Curcumin adds spice to the debate: lipid metabolism in liver disease

Curcumin supplementation effect on liver enzymes in patients with nonalcoholic fatty liver disease: a GRADE-assessed systematic review and dose-response meta-analysis of randomized controlled trials

CONTEXT

Clinical evidence from investigations of the effects of curcumin on liver enzymes in patients with nonalcoholic fatty liver disease (NAFLD) have led to inconsistent results.

OBJECTIVE

The aim of this systematic review and meta-analysis was to investigate the overall effects of curcumin and curcumin plus piperine supplementation on liver enzymes such as alanine aminotransferase (ALT), alkaline phosphatase (ALP), and aspartate aminotransferase (AST) in patients with NAFLD.

DATA SOURCES

The Scopus, Web of Science, PubMed, and Cochrane Library databases were searched from inception through July 2023, using search terms representing NAFLD and liver enzymes. Articles were screened independently by 2 researchers based on PICOS inclusion criteria.

DATA EXTRACTION

The following data were extracted: first author's name, study location, year of publication, mean age, study duration, study design, participants' sex, number of participants in each group, dose of curcumin supplementation, and ALT, ALP, and AST concentrations. Risk of bias was assessed using the Cochrane Collaboration's modified risk-of-bias tool.

DATA ANALYSIS

Fixed- or random-effects meta-analysis was performed to estimate the effects of curcumin on liver enzymes, considering heterogeneity across studies. The I2 and Cochran's Q tests were used to assess heterogeneity between studies.

RESULTS

Overall, 15 randomized controlled trials comprising 905 participants were eligible for this meta-analysis. Curcumin supplementation significantly reduced ALT (weighted mean difference [WMD], -4.10, 95%CI, -7.16 to -1.04) and AST (WMD, -3.27; 95%CI, -5.16 to -1.39), but not ALP (WMD, -0.49; 95%CI, -1.79 to 0.82). Curcumin plus piperine supplementation had no significant effect on ALT (WMD, -3.79; 95%CI, -13.30 to 5.72), and AST (WMD, -1.1; 95%CI, -3.32 to 1.09).

CONCLUSIONS

Curcumin supplementation improved AST and ALT levels compared with the control group. However, better-designed randomized controlled trials with larger sample sizes and of higher quality are needed to assess the effects of curcumin on ALP.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42023448231.

Proteomics revealed the crosstalk between copper stress and cuproptosis, and explored the feasibility of curcumin as anticancer copper ionophore

As an essential micronutrient element in organisms, copper controls a host of fundamental cellular functions. Recently, copper-dependent cell growth and proliferation have been defined as "cuproplasia". Conversely, "cuproptosis" represents copper-dependent cell death, in a nonapoptotic manner. So far, a series of copper ionophores have been developed to kill cancer cells. However, the biological response mechanism of copper uptake has not been systematically analyzed. Based on quantitative proteomics, we revealed the crosstalk between copper stress and cuproptosis in cancer cells, and also explored the feasibility of curcumin as anticancer copper ionophore. Copper stress not only couples with cuproptosis, but also leads to reactive oxygen species (ROS) stress, oxidative damage and cell cycle arrest. In cancer cells, a feedback cytoprotection mechanism involving cuproptosis mediators was discovered. During copper treatment, the activation of glutamine transporters and the loss of Fe-S cluster proteins are the facilitators and results of cuproptosis, respectively. Through copper depletion, glutathione (GSH) blocks the cuproptosis process, rescues the activation of glutamine transporters, and prevents the loss of Fe-S cluster proteins, except for protecting cancer cells from apoptosis, protein degradation and oxidative damage. In addition, the copper ionophore curcumin can control the metabolisms of lipids, RNA, NADH and NADPH in colorectal cancer cells, and also up-regulates positive cuproptosis mediators. This work not only established the crosstalk between copper stress and cuproptosis, but also discolored the suppression and acceleration of cuproptosis by GSH and curcumin, respectively. Our results are significant for understanding cuproptosis process and developing novel anticancer reagents based on cuproptosis.

Effect of Curcumin Nanoemulsions Stabilized with MAG and DAG-MCFAs in a Fructose-Induced Hepatic Steatosis Rat Model

Current changes in diet, characterized by an increase in the intake of sweetened beverages, are heavily related to metabolic disorders such as non-alcoholic fatty liver. This condition can produce simple steatosis and, in worse cases, potentially result in steatohepatitis, fibrosis, and cirrhosis, comparable to the damage caused by the consumption of more or less 20–30 g of alcohol per day. The main objective of this research was to evaluate the effect of curcumin (Curcuma longa) nanoemulsions, using mono- and diacylglycerides medium chain fatty acids as stabilizers in an in vivo hepatic steatosis rat model. Pathology was induced by providing 30% fructose intake in the drinking water. Globule sizes under 200 nm that were stable for 4 weeks were obtained; curcumin encapsulated in the nanoemulsion was >70%. The results revealed an improvement regarding body and liver weight in the animals treated with curcumin nanoemulsions. A decrease in total cholesterol, LDL, AST/ALT, and HDL in serum was observed; however, no apparent improvement regarding serum glucose or triacylglycerides values was noted. Histological analysis showed a significant decrease in the extent of steatosis, inflammation, and brown adipose tissue in the treated animals.

Curcuminoids plus piperine improve nonalcoholic fatty liver disease: A clinical trial

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) as a prevalent hepatic disease is associated with an increased risk of morbidity and mortality related to the liver and cardiovascular disease (CVD). Lifestyle modification and good metabolic control is the first line of treatment, but not always efficacious in reversing NAFLD pathogenesis. Curcumin is a dietary phytochemical with hepatoprotective activities, though its low bioavailability is considered as a major challenge for clinical applications. Therefore, in this study, in order to improve the bioavailability of curcumin, it was coadministered with piperine and we investigated the effects of this bioavailability-enhanced curcumin on serum hepatic enzymes, lipid profile, and glycemic indices in patients with NAFLD.

METHODS

In this randomized controlled parallel-group trial, 70 subjects with ultrasound-determined NAFLD were randomized to either 500 mg curcuminoids coadministered with 5 mg piperine daily or placebo for 12 weeks. NAFLD severity (on the basis of sonography) and hepatic function was assessed at baseline and at the study end.

RESULTS

Seventy subjects completed the study. Supplementation with curcuminoids plus piperine significantly reduced the hematocrit (P = 0.027), erythrocyte sedimentation rate (P = 0.048) and the serum concentrations of alanine aminotransferase (P = 0.035), aspartate aminotransferase (P = 0.042), alkaline phosphatase (P = 0.004), cholesterol (P < 0.016), low-density lipoprotein cholesterol (P < 0.017), Iron (P = 0.026), and Hemoglobin (P = 0.025) and increased total iron-binding capacity (P = 0.003). However, except albumin, changes in other parameters were not statistically different between groups. In addition, administration of curcuminoids plus piperine significantly improved NAFLD severity (P < 0.001), which was statistically different compared with the placebo group (P = 0.022). Also, the percentage of improved patients was marginally higher in the curcuminoids plus piperine group when compared with the placebo group (P = 0.058).

CONCLUSION

This study suggested beneficial effects of combined curcuminoids and piperine supplementation on disease severity in patients with NAFLD.

Evaluation of Cellulosic Polymers and Curcumin to Reduce Aflatoxin B1 Toxic Effects on Performance, Biochemical, and Immunological Parameters of Broiler Chickens

To evaluate the effect of cellulosic polymers (CEL) and curcumin (CUR) on aflatoxin B1 (AFB1) toxic effects on performance, and the biochemical and immunological parameters in broiler chickens, 150 one-day-old male broiler chicks were randomly allocated into five groups with three replicates of 10 chickens per pen: Negative Control (feed); AFB1 (feed + 2 ppm AFB1); CUR (feed + 2 ppm AFB1 + Curcumin 0.2%); CEL (feed + 2 ppm AFB1 + 0.3% Cellulosic polymers); and, CEL + CUR (feed + 2 ppm AFB1 + 0.3% Cellulose polymers + 0.2% Curcumin). Every week, body weight, body weight gain, feed intake, and feed conversion ratio were calculated. On day 21, liver, spleen, bursa of Fabricius, and intestine from five broilers per replicate per group were removed to obtain relative organ weight. Histopathological changes in liver, several biochemical biomarkers, antibody titers, and muscle and skin pigmentation were also recorded. Dietary addition of 0.3% CEL and 0.2% CUR separately significantly diminished some of the toxic effects resulting from AFB1 on performance parameters, relative organs weight, histopathology, immune response, and serum biochemical variables (P < 0.05); however, the combination of CUR and CEL showed a better-integrated approach for the management of poultry health problems that are related with the consumption of AFB1, since they have different mechanisms of action with different positive effects on the responses of broiler chickens.

Modulation of cAMP levels by high-fat diet and curcumin and regulatory effects on CD36/FAT scavenger receptor/fatty acids transporter gene expression

Curcumin, a polyphenol from turmeric (Curcuma longa), reduces inflammation, atherosclerosis, and obesity in several animal studies. In Ldlr^-/- mice fed a high-fat diet (HFD), curcumin reduces plasma lipid levels, therefore contributing to a lower accumulation of lipids and to reduced expression of fatty acid transport proteins (CD36/FAT, FABP4/aP2) in peritoneal macrophages. In this study, we analyzed the molecular mechanisms by which curcumin (500, 1000, 1500 mg/kg diet, for 4 months) may influence plasma and tissue lipid levels in Ldlr^-/- mice fed an HFD. In liver, HFD significantly suppressed cAMP levels, and curcumin restored almost normal levels. Similar trends were observed in adipose tissues, but not in brain, skeletal muscle, spleen, and kidney. Treatment with curcumin increased phosphorylation of CREB in liver, what may play a role in regulatory effects of curcumin in lipid homeostasis. In cell lines, curcumin increased the level of cAMP, activated the transcription factor CREB and the human CD36 promoter via a sequence containing a consensus CREB response element. Regulatory effects of HFD and Cur on gene expression were observed in liver, less in skeletal muscle and not in brain. Since the cAMP/protein kinase A (PKA)/CREB pathway plays an important role in lipid homeostasis, energy expenditure, and thermogenesis by increasing lipolysis and fatty acid β-oxidation, an increase in cAMP levels induced by curcumin may contribute to its hypolipidemic and anti-atherosclerotic effects. © 2016 BioFactors, 43(1):42-53, 2017.

Why it is necessary to translate curcumin into clinical practice for the prevention and treatment of metabolic syndrome?

Curcumin (diferuloylmethane) is the yellow-orange pigment of dried Curcuma longa L. rhizomes (turmeric). During the past two decades, there has been a large volume of published studies describing the biological and pharmacological properties of this phytochemical including anticancer, anti-inflammatory, antioxidant, antithrombotic, antiatherosclerotic, cardioprotective, neuroprotective, memory enhancing, antiparkinsonism, antirheumatic, anti-infectious, antiaging, antipsoriatic, and anticonvulsant activities. In addition, curcumin has been shown to be extremely safe and interact with multiple molecular targets that are involved in the pathogenesis of metabolic syndrome. Curcumin could favorably affect all leading components of metabolic syndrome including insulin resistance, obesity, hypertriglyceridemia, decreased HDL-C and hypertension, and prevent the deleterious complications of MetS including diabetes and cardiovascular disease. Owing to its antioxidant and anti-inflammatory properties, curcumin can also exert several pleiotropic effects and improve endothelial dysfunction, adipokine imbalances, and hyperuricemia which usually accompany MetS. Despite the potential tremendous benefit of this multifaceted phytopharmaceutical, no trial result has yet been publicized on this issue. This review seeks to briefly summarize the ample scientific evidence that supports the therapeutic efficacy of curcumin, at least as an adjunctive treatment, in patients with MetS.

Molecular mechanisms of hypolipidemic effects of curcumin

Recent evidence suggests potential benefits from phytochemicals and micronutrients in reducing the elevated oxidative and lipid-mediated stress associated with inflammation, obesity, and atherosclerosis. These compounds may either directly scavenge reactive oxygen or nitrogen species or they may modulate the activity of signal transduction enzymes leading to changes in the expression of antioxidant genes. Alternatively, they may reduce plasma lipid levels by modulating lipid metabolic genes in tissues and thus reduce indirectly lipid-mediated oxidative and endoplasmic reticulum stress through their hypolipidemic effect. Here we review the proposed molecular mechanisms by which curcumin, a polyphenol present in the rhizomes of turmeric (Curcuma longa) spice, influences oxidative and lipid-mediated stress in the vascular system. At the molecular level, mounting experimental evidence suggests that curcumin may act chemically as scavenger of free radicals and/or influences signal transduction (e.g., Akt, AMPK) and modulates the activity of specific transcription factors (e.g., FOXO1/3a, NRF2, SREBP1/2, CREB, CREBH, PPARγ, and LXRα) that regulate the expression of genes involved in free radicals scavenging (e.g., catalase, MnSOD, and heme oxygenase-1) and lipid homeostasis (e.g., aP2/FABP4, CD36, HMG-CoA reductase, and carnitine palmitoyltransferase-I (CPT-1)). At the cellular level, curcumin may induce a mild oxidative and lipid-metabolic stress leading to an adaptive cellular stress response by hormetic stimulation of these cellular antioxidant defense systems and lipid metabolic enzymes. The resulting lower oxidative and lipid-mediated stress may not only explain the beneficial effects of curcumin on inflammation, cardiovascular, and neurodegenerative disease, but may also contribute to the increase in maximum life-span observed in animal models.

Herbal products: benefits, limits, and applications in chronic liver disease

Complementary and alternative medicine soughts and encompasses a wide range of approaches; its use begun in ancient China at the time of Xia dynasty and in India during the Vedic period, but thanks to its long-lasting curative effect, easy availability, natural way of healing, and poor side-effects it is gaining importance throughout the world in clinical practice. We conducted a review describing the effects and the limits of using herbal products in chronic liver disease, focusing our attention on those most known, such as quercetin or curcumin. We tried to describe their pharmacokinetics, biological properties, and their beneficial effects (as antioxidant role) in metabolic, alcoholic, and viral hepatitis (considering that oxidative stress is the common pathway of chronic liver diseases of different etiology). The main limit of applicability of CAM comes from the lacking of randomized, placebo-controlled clinical trials giving a real proof of efficacy of those products, so that anecdotal success and personal experience are frequently the driving force for acceptance of CAM in the population.

Curcumin prevents chronic alcohol-induced liver disease involving decreasing ROS generation and enhancing antioxidative capacity

Our previous study found that curcumin, a major active component of turmeric, could ameliorate ethanol-induced hepatocytes oxidative stress in vitro. The objective of this work was to investigate the effect of curcumin on chronic alcoholic liver disease (ALD) in vivo. Ethanol-exposed (2.4g/kg/day ethanol for the initial 4 weeks and 4g/kg/day for another 2 weeks) Balb/c mice were simultaneously treated with curcumin for 6 weeks. The results showed that curcumin attenuated ethanol-induced histopathological changes of the liver and ameliorated the evident release of cellular alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Ethanol exposure resulted in reactive oxygen species (ROS) generation, malondialdehyde (MDA) elevation, glutathione (GSH) depletion and antioxidant defense system impairment, which were significantly reversed by curcumin treatment. In conclusion, curcumin provided protection against chronic ALD and the mechanism might be related to the alleviation of oxidative damage.

Curcumin molecular targets in obesity and obesity-related cancers

Obesity is characterized as an increased BMI, which is associated with the increased risk of several common cancers, including colorectal, breast, endometrial, renal, esophageal, gallbladder, melanoma, multiple myeloma, leukemia, lymphoma and prostate cancer. The increased risk of obesity-related cancers could be mediated by insulin resistance, adipokines, obesity-related inflammatory cytokines, sex hormones, transcription factors and oxidative stress, which disrupt the balance between cell proliferation and apoptosis. The yellowish compound, curcumin (diferuloylmethane), is known to possess multifaceted pharmacological effects. The molecular mechanisms linking obesity to cancer risk, and how curcumin mediates anticancer and obesity activities, have not yet been publicized. Curcumin modulates multiple molecular targets and reverses insulin resistance as well as other symptoms that are associated with obesity-related cancers. In this study, we show that ample evidence exists to support recommendations that curcumin mediates multiple molecular pathways, and is considered to be of therapeutic value in the treatment and prevention of obesity-related cancers.

Culinary plants and their potential impact on metabolic overload

Contemporary human behavior has led a large proportion of the population to metabolic overload and obesity. Postprandial hyperlipidemia and hyperglycemia evoke redox imbalance in the short term and lead to complex chronic disease in the long term with repeated occurrence. Complex diseases are best prevented with complex components of plants; thus, current nutrition research has begun to focus on the development of plant-based functional foods and dietary supplements for health and well-being. Furthermore, given the wide range of species, parts, and secondary metabolites, culinary plants can contribute significant variety and complexity to the human diet. Although understanding the health benefits of culinary plants has been one of the great challenges in nutritional science due to their inherent complexity, it is an advantageous pursuit. This review will address the challenges and opportunities relating to studies of the health benefits of culinary plants, with an emphasis on obesity attributed to metabolic overload.

Peroxisome proliferator-activated receptor gamma inhibits hepatic fibrosis in rats

BACKGROUND

Hepatic fibrosis is a necessary step in the development of hepatic cirrhosis. In this study we used lentiviral vector-mediated transfection technology to evaluate the effect of peroxisome proliferator-activated receptor gamma (PPAR-gamma) on rat hepatic fibrosis.

METHODS

Hepatic fibrosis in rats was induced by CCl4 for 2 weeks (early fibrosis) and 8 weeks (sustained fibrosis). The rats were randomly divided into four groups: normal control, fibrosis, blank vector, and PPAR-gamma. They were infected with the recombinant lentiviral expression vector carrying the rat PPAR-gamma gene by portal vein injection. The liver of the rats was examined histologically and hydroxyproline was assessed. In vitro primary hepatic stellate cells (HSCs) were infected with the recombinant lentiviral expression vector carrying the rat PPAR-gamma gene. The status of HSC proliferation was measured by the MTT assay. The protein levels of PPAR-gamma, alpha-smooth muscle actin (alpha-SMA) and type I collagen expression were evaluated by the Western blotting method.

RESULTS

In vitro studies revealed that expression of PPAR-gamma inhibited expression of alpha-SMA and type I collagen in activated HSCs (P<0.01) as well as HSC proliferation (P<0.01). In vivo experiments indicated that in the early hepatic fibrosis group, the hydroxyproline content and the level of collagen I protein in the liver in the PPAR-gamma transfected group were not significantly different compared to the hepatic fibrosis group and the blank vector group; whereas the expressions of PPAR-gamma and alpha-SMA were different compared to the hepatic fibrosis group (P<0.01). In the sustained hepatic fibrosis group, there were significant differences in the hydroxyproline content and the expression of PPAR-gamma, alpha-SMA, and type I collagen between each group.

CONCLUSION

PPAR-gamma can inhibit HSC proliferation and hepatic fibrosis, and suppress alpha-SMA and type I collagen expression.