Quantitation Of A Novel Photosensitizer Zinc Pentalysine β-carbonyl-phthalocyanine In Vivo Or In Vitro And Its Interaction With Serum Albumin

Photodynamic therapy (PDT) has many advantages over current cancer treatment modalities, such as surgery, chemotherapy, and radiation therapy. One of the current focuses in this field is the development of tumor selective photosensitizer for PDT. zinc pentalysineβ-carbonyl-phthalocyanine (5K-β-ZnPc) is a novel anionic tumor-targeting photosensitzer, which shows a higher level tumor cell uptake and 20-fold increased phototoxicity on tumor cells compared to anionic zinc phthalocyanine photosensitizers. Therefor, 5K-β-ZnPc may become a potential photosensitizer to develop into clinical use. Despite the growth of knowledge in phthalocyanine derivatves synthesis and medical applications, there's a disappointing inactivity in the evolution of analytical methods for their characterization and determination in biological samples. Although it is well known that serum proteins are predominatly responsible for the transportation of ZnPc throughout the body, their molecular basis of interaction is still not fully undertood.In the first and second parts, it were studied the fluorescence characteristics of the 5K-β-ZnPc in micellar system. The experiments indicate that the existence of Sodium dodecyl sulfate (SDS) in testing system can enhance the fluorescence intensity of 5K-β-ZnPc greatly. A novel method using the SDS micellar system for the determination of 5K-β-ZnPc in buffer solution, human urine or plasma and rat plasma has been developed. The experimental conditions that influence the fluorescence intensity were investigated and optimized. In buffer solution, human urine or plasma and rat plasma the linear ranges all are 10 ~500 nmol/L; the detection limits are 2.3, 5.3, 3.0, 4.6 nmol/L, respectively, and the relative recoveries are 93.0% ~ 103.8%, 93.1% ~ 110.0% and 97.1% ~ 110.0 %, 97.0% ~ 100.9%, respectively; the relative standard deviations (RSD) are all under 10%. The method has been successfully used to determine 5K-β-ZnPc in spiked Human plasma and urine, and to determine the phamacokinetics parameters in rat plasma.After i.v. single dosing at 2 mg·kg-1 to rats, the 5K-β-ZnPc in the plasma sample was determinated using micellar enhanced spectrofluorometric method. The plasma concentration-time curve was simulated and pharmacokinetic parameters were calculated by Drug And Statistics 1.0 software. The pharmacokinetics fitted as an open two-compartment model. The main pharmacokinetic parameters were estimated to be follows: (0.64±0.15) h for t1/2α, (5.77±2.30) h for t1/2βand (0.0047±0.0014) mL·kg-1 for Vd. The pharmacokinetic parameters indicate that 5K-β-ZnPc is distributed fast and eliminated slowly and have a narrow tissue distribution.In the third part, the interaction of pentalysineβ-carbonyl-phthalocyanine zinc (5K-β-ZnPc) with bovine serum albumin (BSA) was investigated using fluorescence, UV-vis absorbance spectroscopy. The fluorescence quenching was used to discuss the mechanism of quenching, binding intensity and binding site. The mechanism of quenching of fluorescence is static quenching process. The binding constant and the number of binding site was calculated in different temperatures (298, 303, 308, 313, 318 K): Ks = 12.1, 7.69, 6.12, 4.57, 3.76×104 mol·L-1, respectively, n = 0.93, 1.02, 1.07, 1.13, 1.17, respectively; The binding distance r = 2.64 nm between BSA and 5K-β-ZnPc was obtained according to the theory of Forster non-radiation energy transfer. The result indicates that 5K-β-ZnPc strongly bind to BSA with the molar ratio of 1:1.