Anticlastogenic and anticarcinogenic potential of Thai bitter gourd fruits.

Thai bitter gourd fruits (Momordica charantia Linn., TBG) has been previously demonstrated to possess phase II detoxificating enzymes inducing properties, as well as the ability to reduce phase I carcinogen activating enzyme activity in rat liver. In addition, it was partially inhibited 7,12-dimethylbenz(a)anthracene (DMBA)- induced mammary gland carcinogenesis in female Sprague-Dawley rats. In this study, we therefore examined the anticlastogenic and anticarcinogenic effect of TBG against clastogens, cyclophosphamide (CYP) and DMBA, in mice using the in vivo erythrocyte micronucleus assay and azoxymethane (AOM)-induced colon carcinogenesis in rats, respectively. For anticlastogenicity test, male mice were fed with modified AIN-76 diets containing 6.25% and 12.5% of ground freeze-dried TBG for 2 weeks prior to administration of clastogens till the end of experiment. Blood samples were collected and counted for reticulocytes by using the fluorescent microscope. For anticarcinogeicity test, male Wistar rats were fed with modified AIN-76 diets containing 5% and 10% ground freeze-dried TBG for 2 weeks prior to, during and 1 week after the completion of AOM administration (15 mg/kg once a week for 2 weeks). It was found that TBG at 6.25% resulted in a significant reduction in micronucleated peripheral reticulocytes (MNRETs) induced by only CYP. Study on anticarcinogenic potential demonstrated that rats fed with TBG diets at the concentration tested developed significantly higher incidence as well as the multiplicities of colon tumors than the control group. These results demonstrated that Thai bitter gourd fruits possesses anticlastogenic potential against clastogen in the mouse. Interestingly, it had no preventive potential against AOM-induced colon carcinogenesis in rat, rather increasing the incidence of colonic neoplasm when giving during the initiation stage.

Quinone reductase inducers in Azadirachta indica A. Juss flowers, and their mechanisms of action.

We have previously shown that the flowers of neem tree (Azadirachta indica A. Juss, family Meliaceae), Thai variety, strongly induced the activity of glutathione S-transferase (GST) while resulting in a significant reduction in the activities of some cytochrome P(450)-dependent monooxygenases in rat liver, and possess cancer chemopreventive potential against chemically-induced mammary gland and liver carcinogenesis in rats. In the present study, 2 chemicals possessing strong QR inducing activity were fractionated from neem flowers using a bioassay based on the induction of QR activity in mouse hepatoma Hepa 1c1c7 cultured cells. Spectroscopic characteristics revealed that these compounds were nimbolide and chlorophylls, having CD (concentration required to double QR specific activity) values of 0.16 and 3.8 mug/ml, respectively. Nimbolide is a known constituent of neem leaves, but was found for the first time here in the flowers. Both nimbolide and chlorophylls strongly enhanced the level of QR mRNA in Hepa 1c1c7 cells, as monitored by northern blot hybridization, indicating that the mechanism by which these constituents of neem flowers induced QR activity is the induction of QR gene expression. These findings may have implication on cancer chemopreventive potential of neem flowers in experimental rats previously reported.

Mutagenicity of the drinking water supply in Bangkok.

Seventeen samples of tap water in Bangkok and 2 neighboring provinces were collected in winter and summer, concentrated and tested for mutagenic activity using the Ames Salmonella mutagenesis assay. Preliminary results demonstrated that concentrated tap water exhibited clear mutagenicity towards S. typhimurium TA100 and YG1029, but not towards TA98 and YG1024, in the absence of S9 mix, and the addition of S9 mix markedly decreased the mutagenicity to both tester strains. Amberlite( ) XAD-2 resin, but not blue rayon, was able to adsorb mutagens from water at pH 2. Our data clearly demonstrated that all tap water samples prepared by chlorination of Chao Phraya River water were mutagenic to strain TA100 without S9 mix, inducing 3,351 + 741 and 2,216 + 770 revertants/l, in winter and summer, respectively. On the other hand, however, tap water samples prepared from ground water were not mutagenic. Furthermore, it was found that boiling for only 5 min and filtration through home purifying system containing activated charcoal and mixed resin units were very effective to abolish the mutagenicity of water. Storage of water also significantly decreased the mutagenicity, however, it took 2-3 weeks to totally abolish it. Additionally, we also found 1 out of 6 brands of commercially available bottled drinking water to be mutagenic, with about 26 % of the average mutagenicity of tap water. The results in the present study clearly demonstrated that chlorinated tap water in Bangkok and neighboring provinces contain direct-acting mutagens causing capable of causing base-pair substitution. Boiling and filtration of tap water through home purifying systems may be the most effective means to abolish the mutagenicity. Some brands of commercial bottled waters may also contain mutagens which may be derived from tap water.

Chemopreventive Potential of Neem Flowers on Carcinogen-Induced Rat Mammary and Liver Carcinogenesis.

We have previously reported that dietary neem flowers (Azadirachta indica A. Juss var. siamensis Valeton) caused a marked increase in glutathione S-transferase (GST) activity in the liver, while resulting in a significant reduction in the activities of some hepatic P450-dependent monooxygenases. These results strongly indicate that neem flowers may have chemopreventive potential. In the present study, we examined the inhibitory effects of neem flowers on 9,10-dimethyl-1,2-benzanthracene (DMBA)-induced mammary gland carcinogenesis in female Sprague Dawley rats and on aflatoxin B(1)(AFB(1))-induced hepatocarcinogenesis in male Wistar rats. Young animals were fed with AIN-76 purified diets containing either 10-12.5% ground freeze-dried neem flowers for 1 week prior to, during, and for 1 week after the administration of each carcinogen. Interestingly, it was found that neem flowers resulted in a marked reduction of the incidence of mammary gland (about 35.2%) and liver tumors (61.7% and 80.1% for benign and malignant tumors, respectively). Furthermore, the multiplicity of tumors per rats was also lower in the neem flower groups, i.e. those for mammary gland tumors and benign and malignant liver tumors were reduced to 44.0%, 87.9% and 88.9%, respectively. These results clearly demonstrated that neem flowers contain some chemopreventive agents capable of inhibiting AFB(1) and DMBA induced liver and mammary gland carcinogenesis in rats.

Carcinogenicity Testing of the Cosmetic Dye: D&C Red No. 36.

D&C Red No. 36, a drug and cosmetic dye commonly used for coloring lipsticks, was evaluated for its carcinogenic potential in male and female Wistar rats. This dye has been shown to exhibit mutagenic activity towards Salmonella typhimurium TA 98 in the presence of S9 mix. In the present study, 50 male and 50 female rats in each group were given diets containing D&C Red No. 36 at 2 different concentrations, 1,000 ppm and 2,000 ppm, for 78 weeks and sacrificed at week 98. It was found that dye treatment had no significant effect on the survival of either male or female animals as well as the body weight gain in males. However, body weight gain of treated females was slightly lower than that of the control group. Histopathological assessment demonstrated a number of benign and malignant tumors to have developed in various organs of both dye treated and control groups. In male rats, benign liver tumors were found at incidences of 16.7% and 18.8% of the low (1,000 ppm) and high (2,000 ppm) dose groups, respectively, similar to the 20% for the control group. Malignant tumors of the thyroid gland were observed only in the low dose and control groups, at 4.2% and 2%, respectively. In the high dose group, the incidences of lung, liver, urinary bladder and soft tissue cancers were 4.2%, 2.1%, 2.1% and 2.1%, respectively, only one soft tissue cancer being observed in a control group animal. In females, benign tumors were observed in the liver and mammary glands. The incidences of liver tumors in the low and high dose groups were 12.8% and 16%, respectively, and 6% in the control group. Values for mammary gland tumors were 10.6%, 10%, and 18% respectively. Malignant tumors were also observed in various other organs, including the uterus, lung, kidney, thyroid, thymus and salivary gland, but the incidences were very low (about 2-4%) and in dye treated male and female rats were not statistically different from those in the control animals. The results of the present study thus demonstrated that D&C Red No. 36 at the concentrations of 1,000 ppm and 2,000 ppm in the diet is not carcinogenic either to male or female Wistar rats. While the occurrence of benign liver tumors in female rats may be related to dye treatment, the lack of any apparent dose-dependence or any statistically significant difference from the control group (P = 0.06) suggests that this is unlikely.