- Synthesis of a chlorophyll-a derivative fused with an additional exo-five-membered ring and its optical properties
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A C20-free chlorophyll-a derivative with an additional exo-five-membered ring was successfully prepared using an ethylene linkage at the C3- and C5-positions. A bromination at the C20-position was requisite for the cyclization of a 1-hydroxyethyl or vinyl group at the C3-position of methyl bacteriopheophorbide-d or methyl pyropheophorbide-a, respectively. By comparing optical properties of the cyclized product with those of its 3-ethyl uncyclized analog in a diluted dichloromethane solution, it was shown that the cyclization shifted the Qx and Bx absorption maxima to longer wavelengths and reduced the Stokes shift.
- Doi,Tamiaki, Hitoshi
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- Regioisomeric synthesis of chlorin-e 6 dimethyl esters and their optical properties
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Chlorin-e6 dimethyl esters possessing a single carboxy group at the 13-, 151-,or 172-position were prepared by chemically modifying chlorophyll-A. These three synthetic regioisomers were fully characterized by their mass, NMR, and visible absorption spectra. Their molecular structures were unambiguously identified by the specific 1H-13C correlation at the 13-, 15-, and/or 17-substituents in their respective HMBC spectra. Methyl esterification of 13/151-COOH and hydrolysis of 13/151-COOMe affected small shifts of the Qy absorption and fluorescence emission maxima in a diluted CH2Cl2 solution, while no substitution effect of 172-COOH/Me was observed.
- Nagano, Yasunobu,Ogasawara, Shin,Tamiaki, Hitoshi
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p. 1039 - 1046
(2018/11/23)
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- PHEOPHORBIDE-alpha CONJUGATES AND THEIR USES
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The present invention relates to a pheophorbide-α conjugate or its salt, solvate or hydrate. The pheophorbide-α conjugate of the present invention exhibiting fluorescence upon its introduction into cells and degradation inhibits the survival of various cancer cells. Especially, the conjugate of pheophorbide-α and doxorubicin shows higher fluorescence intensity at lower pH (cancer environment). Therefore, the present composition for photodynamic therapy (PDT) of cancers is also very useful in detecting cancers. Interestingly, the anticancer effects of the present composition are dually exerted with help of both the photosensitizer and the anticancer drug of the present conjugates.
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Paragraph 0050
(2013/08/28)
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- Modification of 3-substituents in (bacterio)chlorophyll derivatives to prepare 3-ethylated, methylated, and unsubstituted (nickel) pyropheophorbides and their optical properties
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Methyl mesopyropheophorbide-a possessing an ethyl group at the 3-position, its 31-demethyl analogue (3-methyl homologue), and its 3 1-deethyl analogue (3-unsubstituted chlorin) were prepared by modifying naturally occurring (bacterio)chlorophylls bearing 3-vinyl, formyl, acetyl, and 1-hydroxyethyl groups. These synthetic 3-(un)substituted chlorophyll derivatives and their nickel complexes are probable intermediates during degradation of (bacterio)chlorophylls to chemically stable porphyrinoids. The optical properties (visible absorption, circular dichroism, and fluorescence emission) of the catabolic candidates in a solution were measured, and the substitution effect was investigated.
- Tamiaki, Hitoshi,MacHida, Shinnosuke,Mizutani, Keisuke
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body text
p. 4751 - 4758
(2012/07/14)
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- Methods for Preparing Chlorophyll a and Chlorin e6
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The present invention relates to a method for preparing chlorophyll-a and chlorin e6. This invention extracts chlorophyll-a by use of undisrupted chlorella cells themselves, thereby preparing chlorin e6 from the chlorophyll-a extract. The high contents of chlorophyll-a may be obtained by the pretreatment procedure of chlorella cells themselves selected in this invention. The present method is performed according to relatively simple procedures, and is suitable in the mass production of chlorin e6.
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Page/Page column 6
(2010/05/13)
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- Photophysicochemical properties of chlorophyll-a adsorbed on Mg-containing mesoporous silica
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Chlorophyll-a (chl-a) was found to easily change to pheophytin-a during its adsorption on hexagonal mesoporous silica (HMS) since the centered Mg ions of chl-a easily react with silanol groups as Bronsted acid sites (pheophytinization). This pheophytinization process could be suppressed by adding small amounts of Mg species into the frameworks of HMS. The highly dispersed Mg species work as adsorption sites for chl-a and/or the porphyrin ring of pheophytin-a, resulting in the formation of an original chl-a like complex species. Copyright
- Nakamura, Takahiko,Takeuchi, Masato,Yamashita, Hiromi,Anpo, Masakazu
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p. 106 - 107
(2007/10/03)
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- A Capillary Mixer with Adjustable Reaction Chamber Volume for Millisecond Time-Resolved Studies by Electrospray Mass Spectrometry
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A novel continuous-flow apparatus for on-line kinetic studies of (bio)chemical solution-phase processes by electrospray ionization mass spectrometry (ESI-MS) is described. The device is based on two concentric capillaries. Fluid is released from the inner capillary into the intercapillary space, where it mixes with solution flowing through the outer capillary, thus initiating the reaction of interest. Gas-phase analyte ions are formed near the tip of the outer capillary by pneumatically assisted ESI. This setup allows the mixer to be placed directly within the ion source, thus providing a minimal dead volume of ~8 nL. Time-resolved data can be recorded in both spectral and kinetic modes. In the former case, the position of the inner capillary is fixed at various points, such that entire mass spectra can be recorded for selected reaction times. For experiments in kinetic mode, the mass spectrometer monitors the signal intensity at selected m/z values, while the inner capillary is continuously pulled back, thus providing intensity-time profiles for specific reactive species. A theoretical framework is developed that allows the measured kinetics to be analyzed by taking into account the effects of laminar flow within the reaction capillary. Failure to take these effects into account results in erroneous rate constants. Studies on the demetalation kinetics of chlorophyll reveal that the apparatus can reliably measure rate constants up to at least 100 s-1. This represents a substantial improvement over previous ESI-MS-based kinetic methods. Spectral mode experiments on the refolding of ubiquitin show the changing proportions of denatured and tightly folded protein subpopulations in solution. When monitored in kinetic mode, the refolding process was found to proceed with a rate constant of 5.2 s-1.
- Wilson, Derek J.,Konermann, Lars
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p. 6408 - 6414
(2007/10/03)
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- Effect of dietary chlorophyll derivatives on mutagenesis and tumor cell growth
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Much attention in recent years has been given to the antigenotoxicity of chlorophyll. Chlorophyll, however, is known to be converted into pheophytin, pyropheophytin, and pheophorbide in processed vegetable food and following ingestion by humans. Studies were conducted on the antimutagenic and tumoricidal potencies of these compounds. All the chlorophyll derivatives tested exhibit identical antimutagenic effect towards 3-methylcholanthrene (3-MC), suggesting that the porphyrin nucleus may complex directly with the mutagen. It does not exclude, however, another mechanism of activity involving inactivation the enzymatic transformation of 3-MC. In contrast, the action of N'-nitro-N'-nitrosoguanidine (MNNG) depends upon structural differences between the chlorophyll derivatives. It is significantly lower when the phytol-containing pheophytin and pyropheophytin are tested as to that of the phytol-lacking pheophorbide. The higher concentrations of the chlorophyll derivatives were required to reduce the mutagenicity of MNNG than needed for 3-MC. The cytotoxicity of chlorophyll derivatives against tumor cells also was evaluated. The cellular uptake and inhibition of myeloma cell multiplicity were found to be greater for pheophorbide than for pheophytin. Calculated on the amount of cell associated chlorophyll derivative, however, pheophytin was more cytostatic/cytotoxic than pheophorbide. The results presented in this report indicate that food sources that yield chlorophyll derivatives may play a significant role in cancer prevention.
- Chernomorsky, Simon,Segelman, Alvin,Poretz, Ronald D.
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p. 313 - 322
(2007/10/03)
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