Effect of curcumin supplementation on blood glucose, plasma insulin, and glucose homeostasis related enzyme activities in diabetic db/db mice

Multifaceted physiological and therapeutical impact of curcumin on hormone-related endocrine dysfunctions: A comprehensive review

Over the past five decades, Curcumin (Cur), derived from turmeric (Curcuma longa), has gained considerable attention for its potential therapeutic applications. Synthesizing insights from clinical trials conducted over the last 25 years, this review delves into diseases where Cur has demonstrated promise, offering a nuanced understanding of its pharmacokinetics, safety, and effectiveness. Focusing on specific examples, the impact of Cur on various human diseases is explored. Endocrine glands and associated signaling pathways are highlighted, elucidating how Cur influences cellular signaling. The article underscores molecular mechanisms such as hormone level alteration, receptor interaction, cytokine and adipokine expression inhibition, antioxidant enzyme activity, and modulation of transcription factors. Cur showcases diverse protective mechanisms against inflammation and oxidative damage by suppressing antiapoptotic genes and impeding tumor promotion. This comprehensive overview emphasizes the potential of Cur as a natural agent for countering aging and degenerative diseases, calling for further dedicated research in this realm.

Ameliorative Effects of Curcumin on Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM), a multifactorial and complicated metabolic disorder, is a growing public health problem. Numerous studies have indicated that bioactive compounds from herbal medicine have beneficial effects on T2DM prevention and treatment, owing to their numerous biological properties. Curcumin, the major curcuminoid of turmeric, is one of the most studied bioactive components of herbal supplements, and has a variety of biological activities. Clinical trials and preclinical research have recently produced compelling data to demonstrate the crucial functions of curcumin against T2DM via several routes. Accordingly, this review systematically summarizes the antidiabetic activity of curcumin, along with various mechanisms. Results showed that effectiveness of curcumin on T2DM is due to it being anti-inflammatory, anti-oxidant, antihyperglycemic, anti-apoptotic, and antihyperlipidemic, among other activities. In light of these results, curcumin may be a promising prevention/treatment choice for T2DM.

Impact of Polyphenols on Inflammatory and Oxidative Stress Factors in Diabetes Mellitus: Nutritional Antioxidants and Their Application in Improving Antidiabetic Therapy

Diabetes mellitus is a chronic metabolic disorder characterized by hyperglycaemia and oxidative stress. Oxidative stress plays a crucial role in the development and progression of diabetes and its complications. Nutritional antioxidants derived from dietary sources have gained significant attention due to their potential to improve antidiabetic therapy. This review will delve into the world of polyphenols, investigating their origins in plants, metabolism in the human body, and relevance to the antioxidant mechanism in the context of improving antidiabetic therapy by attenuating oxidative stress, improving insulin sensitivity, and preserving β-cell function. The potential mechanisms of, clinical evidence for, and future perspectives on nutritional antioxidants as adjuvant therapy in diabetes management are discussed.

Food Polyphenols and Type II Diabetes Mellitus: Pharmacology and Mechanisms

Type II diabetes mellitus and its related complications are growing public health problems. Many natural products present in our diet, including polyphenols, can be used in treating and managing type II diabetes mellitus and different diseases, owing to their numerous biological properties. Anthocyanins, flavonols, stilbenes, curcuminoids, hesperidin, hesperetin, naringenin, and phenolic acids are common polyphenols found in blueberries, chokeberries, sea-buckthorn, mulberries, turmeric, citrus fruits, and cereals. These compounds exhibit antidiabetic effects through different pathways. Accordingly, this review presents an overview of the most recent developments in using food polyphenols for managing and treating type II diabetes mellitus, along with various mechanisms. In addition, the present work summarizes the literature about the anti-diabetic effect of food polyphenols and evaluates their potential as complementary or alternative medicines to treat type II diabetes mellitus. Results obtained from this survey show that anthocyanins, flavonols, stilbenes, curcuminoids, and phenolic acids can manage diabetes mellitus by protecting pancreatic β-cells against glucose toxicity, promoting β-cell proliferation, reducing β-cell apoptosis, and inhibiting α-glucosidases or α-amylase. In addition, these phenolic compounds exhibit antioxidant anti-inflammatory activities, modulate carbohydrate and lipid metabolism, optimize oxidative stress, reduce insulin resistance, and stimulate the pancreas to secrete insulin. They also activate insulin signaling and inhibit digestive enzymes, regulate intestinal microbiota, improve adipose tissue metabolism, inhibit glucose absorption, and inhibit the formation of advanced glycation end products. However, insufficient data are available on the effective mechanisms necessary to manage diabetes.

Overview of Curcumin and Piperine Effects on Glucose Metabolism: The Case of an Insulinoma Patient’s Loss of Consciousness

The hypoglycemic properties of curcumin supplements in therapeutic doses are well-known and may represent a useful tool for the treatment of chronic diseases such as metabolic syndrome, insulin resistance and type 2 diabetes. The poor bioavailability of curcumin can be improved with the concomitant administration of piperine, with no severe adverse effects on glycemia reported so far in the literature. In this article, we further discuss a previously reported case of a helicopter pilot, affected by grade I obesity who, under curcumin and piperine treatment, experienced a transient loss of consciousness (TLOC), during a low-altitude flight. This episode led to a diagnosis of insulinoma, previously asymptomatic. We hypothesized that the combined effects of curcumin and piperine might have caused a severe hypoglycemic episode and subsequent TLOC. Therefore, further studies should be conducted to evaluate the safety of curcumin and piperine supplementation in subjects with impaired glucose metabolism and insulin secretion.

Role of Fenugreek, Cinnamon, Curcuma longa, Berberine and Momordica charantia in Type 2 Diabetes Mellitus Treatment: A Review

Type 2 diabetes mellitus (T2DM) is a complex disease that has become a major global health concern. Given the efficacy of antidiabetic drugs, pharmacological therapy is considered the first-line treatment of T2DM; however, due to their potential side effects and high costs, new and cost-effective treatments with minimal side effects are needed. Medicinal plants have been used for centuries as part of traditional medicine to treat T2DM. Among these, fenugreek, cinnamon, Curcuma longa, berberine, and Momordica charantia have demonstrated different degrees of hypoglycemic activity in clinical studies and animal models. Therefore, the aim of this review is to synthesize the mechanisms of action of five medicinal plants, as well as the experimental and clinical evidence of their hypoglycemic activity from the published literature.

Application of botanical products as nutraceutical feed additives for improving poultry health and production

Poultry is one of the most consumed sources of animal protein around the world. To meet the global demands for poultry meat and eggs, it is necessary to improve their nutrition to sustain the poultry industry. However, the poultry industry faces several challenges, including feedstuff availability, the banning of antibiotics as growth promoters, and several environmental stressors. Therefore, there is a critical need to include available nutraceuticals in the diet to sustain the poultry industry. Nutraceuticals are natural chemical substances that positively influence animal physiological and productive traits. Botanical products (such as fenugreek seeds, ginger roots, and olive leaves) are among the most commonly used nutraceuticals and are gradually gaining popularity in the poultry industry due to their immense benefits in nutrition and therapeutic properties. They can be added to the diet separately or in combination (as a natural antioxidant and immunostimulant) to improve poultry health and production. Botanical products are rich in essential oils and essential fatty acids, which have multiple benefits on the animal's digestive system, such as activating the digestive enzymes and restoring microbiota balance, enhancing poultry health, and production. These nutraceuticals have been shown to stimulate the expression of several genes related to growth, metabolism, and immunity. In addition, the essential oil supplementation in poultry diets up-regulated the expression of some crucial genes associated with nutrient transportation (such as glucose transporter-2 and sodium-glucose cotransporter-1). Previous studies have suggested that supplementation of botanical compounds increased broiler body weight and hen egg production by approximately 7% and 15%, respectively. Furthermore, the supplementation of botanical compounds enhanced the reproductive efficiency of hens and the semen quality of roosters by 13%. This review article discusses the significant effects of some botanical products in the poultry industry and how they can benefit poultry, especially in light of the ban on antibiotics as growth promoters.

The effect of Curcumin on metabolic parameters and androgen level in women with polycystic ovary syndrome: a randomized controlled trial

BACKGROUND

Considering the high prevalence of polycystic ovary syndrome (PCOS) in women of reproductive age and the metabolic disorders associated with it, this study was conducted to determine the effects of curcumin on metabolic indices and androgen level (primary outcomes), and menstruation characteristics, and hirsutism (secondary outcomes) in women with PCOS.

METHODS

This triple-blind randomized controlled trial was conducted on women with PCOS who visited the health centers at Eslamshahr County (Tehran Province-Iran) from 2020 to 2022. The participants were allocated into two groups (curcumin and placebo) using block randomization method. The treatment group received two 500 mg edible curcumin tablets together at the same time per day for twelve weeks while the control group received placebo tablets similar to curcumin. Biochemical parameters such as Fasting Blood Insulin (FBI), Fasting Blood Sugar (FBS), triglyceride, total cholesterol, Low Density Lipoprotein- cholesterol (LDL-C), High Density Lipoprotein- cholesterol (HDL-C) were measured before intervention and then 3 months after the intervention. Sex Hormone Binding Globulin (SHBG) and testosterone serum levels were measured 3 months after the intervention. Questionnaires regarding the menstrual cycle characteristics and the Ferriman-Gallwey score were also filled for evaluating hirsutism before the intervention as well as 3 months after the intervention. The independent t-test, Mann-Whitney U test, and ANCOVA were used to analyze the data.

RESULTS

There was no statistically significant difference between the two groups in terms of socio-demographic and the baseline levels of measured outcomes. After 12 weeks of intervention, the mean serum FBS levels in the curcumin group were significantly lower than in the placebo group (mean difference: 6.24; 95%confidence interval: -11.73 to -0.76; P = 0.027) but there was no significant difference between the two groups in terms of triglyceride (P = 0.351), cholesterol (P = 0.528), LDL (P = 0.064), HDL (P = 0.306), FBI (p = 0.929), SHBG (p = 0.682), and testosterone (p = 0.133) serum levels. After the intervention, amenorrhea and oligomenorrhea frequency in the curcumin group was significantly lower than in the placebo group (13% vs. 22%, P = 0.038). There was no significant difference in terms of duration of menstruation (P = 0.286) and hirsutism (P = 0.630) between the two groups.

CONCLUSION

Curcumin decreased FBS levels and improved menstruation characteristics (amenorrhea, oligomenorrhea, and menstrual irregularities) in women with PCOS but did not affect other metabolic, hormonal, and hirsutism indices. More studies using a larger sample size are required for a definitive conclusion.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials (IRCT): IRCT20120718010324N51 Date of registration: 30/11/2019. URL: https://en.irct.ir/user/trial/40597/view ; Date of first registration: 30/11/2020.

Juvenile growth, thermotolerance and gut histomorphology of broiler chickens fed Curcuma longa under hot-humid environments

Background

This study was conducted to assess the juvenile development, thermotolerance, and intestinal morphology of broiler chickens fed Curcuma longa in a hot-humid environment.

Methods

In a Completely Randomized Design, 240 broiler chicks were randomly assigned to four nutritional treatments of baseline diets supplemented with 0 (CN), 4 (FG), 8 (EG), and 12 g (TT) of turmeric powder/Kg of feed, with four replicates of fifteen birds each. Data on feed consumption and body weights were evaluated weekly during the juvenile growth phase. The physiological indicators of the birds were assessed on day 56 of their lives. The birds were subjected to thermal challenge and data were collected on their physiological traits. Eight birds were randomly selected, euthanized and dissected in each treatment, and 2 cm segments of duodenum, jejunum, and ileum were sampled for villi width, villi height, crypt depth, and the villi height: crypt depth ratio measurements.

Results

It was revealed that the weight gain of the birds in EG was significantly greater (p < 0.05) than that of CN birds. The birds in TT, FG, and CN had comparable but smaller duodenal villi than those in EG. The ileal crypt depth in EG chickens was smaller than in CN but comparable to the other treatment groups. In the duodenum, the villi to crypt depth ratio was in the order EG > TT > FG > CN.

Conclusions

To conclude, dietary supplementation of Curcuma longa powder, notably the 8 g/kg diet improved the antioxidant status, thermotolerance, and nutrient absorption by improving intestinal morphology in broiler chickens in a hot-humid environment.

Curcumin and blood lipid levels: an updated systematic review and meta-analysis of randomised clinical trials

The present study was designed to indicate the protective effects of curcumin on dyslipidemia. Main databases were searched to recognise randomised clinical trials evaluating the effect of curcumin on blood lipid profiles. The pooled odds ratio with a 95% confidence interval (CI) was used to evaluate the effect of curcumin on blood lipid parameters. HDL-C levels in the curcumin group were 0.04-fold lower than placebo (95% CI:-0.36-0.29; Z = 0.23; p = .82). LDL-C levels in the curcumin group reduced by 0.17 versus the placebo group (95% CI: -0.43-0.09; Z = 1.27; p = .2). TC levels in the curcumin group were 0.21 lower versus the placebo group (95% CI: -0.55-0.13; Z = 1.22; p = .22). TG level in the curcumin group were 0.05 lower versus the placebo (95% CI: -0.20-0.11; Z = 0.58; p = .56). This study suggests that curcumin may reduce blood lipid levels and can be used as a hypolipidemic agent.

Role of potential bioactive metabolites from traditional Chinese medicine for type 2 diabetes mellitus: An overview

Type 2 diabetes mellitus (T2DM) is a metabolic disease with persistent hyperglycemia primarily caused by insulin resistance (IR). The number of diabetic patients globally has been rising over the past decades. Although significant progress has been made in treating diabetes mellitus (DM), existing clinical drugs for diabetes can no longer fully meet patients when they face complex and huge clinical treatment needs. As a traditional and effective medical system, traditional Chinese medicine (TCM) has a unique understanding of diabetes treatment and has developed many classic and practical prescriptions targeting DM. With modern medicine and pharmacy advancements, researchers have discovered that various bioactive metabolites isolated from TCM show therapeutic on DM. Compared with existing clinical drugs, these bioactive metabolites demonstrate promising prospects for treating DM due to their excellent biocompatibility and fewer adverse reactions. Accordingly, these valuable metabolites have attracted the interest of researchers worldwide. Despite the abundance of research works and specialized-topic reviews published over the past years, there is a lack of updated and systematic reviews concerning this fast-growing field. Therefore, in this review, we summarized the bioactive metabolites derived from TCM with the potential treatment of T2DM by searching several authoritative databases such as PubMed, Web of Science, Wiley Online Library, and Springer Link. For the convenience of readers, the content is divided into four parts according to the structural characteristics of these valuable compounds (flavonoids, terpenoids, alkaloids, and others). Meanwhile, the detailed mechanism and future directions of these promising compounds curing DM are also summarized in the related sections. We hope this review inspires increasingly valuable and significant research focusing on potential bioactive metabolites from TCM to treat DM in the future.

Curcumin as a novel approach in improving lipid profile: An umbrella meta-analysis

AIMS

Several meta-analyses exist supporting the beneficial effects of curcumin supplementation on lipid profile parameters; however, some studies' findings are inconsistent. Therefore, the current umbrella of meta-analysis of clinical trials was performed to evaluate the findings of multiple meta-analyses on the efficacy of curcumin on lipid profiles in adults.

DATA SYNTHESIS

A comprehensive systematic search of PubMed/Medline, Scopus, Embase, Web of Science and Google Scholar were carried out up to May 2022 (in English only). Random-effects model was employed to conduct meta-analysis. The quality assessment of the selected meta-analyses was measured using a measurement tool to assess multiple systematic reviews (AMSTAR). From 101 articles returned in the literature search, 19 articles were met the qualified for inclusion in the umbrella meta-analysis. The results revealed that the curcumin supplementation was effective on reduction of total cholesterol (TC) (ES = -0.81 mg/dl; 95% CI: 1.39, -0.24, p = 0.006; I² = 68.8%, p < 0.001), triglycerides (TG) (ES: 0.84 mg/dl, 95% CI: 1.42, -0.27, p = 0.004; I² = 84.2%, p < 0.001), and low-density lipoprotein cholesterol (LDL-C) levels (ES: 0.49 mg/dl, 95%CI: 0.85, -0.13, p = 0.007; I² = 51.9%, p = 0.004). Beyond that, Curcumin intake significantly increased high-density lipoprotein cholesterol (HDL-C) levels (ES: 1.34 mg/dl, 95% CI: 0.37, 2.31, p = 0.007; I² = 97.8%, p < 0.001).

CONCLUSION

Curcumin have ameliorating effects on TC, TG, LDL-c, and HDL-c levels. Overall, Curcumin could be recommended as an adjuvant anti-hyperlipidemic agent.

REGISTRATION NUMBER

PROSPERO, CRD42021289500.

Advanced Practical Strategies to Enhance Table Egg Production

The global demand for table eggs has increased exponentially due to the growing human population. To meet this demand, major advances in hen genetics, nutrition, and husbandry procedures are required. Developing cost-effective and practically applicable strategies to improve egg production and quality is necessary for the development of egg industry worldwide. Consumers have shown a strong desire regarding the improvement of hens' welfare and egg quality. They also become interested in functional and designer foods. Modifications in the nutritional composition of laying hen diets significantly impact egg nutritional composition and quality preservation. According to previous scientific research, enriched egg products can benefit human health. However, producers are facing a serious challenge in optimizing breeding, housing, and dietary strategies to ensure hen health and high product quality. This review discussed several practical strategies to increase egg production, quality, and hens' welfare. These practical strategies can potentially be used in layer farms for sustainable egg production. One of these strategies is the transition from conventional to enriched or cage-free production systems, thereby improving bird behavior and welfare. In addition, widely use of plant/herbal substances as dietary supplements in layers' diets positively impacts hens' physiological, productive, reproductive, and immunological performances.

Antitoxic Effects of Curcumin against Obesity-Induced Multi-Organs' Biochemical and Histopathological Abnormalities in an Animal Model

Background

Obesity is a significant public health problem that is characterized by an increase in oxidative stress and enhanced inflammatory responses associated with immune cell invasion of adipose tissues. This study assessed several biochemical abnormalities, apoptosis, oxidative stress status, and associated histological changes in the liver, duodenum, and heart brought on by high-fat diet-induced obesity in rats. It also assessed the mechanistic benefits of curcumin in reversing these inflammatory, metabolic, and histological impairments.

Methods

Rats were assigned into three groups each including ten rats: the control group (CD), the high-fat diet group (HFD), and the high-fat diet + curcumin (HFDC) group. Serum glucose, insulin, and triglycerides (TAGs) were observed. In addition, apoptosis (indicated by hepatic DNA fragmentation) and oxidative stress status (indicated by hepatic MPO, GSH, and SOD) were assessed. Histopathological examinations included the GIT (liver and duodenum) and heart in addition to quantitative real-time polymerase chain reaction (qRT-PCR) assays of the adipose tissue genetic expressions for inflammatory signaling pathways (TLR4, IL-6, and TNF-α).

Results

The overall findings showed that the HFD group exhibited significantly higher levels of glucose, TAGs, and insulin than the control group (P < 0.01). The histological abnormalities of the studied organs in the HFD group were paralleled by these biochemical abnormalities, which were strongly associated with increased apoptosis, increased oxidative stress, and increased expression of the inflammatory signaling markers. There were significant improvements in the HFDC group in terms of biochemical, inflammatory, and histological investigations.

Conclusions

This study's findings concluded that obesity is significantly associated with biochemical and microscopic alterations in many organs. Curcumin exerted potent antitoxic, antioxidant, tissue-protective, and antiobesity effects. Curcumin is recommended to be added to various dietary regimens to prevent or delay the organs' dysfunction among obese people.

The role of selected nutraceuticals in management of prediabetes and diabetes: An updated review of the literature

Dysglycemia is a disease state preceding the onset of diabetes and includes impaired fasting glycemia and impaired glucose tolerance. This review aimed to collect and analyze the literature reporting the results of clinical trials evaluating the effects of selected nutraceuticals on glycemia in humans. The results of the analyzed trials, generally, showed the positive effects of the nutraceuticals studied alone or in association with other supplements on fasting plasma glucose and post-prandial plasma glucose as primary outcomes, and their efficacy in improving insulin resistance as a secondary outcome. Some evidences, obtained from clinical trials, suggest a role for some nutraceuticals, and in particular Berberis, Banaba, Curcumin, and Guar gum, in the management of prediabetes and diabetes. However, contradictory results were found on the hypoglycemic effects of Morus, Ilex paraguariensis, Omega-3, Allium cepa, and Trigonella faenum graecum, whereby rigorous long-term clinical trials are needed to confirm these data. More studies are also needed for Eugenia jambolana, as well as for Ascophyllum nodosum and Fucus vesiculosus which glucose-lowering effects were observed when administered in combination, but not alone. Further trials are also needed for quercetin.

Zingiberaceae plants/curcumin consumption and multiple health outcomes: An umbrella review of systematic reviews and meta-analyses of randomized controlled trials in humans

This umbrella review is to recapitulate and grade the available evidence of associations between consumption of Zingiberaceae plants/curcumin (Cur) and multiple health-related outcomes. This study included 161 meta-analyses of randomized controlled trials in 76 articles with 67 unique health outcomes. Data on heterogeneity and publication bias are considered to assess the quality of evidence. Based on the different impact of Zingiberaceae plants/Cur on human health, the advantages outweigh the disadvantages. Zingiberaceae plants/Cur can mainly improve metabolic syndrome, non-alcoholic fatty liver disease, cardiovascular disease, and some chronic inflammatory diseases, likewise, obviously relief the pain of osteoarthritis and related diseases. Ginger supplements have been shown to improve vomiting during pregnancy and to relieve nausea and vomiting caused by chemotherapy and surgery. The surgery is any type of surgery, including laparoscopic surgery, gynecological surgery and mixed surgery. Beneficial associations were found with Cur intervention in gastrointestinal, neurological and oral diseases. Zingiberaceae plants/Cur are generally safe and favorable for multiple health outcomes in humans. High-quality research is further needed to prove the observed associations.

Curcumin in Retinal Diseases: A Comprehensive Review from Bench to Bedside

Recent evidence in basic science is leading to a growing interest in the possible role of curcumin in treating retinal diseases. Curcumin has been demonstrated to be able to modulate gene transcription and reduce ganglion cell apoptosis, downgrade VEGF, modulate glucose levels and decrease vascular dysfunction. So far, the use of curcumin has been limited by poor bioavailability; to overcome this issue, different types of carriers have been used. Multiple recent studies disclosed the efficacy of using curcumin in treating different retinal conditions. The aim of this review is to comprehensively review and discuss the role of curcumin in retinal diseases from bench to bedside.

Potential dual inhibitors of PCSK-9 and HMG-R from natural sources in cardiovascular risk management

Atherosclerotic cardiovascular disease (ASCVD) stands amongst the leading causes of mortality worldwide and has attracted the attention of world's leading pharmaceutical companies in order to tackle such mortalities. The low-density lipoprotein-cholesterol (LDL-C) is considered the most prominent biomarker for the assessment of ASCVD risk. Distinct inhibitors of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-R), the chief hepatic cholesterogenic enzyme, are being used since last seven decades to manage hypercholesterolemia. On the other hand, discovery and the association of proprotein convertase subtilisin/kexin type-9 (PCSK-9) with increased ASCVD risk have established PCSK-9 as a novel therapeutic target in cardiovascular medicine. PCSK-9 is well reckoned to facilitate the LDL-receptor (LDL-R) degradation and compromised LDL-C clearance leading to the arterial atherosclerotic plaque formation. The currently available HMG-R inhibitors (statins) and PCSK-9 inhibitors (siRNA, anti-sense oligonucleotides, and monoclonal antibodies) have shown great promises in achieving LDL-C lowering goals, however, their life long prescriptions have raised significant concerns. These deficits associated with the synthetic HMG-R and PCSK-9 inhibitors called for the discovery of alternative therapeutic candidates with potential dual HMG-R and PCSK-9 inhibitory activities from natural origins. Therefore, this report firstly describes the mechanistic insights into the cholesterol homeostasis through HMG-R, PCSK-9, and LDL-R functionality and then compiles the pharmacological effects of natural secondary metabolites with special emphasis on their dual HMG-R and PCSK-9 inhibitory action. In conclusion, various natural products exhibit atheroprotective effects via targeting HMG-R and PCSK-9 activities and lipoprotein metabolism, however, further clinical assessments are still warranted prior their approval for ASCVD risk management in hypercholesterolemic patients.

Effect of curcumin on body mass index and glycemic indices in females with PCOS: a systematic review and meta-analysis of randomized controlled trial

Purpose

This paper aims to assess the impact of curcumin supplementation body mass index and glycemic indices in women with polycystic ovary syndrome (PCOS).

Design/methodology/approach

A systematic search of the literature was conducted in PubMed, Scopus and ISI web of science to identify all randomized controlled trials (RCTs) published from the earliest record up to February 2021. The authors used a random-effects model to estimate pooled effect sizes.

Findings

A total of four potentially related clinical trials met the inclusion criteria which included a total of 198 participants. Random-effects meta-analysis showed significant effects of curcumin on fasting blood sugar (FBS) (−3.62 mg/dl, 95% CI [−5.65, −1.58], p-value < 0.001, I2 = 0.0%), insulin level (−1.67 µU/mL, 95% CI [−3.06, −0.28], p-value = 0.018, I2 = 0.0%) and homeostasis model of assessment insulin resistance (HOMA-IR) (−0.42, 95% CI [−0.76, −0.09], p-value < 0.01, I2 = 0.0%). No evidence of publication bias was discovered in the meta-analyses.

Originality/value

Present systematic review and meta-analysis of RCTs showed beneficial effects of curcumin consumption on FBS, insulin level and HOMA-IR in patients with PCOS. However, further large-scale studies are needed to confirm these results.

Curcumin Reverts the Protein Differential Expression in the Liver of the Diabetic Obese db/db Mice

Background:

In type 2 diabetic mouse liver, hyperglycemia, and insulin modify gene expression. Curcumin is a powerful antioxidant and antidiabetic agent that regulates the gene expression of different signaling pathways through various transcription factors. Therefore, we hypothesized that curcumin modifies the protein expression profile in the liver of diabetic db/db mice.

Objective:

To determine the effects of curcumin on the liver protein profile of diabetic db/db mice.

Methods:

db/db and wild type (WT) male mice were allocated in four groups, and they were fed for eight weeks. Three WT and three diabetic db/db mice received a standard diet (SD; WT and db/db groups, respectively); three WT and three diabetic db/db mice received a SD supplemented with 0.75 % (w/w) curcumin (WT+C and db/db+C groups, respectively). Liver proteins were separated by 2D electrophoresis. Differential protein expression analysis was performed on ImageMaster 2D Platinum software, and selected proteins were identified by MALDI-TOF-MS and subjected to enrichment analysis using STRING and DAVID databases.

Results:

Thirty-six proteins with differential expression due to the diabetic background and curcumin treatment were found; these proteins participate in the metabolism of amino acids, carbohydrates, and lipids. Interestingly, the altered expression of seven proteins was prevented in the liver of the diabetic mice that received curcumin.

Conclusions:

Among all differentially expressed proteins, curcumin reverted the altered expression of seven proteins. Thus, although it was observed that curcumin did not affect the biochemical parameters, it does modify the expression of some liver proteins in diabetic mice.

Pharmacological Mechanisms and Clinical Applications of Curcumin: Update

Curcumin, a well-known hydrophobic polyphenol extracted from the rhizomes of turmeric (Curcuma longa L.), has attracted great interest in the last ten years due to its multiple pharmacological activities. A growing body of evidence has manifested that curcumin has extensive pharmacological activities including anti-inflammatory, anti-oxygenation, lipid regulation, antiviral, and anticancer with hypotoxicity and minor adverse reactions. However, the disadvantages of low bioavailability, short half-life in plasma, low drug concentration in blood, and poor oral absorption severely limited the clinical application of curcumin. Pharmaceutical researchers have carried out plenty of dosage form transformations to improve the druggability of curcumin and have achieved remarkable results. Therefore, the objective of this review summarizes the pharmacological research progress, problems in clinical application and the improvement methods of curcumin's druggability. By reviewing the latest research progress of curcumin, we believe that curcumin has a broad clinical application prospect for its wide range of pharmacological activities with few side effects. The deficiencies of lower bioavailability of curcumin could be improved by dosage form transformation. However, curcumin in the clinical application still requires further study regarding the underlying mechanism and clinical trial verification.

Calebin-A prevents HFD-induced obesity in mice by promoting thermogenesis and modulating gut microbiota

Background and aim

Obesity is one of the complications of sedentary lifestyle and high-calorie food intake which become a global problem. Thermogenesis is a novel way to promote anti-obesity by consuming energy as heat rather than storing it as triacylglycerols. Over the last decade, growing evidence has identified the gut microbiota as a potential factor in the pathophysiology of obesity. Calebin A is a non-curcuminoid novel compound derived from the rhizome of medicinal turmeric with putative anti-obesity effects. However, its ability on promoting thermogenesis and modulating gut microbiota remain unclear.

Experimental procedure

C57BL/6J mice were fed either normal diet or high-fat diet (HFD) supplement with calebin A (0.1 and 0.5%) diet for 12 weeks. The composition of the gut microbiota was assessed by analyzing 16S rRNA gene sequences.

Results and conclusion

Mice treated with calebin A shows a remarkable alteration in microbiota composition compared with that of normal diet-fed or HFD-fed mice and is characterized by an enrichment of Akkermansia, Butyricicoccus, Ruminiclostridium_9, and unidentified_Ruminococcaceae. We also explored that calebin A reduce the weight and blood sugar of mice that are induced by HFD, and show a dose-dependent reaction. Moreover, calebin A decreases the weight of white, beige, and brown adipose tissue, and also restores liver weight. In cold exposure experiments, calebin A can better maintain rectal temperature through thermogenesis. In summary, calebin A has a good thermogenesis function and is effective in anti-obesity. It can be used as a novel gut microbiota modulator to prevent HFD-induced obesity.

Mechanisms Underlying the Antidiabetic Activities of Polyphenolic Compounds: A Review

Polyphenolic compounds are thought to show considerable promise for the treatment of various metabolic disorders, including type 2 diabetes mellitus (T2DM). This review addresses evidence from in vitro, in vivo, and clinical studies for the antidiabetic effects of certain polyphenolic compounds. We focus on the role of cytotoxic human amylin (hA) aggregates in the pathogenesis of T2DM, and how polyphenols can ameliorate this process by suppressing or modifying their formation. Small, soluble amylin oligomers elicit cytotoxicity in pancreatic islet β-cells and may thus cause β-cell disruption in T2DM. Amylin oligomers may also contribute to oxidative stress and inflammation that lead to the triggering of β-cell apoptosis. Polyphenols may exert antidiabetic effects via their ability to inhibit hA aggregation, and to modulate oxidative stress, inflammation, and other pathways that are β-cell-protective or insulin-sensitizing. There is evidence that their ability to inhibit and destabilize self-assembly by hA requires aromatic molecular structures that bind to misfolding monomers or oligomers, coupled with adjacent hydroxyl groups present on single phenyl rings. Thus, these multifunctional compounds have the potential to be effective against the pleiotropic mechanisms of T2DM. However, substantial further research will be required before it can be determined whether a polyphenol-based molecular entity can be used as a therapeutic for type 2 diabetes.

Diabetic neuropathy: an insight on the transition from synthetic drugs to herbal therapies

The global pandemic of prediabetes and diabetes has led to a severe corresponding complication of these disorders. Neuropathy is one of the most prevalent complication of diabetes is, affecting blood supply of the peripheral nervous system that may eventually results into loss of sensations, injuries, diabetic foot and death. The utmost identified risk of diabetic neuropathy is uncontrolled high blood glucose levels. However, aging, body mass index (BMI), oxidative stress, inflammation, increased HbA1c levels and blood pressure are among the other key factors involved in the upsurge of this disease. The so far treatment to deal with diabetic neuropathy is controlling metabolic glucose levels. Apart from this, drugs like reactive oxygen species (ROS) inhibitors, aldose reductase inhibitors, PKC inhibitors, Serotonin-norepinephrine reuptake inhibitors (SNRIs), anticonvulsants, N-methyl-D-aspartate receptor (NMDAR) antagonists, are the other prescribed medications. However, the related side-effects (hallucinations, drowsiness, memory deficits), cost, poor pharmacokinetics and drug resistance brought the trust of patients down and thus herbal renaissance is occurring all over the word as the people have shifted their intentions from synthetic drugs to herbal remedies. Medicinal plants have widely been utilized as herbal remedies against number of ailments in Indian medicinal history. Their bioactive components are very much potent to handle different chronic disorders and complications with lesser-known side effects. Therefore, the current article mainly concludes the etiology and pathophysiology of diabetic neuropathy. Furthermore, it also highlights the important roles of medicinal plants and their naturally occurring bioactive compounds in addressing this disease.

Botanical Interventions to Improve Glucose Control and Options for Diabetes Therapy

Diabetes mellitus is a major public health problem worldwide. This endocrine disease is clustered into distinct subtypes based on the route of development, with the most common forms associated with either autoimmunity (T1DM) or obesity (T2DM). A shared hallmark of both major forms of diabetes is a reduction in function (insulin secretion) or mass (cell number) of the pancreatic islet beta-cell. Diminutions in both mass and function are often present. A wide assortment of plants have been used historically to reduce the pathological features associated with diabetes. In this review, we provide an organized viewpoint focused around the phytochemicals and herbal extracts investigated using various preclinical and clinical study designs. In some cases, crude extracts were examined directly, and in others, purified compounds were explored for their possible therapeutic efficacy. A subset of these studies compared the botanical product with standard of care prescribed drugs. Finally, we note that botanical formulations are likely suspects for future drug discovery and refinement into class(es) of compounds that have either direct or adjuvant therapeutic benefit.

Dietary curcumin supplementation promotes browning and energy expenditure in postnatal overfed rats

Background

Early postnatal overfeeding could result in metabolic imprinting that decreases energy expenditure following white adipose tissue (WAT) gain throughout life. This research investigated whether curcumin (CUR) supplementation could promote WAT browning and activate thermogenesis in postnatal overfed rats.

Methods and results

This study adjusted the size of litters to three (small litters, SL) or ten (normal litters, NL) to mimic early postnatal overfeeding or normal feeding from postnatal day 3. From postnatal week 3 (weaning period), SL rats were fed a standard diet (SL) or a diet supplemented with 1% (SL_{1% CUR}) or 2% (SL_{2% CUR}) CUR for ten weeks. At postnatal week 13, SL rats with 1% or 2% CUR supplementation had lower body weight and less WAT gain and had an increased lean mass ratio, and their glucose tolerance and blood lipid levels had recovered to normal when compared to SL rats that did not receive the supplement. Moreover, the increased heat generation were consistent with the expression levels of uncoupling protein 1 (UCP1) and other browning-related genes in the subcutaneous adipose tissue (SAT) of the SL_{2% CUR} rats but not in the SL_{1% CUR} rats. In addition, 2% CUR dietary supplementation enhanced the serum norepinephrine levels in SL rats, with upregulated mRNA levels of β3-adrenergic receptor (β3-AR) in SAT.

Conclusion

Dietary CUR supplementation attenuates body fat gain and metabolic disorders in SL, which might be induced by promoting browning of SAT and energy expenditure. Moreover, the benefits were more obvious in SL with 2% CUR supplementation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-021-00625-5.

Diet-Derived Advanced Glycation End Products (dAGEs) Induce Proinflammatory Cytokine Expression in Cardiac and Renal Tissues of Experimental Mice: Protective Effect of Curcumin

The beneficial effect of curcumin (CU) on dietary AGEs (dAGEs) involves blocking the overexpression of proinflammatory cytokine genes in the heart and kidney tissues of experimental mice. The animals were divided into six groups (n = 6/group) and were fed a heat-exposed diet (dAGEs) with or without CU for 6 months. Their blood pressure (BP) was monitored by a computerized tail-cuff BP-monitoring system. The mRNA and protein expression levels of proinflammatory genes were analyzed by RT-PCR and western blot, respectively. A marked increase in BP (108 ± 12 mmHg vs 149 ± 15 mmHg) accompanied by a marked increase in the heart and kidney weight ratio was noted in the dAGE-fed mice. Furthermore, the plasma levels of proinflammatory molecules (C5a, ICAM-1, IL-6, MCP-1, IL-1β and TNF-α) were found to be elevated (3-fold) in dAGE-fed mice. mRNA expression analysis revealed a significant increase in the expression levels of inflammatory markers (Cox-2, iNOS, and NF-κB) (3-fold) in cardiac and renal tissues of dAGE-fed mice. Moreover, increased expression of RAGE and downregulation of AGER-1 (p < 0.001) were noticed in the heart and kidney tissues of dAGE-fed mice. Interestingly, the dAGE-induced proinflammatory genes and inflammatory responses were neutralized upon cotreatment with CU. The present study demonstrates that dietary supplementation with CU has the ability to neutralize dAGE-induced adverse effects and alleviate proinflammatory gene expression in the heart and kidney tissues of experimental mice.

Dehydrozingerone inhibits renal lipotoxicity in high-fat diet-induced obese mice

Ectopic fat accumulation in the kidneys causes oxidative stress, inflammation and cell death. Dehydrozingerone (DHZ) is a curcumin analog that exhibits antitumour, antioxidant and antidiabetic effects. However, the efficacy of DHZ in diabetic nephropathy (DN) is unknown. Here, we verified the efficacy of DHZ on DN. We divided the experimental animals into three groups: regular diet, 60% high‐fat diet (HFD) and HFD with DHZ for 12 weeks. We analysed levels of renal triglycerides and urinary albumin and albumin‐creatinine ratio, renal morphological changes and molecular changes via real‐time polymerase chain reaction and immunoblotting. Furthermore, high glucose (HG)‐ or palmitate (PA)‐stimulated mouse mesangial cells or mouse podocytes were treated with DHZ for 24 h. As a result, DHZ markedly reduced renal glycerol accumulation and albuminuria excretion through improvement of thickened glomerular basement membrane, podocyte loss and slit diaphragm reduction. In the renal cortex in the HFD group, phospho‐AMPK and nephrin expression reduced, whereas arginase 2 and CD68 expression increased; however, these changes were recovered after DHZ administration. Increased reactive oxygen species (ROS) stimulated by HG or PA in podocytes was inhibited by DHZ treatment. Collectively, these findings indicate that DHZ ameliorates DN via inhibits of lipotoxicity‐induced inflammation and ROS formation.

Effect of Curcumin on Glycemic Control in Patients with Type 2 Diabetes: A Systematic Review of Randomized Clinical Trials

Type 2 diabetes mellitus (T2DM) is a chronic metabolic condition, which carries considerable morbidity and mortality. There is growing evidence that curcumin could modulate glucose homeostasis and improve vascular risk in patients with T2DM. The aim of this systematic review was to study the effect of curcumin on glycemic indices in patients with diabetes. A comprehensive search was conducted in PubMed, Scopus, Embase, and Google Scholar up to March 5, 2020, to identify randomized control trials investigating the effect of curcumin supplementation on glycemic indices including fasting blood glucose (FBS), hemoglobin A1c (HbA1C), and the homeostatic model assessment for insulin resistance (HOMA-IR). Eleven articles comprising 1131 individuals with T2DM were included in the study. Treatment with curcumin significantly reduced the level of FBS and HbA1c in 8 and 7 studies, respectively. HOMA-IR was evaluated in five studies, and this was reduced significantly by curcumin supplementation in three of those studies. Patients who took curcumin supplementation over longer periods (≥12 weeks) showed a significant reduction in glycemic indices. The current systematic review showed that curcumin can improve glycemic control in patients with T2DM. However, further studies are required to determine the optimum conditions for these effects of curcumin, particularly regarding readouts of insulin resistance.

Curcumin Improved Glucose Intolerance, Renal Injury, and Nonalcoholic Fatty Liver Disease and Decreased Chromium Loss through Urine in Obese Mice

Obesity-associated hyperglycemia underlies insulin resistance, glucose intolerance, and related metabolic disorders including type 2 diabetes, renal damage, and nonalcoholic fatty liver disease. Turmeric root is commonly used in Asia, and curcumin, one of its pharmacological components, can play a role in preventing and treating certain chronic physiological disorders. Accordingly, this study examined how high-fat diet (HFD)-induced hyperglycemia and hyperlipidemia are reduced by curcumin through changes in fatty liver scores, chromium distribution, and renal injury in mice. Relative to the control group, also fed an HFD, the curcumin group weighed less and had smaller adipocytes; it also had lower daily food efficiency, blood urea nitrogen and creatinine levels, serum alanine aminotransferase and aspartate aminotransferase levels, serum and hepatic triglyceride levels, and hepatic lipid regulation marker expression. The curcumin-treated obese group exhibited significantly lower fasting blood glucose, was less glucose intolerant, had higher Akt phosphorylation and glucose transporter 4 (GLUT4) expression, and had greater serum insulin levels. Moreover, the group showed renal damage with lower TNF-α expression along with more numerous renal antioxidative enzymes that included superoxide dismutase, glutathione peroxidase, and catalase. The liver histology of the curcumin-treated obese mice showed superior lipid infiltration and fewer FASN and PNPLA3 proteins in comparison with the control mice. Curcumin contributed to creating a positive chromium balance by decreasing the amount of chromium lost through urine, leading to the chromium mobilization needed to mitigate hyperglycemia. Thus, the results suggest that curcumin prevents HFD-induced glucose intolerance, kidney injury, and nonalcoholic fatty liver disease.

Salmon food matrix influences digestion and bioavailability of long-chain omega-3 polyunsaturated fatty acids

The natural structure of whole food plays an important role in the physiological impact of bioactive compounds present within the food, also known as the "matrix effect". Long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFAs) are one example of a food-derived nutrient, mostly found in fish, that is believed to be influenced by the food matrix. However, most previous studies have compared only the long-term bioavailability of fish versus fish oil and have used commercial sources of fish oil. The present study aimed to investigate whether fish (salmon) matrix influences the transit of LCn-3PUFAs during in vitro digestion and affects bioavailability in healthy females. Meals containing intact salmon (intact structure), minced salmon (some structure) and defatted salmon + oil (no structure) with identical macronutrient compositions were developed. Healthy female participants (n = 13) consumed the meals in a postprandial crossover study and blood was collected at regular time points for 6 h post meal consumption. In parallel, in vitro digestion of the meals was performed using a human gastric simulator (HGS) and digesta samples were collected at regular time points for 6 h. Results: showed that plasma concentration of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were significantly higher after participants consumed intact salmon compared to the other meals (covariate analysis p < 0.001). The in vitro digestion results showed defatted salmon + oil meal had a faster decrease in pH and faster fat emptying from the HGS than the other two meals. The defatted salmon + oil meal more closely followed fat emptying of a homogeneous unstructured meal, whereas the other meals exhibited phase separation with a delay in fat emptying. Conclusion: The fish matrix (salmon) plays an important role in the bioaccessibility and bioavailability of EPA and DHA. The differences are partly explained by fat digestion and emptying from the stomach. This study suggests that the natural structure of fish has a functional effect on the absorption and bioavailability of fish oil.

Effect of eight-week curcumin supplementation with endurance training on glycemic indexes in middle age women with type 2 diabetes in Iran, A preliminary study

BACKGROUND AND AIMS

The purpose of this study was to determine the effects of curcumin supplementation & endurance training on glycemic indexes in middle-aged women with type 2 diabetes.

METHODS

40 middle-aged women with type 2 diabetes were randomly divided into four groups (control, curcumin, training & curcumin + training). Endurance training protocol included running on treadmill for eight weeks, three sessions per week and each session for 45-60 min, with a maximum intensity of 50-70% of MHR. The experimental groups received a supplementation of curcumin as a daily dose of 80 mg curcumin soft gel for 8 weeks while the control group was subjected to no supplementation or exercise during this period. One day before and one day after the eight-week experimental period, blood samples were taken from the subjects to measure the glycemic indexes, including fasting blood glucose, glycosylated hemoglobin, and serum insulin levels. T-test and two-way covariance analysis tests were used for analyzing the findings at a significant level of less than 0.05.

RESULTS

Eight weeks of curcumin supplementation and endurance training, whether done separately or simultaneously, significantly reduced fasting blood glucose, glycosylated hemoglobin and serum insulin levels (P < 0.05). The combination of curcumin supplementation and endurance training compared to the other two interventions caused a significant further decrease in these glycemic indexes (P < 0.05).

CONCLUSION

The findings of this study showed that eight weeks of curcumin supplementation and endurance training helped each other in improving the glycemic indexes of women with type 2 diabetes.

Protective effects of whey protein concentrate admixtured of curcumin on metabolic control, inflammation and oxidative stress in Wistar rats submitted to exhaustive exercise

This work aimed to evaluate the effects of whey protein concentrate (WPC) admixtured of curcumin on metabolic control, inflammation and oxidative stress in Wistar rats submitted to exhaustive exercise. A total of forty-eight male rats were divided into six experimental groups (n 8): standard diet group (AIN-93M), standard diet submitted to exhaustion test group (AIN-93M ET), WPC admixtured of curcumin group (WPC + CCM), WPC + CCM submitted to exhaustion test group (WPC + CCM ET), CCM group and CCM subjected to exhaustion test group (CCM ET). The swimming exhaustion test was performed after 4 weeks of experiment. The consumption of WPC + CCM as well as isolated CCM did not alter the biometric measurements, the animals' food consumption and the hepatic and kidney function, as well as the protein balance of the animals (P > 0·05), but reduced the glycaemia and the gene expression of TNF-α and IL-6 and increased the expression of IL-10 (P < 0·05). The animals that were submitted to the exhaustion test (AIN-93M ET) showed higher aspartate aminotransferase values when compared to the animals that did not perform the exercise (AIN-93 M) (P < 0·05). WPC + CCM reduced the concentration of nitric oxide, carbonylated protein and increased the concentration of catalase (P < 0·05). Both (WPC + CCM and CCM) were able to increase the concentrations of superoxide dismutase (P < 0·05). We concluded that the WPC admixtured of CCM represents a strategy capable of decreasing blood glucose and oxidative and inflammatory damage caused by exhaustive physical exercise in swimming.

The effects of nano-curcumin supplementation on glycemic control, blood pressure, lipid profile, and insulin resistance in patients with the metabolic syndrome: A randomized, double-blind clinical trial

Metabolic syndrome (MetS) is one of the most important health hazards. Curcumin is extracted from Curcuma longa (turmeric), which can affect the components of MetS. To increase the oral bioavailability of curcumin, nano-micelle curcumin is used instead of curcumin powder. In this randomized, double-blind, controlled clinical trial, 50 patients with MetS were randomly assigned to two groups to receive either 80 mg/day nano-curcumin (n = 25) or placebo (n = 25), for 12 weeks anthropometric measurements, blood pressure, and biochemical factors-including fasting blood sugar (FBS), Hemoglobin A1c (HbA1c), homeostatic model assessment (HOMA) for insulin resistance (HOMA-IR), pancreatic β cell function (HOMA-β) and lipid profile-were assessed at the baseline and the end of the study. Statistical analyses were done using SPSS software (Version 23). The analysis between the two groups has illustrated a significant reduction in the average change of triglyceride (TG) levels (-60.5 ± 121.7 vs. 13.1 ± 78.1 mg/dL; p < .05) and HOMA-β (-5.7 ± 48.2 vs. -4.01 ± 16.9; p < .05). But there were no significant differences in anthropometric measurements, blood pressure and biochemical factors-including FBS, HbA1c, HOMA-IR, HOMA-β, and lipid profile variables include (total cholesterol, LDL-C, and HDL-C) at the end of the study. In conclusion, supplementation with nano-micelle curcumin significantly improved serum TG in MetS patients.

Phytotherapeutic potential of bi-herbal extract of cinnamon and turmeric: in vivo antidiabetic studies

Background

The spices, cinnamon and turmeric have both culinary and pharmaceutical applications. Earlier studies proved their effect on reducing the symptoms associated with type 2 diabetes, a major lifestyle disease affecting millions world over. In our work, we prepared a bi-herbal extract of cinnamon and turmeric and studied its effect to alleviate the symptoms of type 2 diabetes in rat model.

Method

The phenolic rich bi-herbal extract was given to diabetes induced male wistar rats for 28 days at two different concentrations (50 and 150 mg/Kg bwt.). The changes in blood glucose level were monitored at weekly interval. At the end of the experiment, blood serum was collected and used for the estimation of lipid profile, Glucose, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), Total Protein (TP), Albumin, Urea and Creatinine levels.

Result

The serum analysis revealed that administration of the bi-herbal extract at 150 mg/Kg bwt. significantly reduced the blood glucose level (152.60 ± 40.2 mg/dL; p < 0.05) of diabetic animals as compared to diabetic control (335.40 ± 67.3 mg/dL; p < 0.05) at the end of 4 weeks. The treatment also resulted in the reduction of total cholesterol and LDL-cholestrol levels as compared to diabetic control animals. The histopathological examination of tissues showed the improvement in pancreatic architecture and restoration of tissue integrity in liver and kidney.

Conclusion

The study concludes that methanol extract of combination of cinnamon and turmeric has good hypoglycemic, hypolipidemic and organ protective potential in diabetic rats which could be developed into functional food supplementation for the prevention of type 2 diabetes.

Impact of curcumin on fatty acid metabolism

Free fatty acids (FFAs) and fatty acid synthesis (FAS) activity have significantly contributed to disease states such as insulin resistance, obesity, type 2 diabetes, myocardial infarction, blood pressure, and several types of cancer. Currently, several treatment options are available for patients with these conditions. Due to safety concerns, adverse effects, limited efficacy, and low tolerability associated with many medications, the identification of novel agents with less toxicity and a more favorable outcome is warranted. Curcumin is a phenolic compound derived from the turmeric plant with various biological activities, including anticarcinogenic, antioxidant, antiinflammatory, and hypolipidemic properties. PubMed, Scopus, and Web of Science were searched up to February 2020 for studies that demonstrated the efficacy and mechanisms of curcumin action on FFAs, FAS, and β-oxidation activity, as well as the desaturation system. Most of the evidence is in-vivo and in-vitro studies that demonstrate that curcumin possesses regulatory properties on FFAs levels through its effects on FAS and β-oxidation activity as well as desaturation system, which could improve insulin resistance, obesity, and other FFAs-related disorders. The present study provides a review of the existing in-vitro, in-vivo, and clinical evidence on the effect of curcumin on FFAs and FAS activity, β-oxidation, and desaturation system.

Dietary supplementation with curcumin-loaded nanocapsules in lambs: Nanotechnology as a new tool for nutrition

Curcumin-containing nanocapsule powder formulations have not been used in ruminant feed to date, despite the fact that curcumin is known to be a functional food additive. The objective of this study was to determine whether ethyl polymethacrylate (Eudragit L-100) nanocapsules loaded with curcumin (N-CU) would improve health and growth of lambs. Thirty-two male Lacaune lambs (body weight [BW] = 16 ± 0.99 kg; 45 d of age) were randomly assigned to 1 of 4 treatments: T0, T1, T2 and T4, representing supplementation of curcumin at 0, 1, 2, and 4 mg/kg concentrate, respectively. The animals in each treatment were allocated in 4 pens of 2 lambs each (8 lambs per treatment). The experiment lasted 17 d, with samples and measurements collected on d 0, 7, 12, and 17. The T2 lambs had greater average daily gain than T0 lambs. Regression analysis showed that the ideal dose of N-CU to enhance weight gain was 1.89 mg/kg concentrate. There were significant interactions (P < 0.05) between treatments × time for hematological variables, particularly for increases in erythrocytes (T2) and reductions in counts of leukocytes, neutrophils, and lymphocytes in T1 and T2. There were significant interactions between treatment × time for total protein, globulin, urea, and triglyceride levels. Stimulation of the antioxidant system was also observed. There were increased levels of non-protein thiols (NPSH), as well as increased activities of superoxide dismutase (SOD) and glutathione S-transferase (GST) in the supplemented animals. Levels of reactive oxygen species (ROS) were lower in the serum of supplemented lambs. In general, the 4 mg/kg dose had no positive effects on growth or health. This was an unexpected result, given the known properties of curcumin. Taken together, these findings suggest that addition of low concentrations of nanoencapsulated curcumin (T1 and T2) in lamb feed improves health, minimizing oxidative stress and generates anti-inflammatory effects that may have contributed indirectly to greater weight gain. Nanocapsules potentiate the effects of curcumin and may emerge as a new tool in animal nutrition.

Metabolic Reprogramming by Reduced Calorie Intake or Pharmacological Caloric Restriction Mimetics for Improved Cancer Immunotherapy

Caloric restriction and fasting have been known for a long time for their health- and life-span promoting effects, with coherent observations in multiple model organisms as well as epidemiological and clinical studies. This holds particularly true for cancer. The health-promoting effects of caloric restriction and fasting are mediated at least partly through their cellular effects-chiefly autophagy induction-rather than reduced calorie intake per se. Interestingly, caloric restriction has a differential impact on cancer and healthy cells, due to the atypical metabolic profile of malignant tumors. Caloric restriction mimetics are non-toxic compounds able to mimic the biochemical and physiological effects of caloric restriction including autophagy induction. Caloric restriction and its mimetics induce autophagy to improve the efficacy of some cancer treatments that induce immunogenic cell death (ICD), a type of cellular demise that eventually elicits adaptive antitumor immunity. Caloric restriction and its mimetics also enhance the therapeutic efficacy of chemo-immunotherapies combining ICD-inducing agents with immune checkpoint inhibitors targeting PD-1. Collectively, preclinical data encourage the application of caloric restriction and its mimetics as an adjuvant to immunotherapies. This recommendation is subject to confirmation in additional experimental settings and in clinical trials. In this work, we review the preclinical and clinical evidence in favor of such therapeutic interventions before listing ongoing clinical trials that will shed some light on this subject.

Therapeutic potential of curcumin in diabetic retinopathy (Review)

Diabetic retinopathy (DR) is a type of retinal microangiopathy caused by diabetes mellitus. It has become the leading cause of blindness among working individuals worldwide. DR is becoming increasingly common among younger diabetic patients and there is a need for lifelong treatment. The pathogenic mechanisms of DR are influenced by a number of factors, such as hyperglycemia, hyperlipidemia, inflammatory response and oxidative stress, among others. Currently, the treatment methods for DR mainly include retinal photocoagulation, vitrectomy, or anti‑vascular endothelial growth factor (VEGF) therapy. However, these methods have some disadvantages and limitations. Therefore, it is a matter of great interest and urgency to discover drugs that can target the pathogenesis of DR. Since ancient times, traditional Chinese medicine practitioners have accumulated extensive experiences in the use of Chinese herbal medicine for the prevention and treatment of diseases. In the theory of traditional Chinese medicine, curcumin has the effects of promoting blood circulation and relieving pain. A number of studies have also demonstrated that curcumin has multiple biological activities, including exerting anti‑apoptotic, anti‑inflammatory, antioxidant and antitumor properties. In recent years, studies have also confirmed that curcumin can prevent a variety of diabetic complications, including diabetic nephropathy (DN). However, the preventive and curative effects of curcumin on DR and its mechanisms of action have not yet been fully elucidated. The present review aimed to explore the therapeutic potential of curcumin in diabetes mellitus and DR.

Phytosterol Extract Decreases the Oxidative Damage in the Brains of Diabetic db/db Mice

Introduction: Hypercaloric diets induce oxidative stress, and consequently induce hyperglycemia and type 2 diabetes mellitus (T2DM). Thus, oxidative stress is significantly increased in T2DM, leading to oxidative damage to brain, which might contribute to cognitive deficits and neurodegenerative diseases. Therefore, reducing the oxidative stress is important to preserving cognitive functions, and it has been suggested that phytosterols may reduce the oxidative stress. Objective: The objective of the present study was to determine the effects of phytosterols derived from corn on oxidative damage in the cerebellum, frontal cortex, and hippocampus of diabetic db/db mice. Materials and Methods: A phytosterol extract was isolated from yellow corn (Zea mays L.) and 100 mg/kg of the extract was administrated daily to diabetic mice for 8 weeks. At the end of the treatment period, tissues were isolated to determine the levels of oxidized lipid and protein. Results: The phytosterol treatment increased body weight in diabetic db/db mice, but this treatment did not have any effects on body weight in wild-type mice. Moreover, the phytosterol treatment decreased levels of oxidized lipids in the cerebellum, frontal cortex, and hippocampus, and also decreased the levels of oxidized proteins in the cerebellum and frontal cortex in diabetic db/db mice. Conclusion: These important results show that phytosterol treatment can reduce oxidative damage in the brains of diabetic mice.

Potential Therapeutic Effects of Curcumin on Glycemic and Lipid Profile in Uncomplicated Type 2 Diabetes-A Meta-Analysis of Randomized Controlled Trial

Diabetes mellitus is an important issue for public health, and it is growing in the world. In recent years, there has been a growing research interest on efficacy evidence of the curcumin use in the regulation of glycemia and lipidaemia. The molecular structure of curcumins allows to intercept reactive oxygen species (ROI) that are particularly harmful in chronic inflammation and tumorigenesis models. The aim of our study performed a systematic review and meta-analysis to evaluate the effect of curcumin on glycemic and lipid profile in subjects with uncomplicated type 2 diabetes. The papers included in the meta-analysis were sought in the MEDLINE, EMBASE, Scopus, Clinicaltrials.gov, Web of Science, and Cochrane Library databases as of October 2020. The sizes were pooled across studies in order to obtain an overall effect size. A random effects model was used to account for different sources of variation among studies. Cohen’s d, with 95% confidence interval (CI) was used as a measure of the effect size. Heterogeneity was assessed while using Q statistics. The ANOVA-Q test was used to value the differences among groups. Publication bias was analyzed and represented by a funnel plot. Curcumin treatment does not show a statistically significant reduction between treated and untreated patients. On the other hand, glycosylated hemoglobin, homeostasis model assessment (HOMA), and low-density lipoprotein (LDL) showed a statistically significant reduction in subjects that were treated with curcumin, respectively (p = 0.008, p < 0.001, p = 0.021). When considering HBA1c, the meta-regressions only showed statistical significance for gender (p = 0.034). Our meta-analysis seems to confirm the benefits on glucose metabolism, with results that appear to be more solid than those of lipid metabolism. However, further studies are needed in order to test the efficacy and safety of curcumin in uncomplicated type 2 diabetes.

Therapeutic effect of curcumin and C60 fullerene against hyperglycemia-mediated tissue damage in diabetic rat lungs

Increasing evidence suggests that diabetes also targets lung tissues resulting in structural and physiological abnormalities. The present study evaluated the impact of pristine C60 fullerene (C60) against diabetes-induced lung damage for the first time. The objective was to evaluate the impacts of Curcumin (Cur), C60 and C60 fullerene+Curcumin (C60 + Cur) combination on oxidative stress (MDA, GSH, CAT, GST, Retinol, α-tocopherol), apoptosis (Caspase-3, Bcl-2), cholesterol and fatty acid profile (16:0,18:0,18:1,18:2, 22:4, 22:6) against changes in the lung tissue of diabetic rats. Streptozotocin (STZ) was used for inducing diabetes with Cur, C60 and C60 + Cur combination administered for eight weeks to treat diabetic and control rats. Increased oxidative stress, apoptosis and significant changes in cell structure were observed in the lung tissues of diabetic rats. The combination of Cur, C60 and C60 + Cur reduced oxidative stress in the lung tissue of diabetic rats while increasing the antioxidant defense capacity of the tissue, exhibiting tissue protective properties against apoptosis. The diabetic rats displayed favorable properties against lipotoxicity-induced tissue damage due to the increase in the fatty acid and cholesterol levels in lung tissue. It was observed that Cur, C60 and C60 + Cur combination displays protective effects against hyperglycemia induced oxidative damage to lung tissue. Oxidative stress, prevention of lipid and cholesterol accumulation, and weakening of lung apoptosis may be associated with these effects.

A review on mechanism of inhibition of advanced glycation end products formation by plant derived polyphenolic compounds

Advanced glycation end products (AGEs) are naturally occurring biomolecules formed by interaction of reducing sugars with biomolecules such as protein and lipids etc., Long term high blood sugar level and glycation accelerate the formation of AGEs. Unchecked continuous formation and accumulation of AGEs are potential risks for pathogenesis of various chronic diseases. Current mode of antidiabetic therapy is based on synthetic drugs that are often linked with severe adverse effects. Polyphenolic compounds derived from plants are supposed to inhibit glycation and formation of AGEs at multiple levels. Some polyphenolic compounds regulate the blood glucose metabolism by amplification of cell insulin resistance and activation of insulin like growth factor binding protein signaling pathway. Their antioxidant nature and metal chelating activity, ability to trap intermediate dicarbonyl compounds could be possible mechanisms against glycation and AGEs formation and hence, against AGEs induced health complications. Although, few species of polyphenolic compounds are being used in in vitro trials and their in vivo study is still in progress, increasing the area of research in this field may produce a fruitful approach in management of overall diabetic complications.

Curcumin reverses diabetic nephropathy in streptozotocin-induced diabetes in rats by inhibition of PKCβ/p66Shc axis and activation of FOXO-3a

This study investigated if the nephroprotective effect of Curcumin in streptozotocin-induced type 1 diabetes mellitus (DM) in rats involves downregulation/inhibition of p66Shc and examined the underlying mechanisms. Rats were divided into 4 groups (n = 12/group) as control, control + Curcumin (100 mg/kg), T1DM, and T1DM + Curcumin. Curcumin was administered orally to control or diabetic rats for 12 weeks daily. As compared to diabetic rats, Curcumin didn't affect either plasma glucose or insulin levels but significantly reduced serum levels of urea, blood urea nitrogen, and creatinine, and concurrently reduced albumin/protein urea and increased creatinine clearance. It also prevented the damage in renal tubules and mitochondria, mesangial cell expansion, the thickness of the basement membrane. Mechanistically, Curcumin reduced mRNA and protein levels of collagen I/III and transforming growth factor- β-1 (TGF-β1), reduced inflammatory cytokines levels, improved markers of mitochondrial function, and suppressed the release of cytochrome-c and the activation of caspase-3. In the kidneys of both control and diabetic rats, Curcumin reduced the levels of reactive oxygen species (ROS), increased mRNA levels of manganese superoxide dismutase (MnSOD) and gamma-glutamyl ligase, increased glutathione (GSH) and protein levels of Bcl-2 and MnSOD, and increased the nuclear levels of nuclear factor2 (Nrf2) and FOXO-3a. Besides, Curcumin reduced the nuclear activity of the nuclear factor-kappa B (NF-κB), downregulated protein kinase CβII (PKCβII), NADPH oxidase, and p66Shc, and decreased the activation of p66Shc. In conclusion, Curcumin prevents kidney damage in diabetic rats by activating Nrf2, inhibiting Nf-κB, suppressing NADPH oxidase, and downregulating/inhibiting PKCβII/p66Shc axis.

Effects of curcumin supplementation on blood glucose, insulin resistance and androgens in patients with polycystic ovary syndrome: A randomized double-blind placebo-controlled clinical trial

BACKGROUND

Curcumin is a biologically active phytochemical ingredient found in turmeric. It has several pharmacologic effects that might benefit patients with polycystic ovary syndrome (PCOS).

OBJECTIVE

We hypothesized curcumin to be effective in improving blood sugar levels, insulin resistance and hyperandrogenism in individuals with PCOS.

METHODS

In a randomized double-blind placebo-controlled trial, individuals with PCOS were treated with curcumin (500 mg three times daily) or placebo for 12 weeks. Primary outcome measures were fasting plasma glucose (FPG), fasting insulin (FI), sex hormone levels, and hirsutism (Ferriman-Gallwey [mFG] score). Secondary outcomes included anthropometric measurements.

RESULTS

Of 72 randomized individuals, 67 completed the trial. The two groups were comparable at baseline. At the end of the study, FPG and Dehydroepiandrosterone levels had decreased significantly in the intervention group compared to control (difference of change (post-pre) between intervention and placebo groups: -4.11 mg/dL; 95% CI: -8.35, -0.35 mg/dL; p = 0.033 and -26.53 microg/dL; 95% CI: -47.99, -4.34 µg/dL; p = 0.035, respectively). We also observed a statistically non-significant increase (p = 0.082) in Estradiol levels in the intervention group compared to control. No serious adverse events were reported throughout the trial.

CONCLUSIONS

Curcumin might be a safe and useful supplement to ameliorate PCOS-associated hyperandrogenemia and hyperglycemia. However, longer trials investigating different dosages in longer durations are needed to underpin these findings.

Medicinal plants utilized in Thai Traditional Medicine for diabetes treatment: Ethnobotanical surveys, scientific evidence and phytochemicals

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes mellitus remains the most lethal metabolic disease of contemporaneous times and despite the therapeutic arsenal currently available, research on new antidiabetic agents remains a priority. In recent years, the revitalization of Thai Traditional Medicine (TTM) became a clear priority for the Thai government, and many efforts have been undertaken to accelerate research on herbal medicines and their use in medical services in various hospitals. Additionally, and particularly in rural areas, treatment of diabetes and associated symptomatology frequently relies on herbal preparations recommended by practitioners of TTM. In the current work, medicinal plants used in Thailand for treating diabetes, as well as their hypoglycaemic pharmacological evidences and potential therapeutic use for diabetes-related complications were reviewed.

MATERIALS AND METHODS

Ethnopharmacological information on the plant materials used in TTM for diabetes treatment was collected through literature search in a range of scientific databases using the search terms: diabetes, folk medicine, Thailand medicinal plants, traditional medicine. Information regarding scientific evidence on the antidiabetic effects of surveyed species was obtained considering not only the most common taxonomic designation, but also taxonomic synonyms, and including the keywords 'diabetes' and 'hypoglycaemic effect'.

RESULTS

A total of 183 species known to be used for diabetes management in TTM were reviewed, with 30% of them still lacking experimental evidences to support claims regarding the mechanisms and phytochemicals underlying their antidiabetic properties. Moreover, a total of 46 bioactives displaying effective antidiabetic effects have been isolated from 24 species, their underlying mechanism(s) of action being fully or partially disclosed.

CONCLUSIONS

We deliver the most extensive survey dealing with the ethnomedicinal knowledge of Thai medicinal plants utilized on diabetes management. We are certain that the current review will spark further research on Thai plants for the development of new standardized phytomedicines through drug discovery programmes.