4-(Methylthio)-3-butenyl isothiocyanate, a principal antimutagen in daikon (Raphanus sativus; Japanese white radish).

The antimutagenic activity of n-hexane extracts from eight strains of daikon (Raphanus sativus; Japanese white radish) have been examined using the UV-induced mutation assay of Escherichia coli B/r WP2. A correlation was found between the potency of antimutagenicity and the amount of 4-(methylthio)-3-butenyl isothiocyanate (MTBITC) in their n-hexane extracts. Because the pure MTBITC also showed antimutagenicity, MTBITC is presumably the active antimutagen principle in n-hexane extracts of daikon. Among the eight strains of daikon studied, Aokubi, the improved common strain in Japan, contained 71.0 micromol of MTBITC in 100 g of fresh daikon. In contrast, Karami and Momoyama, which are original wild strains, contained much more MTBITC (363.5 and 168.0 micromol/100 g, respectively). In addition, phenethyl isothiocyanate was found in a lesser amount (5-33 nmol/100 g) in eight strains of daikon, and allyl isothiocyanate and benzyl isothiocyanate were not detectable in any strains (<3 nmol/100 g). The amount of total isothiocyanate in grated daikon was 7.0 times higher than that in cut daikon measured after 30 min of cooking. Through eating habits, humans might be able to consume substantial amounts of the antimutagen MTBITC from dishes using the grated form of wild strains of daikon. Therefore, it is possible to substantially increase the intake of the antimutagenic ingredient of daikon (i.e., MTBITC) by changing food preferences and preparation procedures (i.e., using the grated form of the wild strains).

DNA repair effect of traditional sweet pepper Fushimi-togarashi: seen in suppression of UV-induced cyclobutane pyrimidine dimer in human fibroblast.

The aqueous fraction of Fushimi sweet pepper increased the repair effect of the solvent control against UV-induced cyclobutane pyrimidine dimers in human fibroblast to 150%, but ordinary sweet pepper did not have a statistically significant effect. When Fushimi sweet pepper was boiled, the activity of the aqueous fraction was elevated to 209% of the control (p<0.05), while that of the grilled state was decreased to 125% of the control. The repair activity of a dialyzate (MW<12,000) of the aqueous fraction from Fushimi sweet pepper showed 191% of the control (p<0.05). The dialyzate was contained 1.9% in the weight of the fresh fruit body of Fushimi sweet pepper, and the activity can be stable in its boiling state, and it might be therefore considered to be the worthy source for expecting the DNA repair activity in human diet.