Metabolism of oxisuran, an immunosuppressant, by the rat

General Method for Asymmetric Synthesis of alpha-Methylsulfinyl Ketones: Application to the Synthesis of Optically Pure Oxisuran and Bioisosteres

The first asymmetric synthesis of oxisuran [1, (methylsulfinyl)methyl 2-pyridyl ketone], a synthetic immunosuppressive drug, is described. Both enantiomers were efficiently synthesized, in optically pure form, using DAG methodology for the key condensation step. Attempts to couple metal enolates of aryl methyl ketones with chiral sulfinyl compounds led to some epimerization at sulfur. This loss of chirality was circumvented by reacting the alpha-lithio derivatives of the N,N-dimethylhydrazones derived from these ketones with either the (R)- or the (S)-methanesulfinate of diacetone D-glucose, to yield the corresponding alpha-(methylsulfinyl)methylhydrazones, with complete inversion of chirality at sulfur. Hydrolysis of the resulting hydrazones with copper(II) chloride gave 1 in optically pure form. The generality of the method was demonstrated by the preparation of the optically active oxisuran analogs, 2-4, in which the pyridyl moiety was replaced by phenyl, furyl, and thienyl moieties, respectively. The optical purities of these products were determined by proton NMR spectroscopy, using chiral shift reagents, following conditions established by the study of racemic mixtures of the beta-keto sulfoxides.

Oxisuran: influence on allograft rejection and graft versus host reactivity in chickens and mice

Oxisuran, a reported differential suppressant of cell-mediated immunity in several mammalian species, was evaluated for its capacity to prolong allograft survival and reduce graft versus host reactivity in chickens. In addition, the capacity of oxisuran to modulate cell-mediated immunity in mice was reappraised. In the chicken, the administration of 50, 100, or 1000 mg of oxisuran/kg body weight did not significantly prolong allograft survival. Furthermore, graft versus host (GVH) reactivity was not significantly diminished following treatment with 50 or 100 mg of oxisuran/kg body weight; however, GVH reactivity was significantly suppressed after administration of a high dose, 1000 mg of oxisuran/kg body weight. In mice, 100 mg of oxisuran/kg body weight slightly prolonged the survival of H-2a allografts on H-2d recipients, but it did not significantly alter GVH reactivity. Thus, the capacity of oxisuran to significantly suppress cell-mediated immune functions can be questioned at least in the species studied.

A new oxisuran metabolite

1. An unidentified oxisuran metabolite which had been observed in animal urine was biosynthesized by incubating [14C]oxisuran with rat liver cytosol. 2. The metabolite, isolated by preparative t.l.c. and extraction, was identified as oxisuran alcohol sulphide by mass fragmentography. Confirmation of this identification was obtained by biosynthesis of the same compound from oxisuran sulphide. 3. The 9000 g supernatant liquid from rat liver was less effective than cytosol in reducing oxisuran to its alcohol sulphide. Neither rat liver fraction reduced oxisuran alcohol sulphoxides to sulphide. 4. The 9000 g fraction oxidized oxisuran and oxisuran alcohol sulphoxide to oxisuran alcohol sulphone.