Isolation of chlorophylls

The chlorophylls produced by bacteria, algae and plants are a natural source of chlorins. The isolation of chlorophylls from natural material is known to be difficult because of their extreme sensitivity to various reactions, such as enolization, epimerization, allomerization, de-methoxycarbonylation, solvolysis, demctalation, dephytylation, photooxidation, etc. Often the... 

Isolation of Chlorophyll and Carotenoid Pigments from Spinach... 

Adsorptive separations have been in use well before the twentieth century. Tswett (1905, 1906), however, was the first who coined the term Chromatography in 1903 for the isolation of chlorophyll constituents. Kuhn and Brockmarm, in the course of their research recognized the need for more reproducible and also more selective adsorbents, specially tuned for specific separation problems. This recognized demand for reproducible stationary phases led to the development of first materials standardized for adsorption strength and describes the first attempt toward reproducible separations (Unger et al., 2010). 

Tswett s research involved the isolation of chlorophyll from plant material. Whilst carrying out his work, he found a difference in polar and nonpolar solvents as to how well the isolation occurred. He concluded that this... 

The first result demonstrating the uptake of chlorophyll derivatives by human intestinal cells was in 2001 by Schwartz s group [61]. Up to then, only a few studies focussed on the isolation of chlorophyll derivatives in feces of humans and animals assuming negligible absorption. 

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... 

Diets high in red meat and low in green vegetables have been associated with increased colon cancer risk and the opposite has been postulated for diets rich in green vegetables. A plausible explanation for an increased colon cancer risk is that dietary haem is metabolized in the gut to a factor that increases colonic cytotoxicity and hyperproliferation, which are considered important risk factors in the development of cancer. In this sense, it has been shown that spinach and isolated natural chlorophyll, but not sodium-copper chlorophyUin, prevented the proliferation of colonic cells and may therefore reduce colon cancer risk. It has been speculated that haem and chlorophylls, due to their hydrophobicity, form a complex, thus preventing the metabolism of haem. ... 

Although chlorophyll and chlorophyllin colorants seem to be easily obtained, in practice their production as natural food colorants is rather difficult. The sensitivity of chlorophylls to certain enzymes, heat, and low pH, and their low tinctorial strength greatly limit their manufacture and application as food additives, principally when the pigments are isolated from the protective environment of the chloroplasts. The well-known instability of chlorophylls prompted extensive research for developing... 

Isolation of Sesquiterpene Lactones. The ether extract was evaporated and dissolved in 952 ethanol. Then an equal volume of 42 aqueous lead acetate was added. After 1 hour the mixture was filtered to remove precipitated chlorophyll and phenolic products and the ethanol removed under vacuum. The aqueous layer was extracted with chloroform giving a dark colored oil from which the sesquiterpenes were isolated by a combination of chromatographic procedures, i.e., LH-20 gel permeation, silica gel using both packed columns and thin layer plates. A variety of solvents were also used to purify the individual sesquiterpene lactones, e.g., benzene-acetone (1 1), ethyl acetate, chloroform-methanol (9 1). On thin layer chromatographic plates, spots were visualized by spraying with 22 aqueous KMn04 solution. 

Another very common phytochemical isolated was phytol (3,7,11, 15-tetramethyl-2-hexadecen-l-ol), the diterpenoid alcohol which forms the "tail" of chlorophyll. This compound is nearly insoluble in water, but when applied as a 0.1 mM (0.003 wt. %) solution in 0.1% DMS0 it increased onion germination while decreasing germination in sorghum, wheat, and carrot. The germination effects are significant at only the 95% level, but pretreatment studies are planned as part of other terpene chemistry studies at SRRC and LSI). 

Unlike the photosynthetic apparatus of photosynthetic bacteria, that of cyanobacteria consits of two photosystems, PS I and II, connected by an electron transport chain. The only chlorophyll present is chlorophyll a, and, therefore, chlorophylls b—d are not of interest in this article. Chlorophyll a is the principal constituent of PS I. Twenty per cent of isolated pigment-protein complexes contain one P700 per 20—30 chlorophyll a molecules the other 80% contain only chlorophyll a20). The physical and chemical properties of chlorophyll a and its role in photosynthesis have recently been described by Meeks77), Mauzerall75), Hoch60), Butler10), and other authors of the Encyclopedia of Plant Physiology NS Vol. 5. 

Ozone causes both quantitative and qualitative changes in carbon dioxide fixation patterns. Wilkinson and Bames, using carbon dioxide-found a reduction in radioactivity in soluble sugars and increases in free amino acids and sugar phosphates in white pine after a 10-min exposure to ozone at 0.10 ppm. Miller observed a decrease in carbon dioxide-fixation in ponderosa pines that correlated with loss of chlorophyll, after exposure to ozone at 0.30-0.35 ppm. The Hill reaction rates of chloroplasts isolated from healthy and ozone-injured ponderosa pine indicated that both light and dark reactions of the chloroplasts from ozone-injured plants were depressed. Barnes found depressed photosynthesis and stimulated respiration in seedlings of four pine species of the southeastern United States after exposure to ozone at 0.15 ppm. 

Simidjiev, L, Barzda, V., Mustardy, L., and Garab, G. 1997. Isolation of lamellar aggregates of the light-harvesting chlorophyll a/b protein complex of photosystem II with long-range chiral order and structural flexibility. Anal. Biochem. 250 169-75. 

Dendritic derivatives of these macrocycles can be placed in the wider context of studies on metalloporphyrins with sterically hindered faces which have been designed in attempts to mimic the properties of heme proteins and chlorophylls, and there are suggestions that steric isolation of the metalloporphyrin nucleus is important in certain biological functions, The redox properties of metalloporphyrins are well-documented they are dominated by two, reversible one-electron transfers involving both the metal and the ligand. The first dendritic porphyrins of general structure 47 and their Zn complexes were reported by Inoue et al. who... 

The photooxidation of chlorophyll indicated in Eq. 23-31 is accompanied by bleaching in the principal light absorption band. However, since there is so much light-gathering chlorophyll for each reaction center, the effect is small. The study of the process has been aided greatly by preparation of isolated bacterial photochemical reaction centers. 

Following extraction, an efficient way of initiating the isolation of carotenoids is to saponify the extract. This removes many of the unwanted lipids present in the sample as well as chlorophyll. The saponification by-products, which to a great extent are sodium or potassium salts, are easily separated by an aqueous solution of a highly polar salt. The addition of water also helps wash off excess alkali and other water-soluble and water-complexed compounds. This procedure hydrolyzes xantho-phyll esters to form the hydroxylated carotenoid. 

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