450
M. Honda
Fig. 18.1 Chemical structures of a (all-E)-lycopene, b (all-E)-α-carotene, c (all-E)-β-carotene,
d (all-E)-lutein, e (all-E)-astaxanthin, and f (all-E)-fucoxanthin
Carotenoids show strong antioxidant activity such as peroxyl radical and singlet
oxygen scavenging activities and the activity are related to the number of conjugated
double bonds in the molecule; carotenoids with more than 9 conjugated double
bonds display antioxidant activity (Di Mascio et al. 1989; Müller et al. 2011a).
Generally, the antioxidant activity is enhanced with increasing the number of conjugated double bonds. For example, astaxanthin, which contains 13 conjugated double
bonds, shows a higher singlet oxygen scavenging activity than that of β-carotene,
which contains 11 conjugated double bonds (Di Mascio et al. 1989; Ouchi et al.
2010). In addition, each carotenoid has unique bioactivity caused by the specific
structures in the molecule such as conjugated carbonyl and allene groups. Moreover,
several carotenoids such as β-carotene and β-cryptoxanthin are very important as
provitamin A. Since human and nonhuman animals cannot synthesize carotenoids,
the pigments must be supplemented in the diets, and thus the proper understanding of
their influence on the body is very important. The typical bioactivities of carotenoids
are summarized in Fig. 18.2 and the details are as follows .
18.1.1 Lycopene
Lycopene is an acyclic carotenoid principally responsible for the bright red color of
ripe tomatoes and tomato-based products as well as watermelons and gac (Momordica
cochinchinensis Spreng). Lycopene with 11 conjugated double bonds shows especially powerful antioxidant activity of the carotenoids. Di Mascio et al. (1989) have
reported that singlet oxygen scavenging activity of carotenoids, when β-carotene
is defined as a reference (=1.0), was higher in following order: lycopene (2.2) >
γ-carotene (1.8) > astaxanthin (1.7) > canthaxanthin (1.5) > α-carotene (1.4) > βcarotene (1.0) > zeaxanthin (0.7) > lutein (0.6) > α-tocopherol (0.02). The singlet
M. Honda
Fig. 18.1 Chemical structures of a (all-E)-lycopene, b (all-E)-α-carotene, c (all-E)-β-carotene,
d (all-E)-lutein, e (all-E)-astaxanthin, and f (all-E)-fucoxanthin
Carotenoids show strong antioxidant activity such as peroxyl radical and singlet
oxygen scavenging activities and the activity are related to the number of conjugated
double bonds in the molecule; carotenoids with more than 9 conjugated double
bonds display antioxidant activity (Di Mascio et al. 1989; Müller et al. 2011a).
Generally, the antioxidant activity is enhanced with increasing the number of conjugated double bonds. For example, astaxanthin, which contains 13 conjugated double
bonds, shows a higher singlet oxygen scavenging activity than that of β-carotene,
which contains 11 conjugated double bonds (Di Mascio et al. 1989; Ouchi et al.
2010). In addition, each carotenoid has unique bioactivity caused by the specific
structures in the molecule such as conjugated carbonyl and allene groups. Moreover,
several carotenoids such as β-carotene and β-cryptoxanthin are very important as
provitamin A. Since human and nonhuman animals cannot synthesize carotenoids,
the pigments must be supplemented in the diets, and thus the proper understanding of
their influence on the body is very important. The typical bioactivities of carotenoids
are summarized in Fig. 18.2 and the details are as follows .
18.1.1 Lycopene
Lycopene is an acyclic carotenoid principally responsible for the bright red color of
ripe tomatoes and tomato-based products as well as watermelons and gac (Momordica
cochinchinensis Spreng). Lycopene with 11 conjugated double bonds shows especially powerful antioxidant activity of the carotenoids. Di Mascio et al. (1989) have
reported that singlet oxygen scavenging activity of carotenoids, when β-carotene
is defined as a reference (=1.0), was higher in following order: lycopene (2.2) >
γ-carotene (1.8) > astaxanthin (1.7) > canthaxanthin (1.5) > α-carotene (1.4) > βcarotene (1.0) > zeaxanthin (0.7) > lutein (0.6) > α-tocopherol (0.02). The singlet