The superiority of organically cultivated vegetables to general ones regarding antimutagenic activities.
We found organically cultivated (OC) vegetables, using a water-soluble chitosan as a soil improvement agent and leaf surface spray, had much longer shelf life and better taste than that of generally cultivated (GC) vegetables. The purpose of this study is to determine the relative antimutagenic activity between OC and GC vegetables. Eleven OC vegetables were harvested in March and April in 1999 and 2000, and GC ones were supplied as a control from nearby farms on the same date. The former vegetables were planted on the field where no pesticide had been used for the last 3 years. Forward mutation test with Salmonella typhimurium TM677 and 8-azaguanine as a detection agent was used to determine the antimutagenic activity of juices prepared from OC and GC vegetables against authentic mutagens, such as 4-nitroquinoline oxide (4NQO), benzo(a)pyrene (BaP), and 3-amino-1-methyl-5H-pyrido[4,3-b]indole acetate (Trp-P-2). This microbiological test is a convenient method to use for the food samples containing free histidine. Antimutagenic activity was evaluated by the difference of mutagenic activities between mutagenecity of authentic compounds and that observed upon incubation at 37 degrees C for 2h with each vegetable juice. OC Chinese cabbage, carrot, Welsh onion, and Qing-gen-cai suppressed 37-93% of the mutagenic activity of 4NQO, while the GC ones were held down to 11-65%. Against BaP, three species of OC vegetables showed 30-57% antimutagenecity, while GC ones did only 5-30%. Similarly, the OC spinach decreased the activity of Trp-P-2 to 78%, and the GC suppressed it by 49%.