Author Type

Graduate Student

Date of Award

2007

Document Type

Dissertation

Publication Status

Version of Record

Submission Date

October 2026

Thesis/Dissertation Advisor [Chair]

Florida Atlantic University

Thesis/Dissertation Co-Chair

Louda, J. William

Abstract

Cyclopheophorbides absorb light at higher wavelengths (> 670 run) as compared to their precursor pyropheophorbides ( ~ 666 run) and are strong antioxidants. Therefore they could potentially be used as photosensitizers in photodynamic therapy, although this study does not focus on the pharmacology aspect of this class of compounds. The overall goal of this study was to hemisynthesize, purify and characterize certain cyclopheophorbides from both chlorophyll a and b families. The known hemisynthesis of 13^2,17^3-cyclopheophorbide a enol was repeated. A major success in the purification process was achieved by utilizing polystyrene divinylbenzene (PS-DVB a.k .a. PRP-1 TM) as the stationary phase in reversed phase flash chromatography. Altering (TMS)2-NNa with (TMS)2-NLi was found to increase yields. 13^2,17^3 -mesocyclopheophorbide a enol was successfully hemisynthesized as a novel compound. Methyl-3-devinyl-3-[1-hexyloxy]ethyl pyropheophorbide a (HPPH-ME), was prepared, purified and molecular characteri zation on the compound was performed. Hemisynthesis ofHPPH-CYCLO from HPPH-ME was attempted, but was unsuccessful. Zinc and copper pyropheophorbide a methyl esters were prepared with the intent of forming of zinc and copper CYCLO. Hemisynthesis of corresponding metalloCYCLO from both insertion of the metal inside the CYCLO core and cyclizations of metal derivatives of pyropheophorbide a methyl ester were unsuccessful. Chlorophyll b was successfully extracted from green algae Chiarella and purified in mg lots (100%) utilizing RP-LPLC and with a binary solvent gradient program. Pheophorbide b methyl ester and pyropheophorbide b methyl ester were made and characterized. Hemisynthesis of CYCLO-b was unsuccessful likely due to the altered reactivity of pyropheophorbide b (vs. -a) methyl ester. To reduce the reactivity, reduction of formyl group of pyropheophorbide b methyl ester with NaBH4 was performed. Still, formation of a CYCLO derivative was not achieved. Chromatographic purification, mass and NMR characterization of CYCLO, mesoCYCLO, HPPH-ME and all precursor compounds are reported. 2D NMR of most of these compounds are reported here for the first time.

Extent

195 p.

Comments

Includes bibliography.|Dissertation (Ph.D.)--Florida Atlantic University, 2007.|FAU Electronic Theses and Dissertations Collection|Charles E. Schmidt College of Science|Includes bibliography.

Identifier

FA00000872

Format

pdf

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