Design, synthesis, characterization of peripherally tetra-pyridine-triazole-substituted phthalocyanines and their inhibitory effects on cholinesterases (AChE/BChE) and carbonic anhydrases (hCA I, II and IX)

Abstract

In this study, phthalocyanine precursors (5 and 9) and 1,2,3-triazole-substituted metal-free and metallo phthalocyanines (9a-c) were designed and synthesized for the first time and evaluated in vitro for key molecular targets. The structures of the novel compounds were characterized via FT-IR, ¹H/¹³C NMR, UV-Vis, and mass spectroscopy. The inhibitory activities of the compounds were tested against human carbonic anhydrase isoforms hCA I, II (cytosolic, ubiquitous isozymes), and IX (transmembrane, cancer-associated isozyme) and cholinesterases (AChE and BChE, which are associated with Alzheimer's disease). Among the three phthalocyanines and starting compounds, 9b showed the most interesting profile as a nanomolar selective inhibitor of hCA I (K_i = 37.2 nM) and 9c showed the most effective inhibitory effect on hCA II, IX, AChE and BChE (K_i = 41.9, 27.4, 5.8 and 45.8 nM, respectively). This study is also the first example of cancer-associated isozyme hCA IX inhibition by phthalocyanines.