BINDING MEASUREMENTS OF INDOLOCARBAZOLE DERIVATIVES TO IMMOBILIZED HUMAN SERUM-ALBUMIN BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

The binding properties of six indolocarbazole derivatives have been me asured using immobilised human serum albumin (HSA) in an HPLC column. The compounds showed very strong binding to HSA which necessitated the application of a 30 to 40% concentration of 2-propanol in the mobile phase. This represents a much higher concentration than is recommended by the column manufacturers. This HSA column had not changed its bind ing property when it was used again with 4% 2-propanol and 96% phospha te buffer. The binding parameters were estimated by extrapolation to 0 % 2-propanol and were above 99% for each indolocarbazole derivative. T he correlation analysis, including the calculated octanol/water partit ion coefficient (log P), pK(a) values as well as measured reversed-pha se retention data of the compounds, revealed that the extremely strong binding can be explained by the hydrophobic and acidic properties of the compounds.