Conjugation of vitamin C with serum proteins: A potential application for vitamin delivery

Vitamin C plays an important role in human health and therefore, the bioavailability and delivery of this micro-nutrient in solution have been the subject of intensive studies. Serum proteins are known to play an important role as drug delivery tools with important clinical applications. The conjugation of L-ascorbic acid with human serum albumin (HSA), bovine serum albumin (BSA) and beta-lactoglobulin (beta-LG) was investigated in aqueous solution at physiological pH. Multiple spectroscopic methods, thermodynamic analysis and modeling were used to determine the binding efficacy of the vitamin C with serum proteins. Acid-protein conjugation occurred via ionic contacts. Acid forms more stable adducts with beta-LG with the order of stability beta-LG > HSA > BSA. The loading efficacy was 45-60%. Major alterations of protein secondary structures were observed upon acid conjugation. Serum proteins can deliver vitamin C in vitro. (C) 2019 Elsevier B.V. All rights reserved.