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Biomedical subjects

H Tokuda

Publications and source records attributed to H Tokuda.

402 records · Page 23Linked to original sources
PubMedDate not supplied

Studies on inhibitors of skin tumor promotion, VI. Inhibitory effects of quinones on Epstein-Barr virus activation.

To search for possible antitumor promoters, we carried out a primary screening of fifty-one quinones (anthraquinones, naphthoquinones, azaanthraquinones, and azafluorenones) and related compounds, using their possible inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. Some of these quinones, notably 5-hydroxy-1,2-methylenedioxy-anthraquinone [9], shikonin [29], 2-acetylfuranonaphthoquinone [32], 5,8-dihydroxycleistopholine [37], and 5,8-dihydroxy-2-methyl-1-azaanthraquinone [45], were observed to significantly inhibit the EBV-EA activation at low doses. The position and number of hydroxyl groups on phenyl rings of these quinones affected the inhibitory activity on EBV-EA activation. The investigation indicates that 9, 29, 32, 37, and 45 might be valuable anti-tumor promoters.

Animals↗
PubMedDate not supplied

Studies on inhibitors of skin tumor promotion, IX. Neolignans from Magnolia officinalis.

Three neolignans, known as magnolol [1], honokiol [2] and the new monoterpenylmagnolol [3], were isolated from the bark of Magnolia officinalis as inhibitors of Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA). The structure of 3 was determined from 2D nmr spectral data and difference nOe experiments. The MeOH extract of this plant and magnolol exhibited remarkable inhibitory effects on mouse skin tumor promotion in an in vivo two stage carcinogenesis test. This investigation indicates that these neolignans and the extract might be valuable antitumor promoters.

Animals↗
PubMedDate not supplied

Suppression of lung and liver carcinogenesis in mice by oral administration of myo-inositol.

It has been reported that myo-inositol can inhibit carcinogenesis in various organs, such as the mammary gland, colon and lung. In the present study, at first, inhibitory effects of myo-inositol on lung carcinogenesis were confirmed. Then, the influence of myo-inositol on liver carcinogenesis in mice was investigated. In C3H/He male mice, the rate of spontaneous liver carcinogenesis is known to be high. Using this experimental model, the effects of oral administration of myo-inositol (added into the drinking water at the concentration of 1%) were assessed. Significant suppression of liver carcinogenesis was observed in mice treated with myo-inositol for 40 weeks. In the control group without myo-inositol administration, 88% of the animals developed liver tumors, whereas in the myo-inositol-supplemented group, the incidence of liver tumors was 38% (p < 0.05). The average number of liver tumors per mouse was also decreased significantly by myo-inositol treatment; from 7.8 in the control group to 0.8 in the myo-inositol-supplemented group (p < 0.01). Thus, myo-inositol may be useful for cancer chemoprevention in the liver, as well as the lung.

Administration, Oral↗
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A new analytical method for the detection of anti-tumor promoters using flow cytometry.

Flow cytometry analysis was applied to the measurement of Epstein-Barr virus (EBV) induction which is used as a short term assay for anti-tumor promoters. The data obtained by measurement with flow cytometry were parallel with those of the fluorescence microscopic method. Flow cytometry is rapid, quantitative and should be applicable for the EBV activating test.

Anticarcinogenic Agents↗
PubMedDate not supplied

Antitumor effects of soybean hypocotyls and soybeans on the mammary tumor induction by N-methyl-n-nitrosourea in F344 rats.

BACKGROUND: Soybeans are reported to have cancer inhibitory effects, probably due to their isoflavones. Soybean hypocotyls are embryo buds of soybeans and contain a higher amount of isoflavones and other factors than soybeans themselves. MATERIALS AND METHODS: The effects of soybean protein and soybean hypocotyls as diets on the development of N-methyl-n-nitrosourea (MNU) induced tumors were examined in female F344 rats. For this trial, 120 animals were used and at 6 weeks of age, groups of 30 animals were fed diets containing casein, soy protein isolate (SPI), 1.5% soybean hypocotyls and 5% soybean hypocotyls. Three weeks later all the animals except the control animals received a first dose (37.5 mg/kg body weight) of MNU by tail vein injection. At 29 weeks of age the animals received a second MNU dose (50 mg/kg body weight). Testing was performed 42 weeks after the first MNU dose. RESULTS: Analysis of cumulative palpable tumor incidence indicated that final tumor development of the SPI diet group and the hypocotyl diet groups was less than that of the casein diet group. Tumors were detected in one or more sites from 9 out of 24 rats in the casein diet group, 5 of 20 rats in SPI diet group, 6 out of 24 rats in the 1.5% hypocotyl diet group and 6 out of 23 rats in the 5% hypocotyl diet group. Pairwise comparisons indicated that the formation of tumors during the experiment was significantly less rapid in the SPI diet group and the hypocotyl diet groups than the casein group. No difference in tumor promotion was observed between the SPI diet group and the soybean hypocotyl diet groups. CONCLUSION: Our results suggest that dietary soybeans and soybean hypocotyls are capable of suppressing tumor promotion.

Animals↗