Carotenoid pigments systems

Figure 3-6 Noncydic and cyciic photophosphorylation in green plants. Pigment system I (PS I) contains chlorophyll a, P-700 (a pigment that possesses an absorption maximum at 700 nm), and carotenoids. Pigment system II (PS II) contains chlorophylls a, b, c, and d, and phycobilin pigments.

Transferosomes represent another system of encapsulation using ultradeformable vesicle carriers for bioactive molecules, applied until now for direct transdermal drug delivery. They are built from polar lipids and have high flexibility, and are rich in unsaturated fatty acids and carotenoid pigments." ... 

We have chosen carotenoid biosynthesis as the example system for demonstrating the prospects of biotechnology of food colorants for several reasons. Carotenoid biosynthesis is the second most understood system. Multiple examples of valuable food colorant engineering in fungi, bacteria, and plants have been reported. Finally, carotenogenesis in cereal crops such as maize and rice is the primary focus of our research efforts. Hopefully, we provide the food technologist with a template with which to examine other industrially important pigment systems. 

Natural pigment production for food coloration includes the entire spectrum of biotechnologies. For example, biological production of carotenoid pigments has medical implications because carotenoids are nutritive (pro-vitamin A), antioxidant, and photoprotective. Carotenoids are produced alternately in agricultural systems (plants), industrial bioreactors (bacterial and fungi), and marine systems (cyanobacteria and algae). 

Because of their versatility and simplicity, TLC methods have been frequently applied to the separation and semi-quantitative determination of carotenoid pigments in synthetic mixtures and various biological matrices. The retention of pure carotenoid standards has been measured in different TLC systems. Separations have been carried out on silica plates using three mobile phases (1) petroleum ether-acetone, 6 4 v/v (2) petroleum ether-tert-butanol 8 2 v/v, and (3) methanol-benzene-ethyl acetate 5 75 20 v/v. Carotenoids were dissolved in benzene and applied to the plates. Developments were performed in presaturated normal chambers. The chemical structure and the Rv values of the analytes measured in the three mobile phases are listed in Table 2.1. It was concluded from the retention data that mobile phase 3 is the most suitable for the separation of this set of carotenoids [13],... 

The use of supercritical fluid chromatography for carotene separation has been examined and optimized, especially in regard to temperature, pressure, and organic modifiers in the supercritical fluid (71). With an RP column it was possible to resolve an a-carotene-cis isomer from an all-trans carotene as well as two cis isomers of /3-carotene from an all-trans /3-carotene. As with HPLC, only polymeric C,8 columns were able to resolve the cis isomers of a- and /3-carotene from the all-trans isomers. Supercritical fluid chromatography offers the advantage not only of an efficient separation but also of fast analysis. Indeed, the use of SFC with ODS-based columns for the analysis of carotenoid pigments affords a threefold reduction of analysis time compared to HPLC (72). The elution order of carotenoids and their cis isomers was found to be the same as in RP-HPLC. The selectivity of the system could further be increased by adding modifiers (e.g.,... 

Carotenoids are found in all native photosynfhetic organisms. They serve a dual function, as both accessory antenna pigment and also are essential in photoprotection of photosynfhetic systems from the effects of excess light, especially in the presence of oxygen. Bilins are open-chain tetrapyrroles that are present in antenna complexes called phycobilisomes. These complexes are found in cyanobacteria and red algae. Structures of representative carotenoid pigments are shown in Figure 3. 

Polyenes The above rules (Table 1.1) holds fairly well for unsaturated compounds containing up to four conjugated double bonds. However, for systems of extended conjugation, such as those found in carotenoid pigments, Fieser and Kuhn have suggested equations to calculate the basic Xmax and max of UV absorption. 

Lycopene is the major carotenoid pigment found in tomatoes, along with lesser amounts of a-, P-, y-, and -carotene, phytoene, phytofluene, neurosporene, and lutein (Trombly and Porter, 1953 Kargl et al., 1960). The basic physicochemical information on lycopene is fairly well established and is outlined in Table 4.1. Lycopene is dispersible in edible oils and soluble in apolar organic solvents. In aqueous systems, lycopene tends to aggregate and to precipitate as crystals this behavior is suspected to inhibit the bioavailability of lycopene in humans (Zumbrunn et al., 1985). In fresh tomatoes, the crystalline form of lycopene is responsible for the typical bright red of the ripe fruits. 

Fig. 10. Fluorescence emission and excitation (or absorption) spectra in CSj of p-carotene (A) and fucoxanthin (B). See text for details. Figure source (A) Glllbro and Cogdell (1989) Carotenoid fluorescence. Chem Phys Lett. 158 313. (B) Katoh, Nagashima, and Mimuro (1991) Fluorescence properties of the allenic carotenoid fucoxanthin impiication for energy transfer in photosynthetic pigment systems. Photosynthesis Res 27 223.

In connection with their studies on carotenoid pigments. Kuhn mid Winterstein16 found that the colour of diphenylpolyenes, Ph—(CH=CH) —Ph, deepened with increase in n. Extensive data on the electronic absorption spectra of several polyene systems were collected by Hausser, Kuhn and... 

Mimuro M, Nagashima U, Takaichi S, Nishimura Y, Yamazaki 1 and Katoh T (1992) Molecular structure and optical properties of carotenoids for the in vivo transfer function of the algal photosynthetic pigment system. Biochim Biophys Acta 1098 271-274... 

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