Synthesis of oligomethylene-strapped chlorophyll derivatives and optical properties of their stereoisomers in a solution.
Methyl pheophorbide-a/a' derivatives covalently linked with oligomethylene chains at the 3-CH(2)OCO- and 13(2)-COO- moieties in a molecule were prepared by modifying chlorophyll-a through intramolecular ring-closing metathesis of vinyl groups. At least, a C10-length between the 3(3)- and 13(4)-positions was necessary for the cyclization and connection of a C12-strap was the most suitable to achieve the highest closure yield. The oligomethylene chain in 13(2)                         R-epimers derived from methyl pheophorbide-a covered the α-face of the chlorin π-plane and the strap in the corresponding 13(2)                         S-epimers protected the β-face. Synthetic 13(2)                         R-epimer with a dodecamethylene chain gave a flat chlorin π-plane, while the decamethylene chain in the 13(2)                         R-epimer distorted the π-system due to its shorter linkage. The distortion by strapping in the 13(2)                         R-epimer induced a slight blue-shift of Qy peak in dichloromethane. CD spectra of the 13(2)                         R-epimers were similarly dependent on the chain length, i.e., the distortion of π-plane. Visible absorption and CD spectra of all the strapped 13(2)                         S-epimers were almost identical and only slightly different from those of the unstrapped. The strapping in the 13(2)                         S-epimers shifted the Qy peak bathochromically.
Department of Bioscience and Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan. tamiaki@se.ritsumei.ac.jp
Hitoshi
H
Tamiaki
Hiroshi
H
Takebe
Shin-Ichi
S
Sasaki
Yumiko
Y
Kataoka
D002734:Chlorophyll / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D000077194:Chlorophyll A; D002942:Circular Dichroism; D008958:Models, Molecular; D008968:Molecular Conformation; D055095:Optics and Photonics; D012996:Solutions; D013054:Spectrophotometry, Atomic; D053545:Spirulina / Q000737:chemistry*; D013237:Stereoisomerism
D012996:Solutions; D002734:Chlorophyll; C032625:methylpheophorbide; C032623:pheophorbide a; D000077194:Chlorophyll A
Photochem Photobiol. 2007 Jan-Feb;83(1):152-62
16776548
Q Rev Biophys. 2006 Aug;39(3):227-324
17038210
Biochemistry. 2010 Mar 9;49(9):1882-92
20112981
Photochem Photobiol Sci. 2010 Aug;9(8):1152-8
20571638
Biochim Biophys Acta. 2009 Oct;1787(10):1254-65
19481055
FEBS Lett. 2005 Jan 31;579(3):712-6
15670833
Bioorg Med Chem Lett. 2008 Dec 1;18(23):6037-40
18938078
Photosynth Res. 2007 Nov-Dec;94(2-3):387-400
17505910
Bioorg Med Chem. 2005 Oct 15;13(20):5733-9
15993082