Chapter 26 - Spinach and Health: Anticancer Effect

Abstract

Diets rich in vegetables are known to reduce cancer risk, suggesting edible plants as potential sources of anticancer agents. Spinach plays an important role in nutrient supply. Spinach is a superior supplier of vitamin K, vitamin A, manganese, magnesium, folic acid, iron, vitamin C, vitamin B2, and potassium, and it includes a lot of dietary fiber, vitamin B6, vitamin E, and omega-3 fatty acids, which are essential for the maintenance, improvement, and regulation of human tissues. In addition, spinach includes major antioxidants of carotenoids and polyphenols. Spinach contains the most sulfoquinovosyl diacylglycerol (SQDG) and monogalactosyl diacylglycerol (MGDG) in the glycoglycerolipid fraction of green vegetables tested, and a purification method of the spinach glycoglycerolipid fraction was established. This fraction inhibited the activities of mammalian replicative pols and suppressed the growth of human cancer cells. The water-soluble fraction, fat-soluble fraction, and ethanol extract from spinach had no influence, although the ethanol extract contained glycoglycerolipids such as SQDG and MGDG. Therefore, it is suggested that compounds preventing glycoglycerolipid bioactivity may be contained in the spinach ethanol extract. It is also important to purify the glycoglycerolipid fraction from spinach. The spinach glycoglycerolipid fraction can inhibit mammalian pol activity, human cultured cancer cell growth, and in vivo solid tumor proliferation with oral administration. This fraction could help to prevent cancer and be a functional food with anticancer activity.