Disposition in rats and mice of 7-methoxy-2-nitronaphtho[2,1-b]furan

The disposition of 7-methoxy-2-nitronaphtho[2,1-b]furan (MNNF), labelled with 14C in the furan ring (label 1) and in the methoxy group (label 2) has been studied in rats and mice. After i.p. administration to rat (5 mg/kg), both labelled species were absorbed by the lymphatics; and after oral administration, through the intestinal lumen. Excretion of the furan ring (label 1) is mainly urinary (44% dose in 24 h); label 2 was mostly expired as 14CO2 (48% dose in 24 h), indicating considerable demethylation. No target organ was found for MNNF, except liver and kidney. For both labelled species given orally, radioactivity was bound to the intestinal wall. Preliminary metabolic studies, using t.l.c. and h.p.l.c., have shown the presence of an urinary metabolite, namely, the glucuronide of 7-hydroxy-2-nitronaphtho[2,1-b]furan (15-20% of the urinary radioactivity). The remaining radioactivity comprises basic compounds, that bind to a cationic resin, which might be formed by enzymic reduction of the nitro group.