Modulatory effect of crocetin on aflatoxin B1 cytotoxicity and DNA adduct formation in C3H10T1/2 fibroblast cell

Crocetin and Crocin from Saffron in Cancer Chemotherapy and Chemoprevention

INTRODUCTION

Cancer is a disorder which has a powerful impact on the quality life and life expectancy despite the increase in drugs and treatments available for cancer patients. Moreover, many new therapeutic options are known to have adverse reactions without any improvement in outcome than before. Nowadays, natural products or plant derivatives are used as chemoprevention drugs and chemotherapy is the new approach that uses specific cell premalignant transformation in the malignant form. Natural substances derived from plants, such as polyphenols, flavonoids, carotenoids, alkaloids and others, can be biologically active and have a wide spectrum of effects. The protective effects of Saffron carotenoids (crocin and crocetin) have been extensively studied mainly for their antioxidant properties, however, they have various other biological activities including tumor growth inhibition with the induction of cell death.

METHODS

The relevant information on Saffron and its carotenoids was collected from scientific databases (such as PubMed, Web of Science, Science Direct). To identify all published articles in relation to saffron, crocin and crocetin, in different types of cancer, no language restriction has been used.

RESULTS

To date, crossing the words saffron and cancer, approximately 150 articles can be found. If crossing is made between crocin and cancer, approximately 60 articles can be found. With the crossing between crocetin and cancer, the number is approximately 55, while between carotenoids and cancer, the number exceeds 16.000 reports. In all the papers published to date, there are evidences that saffron and its carotenoids exert chemopreventive activity through anti-oxidant activity, cancer cells apoptosis, inhibition of cell proliferation, enhancement of cell differentiation, modulation of cell cycle progression and cell growth, modulation of tumor metabolism, stimulation of cell-to-cell communication and immune modulation.

CONCLUSION

Here, we have tried to offer an up-to-date overview of pre-clinical experimental investigations on the potential use of the main carotenoids of saffron in tumor models and focus the attention on the molecular mechanisms involved.

Pharmacological Properties of Crocetin and Crocin (Digentiobiosyl Ester of Crocetin) from Saffron

Functional plant foods and medicinal herbs provide a wide variety of natural products for new drug research and development. Crocetin and crocin (digentiobiosyl ester of crocetin) are the major bioactive ingredients of saffron which is used as a costly spice, food colorant and traditional herbal medicine. These particular carotenoids have gained much research attention for their extensive pharmacological activities. Following oral administration, crocetin is rapidly absorbed into the blood circulation and widely distributed into the extra-vascular tissues of the body, whereas the water-soluble compound crocin is hardly absorbed through the gastrointestinal tract. Crocetin and crocin have been shown to be effective in the prevention and/or treatment of several diseases such as atherosclerosis, myocardial ischemia, hemorrhagic shock, cancer and cerebral injury. The compounds exert their biological and pharmacological effects largely through their strong antioxidant activity. However, there seems to be substantial variation in the effectiveness of both phytochemicals when used in different diseases. The aim of this review is to discuss the pharmacokinetic and medicinal properties of crocetin and crocin based on related literature and our research results.

Anti-tumor effects of crocetin and related molecular targets

Natural products have gained a wide popularity as chemopreventive and anti-cancer agents owing to their multi-mechanistic mode of action, availability and synergism with several conventional chemotherapeutic agents. Crocetin is a carotenoid compound isolated from the stigma of Crocus sativus L. (saffron). Crocetin has shown promising effects as an anti-tumor agent in animal models and cell culture systems. Crocetin retards the growth of cancer cells via inhibiting nucleic acid synthesis, enhancing anti-oxidative system, and inducing apoptosis and differentiation pathways. The present review outlines natural sources of crocetin, and its pharmacokinetic and pharmacological properties relevant to the prevention and treatment of cancer. Also, we discuss molecular targets underlying the putative anti-tumor effects of crocetin.

Anticarcinogenic effect of saffron (Crocus sativus L.) and its ingredients

Conventional and newly emerging treatment procedures such as chemotherapy, catalytic therapy, photodynamic therapy and radiotherapy have not succeeded in reversing the outcome of cancer diseases to any drastic extent, which has led researchers to investigate alternative treatment options. The extensive repertoire of traditional medicinal knowledge systems from various parts of the world are being re-investigated for their healing properties Crocus sativus L., commonly known as saffron, is the raw material for one of the most expensive spice in the world, and it has been used in folk medicine for centuries. Chemical analysis has shown the presence of more than 150 components in saffron stigmas. The more powerful components of saffron are crocin, crocetin and safranal. Studies in animal models and with cultured human malignant cell lines have demonstrated antitumor and cancer preventive activities of saffron and its main ingredients, possible mechanisms for these activities are discussed. More direct evidence of anticancer effectiveness of saffron as chemo-preventive agent may come from trials that use actual reduction of cancer incidence as the primary endpoint. This review discusses recent literature data and our results on the cancer chemopreventive activities of saffron and its main ingredients.

Anticancer Effect and Molecular Targets of Saffron Carotenoids

Saffron carotenoids, crocin and crocetin, have shown anticancer activity in various animal models of cancer and against different cancerous cell lines. The radical scavenging property and activation of antioxidant defense system are two well-known characteristics of these compounds. However, the results of the studies indicated other mechanisms could also be involved in this function. Insights into various molecular mechanisms of action for crocin and crocetin have been obtained in recent years. The results indicated that despite the structural similarity of crocin and crocetin, their anticancer effects may exert through different mechanisms. Particular interest concerns the ROS-dependent signaling pathways of crocetin. Saffron compounds are safe and may provide inexpensive therapy for treating cancer. They also have protective potential in targeting other disorders including diabetes, Alzheimer's and cardiovascular disease, cognitive deficits, ischemia-induced retinal damage, and many other diseases.

Crocetin: an agent derived from saffron for prevention and therapy for cancer

Cancer is one of the leading causes of death in the United States and accounts for approximately 8 million deaths per year worldwide. Although there is an increasing number of therapeutic options available for patients with cancer, their efficacy is time-limited and non-curative. Approximately 50-60% cancer patients in the United States utilize agents derived from different parts of plants or nutrients (complementary and alternative medicine), exclusively or concurrently with traditional therapeutic regime such as chemotherapy and/or radiation therapy. The need for new drugs has prompted studies evaluating possible anti-cancer agents in fruits, vegetables, herbs and spices. Saffron, a spice and a food colorant present in the dry stigmas of the plant Crocus sativus L., has been used as an herbal remedy for various ailments including cancer by the ancient Arabian, Indian and Chinese cultures. Crocetin, an important carotenoid constituent of saffron, has shown significant potential as an anti-tumor agent in animal models and cell culture systems. Crocetin affects the growth of cancer cells by inhibiting nucleic acid synthesis, enhancing anti-oxidative system, inducing apoptosis and hindering growth factor signaling pathways. This review discusses the studies on cancer preventive potential of crocetin and its future use as an anticancer agent.

Key roles of vitamins A, C, and E in aflatoxin B1-induced oxidative stress

Aflatoxins (Aspergillus flavus toxins) are one of the natural toxic molecules which are produced by a group of fungi called Aspergillus. Foods and drinks contaminated with aflatoxins cause global health and environmental problems. Today in many developing countries, these toxins are leading cause of some liver cancers and serious gastrointestinal problems. Aflatoxins, which are well known to be mutagenic, carcinogenic, hepatotoxic, and immunosuppressive, exert inhibitory effects on biological processes including DNA synthesis, DNA-dependent RNA synthesis, DNA repair, and protein synthesis. Aflatoxins B(1) (AFB(1)) is the most widespread oxidative agent of the aflatoxins. Numerous diverse compounds and extracts have been reported to reduce the aflatoxins induced oxidative stress in the body. Most of these inhibitors including phenylpropanoids, terpenoids, alkaloids, and vitamins are originally derived from plants. Among these, being essential biomolecules, vitamins are used as coenzymes in very significant biological reactions. They also function as nonenzymatic antioxidative agents protecting the cells from oxidative stress-induced toxicity and transformation. This chapter reviews the mechanism of AFB(1)-induced oxidative stress and focuses on the protective effects of vitamins A, C, and E on reducing this stress.

Carotenoid actions and their relation to health and disease

Based on extensive epidemiological observation, fruits and vegetables that are a rich source of carotenoids are thought to provide health benefits by decreasing the risk of various diseases, particularly certain cancers and eye diseases. The carotenoids that have been most studied in this regard are beta-carotene, lycopene, lutein and zeaxanthin. In part, the beneficial effects of carotenoids are thought to be due to their role as antioxidants. beta-Carotene may have added benefits due its ability to be converted to vitamin A. Additionally, lutein and zeaxanthin may be protective in eye disease because they absorb damaging blue light that enters the eye. Food sources of these compounds include a variety of fruits and vegetables, although the primary sources of lycopene are tomato and tomato products. Additionally, egg yolk is a highly bioavailable source of lutein and zeaxanthin. These carotenoids are available in supplement form. However, intervention trials with large doses of beta-carotene found an adverse effect on the incidence of lung cancer in smokers and workers exposed to asbestos. Until the efficacy and safety of taking supplements containing these nutrients can be determined, current dietary recommendations of diets high in fruits and vegetables are advised.

Crocetin from Saffron: An Active Component of an Ancient Spice

The known properties of saffron (Crocus sativus, L.) and its components have been examined. Recently, hormone like effects in green algae and the anti-cancerogenic and anti-toxic effects, have been observed. In particular, the effects of crocetin, a carotenoids (8,8'-diapo-8,8'-carotenoic acid) present in saffron and characterized by a diterpenic and symmetrical structure with seven double bonds and four methyl groups, have been taken into consideration. It has been found that this compound enhances the oxygen diffusivity through liquids, such as plasma. As a consequence of this property, it has been observed that crocetin increases alveolar oxygen transport and enhances pulmonary oxygenation. It improves cerebral oxygenation in hemorrhaged rats and positively acts in the atherosclerosis and arthritis treatment. It inhibits skin tumor promotion in mice (i.e., with benzo(a)pyrene); it has an inhibitory effect on intracellular nucleic acid and protein synthesis in malignant cells, as well as on protein-kinase-C and prorooncogene in INNIH/3T3 cells. This is most likely due to its anti-oxidant activity. Furthermore, crocetin protects against oxidative damage in rat primary hepatocytes. It also suppresses aflatoxin B1-induced hepatotoxic lesions and has a modulatory effect on aflatoxin, B1 cytotoxicity, and DNA adduct formation on C3H10/T1/2 fibroblast cells. It also has a protective effect on the bladder toxicity, induced by cyclophosphamide. The experiments reported in the scientific literature and the interesting results obtained have been carried out in vitro or on laboratory animals, but not yet on man.

Effects of saffron extract and its constituent crocin on learning behaviour and long-term potentiation

Crocus sativus L., commonly known as saffron, is used in folk medicine for various purposes. Modern pharmacological studies have demonstrated that saffron extracts have antitumour effects, radical scavenger properties or hypolipaemic effects. Among the constituents of saffron extract, crocetin is mainly responsible for these pharmacological activities. In addition, recent behavioural and electrophysiological studies have demonstrated that saffron extract affects learning and memory in experimental animals. Saffron extract improved ethanol-induced impairments of learning behaviours in mice, and prevented ethanol-induced inhibition of hippocampal long-term potentiation, a form of activity-dependent synaptic plasticity that may underly learning and memory. This effect of saffron extract is attributed to crocin (crocetin di-gentiobiose ester), but not crocetin. Saffron extract or its active constituents, crocetin and crocin, could be useful as a treatment for neurodegenerative disorders accompanying memory impairment.

Inhibition of protein kinase C and proto-oncogene expression by crocetin in NIH/3T3 cells

Crocetin, a carotenoid isolated from the seeds of Gardenia jasminoides, was found to be a potent inhibitor of tumor promotion induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in mouse skin. When mouse fibroblast NIH/3T3 cells were treated with TPA alone, protein kinase C (PKC) translocated from the cytosolic fraction to the particulate fraction. Pretreatment with 60 and 120 microM crocetin for 15 min inhibited the TPA-induced PKC activity in the particulate fraction by 50% and 66%, respectively, but did not affect the level of PKC protein. Crocetin also reduced the level of TPA-stimulated phosphorylation of cellular proteins. Cells pretreated with crocetin (120 microM) had 55% less PKC [3H]phorbol dibutyrate-binding capacity. Suppression of TPA (100 ng/mL)-induced c-jun and c-fos gene expression was also observed in the mouse fibroblast cells pretreated with crocetin (30, 60, and 120 microM). Our results provided a basis for understanding the inhibitory effect of crocetin on TPA-mediated tumor promotion.

The inhibition of DMBA-induced carcinogenesis by neoxanthin in hamster buccal pouch

Neoxanthin, a major carotenoid pigment of spinach, is found in the Chloroplast membrane and has an unknown function in plants. Neoxanthin inhibited the production of superoxide anions in an artificial xanthine and xanthine oxidase system and depressed DNA synthesis in methylcholanthrene (MCA)-initiated C3H10T1/2 fibroblasts. in two-stage carcinogenesis experiments, neoxanthin at 0.2 micrograms/0.2 ml inhibited the formation of tumors that were induced sequentially by 7,12-dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA) in the buccal pouch of Syrian Golden hamsters. To assess the ongoing process of carcinogenesis, the activity of ornithine decarboxylase (ODC), required for cell proliferation, was analyzed. Neoxanthin inhibited the activity of ODC when animals were treated with neoxanthin one hour before the application of TPA in two-stage carcinogenesis. However, neoxanthin did not inhibit ODC activity when animals were treated with neoxanthin one hour before the application of DMBA in two-stage carcinogenesis, and there was no subsequent tumor formation. In a short-term anti-initiation experiment, neoxanthin inhibited the covalent binding of isotope-labeled DMBA to DNA by 53%. These results indicate that neoxanthin inhibits the initiation stage and the promotion stage in two-stage carcinogenesis. This suggests that neoxanthin may act as a potential chemopreventive agent.

Effects of beta-carotene and canthaxanthin on liver xenobiotic-metabolizing enzymes in the rat

The activities of several phase I and phase II xenobiotic-metabolizing enzymes have been measured in liver microsomes and cytosol of male rats that had been fed for 15 days with diets containing beta-carotene or canthaxanthin (300 mg/kg diet) or an excess of vitamin A (70,000 IU/kg diet), or to which beta-carotene had been administered by ip injections (7 x 10 mg/kg body weight). Microsomal cytochrome P-450 and the associated NADH- and NADPH-cytochrome c reductases were assayed, as well as several phase I and phase II enzyme activities. Phase I activities were markers of the families 1, 2, 3 and 4 of P-450; phase II activities were microsomal UDP glucuronosyl transferases (UGT) and cytosolic glutathione S-transferase (GST). Canthaxanthin accumulated in liver to a much higher level than did ingested or injected beta-carotene. Canthaxanthin increased the liver content of cytochrome P-450 (control value x 1.7), and the activity of NADH-cytochrome c reductase (x 1.5), and of some P-450-dependent enzymes (ethoxy-, methoxy-, pentoxy- and benzoxyresorufin O-dealkylases; x98, x15, x6.5 and x13, respectively), but not of others (erythromycin N-demethylase, nitrosodimethylamine N-demethylase and laurate omega-hydroxylase). Phase II activities were also increased: UGT1 (x3.4), UGT2 (x1.2) and GST (x1.2). This induction profile, characterized by the very strong increase of the activity associated with P4501A1, and the co-induction of UGT1, closely resemble that of a classical inducer, 3-methylcholanthrene. By contrast, neither beta-carotene (fed or injected), nor an excess of vitamin A induced any significant variation of the enzyme activities measured.

Modulatory effect of piperine on benzo[a]pyrene cytotoxicity and DNA adduct formation in V-79 lung fibroblast cells

Piperine, a major component of black pepper and long peppers, has been reported previously to have an effect on the activation and deactivation of some exogenous substances. In the present study, piperine was found to promote DNA damage and cytotoxicity induced by benzo[a]pyrene (B[a]P) in cultured V-79 lung fibroblast cells. The V-79 cells were treated with a non-toxic dose of piperine (1-20 microM) plus 10 microM B[a]P, or pretreated with piperine for 30 min or 2 hr prior to the administration of 10 microM B[a]P. B[a]P cytotoxicity was potentiated significantly by piperine under each experimental condition. The relative plating efficiency (RPE) was 71% when V-79 cells were exposed to 10 microM B[a]P alone. When the culture was exposed to B[a]P plus piperine or pretreated with piperine for 30 min prior to the administration of B[a]P, the RPE values were 63 and 44% (P < 0.001), respectively. Pretreatment with piperine for 2 hr had no significant effect (P > 0.05). Furthermore, the lowest activities (P < 0.05) of glutathione S-transferase (GST) and uridine diphosphate glucuronyl transferase (UDP-GTase) of piperine-treated V-79 cells occurred 30 min to 1 hr after the piperine pretreatment. Pretreatment of V-79 cells with piperine also caused an increase in the covalent binding of B[a]P-diol-epoxide to DNA, 2.3 times greater than that of the V-79 cells without piperine treatment. These results suggest that the promotion by piperine of B[a]P-induced cytotoxicity in V-79 lung fibroblast cells is due to mechanisms that decrease the activities of GST and UDP-GTase and increase the formation of a B[a]P-DNA adduct.

Inhibitory effect of crocetin on intracellular nucleic acid and protein synthesis in malignant cells

The possibility that dietary intake of diverse naturally occurring compounds may influence the occurrence of cancer is receiving considerable scientific attention. Previously, it was reported that an extract (Crocus sativus), which contains carotenoids, had an antitumor effect and inhibited colony formation and nucleic acid synthesis by malignant human cells. Epidemiological and experimental research has indicated that carotenoids might act as antitumor agents. We have studied crocetin, a carotenoid isolated from saffron, which has been shown to have biological activity. In our experiments we utilized three malignant human cell lines: HeLa (cervical epitheloid carcinoma), A549 (lung adenocarcinoma) and VA13 (SV-40 transformed fetal lung fibroblast) cells. The effect of crocetin on colony formation and cellular DNA, RNA and protein synthesis in these cells has been examined. Incubation of these cells with crocetin for 3 h caused a dose-dependent inhibition of nucleic acid and protein synthesis. Crocetin also had a dose-dependent inhibitory effect on DNA and RNA synthesis in isolated nuclei and suppressed the activity of purified RNA polymerase II.

Micronutrients and their influence on mutagenicity and malignant transformation

Many studies have now indicated that micronutrients, such as the carotenoids, tocopherols, and ascorbic acid, can prevent mutagenesis, genotoxic effects, or malignant transformation in bacteria and mammalian tissue, either in cell culture or in organ culture. In addition, multiple papers report that some of these micronutrients act as anticarcinogenic agents in animals treated with either ultraviolet light, ultraviolet light with chemicals, or chemical carcinogens alone. With respect to the carotenoids, early experiments used pharmacological doses of carotenoids, but more recent reports indicate that relatively small doses can be effective. Inasmuch as these effects are seen with both provitamin A and nonprovitamin A carotenoids, it would appear that these effects are intrinsic to the carotenoid molecule, and not due to the metabolic conversion to retinoids. Partially on the basis of these observations, it has been suggested that the micronutrients may function as chemopreventive agents for reducing the risk of cancer in humans. Numerous human intervention studies are underway to test this hypothesis.

Effects of carotenoids on cells

When added to cells, carotenoids display a variety of properties, including inhibition of mutagenesis, genotoxicity, malignant transformation, and growth of tumor cells. In addition, carotenoids increase cell-cell communication, and may have direct effects as cellular antioxidants.

Anticarcinogenic activities of carotenoids in animals and cellular systems

A large number of studies have indicated that carotenoid pigments act as anticarcinogenic agents in animals treated with either ultraviolet light, ultraviolet light with chemicals, or with chemical carcinogens alone. Although pharmacological doses of cartenoids were used in the early experiments, more recent evidence indicates that relatively small doses can be effective. These studies have been complemented by investigations in bacteria and mammalian tissue, either in cell culture or in organ culture, where it has been demonstrated that various carotenoid pigments can prevent mutagenesis, genotoxic effects, or malignant transformation. It would appear that these effects are intrinsic to the carotenoid molecule, and not necessarily due to the metabolic conversion to retinoids. Partially based on these observations, it has been suggested that carotenoid pigments may function as chemopreventive agents for reducing the risk of cancer in humans. Numerous studies are underway to test this hypothesis.