Screening of binding by antidiabetic drugs to normal vs AGE-modified human serum albumin through covalent immobilization and microscale affinity chromatography.

Microscale affinity chromatography (μAC) was used with covalent protein immobilization and zonal elution to quickly screen and compare binding by several sulfonylurea-based antidiabetic drugs with human serum albumin (HSA) and forms of this protein containing advanced glycation end-products (AGEs). The HSA was modified with glyoxal or methylglyoxal and examined for its binding to the following drugs: acetohexamide, chlorpropamide, gliclazide, glipizide, tolbutamide, and tolazamide. The HSA was coupled by the Schiff base method onto HPLC-grade silica, which was then placed into 10 mm × 2.1 mm i.d. affinity microcolumns. These microcolumns each contained ∼1 mg HSA and could be used for over 450-500 sample injections. The drugs were injected onto these microcolumns at 37 °C and pH 7.4, giving retention data at 0.50 mL/min within a few minutes (e.g., less than 5 min for normal HSA). The overall binding constants obtained for normal and AGE-modified HSA were consistent with the literature, showing a strong correlation with prior values estimated when using immunoaffinity chromatography and the biospecific adsorption of HSA. These results indicated that μAC combined with zonal elution screening and Schiff base immobilization was an effective approach for studying the interactions of sulfonylurea drugs with HSA and modified forms of this protein. This approach can be extended to other proteins and drug-protein interactions, as could be used for fundamental research or aid in the development of new treatments through personalized medicine.