Study On Phthalocyanine-protein Complexes As Photosensitizer For Therapy Of Cancer

Photodynamic Therapy (PDT) is a new and developing technique for therapy of cancer, which has been received a greater attention in medical community. Nowadays, how to enhance the selective uptake of photosensitizer (PS) by targeted tumor is one of significant fields in PDT studies. The corresponding studies intercross on several subjects such as coordination chemistry, pharmacochemistry, photochemistry and biomedicine, and are highly regarded for its both important practical and theoretical sense. Considerable effort has been directed towards using delivery carries that can incorporate the PS without loss or alternation of its bioactivity, the method has been demonstrated that it can effectively enhances selective uptake of PS by tumor. Albumin (BSA, HAS) and Low-density lipoprotein (LDL) are some kinds of carriers that are value to evaluate. It has been found that the di-sulfo,di-phthalimidomethyl phthalolcyanine Zinc (ZnPcS₂P₂), an amphiphilic photosensitizer prepared by our group, exhibit higher photodynamic activities against tumors. In this dissertation, based on the previous work of our group, author has carried on some studies including interaction of amphiphilic phthalocyanine with proteins and the application of phthalocyanine-protein complexes as PS. The main results are summarized as following. 1) The interactions of phthalocyanines with proteins have been studied by spectral analysis methods. The method of quenching protein intrinsic tryptophan fluorescence has been improved, and the binding constants and sites of 10 phthalicyanines binding to proteins are obtained. The results shows that amphiphilic phthalicyanines, such as ZnPcS₂P₂ and ZnPc⁴H , bind strongly to BSA and have many sites; ZnPcS₂P₂ binds to LDL more strongly and sites comparing with albumin(BSA,HSA); ZnPcS₂P₂ molecules are combined to BSA or LDL mainly in monomer form, which is help to its PDT efficiency. Some phthalocyanine-protein complexes including LDL-ZnPcS₂P₂ have been prepared, using incubating protein with phthalocyanine, and then separating with gel permeation chromatography. The IR spectra of several complexes have also been analyzed. 2) The kinetic curves of cellular or tumor uptake of ZnPcS₂P₂ as well as LDL-ZnPcS₂P₂ complexes have been determined using fluorescence analyticalmethod. LDL- ZnPcS₂P₂ complexes promotes uptake by cancer cells or tumor comparing with ZnPcS₂P₂,the maximum K562 cellular uptake ratio of LDL-ZnPcS₂P₂ to ZnPcS₂P₂ is 2.0, this value is 4.50ng/10⁶cells for LDL-ZnPcS₂P₂. The maximum U14 tumor uptake ratio is 1.7, this value is 1.2ug/g tissue for LDL-ZnPcS₂P₂. The in vivo activities of LDL-ZnPcS₂P₂ complexes as compared with ZnPcS₂P₂ show that the activities of LDL-ZnPcS₂P₂ complexes are considerably higher than that of ZnPcS₂P₂ alone. For example, the inhibitory rates against U14 solid carcinomas after PDT-ZnPcS₂P₂ in which the dosage of drug was 0.5 mg per kg experimental mouse are 51.1%, while ZnPcS₂P₂-LDL complex after administration the same dosage is 60.3%. These indicate LDL is a good targeting delivery system for ZnPcS₂P₂.3) Three carboxylicphthalocyanines have been synthesized and characterized by elemental analysis, IR, UV/Vis and HNMR. Among them, the unsymmtrical and amphiphilic compounds----2,3,9,10-tetracarboxylic phthalicyanine zinc (ZnPc⁴H) and tetracarboxylicoctachloro phthalocyanine zinc (ZnPcCl4H) have not been reported so far , according to the best of our knowledge. The relative quantum yields of singlet oxygen (¹O₂)as well as in vitro activities of 8 phthalocyanines including ZnPcCl⁴H and ZnPc⁴H have also been investigated. It is found that the amphiphilic ZnPc⁴H is the best one among our test compounds. The relationships between structure and photodynamic activities of metallophthalocyanines are discussed.