Abstract
Inhibitory effects of many species of vegetable and plant extracts (45 species of vegetable, 15 species of fruits, 2 species of nuts, 20 species of grass, 21 species of tree) on the mutagenecity of C-nitro and c-nitroso compounds formed by reaction of sorbic acid with sodium nitrite were investigated by using of Rec-assay method. Extract of persimmon (Diosyros.), knotweed (Polygonum longisetum) and Japanese-aucuba (Aucuba japonica) remarkably inhibited the mutagenecity. The Fraction III separated from persimmon extract by ultracentrifugation inhibited the mutagenecity and moreover its inhibitory effect on the mutagenecity still remained after treatment with some proteases. This facts suggests that the inhibitory factor in the persimmon extract against the mutagenecity may be constituents other than proteins. In another experiment, inhibitory effect of persimmon extract on formation of nitrosomorpholine in the reaction of morpholine with sodium nitrite was investigated using HPLC. Moreover, addition of an excess of sodium nitrite increased the content of nitrosomorpholine formed in the reaction mixture of morpholine with sodium nitrite containing persimmon extract. However, the content did not change by addition of an excess of morpholine. From these results, the inhibitory substance was considered to be kakitannin which can scavenge sodium nitrite.
