Chlorophyll reduction

Lauenroth, W.K. and J.L. Dodd. 1981. Chlorophyll reduction in western wheat-grass (Agropyron smithii Rydb.) exposed to sulfur dioxide. Water Air Soil Pollut. 15 309-315. 

In V tvo the chlorophyll molecules are reduced by water and restored by reducing an appropriate intermediate which in turn reduced CO2 CLynch and French, 1954 Rabinowitch, 1956). Bannister C1959) studied the reversible photochemical chlorophyll reduction and suggested that the triplet form of chlorophyll participated but not the singlet ... 

The immediate electron acceptor for P700 is a special molecule of chlorophyll. This unique Chi a (Aq) rapidly passes the electron to a specialized quinone (Aj), which in turn passes the e to the first in a series of membrane-bound ferredoxins (Fd, Chapter 21). This Fd series ends with a soluble form of ferredoxin, Fd, which serves as the immediate electron donor to the fiavo-protein (Fp) that catalyzes NADP reduction, namely, ferredoxin NADP reductase. 

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. 

Another tetrahydroporphyrin derivative, porphodimethene (7), which consists of two dipyr-rylmethene halves is obtained in the photoreduction of magnesium-containing chlorophyll a (6) with hydrogen sulfide3211 42 as reductant and pyridine as base. 

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. 

Chlorophyll, plastoquinone, and cytochrome are complicated molecules, but each has an extended pattern of single bonds alternating with double bonds. Molecules that contain such networks are particularly good at absorbing light and at undergoing reversible oxidation-reduction reactions. These properties are at the heart of photosynthesis. 

In a clinical trial performed in China, the administration of 300 mg/day of copper chlorophyllin to humans who had detectable levels of serum aflatoxin due to unavoidable food contamination resnlted in a 50% reduction of median urinary levels of aflatoxin-DNA adducts. If health benefits from consuming natural chlorophylls were confirmed, it wonld be easy to add green leafy vegetables to a daily diet to obtain the benefit. Since leafy vegetables contain usually up to 200 mg chloro-phylls/100 g fresh weight, the intake of approximately 1 to 2 cups of raw spinach/day... 

Oberhuber, M. and Krautler, B., Breakdown of chlorophyll electrochemical bilin reduction provides synthetic access to fluorescent chlorophyll catabolites, Chembio-chem, 3, 104, 2002. 

Electrochemical reduction of carbon dioxide has found no extensive application so far, yet it is of great interest for scientists in the fields of theoretical and applied electrochemistry. To a certain extent, it is analogous to the photochemical carbon dioxide reduction, but it involves no chlorophyll and yields simpler products. In recent years some books and reviews on this topic have been published (e.g., Taniguchi, 1989 Sullivan et al., 1993 Bagotsky and Osetrova, 1995). 

Exposed for 35 days to 30, 250, or 3000 pg atrazine/L 100 pg/L, 3-4 weeks 1000 pg/L, 3-4 weeks The high concentration significantly enhanced peroxidase activity but did not affect growth or chlorophyll production (Lytle and Lytle 1998) Biomass reduction of 34% (Stevenson etal. 1982) Biomass reduction of 46% (Stevenson etal. 1982)... 

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