Jiazhu Li

Synthesis, optical properties and preliminary in vitro photodynamic effect of pyridyl and quinoxalyl substituted chlorins.

A series of chlorophyll a-based chlorins conjugated with pyridyl or quinoxalyl group at different positions were synthesized, characterized and evaluated for their photodynamic effect in vitro. It was found that all the pyridyl and quinoxalyl chlorins showed promising photocytotoxicities but nontoxic without irradiation in HeLa cells, and the substituted types and positions had a significant influence on the photocytotoxicities of the chlorophyll a-based chlorins. All the chlorins with a pyridyl group at the C-D ring end exhibited relatively high photocytotoxicity as compared to those with 3(2)-pyridyl. Among them, compound 12 conjugated with a pyridyl group at its C12 position showed the best photodynamic effect in HeLa cells with an IC50 value of 0.033μM. These facts, associated with the relative high long wavelength absorptions of those chlorins may provide valuable ways to design and prepare promising photosensitizers for application in photodynamic therapy.

Regioselective reactions of methyl pyropheophorbide a with formaldehyde based on hydroxymethylation

Regioselective reactions of methyl pyropheophorbide a (MPPa) with formaldehyde based on hydroxymethylation have been studied. It was found that MPPa can react regioselectively with formaldehyde under different conditions to produce a series of 3-dioxane, 12-, 132- or 20-hydroxymethyl and 12-/132-alkenyl-substituted chlorins via Prins reaction, Blanc chloromethylation and aldol reaction, respectively. The first examples of direct C–C bond formation at 12-position of chlorophyll derivatives were also reported to give a series of 12-vinyl-substituted chlorins. These chlorins showed extend Qy absorptions and efficient singlet oxygen generation property, indicating their potential as photosensitizers for application in photodynamic therapy.

Synthesis of Chlorophyllous Chlorins Derivatives Substituted by Aromatic Groups on Their Periphery

Pyropheophorbide-a methyl ester, as a degraded product from chlorophyll-a, was used as a starting material, and the modifications for functional group along N-N-axis and reconstructions for five-membered exocyclic E-ring were completed to introduce different aromatic groups which could conjugated with macrocyclic chromophore at various degrees on the periphery. The syntheses of 12 unreported chlorins related to chlorophyll were accomplished and their chemical structures were characterized by elemental analysis, UV, IR, MS and H NMR spectra. The different effects on the physical and chemical properties of chlorophyllous chlorins by introduction of aromatic groups were discussed.