Carbonic anhydrase inhibition and antioxidant activity of the axially naphthoxazin group substituted silicon phthalocyanines

Abstract

Silicon phthalocyanines are an interesting subclass of phthalocyanines. They are abundant and have extremely low toxicity levels. The low solubility of silicon phthalocyanine is the major obstacle to its use in many different applications. Therefore, in a previous study, two axially substituted silicon phthalocyanines were synthesized to increase their solubility. In this study, these axially substituted silicon phthalocyanines were evaluated for carbonic anhydrase inhibition and antioxidant activities. The carbonic anhydrase (CA) inhibition potential of silicon phthalocyanines was evaluated by esterase activity. The antioxidant activity was tested by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric ion (III) reducing/antioxidant power (FRAP) assays. The silicon phthalocyanines had significant CA inhibitory activity [50% inhibitory values (IC50): 495 ± 12.74 nM and 857 ± 13.03 nM for H4-Si and H3-Si, respectively]. According to the antioxidant studies, 50% scavenging concentration (SC50) values of DPPH• assay were 2.29 ± 0.06 µg/mL and 1.39 ± 0.43 µg/mL for H3-Si and H4-Si and Trolox Equivalent Antioxidant Capacity (TEAC) values of FRAP test were 259.33 ± 48.27 µM and 342.00 ± 44.40 for H3-Si µM and H4-Si, respectively. Consequently, silicon phthalocyanine compounds are considered to have great potential for their use in various fields such as food and medicine.