The effects of sulforaphane nitrile (SN) and iberin nitrilk (IN) on hepatic glutathione (GSH) concentrations and GSH S-transferase (GST) activity

SN is a cyano- congener of sulforaphane and is derived from the same parent glucosinolate. In contrast to sulforaphane. it is unknown whether SN is a monofunctional inducer of detoxification enzymes. In order to assess the potential chemoprotective activity of SN, groups of 6 male F344 rats were dosed with 0, 1, 3 or 5 mmol/kg SN by gavage and necropsied 72 h later. Tissues were examined grossly and fixed for histopathology. Livers were also perfused and homogenized for estimation of GSH concentrations and GST activity as markers of possible chemoprotection. No gross or microscopic lesions were observed in any of the groups. GSH, however, was signficantly depressed to 38%, 22% and 24% that of controls in the 1 mmol, 3 mmol & 5 mmol/kg groups, respectively. GST activity towards CDNB was unaffected by SN at any dose. IN, a shorter chain congener of SN and a common breakdown product in cruciferous vegetables, was tested for its effects on GSH and GSTs in a similar experiment. Groups of male F344 rats were given IN by gavage at doses of 0, 0.1, 0.5, 1 or 2 mmol/kg and necropsied 24 or 72 h later. As with SN, no lesions were observed. Hepatic GSH was unaffected at 24 h and signifciantly depressed to 57% of control at 72 h in the 2 mmol/kg group only. GST activity was unaffected at both time points. The results of these studies suggest that SN and IN, in contrast to sulforaphane, may not have a direct role in chemoprotection by cruciferous vegetables. Rather, they may actually be suppressors of detoxification, even at non-toxic doses.