Inhibition of colonic aberrant crypt foci by curcumin in rats is affected by age

Association of curry consumption with blood lipids and glucose levels

BACKGROUND/OBJECTIVES

Curcumin, an active ingredient in turmeric, is highly consumed in South Asia. However, curry that contains turmeric as its main spice might be the major source of curcumin in most other countries. Although curcumin consumption is not as high in these countries as South Asia, the regular consumption of curcumin may provide a significant health-beneficial effect. This study evaluated whether the moderate consumption of curry can affect blood glucose and lipid levels that become dysregulated with age.

SUBJECTS/METHODS

This study used data obtained from the Korea National Health and Nutrition Examination Survey, conducted from 2012 to 2013, to assess curry consumption frequency as well as blood glucose and blood lipid levels. The levels of blood glucose and lipids were subdivided by age, sex, and body mass index, and compared according to the curry consumption level. The estimates in each subgroup were further adjusted for potential confounding factors, including the diagnosis of diseases, physical activity, and smoking.

RESULTS

After adjusting for the above confounding factors, the blood glucose and triglyceride levels were significantly lower in the moderate curry consumption group compared to the low curry consumption group, both in older (> 45) male and younger (30 to 44) female overweight individuals who have high blood glucose and triglyceride levels.

CONCLUSIONS

These results suggest that curcumin consumption, in an ordinary diet, can have health-beneficial effects, including being helpful in maintaining blood glucose and triglyceride levels that become dysregulated with age. The results should be further confirmed in future studies.

The chemopreventive potential of Curcuma purpurascens rhizome in reducing azoxymethane-induced aberrant crypt foci in rats

Curcuma purpurascens BI. rhizome, a member of the Zingiberaceae family, is a popular spice in Indonesia that is traditionally used in assorted remedies. Dichloromethane extract of C. purpurascens BI. rhizome (DECPR) has previously been shown to have an apoptosis-inducing effect on colon cancer cells. In the present study, we examined the potential of DECPR to prevent colon cancer development in rats treated with azoxymethane (AOM) (15 mg/kg) by determining the percentage inhibition in incidence of aberrant crypt foci (ACF). Starting from the day immediately after AOM treatment, three groups of rats were orally administered once a day for 2 months either 10% Tween 20 (5 mL/kg, cancer control), DECPR (250 mg/kg, low dose), or DECPR (500 mg/kg, high dose). Meanwhile, the control group was intraperitoneally injected with 5-fluorouracil (35 mg/kg) for 5 consecutive days. After euthanizing the rats, the number of ACF was enumerated in colon tissues. Bax, Bcl-2, and proliferating cell nuclear antigen (PCNA) protein expressions were examined using immunohistochemical and Western blot analyses. Antioxidant enzymatic activity was measured in colon tissue homogenates and associated with malondialdehyde level. The percentage inhibition of ACF was 56.04% and 68.68% in the low- and high-dose DECPR-treated groups, respectively. The ACF inhibition in the treatment control group was 74.17%. Results revealed that DECPR exposure at both doses significantly decreased AOM-induced ACF formation, which was accompanied by reduced expression of PCNA. Upregulation of Bax and downregulation of Bcl-2 suggested the involvement of apoptosis in the chemopreventive effect of DECPR. In addition, the oxidative stress resulting from AOM treatment was significantly attenuated after administration of DECPR, which was shown by the elevated antioxidant enzymatic activity and reduced malondialdehyde level. Taken together, the present data clearly indicate that DECPR significantly inhibits ACF formation in AOM-treated rats and may offer protection against colon cancer development.

Estimation of curcumin intake in Korea based on the Korea National Health and Nutrition Examination Survey (2008-2012)

BACKGROUND/OBJECTIVES

Turmeric and its active component curcumin have received considerable attention due to their many recognized biological activities. Turmeric has been commonly used in food preparation and herbal remedies in South Asia, leading to a high consumption rate of curcumin in this region. However, the amount of curcumin in the Korean diet has not yet been estimated, where turmeric is not a common ingredient.

SUBJECTS/METHODS

This study utilized the combined data sets obtained from the Korea National Health and Nutrition Examination Survey conducted from 2008 to 2012 in order to estimate the curcumin intake in the Korean diet. The mean intake of curcumin was estimated from the amount of curcumin-containing foods (curry powder and ready-made curry) consumed using reported curcumin content in commercial turmeric and curry powders.

RESULTS

Only 0.06% of Koreans responded that they consumed foods containing curcumin in a given day, and 40% of them were younger than 20 years of age. Curcumin-containing foods were largely prepared at home (72.9%) and a significant proportion (20.4%, nearly twice that of all other foods) was consumed as school and workplace meals. The estimated mean turmeric intake was about 0.47 g/day corresponding to 2.7-14.8 mg curcumin, while the average curry powder consumption was about 16.4 g, which gave rise to curcumin intake in the range of 8.2-95.0 mg among individuals who consumed curcumin. The difference in estimated curcumin intake by using the curcumin content in curry powder and turmeric may reflect that curry powder manufactured in Korea might contain higher amounts of other ingredients such as flour, and an estimation based on the curcumin content in the turmeric might be more acceptable.

CONCLUSIONS

Thus, the amount of curcumin that can be obtained from the Korean diet in a day is 2.7-14.8 mg, corresponding to nearly one fourth of the daily curcumin intake in South Asia, although curcumin is rarely consumed in Korea.

Curcumin as a therapeutic agent: the evidence from in vitro, animal and human studies

Curcumin is the active ingredient of turmeric. It is widely used as a kitchen spice and food colorant throughout India, Asia and the Western world. Curcumin is a major constituent of curry powder, to which it imparts its characteristic yellow colour. For over 4000 years, curcumin has been used in traditional Asian and African medicine to treat a wide variety of ailments. There is a strong current public interest in naturally occurring plant-based remedies and dietary factors related to health and disease. Curcumin is non-toxic to human subjects at high doses. It is a complex molecule with multiple biological targets and different cellular effects. Recently, its molecular mechanisms of action have been extensively investigated. It has anti-inflammatory, antioxidant and anti-cancer properties. Under some circumstances its effects can be contradictory, with uncertain implications for human treatment. While more studies are warranted to further understand these contradictions, curcumin holds promise as a disease-modifying and chemopreventive agent. We review the evidence for the therapeutic potential of curcumin from in vitro studies, animal models and human clinical trials.

New mechanisms and therapeutic potential of curcumin for colorectal cancer

Curcumin is a polyphenol derived from Curcuma longa. Over the last few years, a number of studies have provided evidence of its main pharmacological properties including chemosensitizing, radiosensitizing, wound healing activities, antimicrobial, antiviral, antifungical, immunomodulatory, antioxidant and anti-inflammatory. More recent data provide interesting insights into the effect of this compound on cancer chemoprevention and chemotherapy. In fact, preclinical studies have shown its ability to inhibit carcinogenesis in various types of cancer including colorectal cancer (CRC). Curcumin has the capacity of interact with multiple molecular targets affecting the multistep process of carcinogenesis. Also, curcumin is able to arrest the cell cycle, to inhibit the inflammatory response and the oxidative stress and to induce apoptosis in cancer cells. Likewise, it has been shown to possess marked antiangiogenic properties. Furthermore, curcumin potentiates the growth inhibitory effect of cyclo-oxygenase (COX)-2 inhibitors and traditional chemotherapy agents implicating another promising therapy regimen in the future treatment of CRC. However, its clinical advance has been hindered by its short biological half-life and low bioavailability after oral administration. This review is intended to provide the reader an update of the bioavailability and pharmacokinetics of curcumin and describes the recently identified molecular pathways responsible of its anticancer potential in CRC.

Anticancer and carcinogenic properties of curcumin: considerations for its clinical development as a cancer chemopreventive and chemotherapeutic agent

A growing body of research suggests that curcumin, the major active constituent of the dietary spice turmeric, has potential for the prevention and therapy of cancer. Preclinical data have shown that curcumin can both inhibit the formation of tumors in animal models of carcinogenesis and act on a variety of molecular targets involved in cancer development. In vitro studies have demonstrated that curcumin is an efficient inducer of apoptosis and some degree of selectivity for cancer cells has been observed. Clinical trials have revealed that curcumin is well tolerated and may produce antitumor effects in people with precancerous lesions or who are at a high risk for developing cancer. This seems to indicate that curcumin is a pharmacologically safe agent that may be used in cancer chemoprevention and therapy. Both in vitro and in vivo studies have shown, however, that curcumin may produce toxic and carcinogenic effects under specific conditions. Curcumin may also alter the effectiveness of radiotherapy and chemotherapy. This review article analyzes the in vitro and in vivo cancer-related activities of curcumin and discusses that they are linked to its known antioxidant and pro-oxidant properties. Several considerations that may help develop curcumin as an anticancer agent are also discussed.

Curcumin inhibits proliferation, invasion, angiogenesis and metastasis of different cancers through interaction with multiple cell signaling proteins

Because most cancers are caused by dysregulation of as many as 500 different genes, agents that target multiple gene products are needed for prevention and treatment of cancer. Curcumin, a yellow coloring agent in turmeric, has been shown to interact with a wide variety of proteins and modify their expression and activity. These include inflammatory cytokines and enzymes, transcription factors, and gene products linked with cell survival, proliferation, invasion, and angiogenesis. Curcumin has been found to inhibit the proliferation of various tumor cells in culture, prevents carcinogen-induced cancers in rodents, and inhibits the growth of human tumors in xenotransplant or orthotransplant animal models either alone or in combination with chemotherapeutic agents or radiation. Several phase I and phase II clinical trials indicate that curcumin is quite safe and may exhibit therapeutic efficacy. These aspects of curcumin are discussed further in detail in this review.

Curcumin as "Curecumin": from kitchen to clinic

Although turmeric (Curcuma longa; an Indian spice) has been described in Ayurveda, as a treatment for inflammatory diseases and is referred by different names in different cultures, the active principle called curcumin or diferuloylmethane, a yellow pigment present in turmeric (curry powder) has been shown to exhibit numerous activities. Extensive research over the last half century has revealed several important functions of curcumin. It binds to a variety of proteins and inhibits the activity of various kinases. By modulating the activation of various transcription factors, curcumin regulates the expression of inflammatory enzymes, cytokines, adhesion molecules, and cell survival proteins. Curcumin also downregulates cyclin D1, cyclin E and MDM2; and upregulates p21, p27, and p53. Various preclinical cell culture and animal studies suggest that curcumin has potential as an antiproliferative, anti-invasive, and antiangiogenic agent; as a mediator of chemoresistance and radioresistance; as a chemopreventive agent; and as a therapeutic agent in wound healing, diabetes, Alzheimer disease, Parkinson disease, cardiovascular disease, pulmonary disease, and arthritis. Pilot phase I clinical trials have shown curcumin to be safe even when consumed at a daily dose of 12g for 3 months. Other clinical trials suggest a potential therapeutic role for curcumin in diseases such as familial adenomatous polyposis, inflammatory bowel disease, ulcerative colitis, colon cancer, pancreatic cancer, hypercholesteremia, atherosclerosis, pancreatitis, psoriasis, chronic anterior uveitis and arthritis. Thus, curcumin, a spice once relegated to the kitchen shelf, has moved into the clinic and may prove to be "Curecumin".

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".

Enhanced estrogenic responses and sensitivity to azoxymethane following dietary soy isoflavone supplementation in older female rats

Soy isoflavones are popular supplements among middle-aged and older women based on their potential protection against cancer and their use as alternative hormone replacement therapy. The purpose of this study was to investigate the effects of dietary soy isoflavones on early stage colon cancer in various ages of female rats. Young (1month), mature (11month) and old (22month) female Fisher 344 rats were fed either the control diet or a diet containing 0.4% soy isoflavone isolate for 1week, injected once with 20mg/kg azoxymethane (AOM) and maintained on the diets for another 15weeks. The concentration of isoflavones in the diet was 2g/kgdiet, composed of 1.2g/kg genistin, 0.7g/kg daidzin and 0.1g/kg other isoflavones including glycitin, acetylgenistin, acetyldaidzin, genistein, daidzein, and glycitein. There was no difference over all ages in the development of preneoplastic colonic aberrant crypt foci between rats fed the soy compared to the control diet, indicating that the soy diet did not provide protection against early stage colonic carcinogenesis. On the contrary, several adverse effects of soy supplementation in female AOM-treated rats were observed. Soy-supplemented rats had greater weight loss and a slower recovery of body weight following the AOM injection compared to rats fed the control diet and these changes increased with age. Five of the 21 rats fed the soy supplement died before the end of the experiment while all animals on the control diet survived to term. The density of normal crypts lining the colonic mucosa was reduced in rats fed the soy compared to control diet, indicating gastrointestinal damage. Uterine weights, serum estradiol and serum isoflavone levels were increased in mature and old female rats fed the soy-supplemented diets compared to age-matched controls, suggesting an increasing estrogenic response with age to isoflavone supplementation. These adverse effects of soy isoflavones in aged female animals need further examination because women, and particularly older women, are the prime target population for consumption of soy supplements.

Effect of azoxymethane and curcumin on transcriptional levels of cyclooxygenase-1 and -2 during initiation of colon carcinogenesis

BACKGROUND

Curcumin is well documented as an effective colonic chemopreventive agent in preclinical studies. Inhibition of arachidonic acid metabolism has been considered one of anticarcinogenic mechanisms of curcumin. We recently reported resistance of middle-aged F344 male rats to inhibition of azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) by curcumin (Nutr Cancer, 48, 37-43). It was important to confirm this finding and to find potential mechanisms responsible, as loss of preventive activity of curcumin due to aging was a novel finding, with important implications for human intervention trials.

METHODS

To confirm our previous findings, and investigate arachidonic acid metabolism as a potential mechanism of age-related differences in response to curcumin, middle-aged F344 male rats were given AOM injections after being fed their experimental diets, 0.6% curcumin or control diet. Colonic ACF were evaluated and colonic levels of cyclooxygenase (COX)-1 and 2 mRNA and prostaglandin E2 (PGE2) were measured. Next, we investigated the short-term effect of AOM and curcumin on arachidonic acid metabolism in young rats. Six week-old rats were given injections of either AOM or untreated following their experimental diets. Colonic COX-1 and COX-2 mRNA as well as PGE2 levels were measured shortly after AOM treatment. Lastly, three different ages of F344 rats were treated with either AOM or saline, and colonic COX-1 and COX-2 mRNA levels were measured shortly after the injections to find if aging alters the effect of AOM on COX mRNA expression.

RESULTS

In middle-aged rats, dietary curcumin did not reduce the number of ACF and surprisingly increased colonic levels of COX-2 mRNA. Colonic COX-2 and PGE2 levels were also significantly increased in young rats fed curcumin after AOM injections. Interestingly, AOM did not affect COX-2 but decreased COX-1 expression in all ages.

CONCLUSIONS

Our study suggests that during initiation, AOM inhibits colonic COX-1 expression without affecting COX-2 and dietary curcumin may increase COX-2 expression to compensate AOM-induced reduction of COX-1 expression.