MODIFYING ACTIONS OF SOLVENT EXTRACTS FROM FRUIT AND VEGETABLE RESIDUES ON 2-AMINO-3-METHYLIMIDAZO[4,5-F]QUINOLINE (IQ) AND 2-AMINO-3,4-DIMETHYLIMIDAZO[4,5-F]QUINOXALINE (MEIQX) INDUCED MUTAGENESIS IN SALMONELLA-TYPHIMURIUM TA-98

The edible parts of 13 fruits - apples, apricots, bananas, blackberrie s, sweet cherries, red currants, white grapes, oranges, peaches, pears , plums, raspberries, and strawberries - and of 12 vegetables - aspara gus, green beans, broccoli, brussels sprouts, red and white cabbage, c arrots, cauliflower, onions, green peppers, spinach, and tomatoes - we re squeezed in order to separate juices and residues. The residues wer e washed, lyophilized, and extracted sequentially with n-hexane, dichl oromethane, acetone, and 2-propanol. Solvent extracted materials were tested in Salmonella typhymurium TA 98 for antimutagenicity against IQ and MeIQx. We found antimutagenic activities in 96% of the n-hexane e xtracts, 64% of the dichloromethane extracts, 44% of the acetone extra cts, and 36% of the 2-propanol extracts. Since no or only minor differ ences were seen between the mutagens IQ and MeIQx investigations were continued with IQ only. Additional antimutagenic activities were detec ted in a total of 29.6% of extracts tested when an enzyme preparation with glycosidase-activities (fecalase) was included in the assay. Thes e activities were found in originally inactive or less active dichloro methane, acetone, and 2-propanol extracts, and are therefore strongly suggestive for the liberation of antimutagenic aglycones from inactive glycosides. The existence of possibly a multitude of antimutagenic fa ctors in fruits and vegetables was further substantiated by: (1) solve nt partitioning of the n-hexane extracts of cauliflower, peaches, and spinach; (2) separation of the n-hexane and dichloromethane extracts o f cauliflower, peaches, and spinach into acidid, neutral, and basic co mpounds; (3) chromatographic analysis of the n-hexane and dichlorometh ane extracts of spinach. Taken together, antimutagenic activities were present in 32 of 36 subfractions, corresponding to 88.9%. In the gree n vegetables beans, broccoli, and spinach the known antimutagen chloro phyll was proven to contribute considerably to antimutagenic potency. Other important contributions may be caused by various fibers: (I) ant imutagenicity of fruit and vegetable solvent extracts was extensively heat stable; (II) heating surprisingly caused an increase of antimutag enic potencies or generated new antimutagenic activities in several so lvent fractions, especially of broccoli, white and red cabbage. Indeed , mutagenicity induced by IQ was strongly reduced by lignin, weakly by alginic acid and pectin A, while cellulose, gum arabic, gum guar, and xylan were ineffective. With respect to the mechanisms of antimutagen icity binding of IQ by various fibers and inhibition of cytochrome P-4 50-dependent monooxygenases might be of major importance since no solv ent fraction of any fruit or vegetable was able to reduce mutagenic ac tivity induced by N-OH-IQ in S. typhimurium TA 98NR.