P-Carotene Carotenoids

Nishikawa, Y., Minenaka, Y, and Ichimura, M., Physiological and biochemical effects of carotenoid (P-carotene and astaxanthin) on rat, Koshien Daigaku Kiyo, 25, 19, 1997 [in Japanese]. 

Figure F4.3.4 Absorption spectra of pigments from a green tobacco leaf extracted with 100% acetone. The leaf extract was measured directly after extracting the leaf. Chi a, Chi b, and the carotenoids p-carotene (P-C) and lutein (Lut) were measured after separation by TLC.

A study on the photoprotective effect of the topical application of 2% vitamin E and 5% vitamin C in humans showed no effect with the application of each substance alone, but an enhanced photo-protective effect after applying vitamins E and C combined, which was attributed to the regeneration of vitamin E by vitamin C.20 This enhanced effect has also been shown with the topical application of a combination of 15% ascorbic acid and 1% a-tocopherol to porcine skin.21 The combined systemic supplementation of vitamins C and E was similarly able to reduce sunburn reactions22 and to increase the minimal erythema dose (MED), a measure for individual photosensitivity, more than supplementation with either vitamin E or vitamin C alone.23,24 An oral supplementation with an anti-oxidative combination of carotenoids (P-carotene and lycopene), vitamin C, vitamin E, selenium, and proanthocyanidins (Seresis , Pharmaton SA, Lugano, Switzerland) also reduced the development and grade of UVB-induced erythema 25... 

Metal chelation Oxygen scavenging and reducing agents Singlet oxygen quenching Cirtic, Malic, Succinic and Tartaric acids Ethylenediaminetetraacetic acid, Phosphates Ascorbic acid, Ascorbyl palmitate, Erythorbic acid. Sodium erythorbate. Sulfites Carotenoids (p-Carotene, Lycopene and Lutein)... 

Fig. 3. Commercially important carotenoids P-carotene (10), canthaxanthin [514-78-3] (11), astaxanthin [472-61-7] (12), p-apo-8 -carotenal [1107-26-2] (13), p-apo-8 -carotenoic acid ethyl ester [1109-11-1] (14), and citranaxanthin [3604-90-8] (15).

Many carotenoids function in humans as vitamin A precursors however, not aU carotenoids have provitamin A activity (Table 3). Of the biologically active carotenoids, P-carotene has the greatest activity. Despite the fact that theoretically one molecule of P-carotene is a biological source of two molecules of vitamin A, this relationship is not observed and 6 jig p-carotene is equivalent to 1 jJ, vitamin A. Although p-carotene and vitamin A have complementary activities, they cannot totally replace each other. Because the conversion of p-carotene to vitamin A is highly regulated, toxic quantities of vitamin A cannot accumulate and P-carotene can be considered as a safe form of vitamin A (8). 

Epi-gallocatechine-3-gallate (EGCG) Cannabinoids (cannabidiol from Cannabis sativa) Capsaicin Carotenoids P-Carotene... 

Photosynthetic Carotenoids p-carotene. Natural food coloring. Microalgae D. salina, S. maxima. Vitamin A precursors. Ben-Amotz, 1993 Gregory,... 

The compoimds which are responsible for antioxidant activity in seaweed include vitamin E (a-tocopherol), carotenoids (p-carotene), and vitamin C (ascorbic acid), and partially vitamin Bi and niacin. 

In certain experimental studies, there is an indication for the correlation between the diet rich in carotenoids (p-carotene) and a diminishing risk of cardiovascular diseases and some type of cancer—lung cancer, and probably also cancer of the esophagus, stomach, colon, rectum, breast, and cervix (Kohlmeier and Hastings, 1995 Krinsky, 1991). Presumably, they are capable of seeking for free radicals and neutralizing them and thus they inhibit cell proliferation (Simon, 2002). 

The main components of tea are essential oil (0.5%) which is formed during fermentation, caffeine (1.8%-5.0%), and tannins (13%-18%). Enzymatic formation of black tea aroma follows biosynthetic pathways. The main precursors are amino acids and carotenoids (P-carotene, lutein, neoxanthin, and violaxanthin). Fermentation significantly reduces carotenoids and forms ionone and terpenoid carbonyls as a result of primary oxidations. During firing, secondary epoxida-tion takes place and forms epoxyionone, dihydroactinidiole, and trimethyl substituted cyclohexanones [35]. 

Carotenoids act as antioxidants in solution, micelles, and liposomes (Hill et al. 1995, Mortensen and Skibsted 1997, Mortensen et al. 1997, Woodall et al. 1997). The scavenging ability of the carotenoids P-carotene, 8 -apo-P-caroten-8 -al, can-thaxanthin, 7 -apo-7 ,7 -dicyano-p-carotene, ethyl 8 -apo-P-caroten-8 -oate, and 7,7 -diapo-7,7 -di-phenylcarotene towards radical HOO correlated with their redox properties (Polyakov et al. 2001). 

Green sulfur bacteria produce some types of carotenoids, p-carotene 13, chlorobactene 46, and their derivatives including their glucoside, and/or isorenieratene 50 (Fig. 106.6) [5, 14]. 

Interestingly, the electroreduction of the complex [p-carotene I] l3 led to the neo-A-retrodehydro-P-carotene with 12 conjugated bonds, i.e., an unusual cathodic dehydrogenation occurs here. The family of carotenoids, p-carotene, a-carotene, lycopene, etc., was studied with the measurement of kinetic parameters [177,178,191,205,209]. The relatively high basicity of anion radicals of carotenes observed was used to perform catalytic endoergic electron transfer to p-carotene from anion radicals of chlorophyll and porphyrins [212] (Sect. 9.2.4). 

The effects of traditional processing practices on the retention of a-carotene, P-carotene, and total provitamin A carotenoids were studied using amaranth, cowpea, peanut, pumpkin and sweet potato leaves (Mosha et al., 1997). The traditional practice of sun drying and storage in ventilated containers resulted in a significant (P<0.05) decrease in the concentration of total carotenoids, P-carotene, and a-carotene for all the vegetables. Conventional blanching and... 

Mosha, TC, Pace, RD, Adeyeye, S, Laswai, HS and Mtebe, K (1997) effect of traditional processing practices on the content of total carotenoid, P-carotene, a-carotene and vitamin A activity of selected Tanzanian vegetables. Plant Foods Hum. Nutr., 50, 189-201. 

Ajikumar PK, Xiao W-H, Tyo KEJ, Wang Y, Simeon F, Leonard E, Mucha O, Phon TH, Pfeifer B, Stephanopoulos G (2010) Isoprenoid pathway optimization for taxol precursor overproduction m Escherichia coli. Science 330(6000) 70-74. doi 10.1126/science.l 191652 Albrecht M, Misawa N, Sandmann G (1999) Metabolic engineering of the terpenoid biosynthetic pathway of Escherichia coli for production of the carotenoids p-carotene and zeaxanthin. Biotechnol Lett 21(9) 791-795... 

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