Effect of storage on carcinogenic activity of bracken fern

Effect of storage on carcinogenic activity of bracken fern was examined with inbred strain ACI rats of both sexes. The experiment was broken down into 3 groupings: Group I received a diet containing fresh dry bracken powder: Group II received a diet which contained the same dry bracken powder used in Group I but preserved for 1 year at 4 degrees C (Group II-C) or room temperature (Group II-R); Group III received the diet containing bracken powder preserved for 2 years at 4 degrees C (Group III-C) or room temperature (Group III-R). Three control groups corresponding to Groups I, II and III were fed a normal basal diet. Significant differences in incidence of ileal tumors were observed between Group I and both groups of Group III and latent period of intestinal tumors in Group II or III was longer than that of Group I. The results indicate a decreased carcinogenic activity of bracken fern by preservation.

Tumor induction in germ-free rats fed bracken (Pteridium aquilinum)

This study indicated that there was no significant difference in the incidence of intestinal tumors between germ-free and conventional rats fed a diet containing bracken, suggesting that gut microflora did not play a definite role in bracken tumorigenesis. However, bracken induced exclusively sarcoma but no adenocarcinoma in germ-free rats, whereas it induced predominantly adenocarcinoma in conventional rats.

Effect of a marginally lipotrope-deficient diet on methylazoxymethanol acetate carcinogenesis

The effect of a lipotrope-deficient diet on methylazoxymethanol acetate (MAM acetate) intestinal carcinogenesis was studied in 2 groups of ACI rats. For 10 weeks, weanling rats were fed a semisynthetic diet that was either high in fat and marginally deficient in the lipotropes (Group 1), or adequate for rats in all known respects (Group 2). Four weeks after the start of the experimental diets, the animals were given a weekly SC injection of MAM acetate, 25 mg/kg body weight, for a total of 5 times. Following the termination of the experimental diets, the animals were fed a basal diet until the end of the experiment (480 days). The tumor incidence in the jejunum-ileum and the number of tumors in the colon were significantly higher in Group 1 than in Group 2. These results suggest that a marginally lipotrope-deficient diet enhances MAM acetate carcinogenesis, probably in its early stage.

Test of carcinogenicity of quercetin, a widely distributed mutagen in food

The carcinogenicity of quercetin, a flavonol, was tested in six-week-old ddY mice of both sexes. Groups of 38 males and 35 females were given pellet diet containing 2% quercetin throughout their life span. As controls, 16 males and 15 females were given basal diet. Animals in both test and control groups developed leukemia and tumors of the lung, forestomach, mammary gland, adrenal, and soft part tissues. In addition, some animals in groups treated with quercetin developed tumors of the heart, liver, salivary gland, ovary, and uterus. The incidences of these tumors in test and control groups were not statistically different.

Effect of leupeptin, a protease inhibitor, on the development of spontaneous tumors in strain A mice

The effect of leupeptin, a protease inhibitor, on the development of spontaneous tumors was studied in strain A mice. Three-week-old mice were divided into two groups: one group was fed on diet containing 0.1% leupeptin and the other was fed on basal diet. The experiment was terminated 480 days after the start of a administration of the leupeptin diet. Almost all animals survived until the end of the experiment. In the group given the leupeptin diet, 15 of 50 mice developed liver tumors (14 of 25 males and 1 of 25 females). In the control group, only male mice developed liver tumors (4 of 23 males). There was a significant difference between the incidences of liver tumors in males fed leupeptin diet and basal diet, but there was not in the case of females.

Genotoxicity of pyrrolizidine alkaloids in the hepatocyte primary culture/DNA-repair test

The genotoxicity of 6 pyrrolizidine alkaloids and 2 related compounds was examined in the hepatocyte primary culture/DNA-repair test and compared to mutagenicity in a modified Salmonella/microsome test. All 6 pyrrolizidine alkaloids were positive in the DNA-repair test, and 4 of these are known to be carcinogenic. Of the 6 positive compounds, only 5 were mutagenic. Thus, the hepatocyte primary culture/DNA-repair test displays a comparable or better capacity than the bacterial mutagenesis test for detecting the genotoxic effects of this class of carcinogens.

CArcinogenic activity of clivorine, a pyrrolizidine alkaloid isolated from Ligularia dentata

The carcinogenic activity of clivorine, a pyrrolizidine alkaloid isolated from Ligularia dentata, was studied in inbred ACI rats. Twelve animals in the experimental group received a 0.005% solution of clivorine in drinking water for 340 days and survived beyond 440 days after the beginning of the experiment. Of this group, 8 developed tumors in the liver; 2 developed hemangioendothelial sarcomas, and 6 developed neoplastic nodules. The hemangioendothelial sarcoma showed metastasis in the lung of one rat. No tumors were observed in the liver of the control animals.

Chromosomal aberrations and mutation in cultured mammalian cells induced by pyrrolizidine alkaloids

4 pyrrolizidine alkaloids, heliotrine, lasiocarpine, petasitenine, and senkirkine, were tested for their effects of V79 Chinese hamster cells. All the alkaloids produced cytoplasmic vacuolization, and caused cellular and nuclear enlargement. Chromosomal aberrations were induced in cells treated with the alkaloids. Heliotrine and petasitenine induced interchromosomal exchanges, and lasiocarpine and senkirkine caused chromatid gaps. All the alkaloids induced an 8-azaguanine-resistant mutation in V79 cells by direct treatment for 48 h. Mutation was also induced by treatment with the alkaloids for 1 h in the presence of a metabolic activation system.

Characterization of mutagenic principles and carcinogenicity of dill weed and seeds

Among the various kinds of spices tested, the aqueous extracts of dill weed from Anethum graveolens L. and dill seeds from A. sowa D.C. (Umbelliferae), exhibited a mutagenicity to Salmonella typhimurium, strains TA98 and TA100. The aqueous methanol extracts were fractionated by the mutation assay using the strain TA98 with S-9 Mix. Isorhamnetin 3-sulfate (persicarin) and quercetin 3-sulfate were characterized as the mutagenic principles. Carcinogenicity was not observed for dill weed and seeds when the diets containing these in 33% were administered for 450 and 410 days, respectively, to the inbred strain ACI rats.

Effect of phenobarbital on induction of liver and lung tumors by dimethylnitrosamine in newborn mice

The effect of phenobarbital on simultaneous induction of liver and lung tumors was examined in inbred DDD mice. Group 1 of newborn mice received a single intraperitoneal (ip) injection of dimethylnitrosamine (DMN) and after weaning they were given 0.05% phenobarbital solution to drink. Group 2 received an injection of DMN like Group 1 but were then given normal water. Group 3 were injected ip with 0.9% NaCl solution and then given phenobarbital solution to drink as in Group 1, and Group 4 were injected with 0.9% NaCl solution like Group 3, and then given tap water to drink. The animals were examined 16 weeks after birth. In Group 1, 27 of 35 mice (77%) had liver tumor and 15 (43%) had lung tumor. In Group 2, 8 of 24 mice (33%) had liver tumor and 16 (67%) had lung tumor. Animals in Groups 3 and 4 did not develop tumors. The difference in the incidences of liver tumor, but not lung tumor, in Groups 1 and 2 was statistically significant (P less than 0.01); that is, a promoting effect of phenobarbital was observed in induction of liver tumor, but not lung tumor.

Induction of hepatic tumors in rats by senkirkine and symphytine

The carcinogenicity of the pyrrolizidine alkaloids senkirkine and symphytine was studied in male inbred ACI rats. Animals were divided into 3 groups: Group I received ip injections of freshly prepared senkirkine at a dose of 10% of the median lethal dose (LD50) twice weekly for 4 weeks and then once a week for 52 weeks. Group II received ip injections of symphytine at a dose of 10% of the LD50 by the same injection schedule as in group I. The control group was given ip injections of a 0.9% NaCl solution following the same injection schedule as in experimental groups. All group I rats survived for more than 290 days after the start of injections, and 9 of 20 rats developed liver cell adenoma. All group II animals survived for more than 330 days after the start of injections. Of 20 rats, 4 had liver tumors, 3 had hemangioendothelial sarcomas, and 1 had liver cell adenoma. The hemangioendothelial sarcomas showed metastasis in the lungs of 2 rats. The control group had no liver tumors.

Transplantable ileal adenocarcinomas of ACI rats

Transplantation of 9 kinds of bracken-induced ileal adenocarcinomas subcutaneously in ACI rats established two transplantable strains of adenocarcinoma (73-357, 77-238). Ascitic conversion succeeded in the strain 73-357. Biological and morphological, particularly electron microscopic, characteristics of these strains are reported.

Carcinogenicity examination of betel nuts and piper betel leaves

A dry powder of betel nuts, piper betel leaves and lime was administered to rats. Epidermal thickening was frequently observed in the upper digestive tracts of rats in groups fed the betel nut diet mixed with lime and the betel leaves diet, and a forestomach papilloma was seen in 1 rat given betel leaves diet. These epidermal changes were scarcely seen in rats given either betel nut or normal diet alone.

Effect of colostomy on intestinal carcinogenesis by methylazoxymethanol acetate in rats

The effect of the fecal stream on the induction of intestinal tumors was studied in 3 groups of SD rats. Rats in group 1 were subjected to single-barreled colostomies for the complete exclusion of the fecal stream at the proximal one-third level of the colons and were given consecutive iv injections of methylazoxymethanol acetate. Rats in group 2 were given methylazoxymethanol acetate alone. Rats in group 3 were not treated and served as controls. Tumors were noted in the small and large intestines of almost all rats in both groups 1 and 2. Even animals with single-barreled colostomies frequently developed tumors in the colon distal to the colostomy where the mucosa did not have contact with the fecal stream. These results indicated that carcinogens could probably reach the intestinal mucosa via the vascular system as well as by biliary transport.

Carcinogenic activity of Symphytum officinale

The carcinogenicity of Symphytum officinale L., Russian comfrey, used as a green vegetable or tonic, was studied in inbred ACI rats. Three groups of 19--28 rats each were fed comfrey leaves for 480--600 days; four additional groups of 15--24 rats were fed comfrey roots for varying lengths of time. A control group was given a normal diet. Hepatocellular adenomas were induced in all experimental groups that received the diets containing comfrey roots and leaves. Hemangioendothelial sarcoma of the liver was infrequently induced.

Carcinogenicity of boiling water extract of bracken, Pteridium aquilinum

Carcinogenicity of an aqueous extract of bracken was studied in inbred strain ACI rats. In Experiment 1, Group 1 rats received a diet containing unprocessed dry bracken powder for 3 months, Group 2 received the boiling water extract of dry bracken as drinking water for 16 months, Group 3 received the cold water extract of dry bracken as drinking water for 16 months, and Group 4 received a diet containing the concentrated boiling water extract of dry bracken during the whole experimental period. Rats in Experiment 2 also received a diet containing the boiling water extract of dry bracken. A control group was fed a normal diet. Majority of the animals in Group 1 developed multiple ileal tumors, such as adenomas and adenocarcinomas. In Group 2, 6 of 11 rats which survived beyond 7 months developed tumors in either the ileum or urinary bladder, or in both. Rats in Group 3 had no tumor. In Group 4 and in Experiment 2, all the animals except 1 rat in Experiment 2 had urinary bladder tumor. Furthermore, almost all the rats in these groups had simultaneously ileal tumors. Based on these results, it may be assumed that the carcinogen in bracken is extractable in boiling water and is most probably also water-soluble.

Effect of carbon tetrachloride on carcinogenicity of petasites japonicus and transplantability of induced tumors

Effect of carbon tetrachloride on the carcinogenicity of the flower stalk of Petasites japonicus was examined in 3 experimental groups of inbred strain ACI rats. Group 1 received 4% petasites diet until termination of the experiment and intragastric administration of CC14, once every 2 weeks, for a total of 15 times. Group 2 received only 4% petasites diet, and Group 3 CC14 and a basal diet. Another group of rats which were fed a basal diet served as a control groups. Both Group 1 and 2 showed the same incidence of hemangioendothelial sarcoma of the liver (6/22). However, the incidence of hyperplastic liver nodules (19/22) and liver cell adenomas (8/22) in Group 1 was significantly higher than in Group 2 (2/22, 0/22). No hyperplastic liver nodules or liver cell adenomas were noted in Group 3. These results indicate that the administration of CC14 probably enhanced the carcinogenic activity of Petasites japonicus in hepatocellular tumorigenesis. Three hemangioendothelial sarcomas of the liver induced in rats in Groups 1 and 2 were subcutaneously transplanted and established as transplantable tumor lines.

Effect of drying with hot forced draft and of mincing bracken fern on its carcinogenic activity

The carcinogenic activity of young bracken dried at a high temperature or minced by a mechanical chopper was compared with that of unprocessed bracken dried at room temperature. Inbred strain ACI rats of both sexes were divided into 4 groups; Group 1 received a diet containing the unprocessed bracken dried at a room temperature of below 30 degrees, Group 2 received a diet containing bracken dried at 70 approximately 90 degrees with a hot, forced draft, and Group 3 received the diet containing processed bracken that had been minced to a paste-like consistency using a mechanical chopper. The control group was fed a normal diet. Rats fed a bracken-containing diet developed tumors most frequently in the ileum. Comparison of Group 1 with Groups 2 and 3 showed no significant difference in the latent period, incidence, histologic types, or multiplicity of the intestinal tumors found in each animal.

Carcinogenic activity of petasitenine, a new pyrrolizidine alkaloid isolated from Petasites japonicus Maxim

The carcinogenic activity of petasitenine, a new pyrrolizidine alkaloid isolated from young flower stalk of Petasites japonicus, was studied in ACI rats. All rats that had received a 0.05% solution of petasitenine in drinking water died or were killed in moribund condition 72 days after the start of experiment. They showed necrosis, hemorrhage, and remarkable proliferation of the bile ducts in the liver. In another group that had received a 0.01% solution, 8 of 10 animals surviving beyond 160 days developed tumors in the liver, i.e., hemangioendothelial sarcomas in 5 rats and liver cell adenomas in 5 rats, 2 of which simultaneously developed hemangioendothelial sarcomas. No tumors were observed in the livers of the control animals.

Carcinogenic activity of coltsfoot, Tussilago farfara l

The carcinogenicity of young, pre-blooming flowers of coltsfoot, Tussilago farfara L., which is a herb of the tribe Senecioneae, family Compositae, and widely used as a herbal remedy, was studied in inbred strain ACI rats. Rats were divided into 4 groups: Group I received 32% coltsfoot diet for 4 days, and subsequently 16% diet until the termination of experiment. Groups II and III respectively received 8% and 4% coltsfoot diet for 600 days. Group IV was fed a normal diet as a control group. The experiments were terminated 600 days after the start of administration of coltsfoot diet. All the rats in Group I survived beyond 380 days after the start of feeding and 8 out of 12 rats developed hemangioendothelial sarcoma in the liver, whereas only one out of 10 rats developed the tumor in Group II, and no tumors were observed in Group III. Chemical studies on the dried, young flowers used in this experiment suggested that the carcinogenicity of coltsfoot is most probably due to senkirkine, a hepatotoxic pyrrolizidine alkaloid.

The occurrence of senkirkine in Tussilago farfara

The medicinal herb, Tussilago farfara L., is shown to contain the hepatotoxic pyrrolizidine alkaloid, senkirkine.

Intracisternal A particles in transplantable reticulum cell sarcoma of rats

Electron microscopic examination on three lines of transplantable reticulum cell sarcomas, induced spontaneously in the mesenteric lymph nodes of inbred strain ACI rats, proved the presence of intracisternal A particles in all the three tumor lines. The doughnut-shaped particles measured 50 to 70 nm and were seen to bud from the membranes of rough-surfaced endoplasmic reticulum. Frequency of appearance of these particles varied with the tumor line.