Carotene zeaxanthin

Replacement of the hydrogen at the 3 or 3 position of the carotene ring with a hydroxyl is the next step in both branches of the pathway. Hydroxylation of the rings of the carotenes leads to biosynthesis of the xanthophylls, including the well-known lutein and zeaxanthin food pigments. Lutein is formed by hydroxylation of a-carotene zeaxanthin is formed by hydroxylation of P-carotene. 

The substrate specificity of these enzymes is not stringent for example, CCD1 from tomato was also shown to cleave at the 9,10- and 9, 10 -positions of (1-carotene, zeaxanthin, lutein, violaxan-thin and neoxanthin all of which have different ionone ring modifications. Unlike NCEDs, CCD1 enzymes have no plastid-targeting sequences and are localized in the cytosol. It is postulated that they access the carotenoids in the plastids through a monotopic membrane association (Kloer et al. 

Reduction of zeaxanthin ditosylate gave a complex mixture of products including /5-carotene, zeaxanthin, and retro-products. Oxidation of... 

High Phytochemical Content carotenoids (beta-carotene, zeaxanthin, beta-cryptoxanthin, lycopene) polyphenols (anthocyanins, oligomeric proanthocyanidins, other mixed polyphenols such as tannins, quercetin, apigenin, ellagic acid)... 

The photosynthetic pigments of higher plants comprise not only the chlorophylls (a and b) but also a range of carotenoids. The main ones of these are B-carotene (usually 25-30% of the total carotenoids) and the xanthophylls lutein (45-50%), violaxanthin (ca. 15%) and neoxanthin (ca. 15%), though small amounts of others, e.g. a-carotene, zeaxanthin, antheraxanthin, lutein-5,6-epoxide and a-cryptoxanthin, may also be detected. The... 

In natural materials, the concentration of C. is usually in the order of 0.02-0.1% of the dry mass. The C. content of the eye ring of the pheasant Narcissus majalis is extremely high, being 16%, or about times that in carrots. An estimated ICf metric tonnes of C. are produced per year by living organisms, the most abundant being fucoxanthin, lutein, violaxan-thin and neoxanthin, followed by p-carotene, zeaxanthin, lycopene, capsanthin and bixin. More than 90 % of the C. in a plant is found in the leaves, usually as a mixture of 20 0% carotenes (containing more than 70 % p-carotene) and 60-80 % xanthophylls like lutein, violaxanthin, cryptoxanthin and zeaxanthin. 

In 2001, Buratti et al. [50] described an electrochemical method to evaluate the antioxidant power of lipophilic food extracts. The method was based on the association between FIA and amperometric detection and a working potential of +0.50 V (vs. Ag/AgCl) was used in the experiments. When applied to pure compounds, it was possible to observe that lycopene presented the greatest antioxidant power of all the lipophilic compounds (lycopene, )5-carotene, zeaxanthin, a-carotene, )5-cryptoxanthin, lutein, a-tocopherol, capsaicin, chlorophyll, astaxanthin, and canthaxanthin) used in this smdy. This result was... 

The same four major carotenoids, )8-carotene, lutein, violaxanthin, and neoxanthin (5, 6 -epoxy-6,7-didehydro-5,6,5, 6 -tetrahydro-)8,)8-carotene-3,5,3 -triol), accumulate in the chloroplasts of all green leaves (Figure 4.1), with minor amounts of a-carotene (j8,e-carotene), zeaxanthin (/3,/3-carotene-3,3 -diol), antheraxanthin (5,6-epoxy-5,6-dihydro-/3,/3-carotene-3,3 -diol) and lutein 5,6-epoxide (3,3 -dihydroxy-5,6-epoxy-ar-carotene). Although quantitative differences between species are found, the carotenes account for about 25% of total leaf carotenoids, while lutein, the main xanthophyll, is about 45% of the total. The xanthophylls are unesterified except in senescing leaves. The distribution of carotenoids in flowers, fruits, and roots of plants can be found in several comprehensive reviews and will not be discussed here. 

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