Search

The anticancer properties of zerumbone (2,6,9 humulatriene-8-one, a sesquiterpenoid) from Zingiber aromaticum were compared with those of curcumin from Curcuma longa in an in vitro MTT tetrazolium salt assay using HT-29, CaCo-2, and MCF-7 cancer cells and in an azoxymethane (AOM)-induced animal model of colon cancer using aberrant crypt foci (ACFs) as a preneoplastic marker. The IC50 of zerumbone was approximately 10 μM and that of curcumin was 25 μM. Cell cycle arrest in HT-29 cells was observed at G0/G1 for 10 and 12.5 mM and G2/M for 25 μM after 24 h at concentrations of 10-25 μM of zerumbone, and a concentration-dependent increase in apoptosis (2-6% of viable cells) was observed after 48 h using the same concentration range. Male Sprague-Dawley rats were fed extracts in an AIN diet prepared from the equivalent of 4% by weight of dried rhizomes of Z. aromaticum and C. longa. ACFs were induced by two doses (15 mg/kg body weight) subcutaneously of AOM 1 wk apart, the rats were killed 10 wk later, and the ACFs were assessed in the colon. Total ACFs were significantly reduced by Z. aromaticum extract (down 21%, P < 0.05) relative to control, the effect being most evident with large ACFs (≥3 aberrant crypts per focus). Similar reductions were observed with 4% C. longa extract in the diet (down 24%, P < 0.01) and with 2,000 ppm curcumin, the effect being particularly evident with large ACFs. The concentration of zerumbone in the Z. aromaticum extract diet was assayed at 300 ppm and of curcumin in the C. longa extract diet was also 300 ppm, i.e., the extract of C. longa was as effective at one-seventh the concentration of curcumin as the positive control. Zerumbone is effective as an anticancer agent, possibly by its apoptosis-inducing and antiproliferative influences. This latter possibility is currently being investigated. [ABSTRACT FROM AUTHOR]

Alterations in folate status may play an important role in carcinogenesis. The aim of this study was to examine the effect of a diminished folate status on azoxymethane (AOM)-induced intestinal tumours in Sprague–Dawley rats. A total of 125 weanling male rats were divided into five equal groups and fed semi-purified diets containing either 8 mg/kg folate or no folate. After 4 weeks on experimental diets, all animals received three weekly subcutaneous injections of AOM at a dose rate of 15 mg/kg bodyweight. The animals were necropsied after 26 weeks. Rats with a diminished folate status, evident by significantly reduced blood and colonic folate concentrations and elevated plasma homocysteine levels, had significantly (P < 0.01) lower incidence and number of small intestinal and colonic tumours compared with rats displaying an adequate folate status. There was a significant decrease in the incidence of colonic adenocarcinomas (P < 0.01) and size of colonic tumours observed in the rats displaying a diminished folate status. This study shows that a diminished folate status was associated with a decrease in the development of AOM-induced colorectal cancers. The decrease in risk may be attributed to the known role of folate in cell multiplication. [ABSTRACT FROM PUBLISHER]

Radionuclide angiography was used to examine the influence of dietary fat on cardiac function in the common marmoset monkey (Callithrix jacchus jacchus) under barbiturate anaesthesia. Animals were fed for 6-8 months with a low fat (4.5%) reference diet or the same diet supplemented (12%) with sunflower seed oil or sheep fat. Although there was a tendency towards increased heart rate, left ventricular ejection fraction, peak ejection rate, and peak filling rate in both fat supplemented groups, significant increases in heart rate (+50%), peak ejection rate (+71%), and peak filling rate (+84%) were found with sheep fat supplementation, whereas only the vegetable oil supplement produced a significant improvement in left ventricular ejection fraction (+23%). There were no differences in resting blood pressure, and the main consequence of dietary fat supplementation was a major increase in apparent cardiac oxygen consumption (+58%) with the sheep fat diet, as determined by the pressure-rate index. Infusion of isoprenaline hydrochloride (0.2 μg·kg−1·min−1) increased all indices of cardiac function towards common maxima. There were no differences in either the depth or duration of anaesthesia between dietary groups. It therefore is unlikely that this contributed to any of the observed dietary induced differences in cardiac function. It is suggested that dietary saturated animal fat increased cardiac work and oxygen consumption at rest to the extent that functional reserve to respond to stress was significantly diminished. Feeding a linoleic acid rich polyunsaturated vegetable oil supplement was, however, accompanied by evidence of some improvement in left ventricular ejection fraction. [ABSTRACT FROM PUBLISHER]

Selenium (Se), an essential trace element, has also been identified as an anticarcinogenic agent, with supporting evidence from epidemiological studies, clinical intervention trials, preclinical intervention studies (animal cancer models) and cell culture studies. Natural organic and inorganic sources of Se as well as synthetic organoselenium compounds have been shown to be effective; safety and efficacy factors favour the organic forms. Intakes that are several fold that purported to meet nutritional requirements (adult recommend dietary allowance--55 μg Se/day) are associated with reductions in cancer risk, but are not currently met by most diets, unless Se-rich foods are included. Further clinical studies and development of tools for speciating Se in foods will enable progress to be made in determining desirable Se forms and foods with respect to providing safe and effective ways of reducing cancer risk.