Absorption, Metabolism and Physiological Functions of Carotenoids

Abstract

Dietary carotenoids are absorbed from the digestive tract and distributed in tissues and fluids in the body. However, little is yet known on their physiological function, except for provitamin A activity. Antioxidant activity of carotenoids, including free radical scavenging and singlet oxygen quenching, has been well documented. Nevertheless, it is unclear whether or not this activity significantly contributes to the antioxidative defense system in vivo. Alternatively, the inhibition of cell proliferation and the induction of cell differentiation explain antitumorigenic effect of carotenoids in animal study. Enhancement of gap junctional communication may be also included in the effect of carotenoids. For the estimation of physiological function of dietary carotenoids, it is essential to understand their absorption and metabolism. 15,15'-Dioxygenase activity responsible for vitamin A activity is widely distributed in tissues and the absorption of carotenoids from digestive tract is significantly affected by diet factors. Finally their metabolic pathway is obscure although oxidative process is recently suggested. Key words: carotenoids, absorption and metabolism, provitamin A, antioxidant, cell proliferation 1 OE¤‹ † ‚Ì "wOEi ƒJƒ•ƒeƒm ƒCƒh ‚Í '· •½‚Ì ‹¤-ðOEn "ñ•dOE‹• ‡‚ð"Á'¥ ‚AE ‚· ‚éˆê OEQ ‚Ì •F'f ‚Ì '• •Ì ‚Å‚ ‚é•BŽ© 'RŠE‚É‚Í-ñ600Ží-Þ ‚Ì ƒJƒ•ƒe ƒm ƒCƒh ‚ª ' ¶ •Ý‚· ‚é ‚ª,‚» ‚Ì '½‚-‚Í 'Y'f •"40OEÂ‚Ì ƒCƒ\ ƒv ƒOE ƒ"•oeŠi ‚Å•\ •¬‚³ ‚ê ‚Ä‚¢‚é ‰» • ‡•¨ ‚Å‚ ‚é•Bƒq ƒg ‚ª •H•¨ ‚© ‚ç•ÛŽae‚· ‚é ƒJƒ•ƒeƒm ƒCƒh ‚Í40Ží ‚ð‰z ‚¦ ‚é'ö"x‚Å‚ ‚é ‚ª, ƒq ƒg OEOE Ÿ÷' †‚É‚Í ‚»‚Ì ‚¤‚¿13Ží-Þ ‚Ì ƒJƒ•ƒeƒm ƒCƒh ‚â ‚»‚ê ‚ç‚Ì 'ãŽÓ ŽY •¨ ‚ª ' ¶ •Ý‚· ‚é ‚±‚AE ‚ª 'm‚ç‚ê ‚Ä‚¢‚é(Table 1)•B ƒJƒ•ƒeƒm ƒCƒh ‚ð•\ '¢‚©‚番-Þ ‚· ‚é ‚AE,Ž_'f •ª Žq‚ðŠÜ‚Ü‚È ‚¢'Y‰» •… 'f ƒJƒ•ƒeƒm ƒCƒh(ƒJ ƒ•ƒeƒ"-Þ ‚â ƒŠƒRƒyƒ"‚È‚Ç) ‚AE ŠÜ Ž_'f ƒJƒ•ƒeƒm ƒCƒh(ƒLƒTƒ"ƒg ƒt ƒB ƒ‹-Þ)‚É•ª-Þ ‚³‚ê ‚é(Fig. 1)1)•B ‚Ü‚½ƒCƒI ƒm ƒ"ŠÂ ‚Ì-L-³ ‚É‚ae‚è,ŠÂ •ó ƒJƒ• ƒeƒm ƒCƒh(ƒJ ƒ•ƒeƒ"-Þ ‚â ƒLƒTƒ"ƒg ƒt ƒB ƒ‹-Þ ‚È‚Ç)‚AE"ñŠÂ •ó ƒJƒ•ƒeƒm ƒCƒh(ƒŠ ƒR ƒyƒ"‚â ƒt ƒBƒg ƒGƒ"-Þ)‚É•ª-Þ ‚· ‚é ‚±‚AE ‚à‚Å‚«‚é•B ‚AE ‚±‚ë‚Å,ƒq ƒg-Ô-OE ‰© "Á‚É' ¶ •Ý‚· ‚é ƒJƒ•ƒeƒm ƒCƒh ‚Í ƒ[ ƒA ƒL ƒTƒ"ƒ` ƒ"‚AE ƒ‹ƒeƒCƒ"‚Ì ‚Ý‚Å‚ ‚é•Bƒ[ƒA ƒLƒTƒ"ƒ` ƒ"‚â ƒ‹ ƒeƒCƒ"‚É•x‚Þ-ì •Ø‰Ê ŽÀ ‚Ì •ÛŽae ‚É‚ae‚è,˜V •l •«-Ô-OE ‰© "Á •Ï •«•Ç(age-related macular degeneration: AMD)‚Ì "-•Ç‚ª-L ˆÓ‚É-} • § ‚³ ‚ê ‚é ‚±‚AE ‚ª •Å‹ß•ñ•• ‚³ ‚ê ‚½2)•B ƒJ ƒ•ƒe ƒm ƒCƒh ‚Ì • ¶-• Šˆ•« ‚AE‚µ‚ÄŠm ŽÀ ‚È‚à‚Ì ‚Í ƒvƒ• ƒrƒ^ƒ~ƒ"A Šˆ•«‚Å‚ ‚é ‚ª,ƒ[ ƒA ƒLƒTƒ"ƒ` ƒ"‚â ƒ‹ƒeƒCƒ"‚Í ƒvƒ•ƒrƒ^ƒ~ ƒ"A‚Å ‚Í ‚È‚¢•B"V'R‚É' ¶ •Ý‚· ‚é ƒJ ƒ•ƒeƒm ƒCƒh ‚Ì ‚¤‚¿, ˜A-• ŽÒ:Ž› "ö•ƒ"ñ 115