Cancer prevention by antioxidants

Abstract

Various antioxidants in foods, such as phenolic compounds and carotenoids, were proven to have anticarcinogenic activity. In the case of carotenoids, the mixture of them was found to be very effective. In fact, the development of hepatoma in the high risk group of liver cancer, was significantly suppressed by the treatment with natural carotenoids mixture. The role of nitric oxide (NO) in carcinogenesis has been pointed out, since large quantity of NO has been detected in cancer tissues, and the expression of inducible NO synthase (iNOS) was found to correlate with tumor growth and metastasis. Recently, we found that NO possessed tumor initiating activity in mouse skin carcinogenesis. It has been suggested that some parts of pathological effects induced by NO may depend on peroxynitrite, an active metabolite of NO. Thus, we accessed the tumor initiating activity of peroxynitrite, and found that treatment with peroxynitrite (initiator) plus TPA (promoter) resulted in the formation of skin tumors. Under this experimental condition, it has been proven that natural antioxidants, such as curcumin and nobiletin, showed anti-tumor initiating effect. In the case of nobiletin, suppressive effect on iNOS induction has also been demonstrated. It is of interest that suppression of iNOS induction was also observed in phytoene synthase transgenic mouse. After administration of glycerol (a lung tumor promoter), lower induction of iNOS gene was observed in lung of the phytoene producing mice, comparing with that of control mice. Combinational use of various kinds of antioxidants distributed in foods, e.g., mixture of carotenoids and flavonoids, seems to be effective methods for cancer prevention.

Protective Effects of Flavonoid Pomiferin on Heart Ischemia-Reperfusion

“…They are commonly present in human diet, especially in fruit and vegetables, and their daily intake is ca 1 -2 g. Many of their effects on plant and animal cells are signifi cant (Lee et al 1998;Havsteen 2002;Rao et al 2005). In oncology the fl avonoids are used as corroborative compounds, reducing the side effects of cytostatics, and on the other hand, they enhance therapeutical effects; this fi eld is very well documented (Kandaswami et al1991;Nishino et al 2004;Scambia et al1992;Štípek 2000).…”

Effects of Prenylated Isoflavones Osajin and Pomiferin in Premedication on Heart Ischemia-Reperfusion

“…In oncology the flavonoids are used as compounds, which reduce the side effects of cytostatics and on the other hand, they enhance the therapeutic effects. This field is documented very well [6][7][8] . Flavonoids are often used in the treatment of inflammation because of their ability to inhibit the key enzyme in PG (prostaglandins) synthesis -COX [9][10][11] .…”

Bioactive phytomolecules and aging in Caenorhabditis elegans

“…stomach dysfunction, flatulence, dysentery, ulcers, jaundice, arthritis, sprains, wounds, skin and eye infections [75]. Recently it has gained the attention as a non steroidal, anti-inflammatory drug with chemopreventive anti-carcinogenic, and antioxidant properties [76][77][78]. Curcumin works as a promising bioactive compound in cancer therapy due to its strong inhibition activity against tumor formation, promotion, progression, and dissemination [79].…”