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Relationship between the covalent binding of N-acetoxy-2-acetylaminofluorene to DNA and a steroidal esterase activity in human mononuclear leukocytes

1988; Elsevier BV; Volume: 66; Issue: 1-2 Linguagem: Inglês

10.1016/0009-2797(88)90037-3

1872-7786

Margaretha Lund‐Pero, Ronald W. Pero, Daniel G. Miller,

Organic Chemistry Cycloaddition Reactions

A method for the quantitative assessment of steroidal esterase activity in viable human mononuclear leukocytes (HML) has been developed. It is based on estimating the conversion of [3H]beclomethasone-17,21-dipropionate (BDP) to beclomethasone-17-monopropionate (BMP) using TLC on silica gel 60 F-254 plates developed in a solvent system of chloroform/methanol (97:3, v/v). The cell assay procedure was dependent on BDP concentration, incubation time and cell concentration. The steroidal esterase activity was competed for by N-acetoxy-N-acetyl-2-aminofluorene (NA-AAF) and completely inhibited by 100 μM paraoxon. When [3H]NA-AAF binding to DNA was used as an indicator of HML esterase (deacylase) activity, BDP functioned as a substrate inhibitor. Parallel estimations of BDP metabolism and NA-AAF binding to DNA indicated striking correlations in the interindividual variations (r = 0.62, P < 0.001) and in relation to the menstrual cycle events of a healthy female. Hence, these data indicate that both BDP and NA-AAF are metabolized by the same non-specific steroidal esterase present in HML.