupling protein 1 (UCP1), and glucagon-like peptide 1 (GLP-1). Modulation of these pathways by capsaicin can increase fat oxidation, improve insulin sensitivity, decrease body fat, and improve heart and liver function. Identifying suitable ways of administering capsaicin at an effective dose would warrant its clinical use through the activation of TRPV1. This review highlights the mechanistic options to improve metabolic syndrome with capsaicin.

Capsaicin reverses the inhibitory effect of licochalcone A/β-Arbutin on tyrosinase expression in b16 mouse melanoma cells

Introduction:

Melanin is synthesized by melanocytes, which are located in the basal layer of the skin. After synthesis, melanin is further deposited on the surface of the skin to form black spots or chloasma. Tyrosinase is a rate-limiting enzyme that plays an important role in melanogenesis. Currently, there are many drugs that inhibit tyrosinase expression to further reduce melanogenesis. Nevertheless, some of these could reverse the pharmacological effect of other drugs, when used simultaneously.

Materials and Methods:

B16 mouse melanoma cells were treated with the tyrosinase inhibitors licochalcone A and β-arbutin, alone or in combination with capsaicin, an alkaloid found in peppers. Cytotoxicity, melanin content, and tyrosinase activity and expression were determined.

Results:

Licochalcone A/β-arbutin inhibited tyrosinase expression and further hindered melanin synthesis when applied individually to B16 mouse melanoma cells. However, licochalcone A/β-arbutin combined with 50 μmol/L capsaicin enhanced the expression of tyrosinase in these cells and further increased melanin content.

Conclusion:

Our data implied that capsaicin could reverse the inhibitory effect of licochalcone A/β-arbutin on tyrosinase expression in B16 mouse melanoma cells.

SUMMARY

B16 mouse melanoma cells were treated with the tyrosinase inhibitors licochalcone A and β-arbutin, alone or in combination with capsaicin, an alkaloid found in peppers. Cytotoxicity, melanin content, and tyrosinase activity and expression were determined. Licochalcone A/β-arbutin inhibited tyrosinase expression and further hindered melanin synthesis when applied individually to B16 mouse melanoma cells. However, licochalcone A/β-arbutin combined with 50 μmol/L capsaicin enhanced the expression of tyrosinase in these cells and further increased melanin content. Our research implied that capsaicin could reverse the inhibitory effect of licochalcone A/β-arbutin on tyrosinase expression in B16 mouse melanoma cells.

Abbreviations used: B16: B16 mouse melanoma cells; L-DOPA: 3, 4-L-dihydroxyphenylalanine; TYR: Tyrosinase; USP: United States Pharmacopeia; FBS: Fetal bovine serum; EDTA: Ethylenediaminetetraacetic acid; DMSO: Dimethyl sulfoxide; RPMI: Roswell Park Memorial Institute; MTT3: 4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, NaOH: Sodium hydroxide; PBS: Phosphate-buffered saline; RIPA: Radio-immunoprecipitation assay; PMSF: Phenylmethanesulfonyl fluoride or phenylmethylsulfonyl fluoride; SDS: Sodium dodecyl sulfate, sodium salt; PVDF: Polyvinylidene fluoride; ECL: Enhanced chemiluminescence.

Anti-obesity effects of yellow catfish protein hydrolysate on mice fed a 45% kcal high-fat diet

Obesity contributes to the etiologies of a variety of comorbid conditions, such as type 2 diabetes, hypertension and cardiovascular disease. In the present study, the anti-obesity effects of yellow catfish protein hydrolysate (YPh) were observed in mice fed a 45% kcal high-fat diet (HFD) compared with those of mice treated with simvastatin. The HFD-fed control mice exhibited noticeable increase in body weight, and whole-body and abdominal fat densities, periovarian and abdominal wall-deposited fat pad weight, as well as in the levels of triglycerides (TG), blood total cholesterol (TC), low-density lipoprotein, alanine aminotransferase, aspartate aminotransferase, creatinine, blood urea nitrogen, and in the fecal TG and TC contents. However, they exhibited a decrease in serum high-density lipoprotein levels. In addition, an increase was detected in periovarian and dorsal abdominally deposited fat pad thickness, adipocyte hypertrophy, the number of steatohepatitis regions, hepatocyte hypertrophy and lipid droplet deposition-related renal tubular vacuolation degenerative lesions, along with increased hepatic lipid peroxidation and a deteriorated endogenous antioxidant defense system (glutathione, catalase and superoxide dismutase). However, all the above-mentioned obesity-related complications were dose-dependently and significantly inhibited after 84 days of thye consecutive oral administration of 125, 250 and 500 mg/kg YPh. In addition, YPh dose-dependently depleted the liver endogenous antioxidant defense system and inhibited hepatic lipid peroxidation. Overall, the effects of 250 mg/kg YPh on HFD-induced obesity and related complications were similar or more potent than those of 10 mg/kg simvastatin. These results indicate that YPh is a promising new potent medicinal ingredient for possible use in the treatment of obesity and related complications.

Blood glycemia-modulating effects of melanian snail protein hydrolysates in mice with type II diabetes

Freshwater animal proteins have long been used as nutrient supplements. In this study, melanian snail (Semisulcospira libertina) protein hydrolysates (MPh) were found to exert anti-diabetic and protective effects against liver and kidney damage in mice with type II diabetes adapted to a 45% kcal high-fat diet (HFD). The hypoglycemic, hepatoprotective and nephroprotective effects of MPh were analyzed after 12 weeks of the continuous oral administration of MPh at 125, 250 and 500 mg/kg. Diabetic control mice exhibited an increase in body weight, and blood glucose and insulin levels, with a decrease in serum high-density lipoprotein (HDL) levels. In addition, an increase in the regions of steatohepatitis, hepatocyte hypertrophy, and lipid droplet deposit-related renal tubular vacuolation degenerative lesions were detected, with noticeable expansion and hyperplasia of the pancreatic islets, and an increase in glucagon- and insulin-producing cells, insulin/glucagon cell ratios in the endocrine pancreas and hepatic lipid peroxidation, as well as decreased zymogen contents. Furthermore, a deterioration of the endogenous antioxidant defense system was observed, with reduced glucose utilization related hepatic glucokinase (GK) activity and an increase in hepatic gluconeogenesis-related phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6pase) activity. However, all of these diabetic complications were significantly inhibited by oral treatment with MPh in a dose-dependent manner. In addition, the marked dose-dependent inhibition of hepatic lipid peroxidation, the depletion of the liver endogenous antioxidant defense system, and changes in hepatic glucose-regulating enzyme activities were also observed. The results of this study suggest that MPh exerts potent anti-diabetic effects, along with the amelioration of related complications in mice with type II diabetes. The overall effects of MPh at a dose of 125 mg/kg on HFD-induced diabetes and related complications were similar or more potent than those of metformin (250 mg/kg).

Capsaicin Supplementation Reduces Physical Fatigue and Improves Exercise Performance in Mice

Chili pepper is used as a food, seasoning and has been revered for its medicinal and health claims. It is very popular and is the most common spice worldwide. Capsaicin (CAP) is a major pungent and bioactive phytochemical in chili peppers. CAP has been shown to improve mitochondrial biogenesis and adenosine triphosphate (ATP) production. However, there is limited evidence around the effects of CAP on physical fatigue and exercise performance. The purpose of this study was to evaluate the potential beneficial effects of CAP on anti-fatigue and ergogenic functions following physiological challenge. Female Institute of Cancer Research (ICR) mice from four groups (n = 8 per group) were orally administered CAP for 4 weeks at 0, 205, 410, and 1025 mg/kg/day, which were respectively designated the vehicle, CAP-1X, CAP-2X, and CAP-5X groups. The anti-fatigue activity and exercise performance was evaluated using forelimb grip strength, exhaustive swimming time, and levels of serum lactate, ammonia, glucose, BUN (blood urea nitrogen) and creatine kinase (CK) after a 15-min swimming exercise. The grip strength and exhaustive swimming time of the CAP-5X group were significantly higher than other groups. CAP supplementation dose-dependently reduced serum lactate, ammonia, BUN and CK levels, and increased glucose concentration after the 15-min swimming test. In addition, CAP also increased hepatic glycogen content, an important energy source for exercise. The possible mechanism was relevant to energy homeostasis and the physiological modulations by CAP supplementation. Therefore, our results suggest that CAP supplementation may have a wide spectrum of bioactivities for promoting health, performance improvement and fatigue amelioration.

Effect of intragastric administration of capsaicin on gastric mucosal barrier in rats

AIM: To explore the effect of different doses of capsaicin (CAP) given for different durations on gastric mucosal barrier, liver and kidney histopathology, blood tests, and blood biochemistry in rats.

METHODS: Two hundred and forty SD rats were randomly divided into either an experimental group or a control group (group D). The experimental group was further divided into subgroups, which were given 0.1 mg/(kg•d) (group A), 1.0 mg/(kg•d) (group B), or 5.0 mg/(kg•d) CAP (group C) for 1 d, 7 d, 14 d or 28 d. Blood tests and blood biochemistry were measured. Gastric mucosa barrier and liver and kidney histopathology were assessed.

RESULTS: The status of rats in each group was good. The weight of all rats increased, and the weight of rats in group C increased relatively slowly, although there was no significant difference compared with group D. Rats of all groups had smooth gastric mucosa and had no erosion or bleeding. Guth score was 0 points for all rats. HE staining analysis showed that Masude score had no statistical differences among all groups (P > 0.05). Routine blood tests, AST, ALT and crea showed no statistical difference among each group. Serum CHOL and TG in groups B and C significantly decreased compared with group D. Liver and kidney histopathology was not affected in all groups.

CONCLUSION: Intragastric administration of low dose capsaicin had no significant impact on gastric mucosa barrier, liver and kidney histopathology, routine blood tests, AST, ALT and crea.

The effect of dietary curcumin and capsaicin on hepatic fetuin-A expression and fat accumulation in rats fed on a high-fat diet

Effects of curcumin (turmeric) and capsaicin (red pepper) on hepatic fat accumulation and fetuin-A expression in rats fed high-fat diet (HFD) is aimed to be investigated. Male Sprague-Dawley rats received HFD (60% of total calories from fat) and 0.15 g capsaicin/kg HFD and/or 1.5 g curcumin/kg HFD for 16 weeks. Hepatic AMPK, p-AMPK and fetuin-A expressions were determined by western blotting, liver lipid levels were measured with colorimetric methods and serum fetuin-A, insulin, leptin and adiponectin levels were detected using commercial ELISA kits. HFD increased hepatic lipid levels, fetuin-A expression and serum leptin, insülin and fetuin-A levels. Curcumin and capsaicin treatments significantly reduced hepatic fat accumulation and leptin levels; liver fetuin-A expression was decreased significantly by the curcumin treatment. Curcumin and capsaicin treatments attenuated hepatic fat accumulation and increased leptin levels related to inflammation. The suppression of hepatic fetuin-A expression is observed to be especially sensitive to curcumin.

Corn Gluten Hydrolysate Affects the Time-Course of Metabolic Changes Through Appetite Control in High-Fat Diet-Induced Obese Rats

This study first investigated the effects of corn gluten hydrolysate (CGH) (1.5 g/day) administration for 7 days on appetite-responsive genes in lean Sprague-Dawley (SD) rats. In a second set of experiments, the metabolic changes occurring at multiple time points over 8 weeks in response to CGH (35.33% wt/wt) were observed in high-fat (HF, 60% of energy as fat) diet-fed SD rats. In lean rats, the hypothalamus neuropeptide-Y and proopiomelanocortin mRNA levels of the CGH group were significantly changed in response to CGH administration. In the second part of the study, CGH treatment was found to reduce body weight and perirenal and epididymal fat weight. CGH also prevented an increase in food intake at 2 weeks and lowered plasma leptin and insulin levels in comparison with the HF group. This reduction in the plasma and hepatic lipid levels was followed by improved insulin resistance, and the beneficial metabolic effects of CGH were also partly related to increases in plasma adiponectin levels. The Homeostasis Model of Assessment - Insulin Resistance (HOMA-IR), an index of insulin resistance, was markedly improved in the HF-CGH group compared with the HF group at 6 weeks. According to the microarray results, adipose tissue mRNA expression related to G-protein coupled receptor protein signaling pathway and sensory perception was significantly improved after 8 weeks of CGH administration. In conclusion, the present findings suggest that dietary CGH may be effective for improving hyperglycemia, dyslipidemia and insulin resistance in diet-induced obese rats as well as appetite control in lean rats.