Antimutagenic and Anticarcinogenic Properties ofKyo-yasai, Heirloom Vegetables in Kyoto

摘要

Heirloom vegetables in Kyoto, termed Kyo-yasai, have had their seeds preserved by traditional cultivation methods. These heirloom vegetables offer a more distinctive flavor than conventional vegetables, and extracts from some Kyo-yasai are known to decrease ultraviolet light induced mutations in Escherichia coli B/r WP2 (trpE65) significantly more than extracts from their counterpart of conventional vegetables. 4-Methylthio-3- butenyl isothiocyanate which causes the pungency in daikon (Raphanus sativus ), and 3-methylthiopropionic acid ethyl ester, which causes melon-like odor, were identified from heirloom vegetables in Kyoto to be antimutagens in Escherichia coli mutagenicity assays. These two chemicals also demonstrated in vivo animal cancer prevention, and induced differentiation, a chemotherapeutic strategy, in an in vitro human colon-cancer cell system. The heirloom daikon varieties in Kyoto produced 2.0–11.5 times higher levels of 4-methylthio-3-butenyl isothiocyanate as compared to the conventional Aokubi variety, because the conventional variety is grown for consumer preferences of milder fiavor, which is corresponding to both quantity of 4-methylthio-3-butenyl isothiocyanate and quality associated with its antimutagenicity. The heirloom pickling melon in Kyoto, Katsura-uri (Cucumis melo var. conomon) began to produce 3-methylthiopropionic acid ethyl ester between the midripening to fully ripening stage of fruit development. Shiro-uri, a conventional variety for Katsura-uri, did not contain 3-methylthiopropionic acid ethyl ester. Results also indicate that antimutagenic and anticarcinogenic properties change over the ripening stage quantitatively. In this review, we discuss the value of retaining the original phenotypes of vegetables, including the fiavors, to maximize the anticarcinogenic properties of these food products.