Photosensitization mechanism of active species by the complex of hypocrellin B with aluminum ion.

摘要

To improve the water solubility and red absorption of the parent hypocrellin B (HB), the complex of HB with aluminum ion has been first synthesized in high yield. The photodynamic action of Al(3+)-HB, especially the generation mechanism of active species, ([Al(3+)-HB].-, O2.- and 1O2) was studied using electron paramagnetic resonance (EPR) and spectrophotometric methods. In the deoxygenated DMSO solution of Al(3+)-HB, the semiquinone anion radical of Al(3+)-HB is photogenerated via the self-electron transfer between the excited and ground state species. The presence of electron donor significantly promotes the reduction of Al(3+)-HB. When oxygen is present, superoxide anion radical (O2.-) is formed via the electron transfer from [Al(3+)-HB].- to the ground state molecular oxygen. Singlet oxygen (1O2) can be produced via the energy transfer from triplet Al(3+)-HB to ground state oxygen molecules. Furthermore, it is very significant that the accumulation of [Al(3+)-HB].- would replace that of O2.- or 1O2 with the consumption of oxygen in the sealed system.