ABSTRACT
Lycopene is a fat-soluble pigment (carotenoid) without provitamin A activity and it is found in selected plant foods such as tomato, watermelon, and pink grapefruit. Diets rich in carotenoids have potential in reducing chronic diseases. Considerable evidence suggests that lycopene may play a significant role in reducing the risk of cardiovascular diseases (CVD) in humans. The factors that contribute to the onset of CVD include hypertension, hypercholesterolemia, hyperlipidemia, obesity, and insulin resistance as well as genetic, environmental and lifestyle factors such as physical inactivity, smoking, and tobacco consumption. This chapter focuses on the mechanisms of action of lycopene in reducing the risk of CVD. Several in vitro assays have shown that lycopene is a potent antioxidant, and its antioxidant mechanisms are likely to provide health benefits against development of CVD. The most accepted theory about the mechanisms of lycopene in controlling various diseases is its singlet oxygen quenching properties. Lycopene has high numbers of conjugated double bonds and is the most potent singlet oxygen quencher among the natural carotenoids. This property of lycopene draws attention in the field of chronic diseases and carotenoids research. However, some non-antioxidant mechanisms or effects may play a role in the protection offered by lycopene against CVD, such as inhibition of 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase, reduction in intima-media thickness of the carotid artery, preventing platelet aggregation and thrombus 244formation, and suppression of endothelial cell tissue factor activity. The data supporting the protective effects of lycopene are mainly derived from epidemiological studies on normal and high-risk populations. Lycopene seems to play a role in the antioxidant as well as non-antioxidant mechanisms related to reduction in CVD.
