SYNTHESIS OF COBALT CARBONYL-COMPLEXES OF CORTISOL AND TESTOSTERONE -STUDY OF THEIR RECOGNITION BY SPECIFIC POLYCLONAL ANTIBODIES

We have synthesized organometallic complexes of steroids (cortisol, te stosterone, dihydrotestosterone for potential use as tracers in noniso topic carbonyl-metal immunoassays (CMIA). An ethynyl/Co2(CO)6 fragment at the end of a five-atom spacer was coupled to position 3 of the ste roid skeleton. In the case of cortisol, we exploited the difference in reactivity of the ketone and enone functions toward amines in order t o form an enamine which was then made to react with carboxymethylamine to yield 3-[(carboxymethyl)oxime] steroid. Activation of the carboxyl ic acid function with N,N'-dicyclohexylcarbodiimide in the presence of propargylamine introduced an acetylenic function at the end of the sp acer. The triple bond was then complexed by Co2(CO)8 to form complexes 5a-c. Complexes for use in CMIA should be stable in biologic media an d effectively recognize specific antibodies. Complexes 5a-c were stabl e in the buffers we use in biochemical tests. Their cross reactivities for anti-cortisol and anti-testosterone antibodies ranged from 50 to 110% according to batch, indicating, first, that the addition of an or ganometallic complex in position 3 of the steroid skeleton does not hi nder recognition between the organometallic steroid and antibody and, second, that their individual behavior differs substantially according to antibody batch. Although all of these complexes could be used as t racers in CMIA, it is necessary, in each case, to establish which trac er-antibody duo gives rise to the most sensitive immunoassay.