BSA/DNA binding behavior and the photophysicochemical properties of novel water soluble zinc (II) phthalocyanines directly substituted with piperazine groups

Abstract

In the current research, two novel zinc(II) phthalocyanines (ZnPcs) (1 and 2) directly connecting with 4-(4-methylpiperazin-1-yl)phenyl groups have been synthesized through the Suzuki–Miyaura coupling reaction. These ZnPcs 1 and 2 were converted to their water-soluble derivatives (1Q and 2Q) by quaternization. The photochemical and photophysical properties were determined in DMSO for the non-ionic zinc(II) phthalocyanines (1 and 2) and in both DMSO and aqueous solutions for the quaternized cationic derivatives (1Q and 2Q) to establish their photosensitizer capabilities in photodynamic therapy (PDT). The spectrofluorometric and spectrophotometric techniques were employed for the determination of interaction between water-soluble ZnPcs (1Q and 2Q) and BSA or ct-DNA. The binding constants of these compounds to BSA were found in the order of 108 M−1. The binding constant of the ct-DNA interaction with 2Q (1.09 × 105 M−1) was found higher than 1Q (6.87 × 104 M−1). The thermodynamic constants were determined for both 1Q and 2Q. The endothermic and spontaneous nature of interaction was observed with ct-DNA. Besides, the thermal denaturation and viscosity studies proved the non-intercalative mode of binding for both compounds to ct-DNA.