Action of curcumin on the cytochrome P450-system catalyzing the activation of aflatoxin B1

Aflatoxin B1 Toxicity and Protective Effects of Curcumin: Molecular Mechanisms and Clinical Implications

One of the most significant classes of mycotoxins, aflatoxins (AFTs), can cause a variety of detrimental outcomes, including cancer, hepatitis, aberrant mutations, and reproductive issues. Among the 21 identified AFTs, aflatoxin B1 (AFB1) is the most harmful to humans and animals. The mechanisms of AFB1-induced toxicity are connected to the generation of excess reactive oxygen species (ROS), upregulation of CYP450 activities, oxidative stress, lipid peroxidation, apoptosis, mitochondrial dysfunction, autophagy, necrosis, and inflammatory response. Several signaling pathways, including p53, PI3K/Akt/mTOR, Nrf2/ARE, NF-κB, NLRP3, MAPKs, and Wnt/β-catenin have been shown to contribute to AFB1-mediated toxic effects in mammalian cells. Curcumin, a natural product with multiple therapeutic activities (e.g., anti-inflammatory, antioxidant, anticancer, and immunoregulation activities), could revise AFB1-induced harmful effects by targeting these pathways. Therefore, the potential therapeutic use of curcumin against AFB1-related side effects and the underlying molecular mechanisms are summarized. This review, in our opinion, advances significant knowledge, sparks larger discussions, and drives additional improvements in the hazardous examination of AFTs and detoxifying the application of curcumin.

Detection of Aflatoxin adducts as potential markers and the role of curcumin in alleviating AFB1-induced liver damage in chickens

In this study, we identified AFB1 adducts as potential markers and investigated the role of curcumin in alleviating AFB1-induced liver damage by suppressing the production of AFB1 adducts and oxidative stress in AA broilers liver. A total of 64 one-day-old Arbor Acres (AA) broilers were randomly divided into four groups, including control group, AFB1 group (5 mg/kg AFB1), cur + AFB1 group (300 mg/kg curcumin+5 mg/kg AFB1) and curcumin group (300 mg/kg). Serum biochemical parameters, liver antioxidant abilities, AFB1 adducts and oxidative stress mechanism were studied in broilers. AFB1 administration accompany with signs of liver injury, including hepatic histological lesions, increased serum enzymes activities, decreased liver antioxidant enzymes activities and the suppression of ROS and 8-OHdG. Meanwhile, Nrf2/HO-1 pathway was depressed by AFB1 treatment. Immunohistochemistry and ELISA showed that AFB1 significantly increased AFB1-DNA adduct in liver (p < 0.05) and AFB1-lysine adduct in serum (p < 0.05). Importantly, supplementation of curcumin can ameliorate these alterations. Intriguingly, curcumin alleviated AFB1-induced toxicity and oxidative stress by inhibiting the generation of ROS, 8-OHdG and AFB1 adducts, and activated Nrf2 signaling pathway in broilers. Conclusively, our experiments suggest that curcumin could be considered as a potential agent for prevention of AFB1-induced toxicity and oxidative stress, and AFB1 adducts could be suitable therapeutic targets.

Detoxification and immunoprotection of Zn(II)-curcumin in juvenile Pacific white shrimp (Litopenaeus vannamei) feed with aflatoxin B1

Aflatoxins, which was produced by Aspergillus flavus or Aspergillus parasiticus fungi during grain and feed processing or storage, could cause severe health problems and reduction of yield during shrimp cultures. To evaluate toxic effects of aflatoxin B1 (AFB1) in juvenile Pacific white shrimp (Litopenaeus vannamei) and potential protective effect of Zn(II)-curcumin (Zn-CM), four experimental diets (control, 500 μg/kg AFB1, 500 μg/kg AFB1+100 mg/kg Zn-CM, 500 μg/kg AFB1+200 mg/kg Zn-CM) were formulated in quadruplicate to feed the shrimp for 8 weeks. The results revealed that AFB1 could induce significant decrease in final body weight (FBW), weight gain (WG, %) and visible variations of the hepatopancreas structures in L.vannamei. Compared with AFB1 group, AFB1+100 mg/kg Zn-CM group significantly ameliorated the toxic effects of AFB1 on growth performance, while AFB1+100 mg/kg Zn-CM group had no effect on growth performance. Dietary AFB1+100 mg/kg Zn-CM enhanced phenoloxidase (PO) (P < 0.05) activity. Both dietary AFB1+100 mg/kg Zn-CM and AFB1+200 mg/kg Zn-CM reduced inducible nitric oxide synthase (iNOS) activity and glutathione (GSH) level, decreased the content of malondialdehyde (MDA) (P < 0.05) in hepatopancreas compared with AFB1 group. Transmission electron microscopy (TEM) analysis demonstrated that Zn-CM could relieve the microvilli transformation and mitochondria accumulation reduction caused by AFB1. Consequently, the results demonstrated that suitable Zn-CM could mitigate the AFB1-induced hepatotoxicity and immunotoxicity effects on L.vannamei.

Tramadol-induced hepato- and nephrotoxicity in rats: Role of Curcumin and Gallic acid as antioxidants

Tramadol is an analgesic used to treat moderate to severe pain caused by cancer, osteoarthritis, and other musculoskeletal diseases. Cytochrome P450 system metabolizes tramadol and induces oxidative stress in different organs. Therefore, the present study aims at investigating the changes in the activities and the protein expressions of CYPs isozymes (2E1, 3A4, 2B1/2), antioxidants status, free radicals levels after pretreatment of rats with Curcumin and/or Gallic as single- and/or repeated-doses before administration of tramadol. In repeated-dose treatments of rats with tramadol, the activities of cytochrome P450, cytochrome b5, and NADPH-cytochrome-c-reductase, and the antioxidant enzymes including glutathione reductase, glutathione peroxidase, glutathione S-transferase, catalase, superoxide dismutase, and levels of glutathione were inhibited in the liver and the kidney of rats. Interestingly, such changes caused by tramadol restored to their normal levels after pretreatment of rats with either Curcumin and/or Gallic acid. On the other hand, repeated-dose treatment of rats with tramadol increased the activities of both dimethylnitrosamine N-demethylase I (DMN-dI), and aryl hydrocarbon hydroxylase (AHH) compared to the control group. However, pretreatment of rats with Curcumin and/or Gallic acid prior to administration of tramadol restored the inhibited DMN-dI activity and its protein expression (CYP 2E1) to their normal levels. On the other hand, tramadol inhibited the activity of ethoxycoumarin O-deethylase (ECOD) and suppressed its protein marker expression (CYP2B1/2), whereas Curcumin, Gallic acid and/or their mixture restored such changes to their normal levels. In conclusion, Curcumin and/or Gallic acid alleviated the adverse effects caused by tramadol. In addition, patients should be advice to take Curcumin and/or Gallic acid prior to tramadol treatment to alleviate the hepatic and renal toxicities caused by tramadol.

Protective role of curcumin in ameliorating AFB1-induced apoptosis via mitochondrial pathway in liver cells

It is well documented that liver is the primary target organ of aflatoxin B₁ (AFB₁) and curcumin proved to be effective against AFB₁-induced liver injury. In the present study, we investigated the preventive effects of curcumin against AFB₁-induced apoptosis through the molecular regulation of p53, caspase-3, Bax, caspase-9, Bcl-2 and cytochrome-C associated with mitochondrial pathway. Liver antioxidant levels were measured. The hallmarks of apoptosis were analysed by methyl green-pyronin-Y staining, transmission electron microscopy, RT-PCR and western blot. Results revealed that dietary curcumin ameliorated AFB₁-induced oxidative stress in a dose-dependent manner. Methyl green-pyronin-Y staining and transmission electron microscopy showed that AFB₁ induced apoptosis and caused abnormal changes in liver cells morphology such as condensation of chromatin material, reduces cell volume and damaged mitochondria. Moreover, mRNA and protein expression results manifested that apoptosis associated genes showed up-regulation in AFB₁ fed group. However, the supplementation of dietary curcumin (dose-dependently) alleviated the increased expression of the apoptosis associated genes at mRNA and protein level, and restored the hepatocytes normal morphology. The study provides an insight and a better understanding of the preventive mechanism of curcumin against AFB₁-induced apoptosis in hepatocytes and provide scientific basis for the therapeutic uses of curcumin.

Dual Role of Dietary Curcumin Through Attenuating AFB1-Induced Oxidative Stress and Liver Injury via Modulating Liver Phase-I and Phase-II Enzymes Involved in AFB1 Bioactivation and Detoxification

It is well understood that liver cytochrome p450 enzymes are responsible for AFB1 bioactivation, while phase-II enzymes regulated by the transcription factor nuclear factor-erythroid-2-related factor 2 (Nrf2) are involved in detoxification of AFB1. In this study, we explored the potential of curcumin to prevent AFB1-induced liver injury by modulating liver phase-I and phase-II enzymes along with Nrf2 involved in AFB1 bioactivation and detoxification. Arbor Acres broiler were divided into four groups including control group (G1; fed only basal feed), curcumin alone-treated group (G2; 450 mg/kg feed), AFB1-fed group (G3; 5 mg/kg feed), and curcumin plus AFB1 group (G4; 5 mg AFB1+450 mg curcumin/kg feed). After 28 days, liver and blood samples were collected for different analyses. Histological and phenotypic results revealed that AFB1-induced liver injury was partially ameliorated by curcumin supplementation. Compared to AFB1 alone-treated group, serum biochemical parameters and liver antioxidant status showed that curcumin supplementation significantly prevented AFB1-induced liver injury. RT-PCR and western blot results revealed that curcumin inhibited CYP enzymes-mediated bioactivation of AFB1 at mRNA and protein level. Transcription factor Nrf2, its downstream genes such as GSTA3, and GSTM2 mRNA, and protein expression level significantly upregulated via dietary curcumin. In addition, GSTs enzyme activity was enhanced with dietary curcumin which plays a crucial role in AFB1-detoxification. Conclusively, the study provided a scientific basis for the use of curcumin in broiler's diet and contributed to explore the multi-target preventive actions of curcumin against AFB1-induced liver injury through the modulation of phase-I and phase-II enzymes, and its potent anti-oxidative effects.

Protective and Detoxifying Effects Conferred by Dietary Selenium and Curcumin against AFB1-Mediated Toxicity in Livestock: A Review

Aflatoxin B1 (AFB1), among other aflatoxins of the aflatoxin family, is the most carcinogenic and hazardous mycotoxin to animals and human beings with very high potency leading to aflatoxicosis. Selenium is an essential trace mineral possessing powerful antioxidant functions. Selenium is widely reported as an effective antioxidant against aflatoxicosis. By preventing oxidative liver damage, suppressing pro-apoptotic proteins and improving immune status in AFB1 affected animals; selenium confers specific protection against AFB1 toxicity. Meticulous supplementation of animal feed by elemental selenium in the organic and inorganic forms has proven to be effective to ameliorate AFB1 toxicity. Curcumin is another dietary agent of importance in tackling aflatoxicosis. Curcumin is one of the major active ingredients in the tubers of a spice Curcuma longa L., a widely reported antioxidant, anticarcinogenic agent with reported protective potential against aflatoxin-mediated liver damage. Curcumin restricts the aflatoxigenic potential of Aspergillusflavus. Curcumin inhibits cytochrome P450 isoenzymes, particularly CYP2A6 isoform; thereby reducing the formation of AFB1-8, 9-epoxide and other toxic metabolites causing aflatoxicosis. In this review, we have briefly reviewed important aflatoxicosis symptoms among animals. With the main focus on curcumin and selenium, we have reviewed their underlying protective mechanisms in different animals along with their extraction and production methods for feed applications.

Protective effects of curcumin against aflatoxicosis: A comprehensive review

Aflatoxicosis is a deleterious medical condition that results from aflatoxins (AFs) or ochratoxins (OTs). Contamination with these toxins exerts detrimental effects on the liver, kidneys, reproductive organs, and also on immunological and cardiovascular systems. Aflatoxicosis is closely associated with overproduction of reactive oxygen species (ROS) as key contributors to oxidative and nitrosative stress responses, and subsequent damages to lipids, proteins, RNA, and DNA. The main target organ for AF toxicity is the liver, where DNA adducts, degranulation of endoplasmic reticulum, increased hepatic lipid peroxide, GSH depletion, mitochondrial dysfunction, and reduction of enzymatic and non-enzymatic antioxidants are manifestations of aflatoxicosis. Curcuma longa L. (turmeric) is a medicinal plant widely utilized all over the world for culinary and phytomedical purposes. Considering the antioxidant characteristic of curcumin, the main active component of turmeric, this review is intended to critically summarize the available evidence supporting possible effectiveness of curcumin against aflatoxicosis. Curcumin can serve as a promising candidate for attenuation of the adverse consequences of aflatoxicosis, acting mainly through intrinsic antioxidant effects aroused from its structure, modulation of the immune system as reflected by interleukin-1β and transforming growth factor-β, and interfering with AF's biotransformation by cytochrome P450 isoenzymes CYP1A, CYP3A, CYP2A, CYP2B, and CYP2C.

Curcumin Successfully Inhibited the Computationally Identified CYP2A6 Enzyme-Mediated Bioactivation of Aflatoxin B1 in Arbor Acres broiler

Cytochrome P450 enzymes are often responsible for the toxic and carcinogenic effects of toxicants, such as aflatoxin B1 (AFB1). The human hepatic CYP2A6 enzyme mediates the oxidative metabolism of several procarcinogens. In this study, we characterized a partial sequence of CYP2A6 gene from Arbor Acres (AA) broiler and studied its role in AFB1 bioactivation. Moreover, the effect of curcumin on CYP2A6 is illustrated. Six groups of AA broiler were treated for 28 days including the control group (fed only basal diet), curcumin alone-treated group (450 mg/kg feed), the group fed AFB1-contaminated feed (5 mg/kg feed) plus the low (150 mg), medium (300 mg) or high (450 mg) of curcumin, and the group fed AFB1-contaminated diet alone (5 mg/kg feed). After the end of treatment period, liver samples were collected for different analyses. The results revealed that the histopathological examination showed clear signs of liver toxicity in AA broliers in AFB1-fed group, but curcumin-supplementation in feed prevented partially AFB1-induced liver toxicity. Liver and body weights were recorded to study the AFB1 harmful effects. We noted an obvious increase in liver weight and decrease in body weight in AFB1-fed group. But, the administration of curcumin partially ameliorated the increase in liver weight and decrease in body weight in a dose-dependent manner. The results (RT-PCR and Elisa) revealed that mRNA and protein expression level enhanced in AFB1-fed group. Consistently, CYP2A6 enzyme activity also increased in AFB1-fed group, suggesting that AA broiler CYP2A6 actively involved in bioactivation of AFB1. However, curcumin treatment inhibited CYP2A6 at mRNA and protein levels in AFB1 treated AA broiler in a dose-dependent manner. Maximum inhibition of liver CYP2A6 enzyme activity in AA broiler has been achieved at a dose of 450 mg/kg curcumin. This is the first study identifying and confirming the role of CYP2A6 enzyme in AFB1 bioactivation in AA broiler liver (in vivo), and the hepatoprotective role of curcumin via inhibiting CYP2A6 expression and enzyme activity. The study contributed to identify an important CYP enzyme involved in AFB1 bioactivation in broilers and thus could pave the way for the prevention of the harmful effects of AFB1 in broilers.

Curcumin Prevents Aflatoxin B₁ Hepatoxicity by Inhibition of Cytochrome P450 Isozymes in Chick Liver

This study was designed to establish if Curcumin (CM) alleviates Aflatoxin B₁ (AFB₁)-induced hepatotoxic effects and to determine whether alteration of the expression of cytochrome P450 (CYP450) isozymes is involved in the regulation of these effects in chick liver. One-day-old male broilers (n = 120) were divided into four groups and used in a two by two factorial trial in which the main factors included supplementing AFB₁ (< 5 vs. 100 μg/kg) and CM (0 vs. 150 mg/kg) in a corn/soybean-based diet. Administration of AFB₁ induced liver injury, significantly decreasing albumin and total protein concentrations and increasing alanine aminotransferase and aspartate aminotransferase activities in serum, and induced hepatic histological lesions at week 2. AFB₁ also significantly decreased hepatic glutathione peroxidase, catalase, and glutathione levels, while increasing malondialdehyde, 8-hydroxydeoxyguanosine, and exo-AFB₁-8,9-epoxide (AFBO)-DNA concentrations. In addition, the mRNA and/or activity of enzymes responsible for the bioactivation of AFB₁ into AFBO-including CYP1A1, CYP1A2, CYP2A6, and CYP3A4-were significantly induced in liver microsomes after 2-week exposure to AFB₁. These alterations induced by AFB₁ were prevented by CM supplementation. Conclusively, dietary CM protected chicks from AFB₁-induced liver injury, potentially through the synergistic actions of increased antioxidant capacities and inhibition of the pivotal CYP450 isozyme-mediated activation of AFB₁ to toxic AFBO.

Curcumin and inflammatory bowel disease: potential and limits of innovative treatments

Curcumin belongs to the family of natural compounds collectively called curcuminoids and it possesses remarkable beneficial anti-oxidant, anti-inflammatory, anti-cancer, and neuroprotective properties. Moreover it is commonly assumed that curcumin has also been suggested as a remedy for digestive diseases such as inflammatory bowel diseases (IBD), a chronic immune disorder affecting the gastrointestinal tract and that can be divided in two major subgroups: Crohn’s disease (CD) and Ulcerative Colitis (UC), depending mainly on the intestine tract affected by the inflammatory events. The chronic and intermittent nature of IBD imposes, where applicable, long-term treatments conducted in most of the cases combining different types of drugs. In more severe cases and where there has been no good response to the drugs, a surgery therapy is carried out. Currently, IBD-pharmacological treatments are generally not curative and often present serious side effects; for this reason, being known the relationship between nutrition and IBD, it is worthy of interesting the study and the development of new dietary strategy. The curcumin principal mechanism is the suppression of IBD inflammatory compounds (NF-κB) modulating immune response. This review summarizes literature data of curcumin as anti-inflammatory and anti-oxidant in IBD, trying to understand the different effects in CD e UC.

Curcumin: a potential candidate in prevention of cancer via modulation of molecular pathways

Cancer is the most dreadful disease worldwide in terms of morbidity and mortality. The exact cause of cancer development and progression is not fully known. But it is thought that cancer occurs due to the structural and functional changes in the genes. The current approach to cancer treatment based on allopathic is expensive, exhibits side effects; and may also alter the normal functioning of genes. Thus, a safe and effective mode of treatment is needed to control the cancer development and progression. Some medicinal plants provide a safe, effective and affordable remedy to control the progression of malignant cells. The importance of medicinal plants and their constituents has been documented in Ayurveda, Unani medicine, and various religious books. Curcumin, a vital constituent of the spice turmeric, is an alternative approach in the prevention of cancer. Earlier studies have shown the effect of curcumin as an antioxidant, antibacterial, antitumor and it also has a noteworthy role in the control of different diseases. In this review, we summarize the understanding of chemopreventive effects of curcumin in the prevention of cancer via the regulation of various cell signaling and genetic pathways.

Therapeutic uses ofCurcuma longa (turmeric)

Curcuma longa commonly known as tumeric is traditionally used as a spice in Indian food. A wide range of biological activities e.g. anticancer, antimicrobial, antiinflammatory and free radical scavenging activity of the plant suggests a logical basis for its traditional use in foodstuff. Various phytothreapeutic uses ofCurcuma longa have been reviewed.

Curcumin could prevent methemoglobinemia induced by dapsone in rats

The curcumin's effect given orally by gavage in single- or multiple-dose regimens on methemoglobinemia induced by dapsone (DDS) was investigated in male Wistar rats. In the single-dose regimen, groups of 10 rats received either vehicle alone, or curcumin at 0.1, 1.0, 10, or 30 mg/kg body weight (bw), or curcumin at 0.02, 0.1, 1, 10, or 30 mg/kg bw plus DDS at 40 mg/kg bw, intraperitoneally (i.p.), 2 hours after. In the multiple-dose regimen, groups of 10 rats received either vehicle alone, or curcumin at 0.1, 1.0, 10, or 30 mg/kg bw for 5 days, with or without DDS (40 mg/kg bw, i.p.) 2 hours after on the fifth day. In both regimens, further groups of 10 rats were given DDS alone (positive controls) or normal saline (negative controls) i.p. Single-dose treatment with curcumin at 0.02 and 0.1 mg/kg bw significantly reduced DDS-induced methemoglobin formation, while the higher doses showed a pro-oxidant effect, significantly increasing DDS-induced methemoglobinemia. In the multiple-dose regimen, treatment with curcumin at 0.1 mg/kg bw significantly reduced DDS-induced methemoglobin formation, but the higher doses were without significant effect compared to DDS alone. It is concluded that curcumin at low doses mitigates methemoglobinemia induced by dapsone in rats, both in single- and multiple-dose regimens.

Anti-carcinogenic properties of curcumin on colorectal cancer

Curcumin has been used in traditional Indian medicine for many centuries for its anti-inflammatory and anti-carcinogenic properties. There has been some promising research concerning curcumin as a safe therapeutic agent for many cancers, colorectal cancer being among them. This has been shown through research in cell cultures, animal models, and humans. At this time, it appears that curcumin’s anti-carcinogenic properties are most likely due to its effects on multiple molecular targets, such as nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) and activator protein 1 (AP-1). NF-κB and AP-1 are both major transcription factors that regulate inflammation and thus affect cell proliferation, differentiation and even apoptosis. Curcumin has also been shown to affect a variety of other key players involved in carcinogenesis, such as cyclooxygenase-2, matrix metallopeptidases 2 and 9 and tumor necrosis factor α induced vascular cell adhesion molecule, just to name a few. Although many molecular targets are involved, curcumin has been well tolerated in many studies: doses up to 8 g a day have been confirmed to be safe for humans. In this brief review, we will examine the current studies and literature and touch upon many molecular pathways affected by curcumin, and demonstrate the exciting possibility of curcumin as a chemopreventive agent for colorectal cancer.

Metabolic intervention of aflatoxin B1 toxicity by curcumin

ETHNO PHARMACOLOGICAL RELEVANCE

Curcumin, bioactive principle of turmeric (Curcuma longa Linn) is an important constituent of Indian traditional medicine. Turmeric has been known to possess several therapeutic properties.

AIM OF THE STUDY

The modulatory effect of dietary curcumin (0.05%, w/w) on drug metabolizing and general marker enzymes of liver and formation of AFB(1)-adducts (DNA and protein) due to dietary AFB(1) exposure for a period of 6 weeks in a rodent model, have been evaluated.

MATERIALS AND METHODS

Drug metabolizing enzymes CYP1A1, GSHT, UGT1A and general marker enzymes (LDH, ALT, AST, ALP and gamma-GT) of liver were estimated by standardized methods. Aflatoxin adducts (DNA and protein) were quantitated by indirect competitive ELISA.

RESULTS

Dietary curcumin enhanced GSHT (p<0.001) and UGT1A1 (p<0.05) activity and significantly reduced the activity of CYP1A1 (p<0.001), in rats exposed to aflatoxin B(1). Supplementation of curcumin in the diet normalized the altered activities of LDH and ALT. At molecular level, curcumin significantly reduced AFB(1)-N(7)-guanine adduct (p<0.001) excretion in the urine, DNA adduct (p<0.05) in the liver and albumin adduct (p<0.001) in the serum.

CONCLUSION

The experimental results substantiates that curcumin intervention ameliorates the AFB(1) induced toxicity.

Curcumin: preventive and therapeutic properties in laboratory studies and clinical trials

Curcumin is a natural polyphenol used in ancient Asian medicine. Since the first article referring to the use of curcumin to treat human disease was published in The Lancet in 1937, >2,600 research studies using curcumin or turmeric have been published in English language journals. The mechanisms implicated in the inhibition of tumorigenesis by curcumin are diverse and appear to involve a combination of antiinflammatory, antioxidant, immunomodulatory, proapoptotic, and antiangiogenic properties via pleiotropic effects on genes and cell-signaling pathways at multiple levels. The potentially adverse sequelae of curcumin's effects on proapoptotic genes, particularly p53, represent a cause for current debate. When curcumin is combined with some cytotoxic drugs or certain other diet-derived polyphenols, synergistic effects have been demonstrated. Although curcumin's low systemic bioavailability after oral dosing may limit access of sufficient concentrations for pharmacologic effects in tissues outside the gastrointestinal tract, chemical analogues and novel delivery methods are in preclinical development to overcome this barrier. This article provides an overview of the extensive published literature on the use of curcumin as a therapy for malignant and inflammatory diseases and its potential use in the treatment of degenerative neurologic diseases, cystic fibrosis, and cardiovascular diseases. Despite the breadth of the coverage, particular emphasis is placed on the prevention and treatment of human cancers.

Pharmacokinetics and pharmacodynamics of curcumin

Curcuma spp. contain turmerin, essential oils, and curcuminoids, including curcumin. Curcumin [1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione] is regarded as the most biologically active constituent of the spice turmeric and it comprises 2-8% of most turmeric preparations. Preclinical data from animal models and phase I clinical studies performed with human volunteers and patients with cancer have demonstrated low systemic bioavailability following oral dosing. Efficient first-pass metabolism and some degree of intestinal metabolism, particularly glucuronidation and sulfation of curcumin, might explain its poor systemic availability when administered via the oral route. A daily oral dose of 3.6 g of curcumin is compatible with detectable levels of the parent compound in colorectal tissue from patients with cancer. The levels demonstrated might be sufficient to exert pharmacological activity. There appears to be negligible distribution of the parent drug to hepatic tissue or other tissues beyond the gastrointestinal tract. Curcumin possesses wide-ranging anti-inflammatory and anticancer properties. Many of these biological activities can be attributed to its potent antioxidant capacity at neutral and acidic pH, its inhibition of cell signaling pathways at multiple levels, its diverse effects on cellular enzymes, and its effects on cell adhesion and angiogenesis. In particular, curcumin's ability to alter gene transcription and induce apoptosis in preclinical models advocates its potential utility in cancer chemoprevention and chemotherapy. With regard to considerable public and scientific interest in the use of phytochemicals derived from dietary components to combat or prevent human diseases, curcumin is currently a leading agent.

CURCUMIN: THE INDIAN SOLID GOLD

Turmeric, derived from the plant Curcuma longa, is a gold-colored spice commonly used in the Indian subcontinent, not only for health care but also for the preservation of food and as a yellow dye for textiles. Curcumin, which gives the yellow color to turmeric, was first isolated almost two centuries ago, and its structure as diferuloylmethane was determined in 1910. Since the time of Ayurveda (1900 Bc) numerous therapeutic activities have been assigned to turmeric for a wide variety of diseases and conditions, including those of the skin, pulmonary, and gastrointestinal systems, aches, pains, wounds, sprains, and liver disorders. Extensive research within the last half century has proven that most of these activities, once associated with turmeric, are due to curcumin. Curcumin has been shown to exhibit antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities and thus has a potential against various malignant diseases, diabetes, allergies, arthritis, Alzheimer's disease, and other chronic illnesses. These effects are mediated through the regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other enzymes. Curcumin exhibits activities similar to recently discovered tumor necrosis factor blockers (e.g., HUMIRA, REMICADE, and ENBREL), a vascular endothelial cell growth factor blocker (e.g., AVASTIN), human epidermal growth factor receptor blockers (e.g., ERBITUX, ERLOTINIB, and GEFTINIB), and a HER2 blocker (e.g., HERCEPTIN). Considering the recent scientific bandwagon that multitargeted therapy is better than monotargeted therapy for most diseases, curcumin can be considered an ideal "Spice for Life".

Nephroprotective and hepatoprotective effects of curcuminoids

Curcumin (U1) has a wide spectrum of therapeutic effects such as antitumor and anti-inflammatory effects, including antibacterial, antiviral, antifungal, and antispasmodic activities. By comparison of the structure-activity relationship, tetrahydrocurcumin (THU1), one of the major metabolites, showed the highest antioxidative activity in both in vitro and in vivo systems. U1 has been reported to have the nephroprotective effect to improve creatinine and urea clearance and also protected the chronic renal allograft nephropathy. These beneficial effects have been explained by the protection of oxidative stress and the induction of antioxidative enzymes. The protective effect of THU1 against ferric nitrilotriacetate (Fe-NTA)-induced oxidative renal damage using male ddY mice was greater than that of U1, by monitoring not only radical scavenging activity measured by ESR, and TBARS, 4-HNE-modified protein and 8-OHdG formation but also induction of anioxidative enzymes and detoxification enzymes. THU1 was also expected to improve redox regulation through glutathione and suppress the oxidative stress in diabetic nephropathy and neuropathy. Earlier studies reported that U1 reduced the iron-induced hepatic damage, aflatoxin- and benzo[a]pyrene- induced mutagenicity and hepatocarcinogenecity and also the formation of the DNA adduct by inhibiting cytochrome P450 in the liver. The hepatoprotective role of U1 has been examined using carbone terachloride-induced liver damage in rats and alcoholic liver disease model rats, but not examined using THU1. Our recent data suggests that THU1 is a more promising hepatprotective agent because of its strong induction activity of antioxidant and phase 2-metabolizing enzymes in liver compared to kidney, although more detaied examinations are required.

Possible inhibitory mechanism of Curcuma drugs on CYP3A4 in 1α,25 dihydroxyvitamin D3 treated Caco-2 cells

Curcuma longa and C. zedoaria, belonging to genus Curcuma, have become prevalent as supplements in East Asia. Curcumin is the most well-studied bioactive component isolated from rhizomes of C. longa and other Curcuma species except C. zedoaria. In this study, we investigated the affects of C. longa, C. zedoaria from Japan and curcumin on CYP3A4. Caco-2 cells, in which CYP3A4 expression was induced by 1alpha,25-(OH)(2)-D(3), were used to mimic the metabolism of small intestine. Caco-2 cells were treated with methanol extracts from two Curcuma rhizomes (0.1mg/ml) or curcumin (30 microM) for 72 h. Both extracts significantly decreased the activity of CYP3A4 by about 85-98%. The 50% inhibitory concentrations of C. longa and C. zedoaria extracts were 0.019 and 0.014 mg/ml, respectively. They caused a 60-70% decrease in CYP3A4 protein. Otherwise, curcumin treatment caused a 30-40% decrease in CYP3A4 catalytic activity and a 38% decrease in CYP3A4 protein expression. Moreover, it was found that both Curcuma extracts and curcumin treatment had no influence on CYP3A4 mRNA expression. Our results suggested that administration of Curcuma drugs might inhibit the catalytic activity of intestinal CYP3A4. However, curcumin was not the major compound responsible for this inhibitory effect.

Multiple molecular targets in cancer chemoprevention by curcumin

Carcinogenesis encompasses 3 closely associated stages: initiation, progression, and promotion. Phytochemicals are nonnutritive components of plants that are currently being studied in chemoprevention of various diseases for their pleiotropic effects and nontoxicity. Cancer chemoprevention involves the use of either natural or synthetic chemicals to prevent the initiation, promotion, or progression of cancer. Curcumin is the active constituent of turmeric, which is widely used as a spice in Indian cooking. It has been shown to possess anti-inflammatory, antioxidant, and antitumor properties. Curcumin has also been shown to be beneficial in all 3 stages of carcinogenesis. Much of its beneficial effect is found to be due to its inhibition of the transcription factor nuclear factor kappa B (NF-kappaB) and subsequent inhibition of proinflammatory pathways. This review summarizes the inhibition of NF-kappaB by curcumin and describes the recently identified molecular targets of curcumin. It is hoped that continued research will lead to development of curcumin as an anticancer agent.

Alleviation of aflatoxin B1-induced oxidative stress in HepG2 cells by volatile extract from Allii Fistulosi Bulbus

The volatile extract from Allii Fistulosi Bulbus (VEAF) was isolated by steam distillation under reduced pressure, followed by continuous liquid-liquid extraction, and its effects on aflatoxin B1 (AFB1)-induced oxidative stress were investigated in human hepatoma cells (HepG2). The main constituents of the VEAF, identified by gas chromatography/mass spectrometry, were 2-octyl-5-methyl-3(2H)-furanone, 2-hexyl-5-methyl-3(2H)-furanone, 2,5-dimethylthiophene, 3,5-diethyl-1,2,4-trithiolane and 3,4-dimethyl-2,5-dihydro-thiophene-2-one. VEAF significantly inhibited the formation of intracellular reactive oxygen species caused by AFB1 in a dose-dependent manner, concomitant with a significant decrease in the AFB1-induced cytotoxicity. VEAF pretreatment significantly reduced the levels of thiobarbituric acid reactive substances, an indicator of lipid peroxidation, whereas increased the level of reduced glutathione. The level of 8-hydroxy-2'-deoxyguanosine, a DNA oxidative stress marker, was also decreased by 49-59% with pretreatment of VEAF. With respect to the activity of AFB1 metabolizing enzymes, VEAF significantly increased the activity of glutathione S-transferase, and significantly decreased the cytochrome (CYP) P450 3A4 activity, but had a little effect on the CYP1As. These results suggest that VEAF may be selectively effective in alleviating the AFB1-induced oxidative stress, and lead to cytoprotection against AFB1 exposure.

Biological properties of curcumin-cellular and molecular mechanisms of action

Curcuminoids, a group of phenolic compounds isolated from the roots of Curcuma longa (Zingiberaceae), exhibit a variety of beneficial effects on health and on events that help in preventing certain diseases. A vast majority of these studies were carried out with curcumin (diferuloyl methane), which is a major curcuminoid. The most detailed studies using curcumin include anti-inflammatory, antioxidant, anticarcinogenic, antiviral, and antiinfectious activities. In addition, the wound healing and detoxifying properties of curcumin have also received considerable attention. As a result of extensive research on the therapeutic properties of curcumin, some understanding on the cellular, molecular, and biochemical mechanism of action of curcumin is emerging. These findings are summarized in this review.

Curcumin: The story so far

Curcumin is a polyphenol derived from the herbal remedy and dietary spice turmeric. It possesses diverse anti-inflammatory and anti-cancer properties following oral or topical administration. Apart from curcumin's potent antioxidant capacity at neutral and acidic pH, its mechanisms of action include inhibition of several cell signalling pathways at multiple levels, effects on cellular enzymes such as cyclooxygenase and glutathione S-transferases, immuno-modulation and effects on angiogenesis and cell-cell adhesion. Curcumin's ability to affect gene transcription and to induce apoptosis in preclinical models is likely to be of particular relevance to cancer chemoprevention and chemotherapy in patients. Although curcumin's low systemic bioavailability following oral dosing may limit access of sufficient concentrations for pharmacological effect in certain tissues, the attainment of biologically active levels in the gastrointestinal tract has been demonstrated in animals and humans. Sufficient data currently exist to advocate phase II clinical evaluation of oral curcumin in patients with invasive malignancy or pre-invasive lesions of the gastrointestinal tract, particularly the colon and rectum.

Chemopreventive and therapeutic effects of curcumin

Chemoprevention is a promising anti-cancer approach with reduced secondary effects in comparison to classical chemotherapy. Curcumin, one of the most studied chemopreventive agents, is a natural compound extracted from Curcuma longa L. that allows suppression, retardation or inversion of carcinogenesis. Curcumin is also described as an anti-tumoral, anti-oxidant and anti-inflammatory agent capable of inducing apoptosis in numerous cellular systems. In this review, we describe both properties and mode of action of curcumin on carcinogenesis, gene expression mechanisms and drug metabolism.

Diet and breast cancer

The preponderance of evidence suggests a role for fat and alcohol as risk factors for breast cancer. The role of milk is more controversial with some studies suggesting that milk is a risk factor and others that consumption of milk is protective against breast cancer. No other major nutrient appears to play a significant role in increasing breast cancer risk. On the other hand, there is increasing evidence that a variety of micronutrients and hormones appear to have significant anticancer activity. These range from steroids such as dehydroepiandrosterone (DHEA) and its analysis to indoles, isothiocyanates, and isoflavone derivatives. These compounds act directly by interfering with cyclins and promoting apoptosis as well as indirectly by altering estrogen metabolism in a favorable direction. These effects are not merely theoretical actions in cell culture and tissue explants; they have been demonstrated in human patients as a range of studies have demonstrated.

Dietary strategies to counteract the effects of mycotoxins: a review

We reviewed various dietary strategies to contain the toxic effects of mycotoxins using antioxidant compounds (selenium, vitamins, provitamins), food components (phenolic compounds, coumarin, chlorophyll and its derivatives, fructose, aspartame), medicinal herbs and plant extracts, and mineral and biological binding agents (hydrated sodium calcium aluminosilicate, bentonites, zeolites, activated carbons, bacteria, and yeast). Available data are primarily from in vitro studies and mainly focus on aflatoxin B1, whereas much less information is available about other mycotoxins. Compounds with antioxidant properties are potentially very efficacious because of their ability to act as superoxide anion scavengers. Interesting results have been obtained by food components contained in coffee, strawberries, tea, pepper, grapes, turmeric, Fava tonka, garlic, cabbage, and onions. Additionally, some medicinal herbs and plant extracts could potentially provide protection against aflatoxin B1 and fumonisin B1. Activated carbons, hydrated sodium calcium aluminosilicate, and bacteria seem to effectively act as binders. We conclude that dietary strategies are the most promising approach to the problem, considering their limited or nil interference in the food production process. Nevertheless, a great research effort is necessary to verify the in vivo detoxification ability of the purposed agents, their mode of action, possible long-term drawbacks of these detoxification-decontamination procedures, and their economical and technical feasibility.

Inhibition of dihydrofolate reductase and cell growth activity by the phenanthroindolizidine alkaloids pergularinine and tylophorinidine: the in vitro cytotoxicity of these plant alkaloids and their potential as antimicrobial and anticancer agents

The phenanthroindolizidine plant alkaloids pergularinine (PGL) and tylophorinidine (TPD) isolated from the Indian medicinal herb Pergularia pallida have been evaluated for their biological activity and assessed for the first time employing dihydrofolate reductase (DHFR) (5,6,7,8-THF: NADP(+) oxidoreductase, EC 1.5.1.3) as the probe in the present investigations. The enzyme is a key target in cancer chemotherapy and has been purified from Lactobacillus leichmannii. Cytotoxicity studies showed that both PGL and TPD are potently toxic and inhibited the growth of L. leichmannii cells (IC(50)=45 and 40 microM, respectively). Both the alkaloids significantly inhibited DHFR activity (IC(50)=40 and 32 microM for PGL and TPD, respectively). Alkaloid concentrations greater than 75-95 microM resulted in a complete loss of DHFR activity. Our results are suggestive of the alkaloids as potential antimicrobial and antitumour compounds. Alkaloid binding to DHFR is slow and reversible. Inhibition kinetics revealed K(i) values of 9x10(-6) M and 7x10(-6) M for PGL and TPD, respectively for the enzyme and inhibition in both the cases was a simple linear 'non-competitive' type.

Dihydrofolate reductase and cell growth activity inhibition by the beta-carboline-benzoquinolizidine plant alkaloid deoxytubulosine from Alangium lamarckii: its potential as an antimicrobial and anticancer agent

Beta-carboline-benzoquinolizidine plant alkaloid deoxytubulosine (DTB) was evaluated and assessed for the first time for its biochemical and biological activity employing the biomarker dihydrofolate reductase (DHFR) (5,6,7,8-tetrahydrofolate: NADP+ oxidoreductase, EC 1.5.1.3) as the probe enzyme, a key target in cancer chemotherapy. DHFR, employed in the present investigations was purified from Lactobacillus leichmannii. DTB, isolated from the Indian medicinal plant Alangium lamarckii was demonstrated to exhibit potent cytotoxicity. The alkaloid potently inhibited the cell growth of L. leichmannii and the cellular enzyme activity of DHFR (IC50=40 and 30 microM for the cell growth and enzyme inhibitions, respectively). DTB concentrations >75 microM resulted in a total loss of the DHFR activity, thus suggesting that the beta-carboline-benzoquinolizidine plant alkaloid is a promising potential antitumor agent. Our results are also suggestive of its potential antimicrobial activity. DTB binding to DHFR appears to be slow and reversible. Inhibition kinetics revealed that DHFR has a Ki value of 5x10(-6) M for DTB and that the enzyme inhibition is a simple linear 'non-competitive' type.

Effect of curcumin on the aryl hydrocarbon receptor and cytochrome P450 1A1 in MCF-7 human breast carcinoma cells

We examined the interaction of curcumin, a dietary constituent and chemopreventive compound, with the carcinogen activation pathway mediated by the aryl hydrocarbon receptor (AhR) in MCF-7 mammary epithelial carcinoma cells. Curcumin caused a rapid accumulation of cytochrome P450 1A1 (CYP1A1) mRNA in a time- and concentration-dependent manner, and CYP1A1 monooxygenase activity increased as measured by ethoxyresorufin-O-deethylation. Curcumin activated the DNA-binding capacity of the AhR for the xenobiotic responsive element of CYP1A1 as measured by the electrophoretic-mobility shift assay (EMSA). Curcumin was able to compete with the prototypical AhR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin for binding to the AhR in isolated MCF-7 cytosol, indicating that it interacts directly with the receptor. Although curcumin could activate the AhR on its own, it partially inhibited the activation of AhR, as measured by EMSA, and partially decreased the accumulation of CYP1A1 mRNA caused by the mammary carcinogen dimethylbenzanthracene (DMBA). Curcumin competitively inhibited CYP1A1 activity in DMBA-treated cells and in microsomes isolated from DMBA-treated cells. Curcumin also inhibited the metabolic activation of DMBA, as measured by the formation of DMBA-DNA adducts, and decreased DMBA-induced cytotoxicity. These results suggest that the chemopreventive effect of curcumin may be due, in part, to its ability to compete with aryl hydrocarbons for both the AhR and CYP1A1. Curcumin may thus be a natural ligand and substrate of the AhR pathway.

Effects of curcumin on P-glycoprotein in primary cultures of rat hepatocytes

Curcumin is a natural phenolic compound found in the rhizomes of Curcuma longa and endowed with beneficial biological activities including antioxidant, anticarcinogenic and hepatoprotective effects. In this study curcumin was tested for its potential ability to interact in vitro with hepatic P-glycoprotein (Pgp), in a model system represented by primary cultures of rat hepatocytes, in which spontaneous overexpression of multidrug resistance (mdr) genes occurs. In both freshly-plated hepatocytes, containing low levels of Pgp, and 72 hour-cultured hepatocytes, containing high levels of Pgp, the Rhodamine-123 (R-123) efflux, which represents a specific functional test for Pgp-mediated transport, was inhibited by curcumin in a dose-dependent manner. Western blot analysis showed that 25microM curcumin, when included in the culture medium throughout the experimental observation (72 hours), was able to significantly lower the increase of mAb C219-immunoreactive protein spontaneously occurring in the cells during culture. Curcumin, at doses ranging from 50 to 150microM was cytotoxic for freshly-plated hepatocytes, as shown by the strong decrease in the cell ability to exclude trypan blue 24 hours later, but it was significantly less cytotoxic when added to 24 or 48 hour-cultured cells. The resistance to curcumin, progressively acquired by cells during culture, was significantly reduced by high concentrations of dexamethasone (DEX) or dimethyl-sulfoxide (DMSO), culture conditions known to inhibit the spontaneous overexpression of Pgp. In addition, in a concentration-dependent manner, verapamil reverted curcumin resistance in Pgp overexpressing hepatocytes. In photoaffinity labeling studies, curcumin competed with azidopine for binding to Pgp, suggesting a direct interaction with glycoprotein. These results suggest that curcumin is able to modulate in vitro both expression and function of hepatic Pgp and support the hypothesis that curcumin, a chemopreventive phytochemical, could reveal itself also as a compound endowed with chemosensitizing properties on mdr phenotype.

Modulation of aflatoxin B1 activated protein kinase C by phenolic compounds

Several natural phenolic compounds were tested in vitro for their effect on the activity of protein kinase C isolated from liver cytosol, particulate and nuclear fractions of normal and aflatoxin B1 treated rats. Quercetin and kaempferol inhibited the enzyme activity of all these fractions at very low dose levels. These phenolics were particularly effective in inhibiting the elevated enzyme activity following aflatoxin B1 administration. Ellagic acid and curcumin were found to be inhibitory only towards particulate enzymes obtained after carcinogen treatment, while curcumin and rutin were moderately active against nuclear enzymes. Constitutive activation of protein kinase C can drive the cell to a proliferative state, thereby initiating the process of carcinogenesis, however, suppression of this activation by phenolic compounds may be an effective way to control carcinogenesis.

Inhibition of thymidylate synthase and cell growth by the phenanthroindolizidine alkaloids pergularinine and tylophorinidine

Biological activity of the phenanthroindolizidine alkaloids pergularinine (PGL) and tylophorinidine (TPD) isolated from the Indian medicinal herb Pergularia pallida has been evaluated and assessed for the first time employing thymidylate synthase (TS) (5,10-CH2H4 PteGlu: dUMP-C-methyltransferase, EC 2.1.1.45), a key target enzyme in cancer chemotherapy. TS used in the present investigations was purified from Lactobacillus leichmannii. Toxicity studies showed that PGL and TPD were potently toxic and inhibited growth of L.leichmannii cells. Both PGL and TPD significantly inhibited TS activity (IC50 = 40 and 45 microM, respectively). PGL concentrations > 80 microM and TPD concentrations > 90 microM resulted in a complete loss of the TS activity, thus suggesting that both these phenanthroindolizidine alkaloids are promising potential antitumor agents. Our results show that the alkaloid-binding to TS is irreversibly tight through a probable covalent linkage. Inhibition kinetics reveal that the enzyme has Ki values of 10 x 10(-6) and 9 x 10(-6) M for PGL and TPD, respectively and that the inhibition in both the cases is a simple linear 'noncompetitive' type.