Productivity chlorophyll

Chlorophylls and degradation products (chlorophylls a, b, c, chlorophyllide a, phaeophorebide a, phaeophytins a,b) Spectrofluorometric [150]... 

Shoaf and Lium [103] used thin layer chromatography to separate algal chlorophylls from their degradation products. Chlorophyll is extracted from the algae with dimethyl sulphide and chromatographed on commercially available thin layer cellulose sheets, using 2% methanol and 98% petroleum ether as solvents, before determination by either spectrophotometry or fluorometry. 

Gargas, E., TErtebjerg Nielsen, G., Mortensen, S., 1978. The Belt project. Phytoplankton production, chlorophyll-fl and nutrients in the open Danish waters 1975-1977. The National Agency of Environmental Protection, Denmark, 61 pp. JJ trykteknik al/s. Copenhagen. 

Ochocki, S., Mackiewicz, T., Nakonieczny, J., Zalewski, M., 1995. Primary production, chlorophyll, quantitative and qualitative composition of phytoplankton in the Pomeranian Bay. Bulletin of the Sea Fisheries Institute, 3(136), 33 42. 

Crude chlorophyll is prepared commercially from alfalfa meal or nettles by extraction with alcohol and partition into benzene. It is used as a colouring matter, particularly for foods and pharmaceutical products. 

Solvent extraction removes chlorophyll and other pigments to give a light-colored product but increases processing costs. Furthermore, solvent extraction removes p-carotene and reduces vitamin A activity (89) (see Terpenoids Vitamins). Supercritical CO2 extraction at 30 and 70 MPa (4,350 and 10,150 psi) and 40°C removed 90 and 70% carotene and lutein, respectively, from alfalfa LPC (96). This process avoids organic solvent residues and recovers valuable by-products. 

Fats and Oils. The oxidation of fats and oils in food products can be prevented by the addition of citric acid to chelate the trace metals that catalyze the oxidation. Citric acid is also used in the bleaching clays and the degumming process during oil refining to remove chlorophyll and phosphohpids (59—63). 

A method of detecting herbicides is proposed the photosynthetic herbicides act by binding to Photosystem II (PS II), a multiunit chlorophyll-protein complex which plays a vital role in photosynthesis. The inhibition of PS II causes a reduced photoinduced production of hydrogen peroxide, which can be measured by a chemiluminescence reaction with luminol and the enzyme horseradish peroxidase (HRP). The sensing device proposed combines the production and detection of hydrogen peroxide in a single flow assay by combining all the individual steps in a compact, portable device that utilises micro-fluidic components. 

Although /3-oxidation is universally important, there are some instances in which it cannot operate effectively. For example, branched-chain fatty acids with alkyl branches at odd-numbered carbons are not effective substrates for /3-oxidation. For such species, a-oxidation is a useful alternative. Consider phy-tol, a breakdown product of chlorophyll that occurs in the fat of ruminant animals such as sheep and cows and also in dairy products. Ruminants oxidize phytol to phytanic acid, and digestion of phytanic acid in dairy products is thus an important dietary consideration for humans. The methyl group at C-3 will block /3-oxidation, but, as shown in Figure 24.26, phytanic acid a-hydroxylase places an —OFI group at the a-carbon, and phytanic acid a-oxidase decar-boxylates it to yield pristanie add. The CoA ester of this metabolite can undergo /3-oxidation in the normal manner. The terminal product, isobutyryl-CoA, can be sent into the TCA cycle by conversion to succinyl-CoA. 

Phytanic acid, the product of chlorophyll that causes problems for individuals with Refsum s disease, is 3,7,11,15-tetramethyl hexa-decanoic acid. Suggest a route for its oxidation that is consistent with what you have learned in this chapter. Hint The methyl group at C-3 effectively blocks hydroxylation and normal /3-oxidation. You may wish to initiate breakdown in some other way.)... 

Methods for the synthesis of pyrroles are of importance, since the pyrrole unit is found in natural products widespread in nature. For example a pyrrole unit is the building block of the porphyrin skeleton, which in turn is the essential structural subunit of chlorophyll and hemoglobin. 

The influence of sunlight on vegetable growth, and the results of etiolation are, of course, well known to botanical students. There is no room for doubt that the production and evolution of the odour-bearing constituents of a plant are in direct relationship with the chlorophyll... 

In plants, chlorophyll is the pigment that absorbs radiant energy from the Sun. This allows the transfer of electrons from water to carbon dioxide, creating the products glucose and oxygen. The equation for photosynthesis is ... 

Chlorophyll a, the green photosynthesis pigment, is the prototype of the chlorin (2,3-dihydro-porphyrin) class of products. It was first isolated by Willstatter1 at the turn of the century. The common structural unit in this class is the chlorin framework named after chlorophyll. The chromophore with a partially saturated pyrrole ring, which is formally derived from the completely unsaturated porphyrin, is less symmetric than the latter and systematically named according to IUPAC nomenclature as 2,3-dihydroporphyrin. 

For more than two decades Woodward s total synthesis1 1 "d of chlorophyll a was in fact the only total synthetic approach to a chlorin. When, in the early eighties, new chlorin-type natural products were isolated from different biological sources, a systematic investigation of selective synthetic approaches leading to chlorins was induced.4... 

Electrochemical reduction has been studied intensively in the chlorophyll series due to the possibility to utilize the formed reduction products for the preparation of bacterio-chlorophylls.31c-d 41 For instance, methyl 3 -oxorhodochlorin-l5-acetate (4), a metal-free chlorin, can be electrochemically reduced to the corresponding chlorin 5 which is at the same oxidation level as a tetrahydroporphyrin. 

The formation of bacteriochlorins from chlorophyll derivatives has also been studied.8 The reduction product 16 of methyl 3 -oxorhodochlorin-l 5-acetate (see Section 1.2.2.) undergoes photooxygenation with singlet oxygen to yield finally a bacteriochlorin 17. 

Although phthalocyanines are structurally similar to porphyrins such as hemoglobin, chlorophyll a and vitamin B12, they do not occur in nature. Formally, phthalocyanines can be regarded as tetrabenzotetraazaporphyrins and as the condensation products of four iso-indoline units. 

Fig. 8.8 The chemical structures of dinoflagellate luciferin (5), the product of luminescence reaction catalyzed by luciferase (6), air-oxidation product formed at — 20°C (7), and the blue oxidation product (8). Note structural resemblance between these compounds and chlorophylls.

Over 20% of the world s open ocean surface waters are replete in light and major nutrients (nitrate, phosphate, and silicate), yet chlorophyll and productivity values remain low. These so-called "high-nitrate low-chlorophyll" or HNLC regimes (Chisholm and Morel, 1991) include the sub-arctic North Pacific (Martin and Fitzwater, 1988 Martin et al, 1989 Miller et al, 1991), the equatorial Pacific (Murray et al, 1994 Fitzwater et al, 1996) and the southern Ocean (Martin et al.,... 

Recently, the ocean-basin distribution of marine biomass and productivity has been estimated by satellite remote sensing. Ocean color at different wavelengths is determined and used to estimate near-surface phytoplankton chlorophyll concentration. Production is then estimated from chlorophyll using either in situ calibration relationships or from empirical functional algorithms (e.g., Platt and Sathyendranth, 1988 Field et al., 1998). Such studies reveal a tremendous amount of temporal and spatial variability in ocean biological production. 

Antoine, D., Andre, J.-M., and Morel, A. (1996). Oceanic primary production, 2. Estimation at global scale from satellite (coastal zone color scanner) chlorophyll. Global Biogeochem. Cycles 10, 57-70. 

Allomerized chlorophylls are oxidized compounds at C-13, forming theC-13 OH-chlorophyU catabolites. Other common positions for modifications and/or oxidation have been found at C-3, C-7, and C-8. Pyroderivatives of chlorophylls and their degradation products, usually found in heated and processed vegetables, lack the carbomethoxy group (-COOCH3) at C-13 of ring E, which is replaced by hydrogen. 

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