Biomolecular study and conjugation of two para-aminobenzoic acid derivatives with serum proteins: drug binding efficacy and protein structural analysis

Abstract

Two aminobenzoic acid derivatives DAB-0 and DAB-1 showed distinct biological properties on murine bladder cancer (BCa) cell line MB49-I. In contrast to DAB-1, DAB-0 does not possess any anti-inflammatory activity and is less toxic. Furthermore, DAB-0 does not interfere with INFγ-induced STAT1 activation and TNFα-induced IκB phosphorylation, while DAB-1 does. In order to rationalize these results, the binding efficacy of DAB-0 and DAB-1 with serum proteins such a human serum albumin (HSA), bovine serum albumin (BSA) and beta-lactoglobulin (β-LG) was investigated in aqueous solution at physiological pH. Multiple spectroscopic methods and thermodynamic analysis were used to determine the binding efficacy of DAB-0 and DAB-1 with serum proteins. Drug-protein conjugation was observed via through ionic contacts. DAB-1 forms stronger adducts than DAB-0, while β-LG shows more affinity with the order of stability β-LG > BSA > HSA. The stronger complexation of DAB-1 with serum proteins might account for its biological potential and transport in the blood. The binding efficacy ranged from 40 to 60%. Major alterations of protein secondary structures were detected upon drug complexation. Serum proteins are capable of delivering DAB-1 in vitro.

Communicated by Ramaswamy H. Sarma

Keywords:

• DAB-0
• DAB-1
• serum protein
• delivery
• binding efficacy
• thermodynamic analysis

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The financial support of the Natural Sciences and Engineering Research Council of Canada (NSERC) to H.A. Tajmir-Riahi is highly appreciated. This study was also supported by grants from the Cancer Institute of Canadian Institutes of Health Research (CIHR; number 392334) the Cancer Research Society (CRS; number 22471), and Aligo Innovation (number 150923) to C. Reyes-Moreno and G. Bérubé. Y. Oufqir holds a M.Sc. fellowship from the CIHR.