Chemopreventive properties

Studies by Hudson et al, (2000) have demonstrated the presence of eight polyphenols in rice bran by using high-pressure liquid chromatography. They are protocatechuic acid, p-coumaric acid, ferulic acid, sinapic aci vanillic acid, caffeic acid, which is a methoxycirmamic acid derivative, and tricin. The effect of these polyphenols on cell viability and on the colony-forming ability of human-derived MDA MB 468 and HBL 100 breast cells, colon-derived SW 480 and human colonic epithelial cells was assessed. These authors concluded that rice bran polyphenols have putative cancer chemopreventive properties. 

Dashwood, R.H. et al., Chemopreventive properties of chlorophylls towards aflatoxin Bp A review of the antimutagenicity and anticarcinogenicity data in rainbow trout, Mutat. Res., 399, 245, 1998. 

Murakami A, Matsumoto K, Koshimizu K, Ohigashi H. 2003. Effects of selected food factors with chemopreventive properties on combined lipopolysaccharide- and interferon-gamma-induced IkappaB degradation in RAW264.7 macrophages. Cancer Lett 195 17-25. 

Moreover, star anise contains bioactive compounds possessing insecticidal properties, which can be exploited for evolving natural grain protectants. More attention also has to be focused on the antimicrobial, antioxidant and chemopreventive properties of the spice. 

Ngameni, B., Touaibia, M., Patnam, R., Belkaid, A., Sonna, P, Ngadjui, B.T., Annabic, B. and Roy, R. (2006) Inhibition of MMP-2 secretion from brain tumor cells suggests chemopreventive properties of a furanocoumarin glycoside and of chalcones isolated from the twigs of Dorstenia turbinata. Phytochemistry, 67, 2573-9. 

Although flavanols, also called catechins, seem to be widely distributed in plants, they are rich only in tea leaves, where catechins may contribute up to 30% of dry leaf weight. The antioxidative and antitumor properties of green and black teas and their tea polyphenols are extensively studied. It seems that tea polyphenols are important not only for plants but also for humans. Therefore, this brief review will discuss the current data with a particular emphasis on the effects of tea polyphenols on the cellular oxidative stress and cancer chemopreventive properties. The action mechanisms of several phytopolyphenols on cancer chemoprevention will be elaborated. 

Another area of research focuses on the chemopreventive properties of curcumin against prostate cancer. Curcumin decreased the proliferative potential and induced apoptosis in both androgen-dependent and androgen-independent prostate cancer cells in Dietary administration of 2% curcumin also caused a marked... 

Rao, C.V., Cooma, I., Simi, B., Maiming, P.T., Connor, J.R. and Reddy, B.S., Chemopreventive properties of a selective inducible nitric oxide synthase inhibitor in colon carcinogenesis, administered alone or in combination with celecoxib, a selective cyclooxygenase-2 inhibitor. Cancer Res., 62, 165, 2002. 

The discovery of anticarcinogenic properties of many plant-borne compounds present in food is undoubtedly one of the most important developments, encouraging the hope that the cancer death toll can be diminished. The fact that these substances are found in liked and widely appreciated food products should facilitate the utilization of their precious chemopreventive properties. 

Maxuitenko YY, Libby AH, Joyner HH, et al. 1998. Identification of dithiolethiones with better chemopreventive properties than oltipraz. Carcinogenesis 19(9) 1609-1615. 

Geniposide and derivatives have also shown very interesting antitumoral and chemopreventive properties ... 

Galvez, A.F. N. Chen J. Macasieb B.O. de Lumen. Chemopreventive property of a soybean peptide (lunasin) that binds to deacetylated histones and inhibits acetylation. Cancer Res. 2001, 61, 7473-7478. 

Holmes-McNary M, Baldwin AS. Chemopreventive properties of trans-resveratrol are associated with inhibition of activation of the IkappaB kinase. Cancer Res 2000 60 3477-3483. 

Oltipraz [4-methyl-5-(2-pyrazinyl)-l, 2-dithiole-3-thione] (OPZ), a synthetic derivative of 1, 2-dithiole-3-thione, has been extensively investigated for its chemopreventive properties first developed as an antischistosomal agent, this compound was found to increase cellular thiol levels and to induce enzymes involved in the maintenance of reduced glutathione (GSH) pools and in detoxification of electrophilic intermediates. Induction of phase 2 enzymes such as GSTs, epoxide hydrolases, and NADP(H) quinone reductases was considered to represent the key mechanism of chemoprotection of OPZ. More recently this compound was also found to modulate phase 1 enzymes, antioxidant enzymes, and other inactivating proteins, thereby indicating that its chemoprevention mechanism(s) are more complex than first envisaged. In this chapter, current information about the effects of OPZ on phase 1 and phase 2 enzymes is presented. 

In order to determine the exact mechanism, structure-activity studies were performed OPZ and 5-(4-methoxyphenyl)-3H-l, 2-dithiole-3-thione were shown to be similarly effective on the inhibition of preneoplastic lesions induced by AFBi, while treatment with 1,3-dithiole-2-thione was without effect [31]. The efficacy of OPZ compared to other dithiolethiones was further studied by evaluating the effects of 17 dithiolethiones on acute hepatotoxicity of AFBl in rats [32]. The results demonstrated that, although several dithiolethiones were more active than OPZ in inhibiting toxicity, no structural motif linked to these chemoprevention properties could be identified. 

Aloe exhibited antitumor, anticarcinogenic, and cancer chemopreventive properties in animal models. According to a Russian report, treatment of experimental tumors in mice and rats with aloe juice contributed to reduction of tumor mass, metastatic foci, and metastasis frequency. Bioassay-guided purification of an aloe species afforded a hydroxyanthraquinone compound called aloe-emodine, which significantly inhibited P-388 lymphocytic leukemia and human neuroectodermal tumors implanted in mice 157,158 inhibited human hepatoma cell lines, Hep G2 and Hep 3B, human... 

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