Inhibition of chemically induced

Hix LM, Frey DA, McLaws MD, 0sterlie M, Lockwood SF, and Bertram JS. 2005. Inhibition of chemically-induced neoplastic transformation by a novel tetrasodium diphosphate astaxanthin derivative. Carcinogenesis 26(9) 1634-1641. 

Klurfeld, D.M., Weber, M.M. Kritchevsky, D. (1987) Inhibition of chemically induced mammary and colon tumor promotion by caloric restriction in rats fed increased dietary fat. Cancer Res., 47, 2759-2762... 

The potential anti-inflammatory properties of southern African soft coral metabolites were further exemplified by the isolation of five diterpene esters valdivones A (101), B (102), their corresponding methoxy ketals (103, 104) and dihydrovaldivone A (105) from Alcyonium valdivae (Family Alcyoniidae) collected off Coffee Bay on the warm temperate east coast of southern Africa (Figure 1) [94]. The structures of these compounds were determined from analysis of their 2D-NMR data with coupling constant analysis and nOe data providing the relative stereochemistry of 101 and 102. Valdivones A and B showed fairly strong inhibition of chemically-induced inflammation in the mouse ear assay (93% and 72% inhibition at 50 pg/ear respectively) but did not significantly inhibit bee venom phospholipase A2 (ca. 43% at 16 pgmL1) [94]. 

Inhibition of Chemically Induced Carcinogenesis by 2-/i-Heptylfuran and 2-7i-Butylthiophene from Roast Beef Aroma... 

Benedict, W. F., Wheatlet, W. L., and Jones, P. A., 1980, Inhibition of chemically induced morphologic transformation and reversion of the transformed phenotype by ascorbic acid in C3H/10T1/2 cells. Cancer Res. 40 2796-2801. 

A method based on inhibition of ABAP-induced oxidation of a fluorogenic probe, 2, 7-dichlorodihydrofluorescein diacetate (H2-DCF-DA), commonly used for detection of production of reactive oxygen species, has been proposed (V2). Oxidation of the probe can be monitored either spectrophotometrically or fluori-metrically. A drawback of the method is the necessity of hydrolysis of the ester because only the deesterified from can be oxidized. The rate of hydrolysis depends on the hydrolytic activity of the samples measured. A modification consisting of chemical hydrolysis of H2-DCF-DA before measurement is impractical because 2,7 -dichlorodihydrofluorescein oxidizes rapidly. 

There have been several epidemiological and several case reports inversely relating ascorbic acid intake from food to human cancer mortality. These studies are interesting, but may be confounded with the fact that the same ascorbic acid containing foods, namely fruits and vegetables, also contain large amounts of vitamin A and fiber. Both vitamin A and fiber have been inversely related to human cancer mortality and have been shown to inhibit several types of chemically-induced carcinogenesis in animals. Therefore, the possible anti cancer effect of ascorbic acid may be due to other factors. 

Wattenberg, L.W. Inhibition of chemical-carcinogen-induced pulmonary neoplasia by butylated hydroxyanisole. J. Natl. Cancer Inst., 50 1541-1544, 1973. 

Together with y-oryzanol, tocotrienols are responsible for the cholesterol-lowering effect of rice bran oil (250). Tocotrienol concentrates have been shown to have a hypocholesterolemic effect in animals and humans (251-257) possibly because of inhibition of hepatic 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA reductase) (251, 258, 259). The presence of a-tocopherol at concentrations >20% in tocotrienol concentrates was, however, found to attenuate the inhibitory elfect of tocotrienols on HMG-COA reductase, thereby weakening their cholesterollowering activities (254). Tocotrienols were especially found to synergize the cholesterol-lowering effect of lovastatin (254). In addition, tocotrienols have been shown to influence certain hemostatic parameters and to reduce the occurrence of chemical-induced tumors in the rat (253). 

The hallmark of the anticarcinogenic effect of DR is the ability of diet restriction to prevent chemical-induced tumors. The first reports of inhibition of chemical carcinogenesis came in the 1940s. 

Inhibition of chemical carcinogen-induced neoplasia by coumarins and alpha-angelicalactone. Cancer Res. 39, 1651-1654. 

Tyrey, L. and Hughes, C.L. (1984) Inhibition of suckling-induced prolactin secretion by delta-9-tetrahydrocannabinol, in The Cannabinoids Chemical, Pharmacologic and Therapeutic Aspects, S. Agurell, W.L. Dewey, and R.E. Wilette, lids., pp. 487-495, San Diego, CA Academic Press. 

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