Photodynamic Effect of Hypericin on the Conformation and Catalytic Activity of Hemoglobin

Abstract

Hypericin, extracted from H. perforatum, can induce the generation of reactive oxygen species by visible light irradiation, which may consequently induce the conformational change of hemoglobin. We have not only employed UV-vis spectroscopy to observe the changes of UV-vis spectra of the protein, which reveals the conformational changes of the protein, but also employed electrochemical method to obtain its enhanced peroxidase activity. The photodynamic effect of hypericin on the conformation and catalytic activity of the protein has also been proven to be strongly dependent on the irradiation time, the hypericin concentration and the presence of oxygen. This work is beneficial not only to the fabrication of more sensitive hydrogen peroxide biosensor, but also to the guidance of the usage of this medicinal herb molecule, since the conformational change of the protein and the enhanced peroxidase can be easily obtained only by visible light irradiation on hypericin, the process of which is so common to happen.

A review of the antibacterial activity of Hypericum perforatum L.

“…The process depends not only on the irradiation time but also on the concentration of hypericin. This study not only confirmed the photosensitization by hypericin and revealed the enhanced peroxidase activity of hemoglobin but may also find application in the development of a more sensitive H 2 O 2 biosensor using this molecule (Zhao et al, 2008).…”

Ultraviolet Irradiation-Dependent Fluorescence Enhancement of Hemoglobin Catalyzed by Reactive Oxygen Species

“…This second pathway is the so-called photodynamic effect. In particular, ROS induces structural changes of hemoglobin [17] , [18] and participates in the degradation process [19] , [20] . In a further series of experiments we therefore targeted to test for involvement of ROS in the observed UVI-induced fluorescence enhancement.…”

Electron transfer and interfacial behavior of redox proteins

“…For example, hypericin (HY), a phenanthroperylene quinine derivative, which is a widely used medicine for the treatment of depression, could induce the generation of ROS by visible light irradiation [121]. Therefore, irradiation on the surface of Hb and HY comodified electrode has been conducted and enhanced peroxidase activity of the protein has been obtained [122]. It is noteworthy that long time and strong irradiation need to be avoided, as more ROS than expected would interact with the amino acid residues of the protein and intensively damage the structure and activity of the protein.…”