Carotenoids: Biochemistry, pharmacology and treatment.

Carotenoids and retinoids have several similarities in biological activities such as antioxidant properties, the inhibition of malignant tumor growth, and the induction of apoptosis. Supplementation with carotenoids can influence cell growth regulation, and modulate gene expression and immune response. Epidemiologic studies have shown the correlation of high carotenoid intake from food sources with reduced risk of breast, cervical, ovarian, colorectal cancers, and cardiovascular or eye diseases. Cancer chemoprevention by dietary carotenoids involves some approaches including gap junctional intercellular communication (GJIC), growth factor signaling, cell cycle progression, differentiation-related proteins, retinoid-like receptors, antioxidant response element, nuclear receptors, AP-1 transcriptional complex, Wnt/β-Catenin pathway, and inflammatory cytokines. Moreover, carotenoids could stimulate the proliferation of B- and T-lymphocytes, the activity of macrophage and cytotoxic T-cell (CTL), the effector T-cell function, and the production of cytokines. Recently, the beneficial effects of carotenoid-rich vegetables and fruits in health and decreasing the risk of diseases relied on some major carotenoids such as β-carotene, lycopene, lutein, zeaxanthin, crocin (/crocetin), and also curcumin due to their role as antioxidants. It should be considered that carotenoids act in a time- and dose-dependent manner. In this review, biochemical and immunological activities of main carotenoids and their possible mechanisms of action are described.