Highly Dispersible and Bioavailable Curcumin but not Native Curcumin Induces Brown-Like Adipocyte Formation in Mice

Anti-Obesity Drug Delivery Systems: Recent Progress and Challenges

Obesity has reached an epidemic proportion in the last thirty years, and it is recognized as a major health issue in modern society now with the possibility of serious social and economic consequences. By the year 2030, nearly 60% of the global population may be obese or overweight, which emphasizes a need for novel obesity treatments. Various traditional approaches, such as pharmacotherapy and bariatric surgery, have been utilized in clinical settings to treat obesity. However, these methods frequently show the possibility of side effects while remaining ineffective. There is, therefore, an urgent need for alternative obesity treatments with improved efficacy and specificity. Polymeric materials and chemical strategies are employed in emerging drug delivery systems (DDSs) to enhance therapy effectiveness and specificity by stabilizing and controlling the release of active molecules such as natural ingredients. Designing DDSs is currently a top priority research objective with an eye towards creating obesity treatment approaches. In reality, the most recent trends in the literature demonstrate that there are not enough in-depth reviews that emphasize the current knowledge based on the creation and design of DDSs for obesity treatment. It is also observed in the existing literature that a complex interplay of different physical and chemical parameters must be considered carefully to determine the effectiveness of the DDSs, including microneedles, for obesity treatment. Additionally, it is observed that these properties depend on how the DDS is synthesized. Although many studies are at the animal-study stage, the use of more advanced DDS techniques would significantly enhance the development of safe and efficient treatment approaches for obese people in the future. Considering these, this review provides an overview of the current anti-obesity treatment approaches as well as the conventional anti-obesity therapeutics. The article aims to conduct an in-depth discussion on the current trends in obesity treatment approaches. Filling in this knowledge gap will lead to a greater understanding of the safest ways to manage obesity.

Lactate induces the development of beige adipocytes via an increase in the level of reactive oxygen species

Recent studies have indicated that lactate acts as a signaling molecule in various tissues. We previously demonstrated that intake of an amino acid mixture combined with exercise synergistically induced beige adipocyte formation in inguinal white adipose tissue (iWAT) in mice. Moreover, plasma lactate levels remained significantly elevated in the amino acid mixture + exercise group even 16 h after exercise, indicating that a lactate-mediated pathway may be involved in the induction of beige adipocyte formation. Against this background, we hypothesized that oral intake of lactate would induce beige adipocyte formation via the lactate signaling pathway without exercise. Furthermore, if oral intake of lactate can produce the same effect as exercise, lactate might be used as a food-derived exercise replacement-factor. Oral intake of lactate (100 mM in drinking water) for 4 weeks significantly induced beige adipocyte formation in iWAT in mice as well as a significant elevation of lactate transporter (monocarboxylic acid transporter 1; MCT1) and lactate dehydrogenase B levels. Administration of lactate to adipocytes significantly increased reactive oxygen species (ROS) and superoxide levels and the NADH/NAD+ ratio. The induction of lactate-mediated uncoupling protein 1 (UCP1) expression and ROS production were significantly suppressed by antioxidant treatment or inhibition of MCT1. However, UCP1 induction was not significantly affected by the inhibition of lactate receptor (hydroxycarboxylic acid receptor 1). These findings suggest that lactate-mediated ROS production induces beige adipocyte formation, and thus oral intake of lactate may confer some benefits of exercise without the need to perform exercise.

Dietary Ferulic Acid-Mediated Suppression of Fat Deposits Is Associated with Induction of Beige Adipocyte Formation and Thermogenesis in Inguinal White Adipose Tissue in Mice

Ferulic acid (FA) is the most abundant phenolic acid in wheat grains. Recent studies have reported that FA intake significantly suppresses body weight gain and accumulation of fat deposits in mice. However, the mechanism by which FA intake affects body fat accumulation remains unclear. We hypothesized that dietary FA induces the formation of beige adipocytes and contributes to the suppression of body fat accumulation. In this study, we investigated whether dietary FA significantly induces beige adipocyte formation and thermogenesis in mice. We found that intake of dietary FA (control diet supplemented with 10 g of FA/kg diet) for 4 wk significantly decreased white adipose tissue (WAT) deposits and body weight gain and significantly induced beige adipocyte formation in inguinal WAT (iWAT) in mice. Furthermore, dietary FA specifically induced thermogenesis in iWAT, dependent upon the significant induction of uncoupling protein 1 expression. These findings suggest that the dietary FA-mediated reduction of WAT accumulation and body weight gain is associated with the induction of beige adipocyte formation and thermogenesis in iWAT, which increases energy expenditure. Our study presents a novel example of dietary FA intake-mediated bioactivity as a functional food-derived factor.

Protective Effects of Curcumin in Cardiovascular Diseases—Impact on Oxidative Stress and Mitochondria

Cardiovascular diseases (CVDs) contribute to a large part of worldwide mortality. Similarly, two of the major risk factors for these diseases, aging and obesity, are also global problems. Aging, the gradual decline of body functions, is non-modifiable. Obesity, a modifiable risk factor for CVDs, also predisposes to type 2 diabetes mellitus (T2DM). Moreover, it affects not only the vasculature and the heart but also specific fat depots, which themselves have a major impact on the development and progression of CVDs. Common denominators of aging, obesity, and T2DM include oxidative stress, mitochondrial dysfunction, metabolic abnormalities such as altered lipid profiles and glucose metabolism, and inflammation. Several plant substances such as curcumin, the major active compound in turmeric root, have been used for a long time in traditional medicine and for the treatment of CVDs. Newer mechanistic, animal, and human studies provide evidence that curcumin has pleiotropic effects and attenuates numerous parameters which contribute to an increased risk for CVDs in aging as well as in obesity. Thus, curcumin as a nutraceutical could hold promise in the prevention of CVDs, but more standardized clinical trials are required to fully unravel its potential.

Propolis: Chemical Constituents, Plant Origin, and Possible Role in the Prevention and Treatment of Obesity and Diabetes

Honeybee products are not only beneficial to human health but also important to the food industry. One such product is propolis, a resinous substance that honeybees collect from certain trees and plants and store inside their hives. Although various health benefits of propolis have been reported, the chemical composition of propolis varies greatly depending on the growing region and plant origin. These differences have led to many misconceptions and conflicting research results. In this paper, we review research findings on how the growing region and plant origin of propolis affects its composition. We also discuss trends in research on the antiobesity and antidiabetes effects of propolis as well as recent findings that a major component of Brazilian green propolis modulates adipocyte function. Finally, we discuss challenges to be tackled in future research on the health benefits of propolis and share our perspective on the future of this field.

Transdermal Drug Delivery Systems and Their Use in Obesity Treatment

Transdermal drug delivery (TDD) has recently emerged as an effective alternative to oral and injection administration because of its less invasiveness, low rejection rate, and excellent ease of administration. TDD has made an important contribution to medical practice such as diabetes, hemorrhoids, arthritis, migraine, and schizophrenia treatment, but has yet to fully achieve its potential in the treatment of obesity. Obesity has reached epidemic proportions globally and posed a significant threat to human health. Various approaches, including oral and injection administration have widely been used in clinical setting for obesity treatment. However, these traditional options remain ineffective and inconvenient, and carry risks of adverse effects. Therefore, alternative and advanced drug delivery strategies with higher efficacy and less toxicity such as TDD are urgently required for obesity treatment. This review summarizes current TDD technology, and the main anti-obesity drug delivery system. This review also provides insights into various anti-obesity drugs under study with a focus on the recent developments of TDD system for enhanced anti-obesity drug delivery. Although most of presented studies stay in animal stage, the application of TDD in anti-obesity drugs would have a significant impact on bringing safe and effective therapies to obese patients in the future.

Combination of Exercise and Intake of Amino Acid Mixture Synergistically Induces Beige Adipocyte Formation in Mice

Exercise combined with dietary factors may have significant effects on the suppression of body fat accumulation. Several trials suggest that amino acid mixtures containing alanine, arginine, and phenylalanine (ARF) combined with exercise can significantly reduce body fat accumulation in overweight adults and high-fat diet-induced obesity in mice. We therefore hypothesized that combining ARF and exercise would significantly induce beige adipocyte formation and that this would contribute to reducing body weight, whereas administration of ARF or exercise alone would not. Administration of ARF (1 g/kg body weight, daily) combined with exercise (5 sessions per week) for 4 wk significantly induced formation of beige adipocytes in inguinal white adipose tissue (iWAT) in mice, although ARF or exercise alone did not. Metabolomic analysis showed that plasma lactate concentration was significantly elevated in the exercise+ARF group relative to the exercise group. Furthermore, lactate dehydrogenase B, which increases redox stress by converting lactate to pyruvate in iWAT and triggers induction of uncoupling protein 1 expression was significantly upregulated in iWAT of the exercise+ARF group. These findings demonstrate the unique effect of ARF combined with exercise for inducing beige adipocyte formation, which may be associated with the suggested lactate-mediated pathway. Appropriate mixtures of amino acids could be used as a dietary supplement before exercise and contributed to increasing energy expenditures.

Co-Administration of Curcumin and Artepillin C Induces Development of Brown-Like Adipocytes in Association with Local Norepinephrine Production by Alternatively Activated Macrophages in Mice

Classical brown adipocytes, characterized by interscapular depots, have multilocular fat depots and are known to release excess energy. Recent studies have shown that induction of brown-like adipocytes, also referred to as beige or brite cells, in white adipose tissue (WAT) results in the release of excess energy through mitochondrial heat production via uncoupling protein 1. This has potential a therapeutic strategy for obesity and related diseases as well as classical brown adipocytes. In our previous studies, we found that artepillin C (ArtC, 10 mg/kg body weight), a characteristic constituent of Brazilian propolis, significantly induced the development of brown-like adipocytes in inguinal WAT (iWAT) of mice. Furthermore, we recently demonstrated that curcumin (Cur, 4.5 mg/kg) also significantly induced the development of brown-like adipocytes in mice. The combined administration of several food-derived factors can enhance their bioactivity and reduce their required functional doses. In this study, we showed that co-administration of Cur and ArtC at lower doses (Cur, 1.5 mg/kg; ArtC, 5 mg/kg) additively induce brown-like adipocyte development in mouse iWAT. Moreover, this induction is associated with the localized production of norepinephrine following accumulation of alternatively activated macrophages in iWAT. These findings suggest that co-administration of Cur and ArtC is significantly effective to reduce the dose and enhance the formation of brown-like adipocyte via a unique molecular mechanism.

Artepillin C, a Key Component of Brazilian Propolis, Induces Thermogenesis in Inguinal White Adipose Tissue of Mice through a Creatine-Metabolism-Related Thermogenic Pathway

Induction of beige adipocytes in white adipose tissue (WAT) is a potential therapeutic target for the treatment of obesity because beige adipocytes release excess energy via uncoupling-protein-1-associated thermogenesis. In this study, we investigated how artepillin C (ArtC) promotes thermogenesis in vivo. We demonstrated that 28 day administration of ArtC (10 mg/kg of body weight) to mice significantly induced thermogenesis in beige adipocytes in inguinal WAT (iWAT) and suppressed reductions in core body temperature induced by cold exposure at 4 °C. Moreover, ArtC-induced thermogenesis in iWAT was significantly inhibited by treatment with a creatine metabolism inhibitor, and ArtC significantly upregulated the expression of creatine-metabolism-related enzymes in the thermogenic pathway. These results indicate that ArtC induces thermogenesis in beige adipocytes in iWAT, and the observed ArtC-induced thermogenesis is associated with the creatine-metabolism-related thermogenic pathway, which is characteristically observed in beige adipocytes.

Milagro F, Sánchez J, de la Garza AL, Castro H. miRNAs and Novel Food Compounds Related to the Browning Process

Obesity prevalence is rapidly increasing worldwide. With the discovery of brown adipose tissue (BAT) in adult humans, BAT activation has emerged as a potential strategy for increasing energy expenditure. Recently, the presence of a third type of fat, referred to as beige or brite (brown in white), has been recognized to be present in certain kinds of white adipose tissue (WAT) depots. It has been suggested that WAT can undergo the process of browning in response to stimuli that induce and enhance the expression of thermogenesis: a metabolic feature typically associated with BAT. MicroRNAs (miRNAs) are small transcriptional regulators that control gene expression in a variety of tissues, including WAT and BAT. Likewise, it was shown that several food compounds could influence miRNAs associated with browning, thus, potentially contributing to the management of excessive adipose tissue accumulation (obesity) through specific nutritional and dietetic approaches. Therefore, this has created significant excitement towards the development of a promising dietary strategy to promote browning/beiging in WAT to potentially contribute to combat the growing epidemic of obesity. For this reason, we summarize the current knowledge about miRNAs and food compounds that could be applied in promoting adipose browning, as well as the cellular mechanisms involved.

Low-Dose Curcumin Nanoparticles Normalise Blood Pressure in Male Wistar Rats with Diet-Induced Metabolic Syndrome

Nanoparticle formulations improve bioavailability and so may allow low-dose formulations of food-derived compounds such as curcumin to attenuate chronic systemic disease despite intrinsically low oral bioavailability. The current study induced metabolic syndrome in male Wistar rats aged eight–nine weeks using a high-carbohydrate, high-fat diet (H) with corn starch diet (C) as control. Using a reversal protocol, rats were given curcumin as either nanoparticles encapsulated in poly(lactic–co–glycolic acid) (5 mg/kg/day, HCNP) or as an unformulated low dose or high-dose suspension in water (low-dose, 5 mg/kg/day, HC5; high-dose, 100 mg/kg/day, HC100) or blank nanoparticles (HBNP) for the final eight weeks of the 16 week study. We analysed cardiovascular parameters including systolic blood pressure and left ventricular diastolic stiffness along with histopathology, liver parameters including plasma liver enzymes, histopathology and metabolic parameters, including glucose tolerance, blood lipid profile and body composition, and plasma curcumin concentrations. HC100 and HCNP but not HBNP normalised systolic blood pressure (C = 120 ± 4; H = 143 ± 5; HBNP = 141 ± 3; HC5 = 143 ± 4; HC100 = 126 ± 4; HCNP = 128 ± 4 mmHg), left ventricular diastolic stiffness and liver fat deposition. No other improvements were induced in HC100 or HCNP or other intervention groups (HC5 and HBNP). We conclude that 5 mg/kg/day curcumin nanoparticles in H rats showed similar improvements in cardiovascular function as 100 mg/kg/day unformulated curcumin correlating with similar plasma curcumin concentrations.

α-Monoglucosyl Hesperidin but Not Hesperidin Induces Brown-Like Adipocyte Formation and Suppresses White Adipose Tissue Accumulation in Mice

Hesperidin (HES) is a flavanone glycoside found in citrus peel that contributes to its bitter taste. It has low water solubility and poor oral bioavailability. To improve its solubility and bioavailability, α-monoglucosyl hesperidin (αGH) has been synthesized from HES by transglucosylation using cyclodextrin glucanotransferase. Several reports indicate that αGH significantly decreases body fat, but the underlying molecular mechanism remains unclear. We hypothesized that the antiobesity effects of αGH occur through the induced formation of brown-like adipocytes. The present study verified that dietary αGH induces brown-like adipocytes to form in mouse inguinal white adipose tissue (iWAT), thereby significantly decreasing the weight of white adipose tissue (WAT). Furthermore, dietary αGH significantly induced thermogenesis in iWAT. Dietary αGH also significantly suppressed high-fat-diet-induced WAT accumulation in mice, which may be mediated by brown-like adipocyte formation. These results indicate that dietary αGH induces increased energy expenditure by stimulating the formation of brown-like adipocytes.

Food Ingredients Involved in White-to-Brown Adipose Tissue Conversion and in Calorie Burning

Obesity is the consequence of chronic positive energy balance and considered a leading risk factor for cardiovascular and metabolic diseases. Due to its epidemic trends among children and adults, there is an increasing interest in implementing new therapeutic interventions to tackle overweight and obesity. Activation of brown adipose tissue (BAT) represents today a promising strategy to enhance energy expenditure (EE) through heat production. More recently, “browning” of white adipose tissue (WAT) has gained increasing attention in research area as an alternative method in stimulating energy dissipation. This minireview aims to summarize the current knowledge of some dietary compounds that have been shown to promote BAT activation and WAT browning with subsequent beneficial health effects.

Curcuma supplementation in high-fat-fed C57BL/6 mice: no beneficial effect on lipid and glucose profile or prevention of weight gain

PURPOSE

This experimental study investigated the effects of curcuma supplementation on weight gain, Body Adiposity Index, glucose and lipid profile, and liver and pancreas histology in C57BL/6 mice fed with a high-fat diet.

METHODS

40 animals were separated into four groups: standard diet (SD), standard diet plus curcuma (SD + C), high-fat diet (HFD), and high-fat diet plus curcuma (HFD + C). Curcuma dose was 8 mg/animal/day. Histological and biochemical analyses were performed at the end of the experimental period.

RESULTS

Curcuma prevented weight gain, despite a higher food intake, and increased brown adipose tissue weight only in mice receiving standard diet. However, these changes were not observed in HFD + C group. The groups that received curcuma (SD + C and HFD + C) showed a pancreas with diffuse macro- and microgoticular steatosis.

CONCLUSIONS

Curcuma supplementation did not prevent weight gain or improved glucose and lipid profile in mice receiving high-fat diet. Furthermore, there was evidence of possible curcuma toxicity in the pancreas of C57BL/6 mice. The implications of these findings on humans still need to be investigated.

Effects of Highly Absorbable Curcumin in Patients with Impaired Glucose Tolerance and Non-Insulin-Dependent Diabetes Mellitus

Oxidative stress is enhanced by various mechanisms. Serum oxidized low-density lipoprotein (LDL) is a useful prognostic marker in diabetic patients with coronary artery disease. To examine the effects of Theracurmin®, a highly absorbable curcumin preparation, on glucose tolerance, adipocytokines, and oxidized LDL, we conducted a double-blind placebo-controlled parallel group randomized trial in patients with impaired glucose tolerance or non-insulin-dependent diabetes mellitus. We randomly divided the patients with impaired glucose tolerance or non-insulin-dependent diabetes mellitus and stable individuals into the placebo group and the Theracurmin® (180 mg daily for 6 months) group. Of the 33 patients analyzed, 18 (14 males and 4 females) were administered placebo and 15 (9 males and 6 females) were administered Theracurmin®. The patient characteristics did not differ between the two groups. The primary endpoint, HbA1c, did not differ significantly between the two groups. However, the level of α1-antitrypsin-low-density lipoprotein (AT-LDL), the oxidized LDL, significantly increased (p = 0.024) in the placebo group from the beginning of the trial up to 6 months, although there was no such change in the Theracurmin® group. The percentage change in BMI from the beginning of the trial up to 6 months tended to be higher in the Theracurmin® group than in the placebo group. Patients in the Theracurmin® group tended to have a larger percentage change in adiponectin and LDL-C than those in the placebo group. Patients in the Theracurmin® group showed a smaller percentage change in AT-LDL than those in the placebo group. This study suggests that the highly absorbable curcumin could potentially inhibit a rise in oxidized LDL in patients with impaired glucose tolerance or non-insulin-dependent diabetes mellitus. This trial is registered with UMIN000007361.