Efficient production of the cyclosporin metabolite AM1 by rabbit hepatic enzymes.

We describe here conditions for the in vitro preparation of the main metabolite of cyclosporin A, namely AM1, with rabbit liver enzymes. The compound was purified and was identified by comparison with the metabolite isolated from urine of rats treated with [3H]CsA and by its Mass-Spectrometry Fast Ion Bombardment (MS-FIB) and 1HNMR spectra. The procedure is simple and with the enzyme fraction derived from one rabbit liver 3-4 mg of the pure metabolite can be obtained.