Antihyperlipidemic effect of curcumin and tetrahydrocurcumin in experimental type 2 diabetic rats

The role of tetrahydrocurcumin in disease prevention and treatment

In recent decades, natural compounds derived from herbal medicine or dietary sources have played important roles in prevention and treatment of various diseases and have attracted more and more attention. Curcumin, extracted from the Curcumae Longae Rhizoma and widely used as food spice and coloring agent, has been proven to possess high pharmacological value. However, the pharmacological application of curcumin is limited due to its poor systemic bioavailability. As a major active metabolite of curcumin, tetrahydrocurcumin (THC) has higher bioavailability and stability than curcumin. Increasing evidence confirmed that THC had a wide range of biological activities and significant treatment effects on diseases. In this paper, we reviewed the research progress on the biological activities and therapeutic potential of THC on different diseases such as neurological disorders, metabolic syndromes, cancers, and inflammatory diseases. The extensive pharmacological effects of THC involve the modulation of various signaling transduction pathways including MAPK, JAK/STAT, NF-κB, Nrf2, PI3K/Akt/mTOR, AMPK, Wnt/β-catenin. In addition, the pharmacokinetics, drug combination and toxicology of THC were discussed, thus providing scientific basis for the safe application of THC and the development of its dietary supplements and drugs.

Curcuminoids as Cell Signaling Pathway Modulators: A Potential Strategy for Cancer Prevention

Despite substantial advancements in curative modern medicine in the last few decades, cancer risk and casualty rates have continued to mount globally. The exact reason for cancer's onset and progression is still unknown. However, skeletal and functional abnormalities in the genetic code are assumed to be the primary cause of cancer. Many lines of evidence reported that some medicinal plants can be utilized to curb cancer cell proliferation with a safe, fruitful, and cost-efficient perspective. Curcuminoid, isolated from Curcuma longa, have gotten a lot of focus due to their anticancer potential as they reduce tumor progression, invasion, and dissemination. Further, they modulated signal transduction routes like MAPK, PI3K/Akt/mTOR, JAK/STAT, and Wnt/β-catenin, etc., and triggered apoptosis as well as actuated autophagy in malignant cells without altering the normal cells, thus preventing cancer progression. Besides, Curcuminoid also regulate the function and expression of anti-tumor and carcinogenic miRNAs. Clinical studies also reported the therapeutic effect of Curcuminoid against various cancer through decreasing specific biomarkers like TNF-α, Bcl-2, COX-2, PGE2, VEGF, IκKβ, and various cytokines like IL-12p70, IL-10, IL-2, IFN-γ levels and increasing in p53 and Bax levels. Thus, in the present review, we abridged the modulation of several signal transduction routes by Curcuminoids in various malignancies, and its modulatory role in the initiation of tumor-suppressive miRNAs and suppression of the oncogenic miRNAs are explored. Additionally, various pharmacokinetic approaches have been projected to address the Curcuminoids bioavailability like the use of piperine as an adjuvant; nanotechnology- based Curcuminoids preparations utilizing Curcuminoids analogues are also discussed.

Statistical optimization of tetrahydrocurcumin loaded solid lipid nanoparticles using Box Behnken design in the management of streptozotocin-induced diabetes mellitus

In the past, curcumin was the go-to medication for diabetes, but recent studies have shown that tetrahydrocurcumin is more effective. The problem is that it's not very soluble in water or very bioavailable. So, our research aims to increase the bioavailability and anti-diabetic efficacy of tetrahydrocurcumin in streptozotocin-induced diabetic rats by synthesizing tetrahydrocurcumin-loaded solid lipid nanoparticles. Box Behnken Design was employed for the optimization of tetrahydrocurcumin-loaded solid lipid nanoparticles (THC-SLNs). The optimal formulation was determined by doing an ANOVA to examine the relationship between the independent variables (drug-to-lipid ratio, surfactant concentration, and co-surfactant concentration) and the dependent variables (particle size, percent entrapment efficiency, and PDI). Particle size, PDI, and entrapment efficiency all showed statistical significance based on F-values and p-values. The optimized batch was prepared using a drug-to-lipid ratio (1:4.16), 1.21% concentration of surfactant, and 0.4775% co-surfactant (observed with a particle size of 147.1 nm, 83.58 ± 0.838 % entrapment efficiency, and 0.265 PDI, and the values were found very close with the predicted ones. As the THC peak vanishes from the DSC thermogram of the improved formulation, this indicates that the drug has been transformed from its crystalline form into its amorphous state. TEM analysis of optimized formulation demonstrated mono-dispersed particles with an average particle size of 145 nm which are closely related to zetasizer's results. In-vitro release study of optimized formulation demonstrated burst release followed by sustained release up to 71.04% throughout 24 hrs. Increased bioavailability of the adjusted THC-SLN was found in an in vivo pharmacokinetics research with 9.47 folds higher AUC(0-t) compared to plain THC-suspension. Additionally, pharmacodynamic experiments of optimized formulation demonstrated a marked decrease in blood glucose level to 63.7% and increased body weight from 195.8 ± 7.223 to 231.2 ± 7.653 on the 28th day of the study and showed a better anti-diabetic effect than plain drug suspension. Results of stability studies revealed that formulation can be stored for longer periods at room temperature. Tetrahydrocurcumin can be effectively administered by SLN for the treatment of diabetes.

Tetrahydrocurcumin Add-On therapy to losartan in a rat model of diabetic nephropathy decreases blood pressure and markers of kidney injury

Tetrahydrocurcumin (THC), a principal metabolite of curcumin, was tested in a rat model of type 2 diabetes mellitus. THC was administered via daily oral gavage with the lipid carrier polyenylphosphatidylcholine (PPC) as add-on therapy to losartan (angiotensin receptor blocker) to examine effects on kidney oxidative stress and fibrosis. A combination of unilateral nephrectomy, high-fat diet and low-dose streptozotocin was used to induce diabetic nephropathy in male Sprague-Dawley rats. Animals with fasting blood glucose >200 mg/dL were randomized to PPC, losartan, THC + PPC or THC + PPC + losartan. Untreated chronic kidney disease (CKD) animals had proteinuria, decreased creatinine clearance, and evidence of kidney fibrosis on histology. THC + PPC + losartan treatment significantly lowered blood pressure concurrent with increased messenger RNA levels of antioxidant copper-zinc-superoxide dismutase and decreased protein kinase C-α, kidney injury molecule-1 and type I collagen in the kidneys; there was decreased albuminuria and a trend for increased creatinine clearance compared to untreated CKD rats. There was decreased fibrosis on kidney histology in PPC-only and THC-treated CKD rats. Plasma levels of kidney injury molecule-1 were decreased in THC + PPC + losartan animals. In summary, add-on THC to losartan therapy improved antioxidant levels and decreased fibrosis in the kidneys, and lowered blood pressure in diabetic CKD rats.

A systematic review and meta-analysis of randomized controlled trials investigating the effect of the curcumin and piperine combination on lipid profile in patients with metabolic syndrome and related disorders

Metabolic syndrome is characterized by multiple metabolic disorders. Several studies indicated that curcumin plus piperine could affect lipids profiles in various diseases. The present meta-analysis aims to assess the effect of curcumin plus piperine on lipid profiles in patients with MetS and associated disorders using a systematic review and meta-analysis of randomized controlled trials. Trials were searched by several electronic databases up to May 2022. The Comprehensive Meta-Analysis (CMA) version3 software carried out this systematic review and meta-analysis. Random-effects model and the inverse variance method were used to conduct the meta-analysis. We evaluated the publication bias and heterogeneity of all eligible studies. In addition, subgroup analyses and sensitivity assessments were performed to assess potential sources of heterogeneity. The combined results by the random-effects model demonstrated that curcumin plus piperine significantly decreased total cholesterol and LDL-C in patients suffering from metabolic syndrome. In comparison, the results of the overall effect size did not show any significant change in triglyceride concentrations. Our results were robust in sensitivity analysis and were not dependent on the dose of curcumin, the dose of piperine, and the duration of treatment. Our results showed that co-administration of piperine and curcumin supplementation improves the lipid profile in metabolic syndrome. However, further long-term RCTs are required to ascertain their clinical benefit.

Protective effects of curcumin on ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is a term used to describe phenomena connected to the dysfunction of various tissue damage due to reperfusion after ischemic injury. While I/R may result in systemic inflammatory response syndrome or multiple organ dysfunction syndrome, there is still a long way to improve therapeutic outcomes. A number of cellular metabolic and ultrastructural alterations occur by prolonged ischemia. Ischemia increases the expression of proinflammatory gene products and bioactive substances within the endothelium, such as cytokines, leukocytes, and adhesion molecules, even as suppressing the expression of other "protective" gene products and substances, such as thrombomodulin and constitutive nitric oxide synthase (e.g., prostacyclin, nitric oxide [NO]). Curcumin is the primary phenolic pigment derived from turmeric, the powdered rhizome of Curcuma longa. Numerous studies have shown that curcumin has strong antiinflammatory and antioxidant characteristics. It also prevents lipid peroxidation and scavenges free radicals like superoxide anion, singlet oxygen, NO, and hydroxyl. In our study, we highlight the mechanisms of protective effects of curcumin against I/R injury in various organs.

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.

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.

Turmeric extract alleviates endocrine-metabolic disturbances in letrozole-induced PCOS by increasing adiponectin circulation: A comparison with Metformin

One of the most common causes of female infertility is polycystic ovarian syndrome, which affects 6–21% of the population. Regrettably, the currently available treatments are mostly symptomatic and ineffective. As a result, safer options are needed now more than ever. In a letrozole PCOS albino mouse model, the current study compares the therapeutic advantages of Turmeric extract (Curcuma longa) to metformin. Adiponectin is a circulating protein generated by adipocytes that has been linked to metabolic diseases (MDs) in an inverse relationship. The effects of Turmeric Extract (Curcuma Longa) in contrast to Metformin, as well as the involvement of adiponectin in endocrine-metabolic abnormalities in experimentally induced PCOS mice model, were studied in this study. Letrozole (6 mg/kg) was administered orally (p.o) for 21 days to induce PCOS, followed by a dose of Turmeric Extract (Curcuma longa) (175 mg/kg and p.o) and Metformin (150 mg/kg) for 30 days, both with normal saline water (0.9%) as the carrier. The findings revealed that LET-treated mice displayed PCOS-like characteristics, such as higher LH levels, increased body weight growth, and ovarian morphology with numerous cysts, increase in fasting blood glucose, lipid profile, plasma lipid peroxidation (MDA) and IL-6, as well as a decrease in serum Progesterone, Estrogen, FSH, SOD and GSH levels in the ovary. These changes were linked to lower levels of circulating adiponectin and were reversed when treated Turmeric extract. By altering circulating androgen-adiponectin balance, the data implies that Turmeric extract alleviates endocrine-metabolic abnormalities and inflammation-related comorbidities associated with LET-induced PCOS.

Tetrahydrocurcumin Upregulates the Adiponectin-AdipoR Pathway and Improves Insulin Signaling and Pancreatic β-Cell Function in High-Fat Diet/Streptozotocin-Induced Diabetic Obese Mice

Impairment of adiponectin production and function is closely associated with insulin resistance and type 2 diabetes, which are linked to obesity. Studies in animal models have documented the anti-diabetic effects of tetrahydrocurcumin (THC). Although several possible mechanisms have been proposed, the contribution of adiponectin signaling on THC-mediated antihyperglycemic effects remains unknown. Here, we report that adiposity, steatosis, and hyperglycemia were potently attenuated in high-fat diet/streptozotocin-induced diabetic obese mice after they received 20 and 100 mg/kg THC for 14 weeks. THC upregulated UCP-1 in adipose tissue and elevated adiponectin levels in the circulation. THC upregulated the AdipoR1/R2-APPL1-mediated pathway in the liver and skeletal muscle, which contributes to improved insulin signaling, glucose utilization, and lipid metabolism. Furthermore, THC treatment significantly (p < 0.05) preserved islet mass, reduced apoptosis, and restored defective insulin expression in the pancreatic β-cells of diabetic obese mice, which was accompanied by an elevation of AdipoR1 and APPL1. These results demonstrated a potential mechanism underlying the beneficial effects of THC against hyperglycemia via the adiponectin-AdipoR pathway, and thus, may lead to a novel therapeutic use for 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.

Production of Optically Active Hexahydrocurcumin by Human Intestinal Bacterium in Vitro

A hexahydrocurcumin-producing bacterium named 2a1-2b was isolated from human feces. It was observed that the bacterium had more than 99% similarity with Enterococcus avium ATCC14025^T according to 16S ribosomal DNA (rDNA) sequence. The strain 2a1-2b produced optically active 5R-hexahydrocurcumin (enantiomeric excess (e.e.) > 95%) from tetrahydrocurcumin but not from curcumin. Our results showed that intestine is an important place for producing hexahydrocurcumin.

Intravenous Curcumin Mitigates Atherosclerosis Progression in Cholesterol-Fed Rabbits

Orally administered curcumin has been found to have a moderate therapeutic effect on dyslipidemia and atherosclerosis. The present study was conducted to determine lipid-modulating and antiatherosclerosis effects of injectable curcumin in the rabbit model of atherosclerosis induced by a high cholesterol diet (HCD). New Zealand white male rabbits were fed on a normal chow enriched with 0.5% (w/w) cholesterol for 8 weeks. Atherosclerotic rabbits were randomly divided into three groups, including a control group receiving intravenous (IV) injection of the saline buffer, two treatment groups receiving IV administration of the injectable curcumin at low (1 mg/kg/week) and high (10 mg/kg/week) over 4 weeks. Plasma lipid parameters, including low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), and total cholesterol (TC) were measured. Aortic arch atherosclerotic lesions were assessed using hematoxylin and eosin (H&E) staining. The low dose of curcumin significantly reduced plasma levels of TC, LDL-C, and TG by -14.19 ± 5.19%, -6.22 ± 1.77%, and - 29.84 ± 10.14%, respectively, and increased HDL-C by 14.05 ± 6.39% (p < 0.05). High dose of curcumin exerted greater lipid-modifying effects, in which plasma levels of TC, LDL-C, and TG were significantly (p < 0.05) decreased by -56.59 ± 10.22%, -44.36 ± 3.24%, and - 25.92 ± 5.57%, respectively, and HDL-C was significantly increased by 36.24 ± 12.5%. H&E staining showed that the lesion severity was lowered significantly in the high dose (p = 0.03) but not significantly (p > 0.05) in the low-dose curcumin groups, compared to control rabbits. The median (interquartile range) of plaque grades in the high dose and low dose, and control groups was found to be 2 [2-3], 3 [2-3], and 4 [3-4], respectively. The injectable curcumin could significantly improve dyslipidemia and alleviate atherosclerotic lesion in HCD-induced atherosclerotic rabbits.

Safely effective hypoglycemic action of stevia and turmeric extracts on diabetic Albino rats

The potentiality of Stevia leaves and turmeric roots as remedies against diabetes mellitus type 2 was tested in this study. Stevia leaves and turmeric roots were extracted with ethanol:water (80:20 v/v) and analyzed by HPLC. Turmeric extract (TUE) was rich in; curcumin, gallic acid, and eugenol. Stevia extract (STE) contained 28 known compounds, including glycosides, aromatic organic acids, and catechin. Fifty rats were divided into five groups (10 rats each); the control group were fed with feed and water ad libitum. Forty rats were injected a single dose of alloxan, then treated with either 10 mg/kg glibenclamide (GLI), 300 mg/kg STE, or 200 mg/kg TUE or water (positive control) through daily gastric oral gavages for 56 days. Treating diabetic rats with TUE significantly reduced serum glucose and glycated hemoglobin down to the negative control levels. Both GLI and STE produced similar but less effective actions. Animals treated with either STE or TUE exhibited reduced levels of liver and kidney markers compared to the negative control, while GLI increased them significantly. It could be concluded that turmeric roots and stevia leaves extracts can be used treatment for type 2 diabetes. PRACTICAL APPLICATIONS: Turmeric roots and stevia leaves extracts may be used as a remedy for type 2 diabetic patients as aiding substituting treatments under medical supervision. The two plant sources can be used as raw materials for the extracts, which can be used under medical supervision as a gradual replacement of the synthetic antidiabetic drugs. These extracts can be used after a preliminary clinical study to determine the dose and frequency of administration. Stevia extract can be incorporated in drinks as a sweetener and drug. Turmeric extract has a bitter taste, so it may be incorporated in some foods such as bread, which is a traditional practice in some kinds of bread in Egypt. But its content in the bread and the acceptability of the taste should be adjusted. Alternatively, this food can incorporate both TUE and STE to get the best biological action and to conceal the bitter taste of turmeric.

Molecular docking analysis and anti-hyperglycaemic activity of Synacinn™ in streptozotocin-induced rats

Synacinn™ is a standardized polyherbal supplement formulated from Cinnamomum zeylanicum Blume, Curcuma zanthorrhiza Roxb., Syzygium polyanthum (Wight) Walp., Orthosiphon stamineus Benth. and Andrographis paniculata (Burm.f.) Nees. It is designed for the synergistic treatment of diabetes mellitus and its complications. Although the beneficial effects are yet to be verified scientifically, it is traditionally used to improve general health in patients with diabetes. This study aimed to evaluate the anti-hyperglycemic effects of Synacinn™ in a streptozotocin-induced type 1 diabetes rat model. Initially, Synacinn™ was used for in vivo acute oral toxicity tests and 14 day repeated dose toxicity tests to determine the toxicity levels. An efficacy study of Synacinn™ was carried out via the oral administration of 10, 50, 100, 250, and 250 (b.i.d.) mg kg-1 doses to streptozotocin-induced diabetic rats. After 28 days, blood serum was collected to measure the fasting blood glucose, triglyceride, cholesterol, alanine aminotransferase, alkaline phosphatase, creatinine, and uric acid levels. The liver, kidney, and pancreas structures were histopathologically analyzed. In silico binding interaction studies of five phytochemicals in Synacinn™ identified via HPLC with glucokinase were performed using molecular docking analysis. The results showed that although no mortality was observed during the acute oral toxicity tests, notable damage to the liver and kidney occurred during the 14 day repeated dose testing at Synacinn™ levels of 600 mg kg-1 and 2000 mg kg-1. Treatment with 250 mg kg-1 (b.i.d.) Synacinn™ of the streptozotocin-induced type 1 diabetic rats significantly (p < 0.05) improved the fasting blood glucose (59%), triglyceride (58%), cholesterol (47%), alanine aminotransferase (60%), alkaline phosphatase (90%), and creatinine (32%) levels. Synacinn™ also improved the relative weights of liver (35%), kidney (36%), and pancreatic (36%) tissue. Histological analysis showed improvements in the conditions of the central vein of the liver, the kidney Bowman's capsule and glomerulus, and the pancreatic islets of Langerhans. HPLC analysis of a standardized extract identified five active phytochemicals: andrographolide (17.36 mg g-1), gallic acid (11.5 mg g-1), curcumin (2.75 mg g-1), catechin (3.9 mg g-1), and rosmarinic acid (5.54 mg g-1). Molecular docking studies with glucokinase showed that andrographolide yields the highest binding energy (-12.1 kcal mol-1), followed by catechin (-10.2 kcal mol-1), rosmarinic acid (-8.6 kcal mol-1), curcumin (-7.8 kcal mol-1), and gallic acid (-5.6 kcal mol-1). These current findings suggest that Synacinn™ at a dose of 250 mg kg-1 was non-toxic to rats. A twice-daily 250 mg kg-1 dose of Synacinn™ is an effective anti-hyperglycemic agent, lowering blood glucose, triglyceride, and cholesterol levels, and assisting the recovery of organ impairment caused by streptozotocin in type 1 diabetic rats.

Protective effect of pristine C60 fullerene nanoparticle in combination with curcumin against hyperglycemia-induced kidney damage in diabetes caused by streptozotocin

The present study aims to examine the protective effects of C60 fullerene (C60), Curcumin (CUR; Curcuma longa), C60 + CUR combination against oxidative stress, apoptosis, and changes in cellular level in kidney tissue of diabetic rats. Treatment practices were administered separately to groups for 8 weeks following the approval of diabetes induction. It was observed that the treatment groups had increased antioxidant potential, decreased oxidative stress levels, decreased cholesterol, alpha tocopherol, retinol levels along with improved important changes in fatty acid metabolism compared with the diabetic group. C60, CUR, and C60 + CUR were also determined to act in the direction of reducing kidney damage by activating apoptotic pathways. It can be concluded based on these findings that C60, CUR, and especially C60 + CUR combination has beneficial properties in maintaining kidney tissue and function by effectively preventing oxidative stress, apoptotic changes, and changes at the cellular level in kidney tissue under hyperglycemia conditions. PRACTICAL APPLICATIONS: C60 and CUR have various biological activities which can be indicated as antioxidant, anti-inflammatory, anticancer, neuroprotective, and hepatoprotective. It has been reported that C60 and CUR protect the cells against oxidative injury brought about by reactive oxygen species (ROS). Data acquired from the present study puts forth that C60 and C60 + CUR may be promising agents to prevent damage induced by hyperglycemic conditions in kidney tissue.

Obstacles against the Marketing of Curcumin as a Drug

Among the extensive public and scientific interest in the use of phytochemicals to prevent or treat human diseases in recent years, natural compounds have been highly investigated to elucidate their therapeutic effect on chronic human diseases including cancer, cardiovascular disease, and neurodegenerative disease. Curcumin, an active principle of the perennial herb Curcuma longa, has attracted an increasing research interest over the last half-century due to its diversity of molecular targets, including transcription factors, enzymes, protein kinases, growth factors, inflammatory cytokines, receptors, and it's interesting pharmacological activities. Despite that, the clinical effectiveness of the native curcumin is weak, owing to its low bioavailability and rapid metabolism. Preclinical data obtained from animal models and phase I clinical studies done in human volunteers confirmed a small amount of intestinal absorption, hepatic first pass effect, and some degree of intestinal metabolism, might explain its poor systemic availability when it is given via the oral route. During the last decade, researchers have attempted with new pharmaceutical methods such as nanoparticles, liposomes, micelles, solid dispersions, emulsions, and microspheres to improve the bioavailability of curcumin. As a result, a significant number of bioavailable curcumin-based formulations were introduced with a varying range of enhanced bioavailability. This manuscript critically reviews the available scientific evidence on the basic and clinical effects and molecular targets of curcumin. We also discuss its pharmacokinetic and problems for marketing curcumin as a drug.

Curcumin-loaded super-paramagnetic iron oxide nanoparticle affects on apoptotic factors expression and histological changes in a prepubertal mouse model of polycystic ovary syndrome-induced by dehydroepiandrosterone - A molecular and stereological study

AIMS

This study investigated the effects of curcumin-loaded super-paramagnetic iron oxide (Fe₃O₄) nanoparticles (NPs) (SPIONs) on histological parameters and apoptosis-inducing factors (AIFs) in an experimental mouse model of polycystic ovary syndrome (PCOS).

MATERIALS AND METHODS

A total number of 40 female prepuberal BALB/c mice were randomly divided into four groups. Group 1 was selected as control and Group 2 was considered as a vehicle taking sesame oil, in the form of a curcumin carrier. Moreover, Group 3 was administered with dehydroepiandrosterone (DHEA) at 6 mg/100 g of the body weight and Group 4 received the DHEA plus the NPs of curcumin (5.4 mg/100 g) for twenty consecutive days. Finally, histology, stereology, and apoptosis of the ovary were evaluated.

KEY FINDINGS

The results revealed that the NPs of curcumin had reduced ovarian volume (p < 0.05) and a total number of primary, secondary, antral, and primordial follicles in comparison with the PCOS and vehicle groups (p < 0.05). Furthermore, curcumin treatment following administration of the DHEA resulted in a significant decrease in BAX (p < 0.001) and levels of expression of Caspase3 (CASP3) protein, increased levels of B-cell lymphoma 2 (Bcl2) expression (p < 0.05), and moderated apoptosis in granulosa cells in comparison with the ones seen in the PCOS group.

SIGNIFICANCE

Ovarian injuries and DHEA-induced apoptosis were efficiently suppressed by curcumin, indicating the probable protective property of NPs of curcumin against PCOS.

Chronic treatment of curcumin improves hepatic lipid metabolism and alleviates the renal damage in adenine-induced chronic kidney disease in Sprague-Dawley rats

Background

Chronic kidney disease (CKD), including nephrotic syndrome, is a major cause of cardiovascular morbidity and mortality. The literature indicates that CKD is associated with profound lipid disorders due to the dysregulation of lipoprotein metabolism which progresses kidney disease. The objective of this study is to evaluate the protective effects of curcumin on dyslipidaemia associated with adenine-induced chronic kidney disease in rats.

Methods

Male SD rats (n = 29) were divided into 5 groups for 24 days: normal control (n = 5, normal diet), CKD control (n = 6, 0.75% w/w adenine-supplemented diet), CUR 50 (n = 6, 50 mg/kg/day curcumin + 0.75% w/w adenine-supplemented diet), CUR 100 (n = 6, 100 mg/kg/day curcumin + 0.75% w/w adenine-supplemented diet), and CUR 150 (n = 6, 150 mg/kg/day curcumin + 0.75% w/w adenine-supplemented diet). The serum and tissue lipid profile, as well as the kidney function test, were measured using commercial diagnostic kits.

Results

The marked rise in total cholesterol, low-density lipoprotein (LDL) cholesterol, very low-density lipoprotein (VLDL) cholesterol, triglycerides and free fatty acids in serum, as well as hepatic cholesterol, triglyceride and free fatty acids of CKD control rats were significantly protected by curcumin co-treatment (at the dose of 50, 100 and 150 mg/kg). Furthermore, curcumin significantly increased the serum high-density lipoprotein (HDL) cholesterol compared to the CKD control rats but did not attenuate the CKD-induced weight retardation. Mathematical computational analysis revealed that curcumin significantly reduced indicators for the risk of atherosclerotic lesions (atherogenic index) and coronary atherogenesis (coronary risk index). In addition, curcumin improved kidney function as shown by the reduction in proteinuria and improvement in creatinine clearance.

Conclusion

The results provide new scientific evidence for the use of curcumin in CKD-associated dyslipidaemia and substantiates the traditional use of curcumin in preventing kidney damage.

Mechanics insights of curcumin in myocardial ischemia: Where are we standing?

Cardiovascular disorders are known as one of the main health problems which are associated with mortality worldwide. Myocardial ischemia (MI) is improper blood supply to myocardium which leads from serious complications to life-threatening problems like AMI, atherosclerosis, hypertension, cardiac-hypertrophy as well as diabetic associated complications as diabetic atherosclerosis/cardiomyopathy/hypertension. Despite several efforts, the current therapeutic platforms are not related with significant results. Hence, it seems, developing novel therapies are required. In this regard, increasing evidences indicated, curcumin (CRC) acts as cardioprotective agent. Given that CRC and its analogs exert their cardioprotective effects via affecting on a variety of cardiovascular diseases-related mechanisms (i.e., Inflammation, and oxidative stress). Herein, for first time, we have highlighted the protective impacts of CRC against MI. This review might be a steppingstone for further investigation into the clinical implications of the CRC against MI. Furthermore, it pulls in light of a legitimate concern for scientific community, seeking novel techniques and characteristic dynamic biopharmaceuticals for use against myocardial ischemia.

Curcumin in Autoimmune and Rheumatic Diseases

Over recent decades, many clinical trials on curcumin supplementation have been conducted on various autoimmune diseases including osteoarthritis, type 2 diabetes, and ulcerative colitis patients. This review attempts to summarize the highlights from these clinical trials. The efficacy of curcumin either alone or in conjunction with existing treatment was evaluated. Sixteen clinical trials have been conducted in osteoarthritis, 14 of which yielded significant improvements in multiple disease parameters. Eight trials have been conducted in type 2 diabetes, all yielding significant improvement in clinical or laboratory outcomes. Three trials were in ulcerative colitis, two of which yielded significant improvement in at least one clinical outcome. Additionally, two clinical trials on rheumatoid arthritis, one clinical trial on lupus nephritis, and two clinical trials on multiple sclerosis resulted in inconclusive results. Longer duration, larger cohort size, and multiple dosage arm trials are warranted to establish the long term benefits of curcumin supplementation. Multiple mechanisms of action of curcumin on these diseases have been researched, including the modulation of the eicosanoid pathway towards a more anti-inflammatory pathway, and the modulation of serum lipid levels towards a favorable profile. Overall, curcumin supplementation emerges as an effective therapeutic agent with minimal-to-no side effects, which can be added in conjunction to current standard of care.

Effects and Underlying Mechanisms of Bioactive Compounds on Type 2 Diabetes Mellitus and Alzheimer's Disease

Type 2 diabetes mellitus is a complicated metabolic disorder characterized by hyperglycemia and glucose intolerance. Alzheimer's disease is a progressive brain disorder characterized by a chronic loss of cognitive and behavioral function. Considering the shared characteristics of both diseases, common therapeutic and preventive agents may be effective. Bioactive compounds such as polyphenols, vitamins, and carotenoids found in vegetables and fruits can have antioxidant and anti-inflammatory effects. These effects make them suitable candidates for the prevention or treatment of diabetes and Alzheimer's disease. Increasing evidence from cell or animal models suggest that bioactive compounds may have direct effects on decreasing hyperglycemia, enhancing insulin secretion, and preventing formation of amyloid plaques. The possible underlying molecular mechanisms are described in this review. More studies are needed to establish the clinical effects of bioactive compounds.

Interaction between gut microbiota and ethnomedicine constituents

This highlight reviews the interaction processes between gut microbiota and ethnomedicine constituents, which may conceptualize future therapeutic strategies.

Curcumin attenuates nephrotoxicity induced by zinc oxide nanoparticles in rats

Curcumin (Cur) effects on renal injury induced by zinc oxide nanoparticles (NZnO) in rats were investigated. NZnO at a dose of 50 mg/kg for 14 days was administered to rats as intoxicated group. In protection group, Cur at a dose of 200 mg/kg was administered for 7 days prior to NZnO treatment and followed by concomitant administration of NZnO for 14 days. Plasma concentrations of uric acid, creatinine (Cr), and blood urea nitrogen (BUN) were detected to evaluate renal injury. Malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GPx) levels were determined for evaluation oxidative stress. TUNEL staining and histological changes were also performed. Administration of NZnO caused a significant elevation in the uric acid, Cr, and BUN levels. Oxidative stress was increased in the kidney by NZnO through enhancing MDA contents and reducing activities of SOD and GPx enzymes. According to histological examinations, treatment with NZnO caused proximal tubule damages, which was accompanied by the accumulation of red blood cells, infiltration of inflammatory cells, and reducing glomerular diameters. Significant increase was observed in the apoptotic index of the renal tubules in NZnO-treated rats. In present work, pretreatment of Cur reduced the histological changes, decreased biomarker levels, attenuated apoptotic index, and ameliorated oxidative stress by decreasing the MDA contents and increasing the activities of SOD and GPx enzymes. These findings indicate that Cur effectively protects against NZnO-induced nephrotoxicity in the rats.

Attenuation by Tetrahydrocurcumin of Adiposity and Hepatic Steatosis in Mice with High-Fat-Diet-Induced Obesity

Diet-induced obesity is strongly associated with nonalcoholic fatty-liver disease (NAFLD) and insulin resistance. We aimed to investigate the in vivo therapeutic value of tetrahydrocurcumin (THC) intervention in high-fat-diet (HFD)-induced obesity and hepatic steatosis. C57BL/6 mice were fed an HFD for 10 weeks, and then they received 20 or 100 mg/kg THC along with the HFD for another 10 weeks. Mice fed an HFD for 20 weeks experienced obesity, hepatic steatosis, hyperlipidemia, and insulin resistance. Tetrahydrocurcumin (THC) intervention for 10 weeks significantly reduced adiposity (epididymal-fat weights of 6.6 ± 0.4 g for the HFD-only group and 5.3 ± 0.8 and 5.6 ± 0.7 g for the HFD with 20 mg/kg THC and HFD with 100 mg/kg THC groups, respectively; p < 0.05) via downregulation of adipogenic factors. Inflammatory macrophage infiltration and polarization were decreased by THC in mouse epididymal adipose tissues. In the liver, THC markedly alleviated steatosis by approximately 28-37% ( p < 0.05) via the downregulation of lipogenesis, the activation of AMP-activated protein kinase (AMPK), and the increase of fatty acid oxidation. Elevated blood glucose and insulin resistance were also improved by THC, which might be caused by regulation of the hepatic insulin signaling cascade, gene transcription involved in glucose metabolism, and reduced macrophage infiltration in the liver and adipose tissue. Our results demonstrated the beneficial effects of THC-mediated intervention against obesity and NAFLD as well as other metabolic syndromes, revealing a novel therapeutic use of THC in obese populations.

Micro-Particle Curcumin for the Treatment of Chronic Kidney Disease-1: Study Protocol for a Multicenter Clinical Trial

Background

The progression to end-stage renal disease (ESRD) is the most important complication of chronic kidney disease (CKD). Patients with ESRD require dialysis or transplantation to survive, incur numerous complications, and have high mortality rates. Slowing the progression of CKD is an important goal. Unfortunately, even when current treatments are appropriately applied, patients with CKD still progress to ESRD. Current treatments do not address the inflammation and fibrosis that mediate progression to ESRD, but micro-particle curcumin, a natural health product, has both anti-inflammatory and anti-fibrotic properties and may be an effective treatment for patients with CKD.

Objective

Micro-particle curcumin for the treatment of CKD-1 (MPAC-CKD-1) will measure the effect of micro-particle curcumin on 2 important markers of CKD progression: albuminuria and estimated glomerular filtration rate (eGFR). Efficacy in either of these markers will justify a larger, international trial to investigate micro-particle curcumin's ability to lower the risk of ESRD in patients with CKD.

Design

MPAC-CKD-1 is a multicenter, double-blind prospective randomized controlled trial.

Setting

Four kidney disease clinics in Ontario, Canada (3 in London and 1 in Hamilton).

Patients

We will enroll patients with CKD, defined by an eGFR between 15 and 60 mL/min/1.73 m² and a daily albumin excretion of more than 300 mg (or a random urine sample albumin-to-creatinine ratio more than 30 mg/mmol).

Measurements

We will measure changes in the co-primary outcomes of urinary albumin-to-creatinine ratio and eGFR at 3 months and 6 months. We will also measure compliance, safety parameters, and changes in health-related quality of life.

Methods

Participants will be randomly assigned to receive micro-particle curcumin 90 mg once daily or matching placebo for 6 months. We will enroll at least 500 patients to exclude clinically meaningful 6-month changes in these 2 co-primary outcomes (16% difference in albuminuria, and a 2.3 mL/min/1.73 m² between-group difference in the 6-month change in eGFR, at a two-tailed alpha of 0.025, power of 0.80).

Results

Patient enrollment began on October 1, 2015, with 414 participants randomized as of July 2018. We expect to report the results in 2020.

Limitations

MPAC-CKD-1 is not powered to assess outcomes such as the need for renal replacement therapy or death.

Conclusions

MPAC-CKD-1 is a multicenter, double-blind prospective randomized controlled trial designed to test whether micro-particle curcumin reduces albuminuria and slows eGFR decline in patients with albuminuric CKD. MPAC-CKD-1 will also test the feasibility of this intervention and inform the need for a future larger scale trial (MPAC-CKD-2).

Trial registration

MPAC-CKD-1 is registered with U.S. National Institutes of Health at clinicaltrials.gov (NCT02369549). Protocol version 2.0, December 6, 2014.

Antidiabetic, antihyperlipidemic and antioxidant effect of Vincamine, in streptozotocin-induced diabetic rats

Diabetes mellitus is the most common endocrine disorder characterized by hyperglycemia resulting from defects in insulin secretion or insulin action. The present study was designed to investigate the antidiabetic effects of vincamine, one of the monoterpenoid indole alkaloid, in streptozotocin-induced diabetic rat model. Diabetes was induced in rats by an intraperitoneal injection of streptozotocin (40 mg/kg bw). Vincamine 20 and 30 mg/kg.bw were administrated orally as a single dose per day to the diabetic rats for 30 days. The vehicle control group received 0.5% dimethyl sulfoxide for the same duration. After 30 days of treatment, fasting blood glucose, glycosylated haemoglobin, total cholesterol, triglyceride, low-density lipoprotein cholesterol and very low-density lipoprotein cholesterol levels were significantly increased, whereas, body weight, plasma insulin, high-density lipoprotein cholesterol, antioxidant enzymes and reduced glutathione were markedly decreased in diabetic rats. Treatment with vincamine significantly restored these parameters to the normal level. The protective effect of vincamine was compared with glibenclamide, a well-known hypoglycemic drug. Our results clearly suggest that vincamine exhibit hypoglycemic, hypolipidemic and antioxidant activity. The anti-diabetic effect of vincamine was comparable to the protective effect of glibenclamide, suggesting its potential as a natural anti-diabetic compound with therapeutic benefits.

Structural and Biochemical Characterization of the Curcumin-Reducing Activity of CurA from Vibrio vulnificus

Curcumin is a yellow-colored ingredient in dietary spice turmeric ( Curcuma longa Linn). This nontoxic polyphenol has antitumor, anti-inflammatory, apoptotic, and antioxidant activities. The ingested curcumin is reduced to multihydrated forms with more potent therapeutic potentials by the curcumin reductase (CurA) from commensal Escherichia coli. In this study, we demonstrated that Vibrio vulnificus CurA ( VvCurA) with 87% sequence similarity to the E. coli CurA exhibits the curcumin-reducing activity through spectrophotometric detection of NADPH oxidation and high performance liquid chromatographic analysis of curcumin consumption and product generation. Afterward, we determined the crystal structures of VvCurA and the VvCurA/NADPH complex, and made the in silico model of the VvCurA/NADPH/curcumin ternary complex through induced fit docking. Based on structural information, active site residues that play critical roles in catalysis have been identified and characterized by mutational and kinetic studies, leading us to propose the reaction mechanism of CurA.

Spice-Derived Bioactive Ingredients: Potential Agents or Food Adjuvant in the Management of Diabetes Mellitus

Spices possess tremendous therapeutic potential including hypoglycemic action, attributed to their bioactive ingredients. However, there is no study that critically reviewed the hypoglycemic potency, safety and the bioavailability of the spice-derived bioactive ingredients (SDBI). Therefore, the aim of the study was to comprehensively review all published studies regarding the hypoglycemic action of SDBI with the purpose to assess whether the ingredients are potential hypoglycemic agents or adjuvant. Factors considered were concentration/dosages used, the extent of blood glucose reduction, the IC50 values, and the safety concern of the SDBI. From the results, cinnamaldehyde, curcumin, diosgenin, thymoquinone (TQ), and trigonelline were showed the most promising effects and hold future potential as hypoglycemic agents. Conclusively, future studies should focus on improving the tissue and cellular bioavailability of the promising SDBI to achieve greater potency. Additionally, clinical trials and toxicity studies are with these SDBI are warranted.

Tetrahydrocurcumin ameliorates free fatty acid-induced hepatic steatosis and improves insulin resistance in HepG2 cells

Elevated levels of free fatty acids (FFAs) in the liver, resulting from either increased lipolysis or imbalanced FFAs flux, is a key pathogenic factor of hepatic steatosis. This study was conducted to examine the therapeutic effect of tetrahydrocurcumin (THC), a naturally occurring curcuminoid and a metabolite of curcumin, on oleic acid (OA)-induced steatosis in human hepatocellular carcinoma cells and to elucidate the underlying mechanism. HepG2 cells were incubated with OA to induce steatosis, and then treated with various concentrations of THC. The results showed that THC treatment significantly decreased lipid accumulation in OA-treated HepG2 cells, possibly, by inhibiting the expression of the lipogenic proteins, sterol regulatory element-binding protein 1 (SREBP-1c), peroxisome proliferator-activated receptor gamma (PPARγ), fatty acid synthase (FAS), and fatty acid-binding protein 4 (FABP4). Moreover, THC attenuated OA-induced hepatic lipogenesis in an adenosine monophosphate–activated protein kinase (AMPK)-dependent manner, which was reversed by pretreatment with an AMPK inhibitor. THC promoted lipolysis and upregulated the expression of genes involved in β-oxidation. Glucose uptake and insulin signaling impaired in HepG2 cells incubated with OA were abated by THC treatment, including phosphorylation of the insulin receptor substrate 1 (IRS-1)/phosphoinositide 3-kinase (PI3K)/Akt and downstream signaling pathways, forkhead box protein O1 (FOXO1) and glycogen synthase kinase 3 β (GSK3β), which are involved in gluconeogenesis and glycogen synthesis, respectively. Altogether, these results demonstrated the novel therapeutic benefit of THC against hepatic steatosis and, consequently, a potential treatment for non-alcoholic fatty liver disease (NAFLD).

Subchronic and Reproductive/Developmental Toxicity Studies of Tetrahydrocurcumin in Rats

Tetrahydrocurcumin (THC) is a major metabolite of curcumin, which is obtained from Curcuma longa. THC has various benefits and overcomes the bioavailability issue of curcumin. To establish it as a pharmacologically active molecule, its safety profile has to be determined. Thus, the present study aimed to determine the preclinical safety profile of THC in a 90-day subchronic and reproductive/developmental toxicity study in Wistar rats. THC at oral doses of 100, 200, and 400 mg/kg was administered daily for 90 days. Rats in the recovery group were kept for 14 days after treatment termination. The animals were observed for treatment-related morbidity, mortality, and changes in clinical signs, clinical pathology, and histopathology. In the reproductive/developmental toxicity study, THC at 100, 200, and 400 mg/kg was administered orally to rats and the reproductive/developmental parameters in adult male and female rats and pups were observed. THC at up to 400 mg/kg/day of did not have any significant effect on all parameters in male and female rats in both toxicity studies. Thus, 400 mg/kg/day can be considered as the no-observed-adverse-effect-level of THC in rats.

Polyphenols and their effects on diabetes management: A review

Background: Type 2 diabetes is a growing public health problem and is associated with increased morbidity and mortality. The worldwide prevalence of type 2 diabetes is rising. Polyphenols, such as flavonoids, phenolic acid, and stilbens, are a large and heterogeneous group of phytochemicals in plant-based foods. In this review, we aimed at assessing the studies on polyphenols and diabetes management. Methods: A literature search in the PubMed, EMBASE, Scopus, and ISI Web of Science databases was conducted to identify relevant studies published from 1986 to Jan 2017. Results: Several animal models and a limited number of human studies have revealed that polyphenols decrease hyperglycemia and improve acute insulin secretion and insulin sensitivity. The possible mechanisms include decrease in glucose absorption in the intestine, inhibition of carbohydrates digestion, stimulation of insulin secretion, modulation of glucose release from the liver, activation of insulin receptors and glucose uptake in insulin-sensitive tissues, modulation of intracellular signaling pathways, and gene expression. Conclusion: Growing evidence indicates that various dietary polyphenols may influence blood glucose at different levels and may also help control and prevent diabetes complication. However, we still need more clinical trials to determine the effects of polyphenols- rich foods, their effective dose, and mechanisms of their effects in managing diabetes.

Multifunctional Curcumin Mediate Multitherapeutic Effects

Inflammation can promote the development of arthritis, obesity, cardiovascular, type II diabetes, pancreatitis, metabolic and neurodegenerative diseases, and certain types of cancer. Compounds isolated from plants have been practiced since ancient times for curing various ailments including inflammatory disorders and to support normal physiological functions. Curcumin (diferuloylmethane) is a yellow coloring agent, extracted from turmeric that has been used for the prevention and treatment of various inflammatory diseases. Numerous studies have shown that curcumin modulate multiple molecular targets and can be translated to the clinics for multiple therapeutic processes. There is compelling evidence that curcumin can block cell proliferation, invasion, and angiogenesis as well as reduced the prolonged survival of cancer cells. Curcumin mediates anti-inflammatory effect through downregulation of inflammatory cytokines, transcription factors, protein kinases, and enzymes that promote inflammation and development of chronic diseases. In addition, curcumin induces apoptosis through mitochondrial and receptor-mediated pathways by activating caspase cascades. Curcumin is a safe and nontoxic drug that has been reported to be well tolerated. Available clinical trials support the potential role of curcumin for treatment of various inflammatory disorders. However, curcumin's efficacy is hindered by poor absorption and low bioavailability, which limit its translation into clinics. This review outlines the potential pharmacological and clinical role of curcumin, which provide a gateway for the beneficial role of plant isolated compounds in treatment of various inflammatory diseases and cancer.

Curcumin improves the metabolic syndrome in high-fructose-diet-fed rats: role of TNF-α, NF-κB, and oxidative stress

This study aimed to investigate effects of curcumin on high fructose diet (HFD)-induced metabolic syndrome (MetS) in rats and the possible mechanisms involved. MetS was induced in male albino rats (n = 20), over 8 weeks, by 65% HFD. For 8-week experiment period, rats were assigned to 2 equal groups: curcumin-treated rats received curcumin (200 mg/kg, p.o, once daily) along with HFD, and untreated rats were fed with HFD only. We evaluated body mass (BM), systolic blood pressure (SBP), homeostasis model assessment of insulin resistance (HOMA-IR), and serum levels of glucose, insulin, leptin, total cholesterol (TC), triglycerides (TGs), uric acid, malondialdehyde (MDA; lipid peroxidation product), and tumor necrosis factor-α (TNF-α; inflammatory cytokine), and serum catalase (endogenous antioxidant) activity and immunohistochemical expression of nuclear factor κB (NF-κB; inflammation-related transcription factor) in hepatocytes. HFD produced increases in BM, SBP, HOMA-IR, and serum levels of glucose, insulin, leptin, TC, TGs, uric acid, MDA, and TNF-α, a decrease in catalase activity, and strong positive expression of NF-κB in hepatocytes. Curcumin, in presence of HFD, produced significant improvements in all glucose and fat metabolism parameters, and in oxidative stress and inflammation biomarkers. Curcumin may potentially be useful in the treatment of MetS through its ability to modulate oxidation stress status and inflammation cascades.

Protective Effects of Curcumin on Renal Oxidative Stress and Lipid Metabolism in a Rat Model of Type 2 Diabetic Nephropathy

PURPOSE

Diabetic nephropathy is a serious complication of type 2 diabetes mellitus, and delaying the development of diabetic nephropathy in patients with diabetes mellitus is very important. In this study, we investigated inflammation, oxidative stress, and lipid metabolism to assess whether curcumin ameliorates diabetic nephropathy.

MATERIALS AND METHODS

Animals were divided into three groups: Long-Evans-Tokushima-Otsuka rats for normal controls, Otsuka-Long-Evans-Tokushima Fatty (OLETF) rats for the diabetic group, and curcumin-treated (100 mg/kg/day) OLETF rats. We measured body and epididymal fat weights, and examined plasma glucose, adiponectin, and lipid profiles at 45 weeks. To confirm renal damage, we measured albumin-creatinine ratio, superoxide dismutase (SOD), and malondialdehyde (MDA) in urine samples. Glomerular basement membrane thickness and slit pore density were evaluated in the renal cortex tissue of rats. Furthermore, we conducted adenosine monophosphate-activated protein kinase (AMPK) signaling and oxidative stress-related nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling to investigate mechanisms of lipotoxicity in kidneys.

RESULTS

Curcumin ameliorated albuminuria, pathophysiologic changes on the glomerulus, urinary MDA, and urinary SOD related with elevated Nrf2 signaling, as well as serum lipid-related index and ectopic lipid accumulation through activation of AMPK signaling.

CONCLUSION

Collectively, these findings indicate that curcumin exerts renoprotective effects by inhibiting renal lipid accumulation and oxidative stress through AMPK and Nrf2 signaling pathway.

Curcumin attenuates palmitate-induced apoptosis in MIN6 pancreatic β-cells through PI3K/Akt/FoxO1 and mitochondrial survival pathways

Lipotoxicity plays a vital role in development and progression of type 2 diabetes. Prolonged elevation of free fatty acids especially the palmitate leads to pancreatic β-cell dysfunction and apoptosis. Curcumin (diferuloylmethane), a polyphenol from the curry spice turmeric, is considered to be a broadly cytoprotective agent. The present study was designed to determine the protective effect of curcumin on palmitate-induced apoptosis in β-cells and investigate underlying mechanisms. Our results showed that curcumin improved cell viability and enhanced glucose-induced insulin secretory function in MIN6 pancreatic β-cells. Palmitate incubation evoked chromatin condensation, DNA nick end labeling and activation of caspase-3 and -9. Curcumin treatment inhibited palmitate-induced apoptosis, relieved mitochondrial depolarization and up-regulated Bcl-2/Bax ratio. Palmitate induced the generation of reactive oxygen species and inhibited activities of antioxidant enzymes, which could be neutralized by curcumin treatment. Moreover, curcumin could promote rapid phosphorylation of Akt and nuclear exclusion of FoxO1 in MIN6 cells under lipotoxic condition. Phosphatidylinositol 3-kinase and Akt specific inhibitors abolished the anti-lipotoxic effect of curcumin and stimulated FoxO1 nuclear translocation. These findings suggested that curcumin protected MIN6 pancreatic β-Cells against apoptosis through activation of Akt, inhibition of nuclear translocation of FoxO1 and mitochondrial survival pathway.

Insight into the mechanism of polyphenols on the activity of HMGR by molecular docking

Statins are hypolipidemic drugs that are effective in the treatment of hypercholesterolemia by attenuating cholesterol synthesis in the liver via competitive inhibition of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. Recently, dietary changes associated with drug therapy have garnered attention as novel drugs to mitigate or ameliorate hypercholesterolemia. The present study was undertaken to observe different dietary polyphenols that can bind to the active site of HMGR and inhibit it. Results from the 12 dietary polyphenols tested reveal that polyphenols can bind to HMGR and block the binding of nicotinamide adenine dinucleotide phosphate (NADP⁺). We observed that the rigidity of phenolic rings prevents the polyphenols from docking to the enzyme activity site. The presence of an ester linkage between the phenolic rings in (–)-epigallocatechin-3-gallate (EGCG) and the alkyl chain in curcumin allows them to orient in the active site of the HMGR and bind to the catalytic residues. EGCG and curcumin showed binding to the active site residues with a low GRID score, which may be a potential inhibitor of HMGR. Kaempferol showed binding to HMG-CoA, but with low binding affinity. These observations provide a rationale for the consistent hypolipidemic effect of EGCG and curcumin, which has been previously reported in several epidemiological and animal studies. Therefore, this study substantiates the mechanism of polyphenols on the activity of HMGR by molecular docking and provides the impetus for drug design involving further structure–function relationship studies.

Beyond Yellow Curry: Assessing Commercial Curcumin Absorption Technologies

BACKGROUND: Few natural products have demonstrated the range of protective and therapeutic promise as have turmeric and its principal bioactive components: curcumin, demethoxycurcumin, and bisdemethoxycurcumin. Success in translating this potential into tangible benefits has been limited by inherently poor intestinal absorption, rapid metabolism, and limited systemic bioavailability. Seeking to overcome these limitations, food ingredient formulators have begun to employ a variety of approaches to enhance absorption and bioactivity. Many of these strategies improve upon the age-old practice of consuming turmeric in fat-based sauces, such as in a fat-rich yellow curry. However, there exists uncertainty as to how the various commercially available offerings compare to each other in terms of either uptake or efficacy, and this uncertainty leaves physicians and nutritionists with a dearth of data for making recommendations to interested patients and consumers. Further complicating the issue are recent data suggesting that formulation strategies may not equally enhance the absorption of individual curcuminoids, a significant issue in that these curcuminoids exhibit somewhat different physiologic properties.

OBJECTIVE: This review introduces needed order to the curcumin marketplace by examining bioavailability studies on a number of commercial curcumin ingredients and evaluating them on a level playing field.

METHODS: The comparative analysis includes standard pharmacokinetic parameters and a new metric, relative mass efficiency (E). Relative mass efficiency allows for the comparison of different formulations even in cases in which the weight percentage of curcuminoids is vastly different.

RESULTS: A hydrophilic carrier dispersed curcuminoid formula exhibits 45.9 times the bioavailability of the standard purified 95 percent curcuminoid preparation and, based on relative mass efficiency, 1.5 times the bioavailability of the next best commercial ingredient, a cyclodextrin complex.

CONCLUSIONS: Delivery strategies can significantly improve the bioavailability of curcuminoids. Total formula mass is important for making practical formulation decisions about dosing, cost and space.