Michiaki Murakoshi

Cancer prevention by carotenoids

Various natural carotenoids seem to be valuable for cancer prevention, and these carotenoids may be more suitable in combinational use, rather than in single use. In fact, we have proven that combinational use of natural carotenoids resulted in significant suppression of liver cancer. Patients of viral hepatitis with cirrhosis were administered with beta-cryptoxanthin-enriched Mandarin orange juice, in addition to capsules of carotenoids mixture. Cumulative incidence of hepatocellular carcinoma development was compared with that in the group treated with carotenoids mixture capsules alone, or in the group without treatment (control group). In the data analysis at year 2.5, cumulative incidence of liver cancer in beta-cryptoxanthin-enriched orange juice with carotenoids mixture capsules-treated group was lower than that in the control group (p=0.05). Cumulative incidence of liver cancer in the group treated with carotenoids mixture capsules alone was also lower than that in the control group, but not statistically significant.

Inhibitory effects of natural carotenoids, α-carotene, β-carotene, lycopene and lutein, on colonic aberrant crypt foci formation in rats

Inhibitory effect of four carotenoids prevalent in human blood and tissues against the formation of colonic aberrant crypt foci was examined in Sprague-Dawley rats. They received three intrarectal doses of N-methylnitrosourea in week 1, and a daily gavage of de-escalated doses of carotenoids during weeks 2 and 5. Lycopene, lutein, α-carotene and palm carotenes (a mixture of α-carotene, β-carotene and lycopene) inhibited the development of aberrant crypt foci quantitated at week 6, but β-carotene did not. The results suggested that lycopene and lutein in small doses may potentially prevent colon carcinogenesis.

Inhibitory effects of fucoxanthin, a natural carotenoid, on N-myc expression and cell cycle progression in human malignant tumor cells

Fucoxanthin, a natural carotenoid prepared from brown algae, inhibited the growth of GOTO cells, a human neuroblastoma cell line. Fucoxanthin at 10 micrograms/ml reduced the growth rate of GOTO cells to 38% of the control at day 3 after drug treatment. Flowcytometric analysis revealed that fucoxanthin caused the arrest in the G0-G1 phase of cell cycle. Expression of N-myc gene was proved to be decreased by fucoxanthin as early as 4 h after treatment at 10 micrograms/ml and that may be important for the mechanism of anti-proliferative action of the carotenoid.

Chemoprevention by lycopene of mouse lung neoplasia after combined initiation treatment with DEN, MNU and DMH

An investigation was conducted to assess the chemopreventive potential of lycopene (LP), a naturally occurring hydrocarbon carotenoid found in tomatoes and their products, administered during the post-initiation stage in a multiorgan carcinogenesis model. One hundred eighteen B6C3F1 mice of both sexes were subjected to combined treatment with diethylnitrosamine (DEN), N-methyl-N-nitrosourea (MNU) and 1,2-dimethylhydrazine (DMH) from day 11 after birth to week 9 (DMD treatment) (groups 1 and 2) or their vehicles (group 3). Then group 1 received LP (25 or 50 ppm in drinking water) for 21 weeks from weeks 11 to 32. Group 2 served as a carcinogen alone control and group 3 was given only LP (25 or 50 ppm). All surviving animals were sacrificed at week 32 and the major organs, including the liver, lung, kidney and colon, were histologically examined. The incidences and multiplicities of lung adenomas plus carcinomas combined in male mice in group 1 receiving 50 ppm LP were significantly decreased as compared to the DMD alone or DMD and 25 ppm LP groups (75.0 versus 18.8%, P < 0.02; 0.94 +/- 0.17 versus 0.25 +/- 0.14, P < 0.001). No such effect was observed for females. Although hepatocellular carcinomas were lacking in the DMD and LP groups while two cases were found in the DMD alone group, this difference was not statistically significant. The values for aberrant crypt foci (ACF) and tumors in the colon and kidney did not show any significant variation among the carcinogen-treated subgroups. The results suggest that LP exerts a chemopreventive effect limited to male lung carcinogenesis when given in the post-initiation stage to B6C3F1 mice.

Inhibition of initiation and early stage development of aberrant crypt foci and enhanced natural killer activity in male rats administered bovine lactoferrin concomitantly with azoxymethane

The influence of concomitant administration of bovine lactoferrin (bLF) on induction of aberrant crypt foci (ACF) by azoxymethane was investigated in male F344 rats. Two percent bLF and 3% Bifidobacterium longum (B. longum), as a positive control, significantly decreased the numbers of ACF as well as the total numbers of aberrant crypts reproducibly in three independent studies (2% bLF, P < 0.01; 3% B. longum, P < 0.05). Most importantly large size foci composed of four or more crypts were always significantly decreased by 2% bLF (P < 0.05). Additional investigation of the natural killer activity of spleen cells demonstrated enhancement by bLF (P < 0.01) and B. longum (P < 0.01) in line with the levels of influence on foci induction, indicating a possible role for elevated immune cytotoxicity in the observed inhibition.

Cancer Prevention by Phytochemicals

Information has been accumulated indicating that diets rich in vegetables and fruits can reduce the risk of a number of chronic diseases, including cancer, cardiovascular disease, diabetes and age-related macular degeneration. Phytochemicals (various factors in plant foods), such as carotenoids, antioxidative vitamins, phenolic compounds, terpenoids, steroids, indoles and fibers, have been considered responsible for the risk reduction. Among them, a mixture of natural carotenoids has been studied extensively and proven to show beneficial effects on human cancer prevention.

Potent anti-obesity effect of enteric-coated lactoferrin: decrease in visceral fat accumulation in Japanese men and women with abdominal obesity after 8-week administration of enteric-coated lactoferrin tablets.

Lactoferrin (LF), a multifunctional glycoprotein in mammalian milk, is reported to exert a modulatory effect on lipid metabolism. The aim of the present study was to elucidate whether enteric-coated LF (eLF) might improve visceral fat-type obesity, an underlying cause of the metabolic syndrome. Using a double-blind, placebo-controlled design, Japanese men and women (n 26; aged 22-60 years) with abdominal obesity (BMI>25 kg/m2, and visceral fat area (VFA)>100 cm2) consumed eLF (300 mg/d as bovine LF) or placebo tablets for 8 weeks. Measurement of the total fat area, VFA and subcutaneous fat area from computed tomography images revealed a significant reduction in VFA ( - 14.6 cm2) in the eLF group, as compared with the placebo controls ( - 1.8 cm2; P = 0.009 by ANCOVA). Decreases in body weight, BMI and hip circumference in the eLF group ( - 1.5 kg, - 0.6 kg/m2, - 2.6 cm) were also found to be significantly greater than with the placebo (+1.0 kg, +0.3 kg/m2, - 0.2 cm; P = 0.032, 0.013, 0.041, respectively). There was also a tendency for a reduction in waist circumference in the eLF group ( - 4.4 cm) as compared with the placebo group ( - 0.9 cm; P = 0.073). No adverse effects of the eLF treatment were found with regard to blood lipid or biochemical parameters. From these results, eLF appears to be a promising agent for the control of visceral fat accumulation.

Differential Dose‐dependent Effects of α‐, β‐Carotenes and Lycopene on Gap‐junctional Intercellular Communication in Rat Liver in vivo

In order to examine the relevance of alteration of gap‐junctional intercellular communication (GJIC) to chemopreventive activity against carcinogenesis, the effects of α andβ ‐carotene as well as lycopene, typical chemopreventive carotenoids, on cell coupling via gap junctions in rat liver in vivo were studied using a direct functional dye‐transfer technique. We found that all three test compounds given at a dose of 50 mg/kg‐body weight (b.w.) daily, 5 times by gavage, inhibited GJIC, while similar treatment with 5 mg/kg b.w. caused enhancement, especially in the β‐carotene and lycopene‐treated groups. At the dose level of 0.5 mg/kg b.w., the three compounds had no effect. The findings show that all three agents differentially modulate GJIC depending on the dose, with beneficial effects on cell communication only detected at the one dose. The result suggests that determination of the dose of chemicals to be used is crucial for human intervention studies.

Effects of pepsin and trypsin on the anti-adipogenic action of lactoferrin against pre-adipocytes derived from rat mesenteric fat

Lactoferrin (LF) is a multifunctional glycoprotein in mammalian milk. In a previous report, we showed that enteric-coated bovine LF tablets can decrease visceral fat accumulation, hypothesising that the enteric coating is critical to the functional peptides reaching the visceral fat tissue and exerting their anti-adipogenic activity. The aim of the present study was to assess whether ingested LF can retain its anti-adipogenic activity. We therefore investigated the effects of LF and LF treated with digestive enzymes (the stomach enzyme pepsin and the small intestine enzyme trypsin) on lipid accumulation in pre-adipocytes derived from the mesenteric fat tissue of male Sprague-Dawley rats. Lipid accumulation in pre-adipocytes was significantly reduced by LF in a dose-dependent manner and was associated with reduction in gene expression of CCAAT/enhancer binding protein delta, CCAAT/enhancer binding protein alpha and PPARγ as revealed by DNA microarray analysis. Trypsin-treated LF continued to show anti-adipogenic action, whereas pepsin-treated LF abrogated the activity. When an LF solution (1000 mg bovine LF) was administered by gastric intubation to Sprague-Dawley rats, immunoreactive LF determined by ELISA could be detected in mesenteric fat tissue at a concentration of 14·4 μg/g fat after 15 min. The overall results point to the importance of enteric coating for action of LF as a visceral fat-reducing agent when administered in oral form.

Japanese sake yeast supplementation improves the quality of sleep: a double‐blind randomised controlled clinical trial

Activation of adenosine A2a receptors in cerebral neurons induces sleep in various mammals. It was previously found that Japanese sake yeast enriched in adenosine analogues activates A2a receptors in vitro and induces sleep in mice. Here it is reported that sake yeast activated A2a receptors in a cultured human cell line and improved human sleep quality in a clinical trial. Sake yeast activated A2a receptors in HEK cells in a dose‐dependent manner with an EC50 of 40 μg mL−1, and the activation was attenuated almost completely by the A2a receptor antagonist ZM241385 with an IC50 of 73 nm. In a double‐blind placebo‐controlled crossover clinical study, 68 healthy participants ingested tablets containing either 500 mg of sake yeast powder or a placebo (cellulose) 1 h before sleep for 4 days. Electroencephalograms were recorded during sleep at home with a portable device for 4 week days. Electroencephalogram analyses revealed that sake yeast supplementation significantly (P = 0.03) increased delta power during the first cycle of slow‐wave sleep by 110%, without changing other sleep parameters. Sake yeast supplementation also significantly increased growth hormone secretion in the urine on awakening by 137% from 3.17 ± 0.41 (placebo) to 4.33 ± 0.62 (sake yeast) pg mg−1 creatinine (P = 0.03). Subjective sleepiness (P = 0.02) and fatigue (P = 0.06) in the morning were improved by sake yeast. Given these benefits and the absence of adverse effects during the study period, it was concluded that sake yeast supplementation is an effective and safe way to support daily high‐quality, deep sleep.