Evaluation of the cytotoxicity, mutagenicity and antimutagenicity of emerging edible plants

This study evaluates the toxic, mutagenic and antimutagenic effects of emer ging edible plants that are consumed as new leafy vegetables in Taiwan. Amo ng eight plant extracts, only the extracts of Sol (Solanum nigrum L.) showe d cytotoxicity to Salmonella typhimurium TA100 in the absence of S9 mix. Th e toxicity of extracts from different parts of the Sol plant, such as leaf and stem, immature fruit and mature fruit, towards S. typhimurium TA100 and human lymphocytes was also assayed. The immature fruit extracts of Sol exh ibited strong cytotoxicity with dose dependence and induced significant DNA damage in human lymphocytes based on the comet assay. However, no mutageni city was found in eight plant extracts to TA98 or TA100 either with or with out the S9 mixture. Sol and Sec [Sechium edule (Jacq.) Swartz] extracts sho wed the strongest inhibitory effect towards the mutagenicity of 2-amino-3-m ethyl-imidazo[4,5-f]quinoline (IQ) in S. typhimurium TA98 and TA100; the ID 50 was less then 1 mg/plate. Cra [Crassocephalum creidioides (Benth.) S. Mo ore] extracts also expressed moderate antimutagenic activities towards IQ a nd benzo[a]pyrene (B[a]P) either in TA98 or in TA100; the ID50 was 1.63-2.4 1 mg/plate. The extracts from Bas (Basella alba L.), Bou (Boussingaultia gr acilis Miers var. pseudobaselloides Bailey), Cen (Centella asiatica L. Urba n), Cor (Corchorus olitorius L.) and Por (Portulaca oleracea L.) showed wea k to moderate inhibition of mutagenicity of IQ. However, the potential anti mutagenicity of these plant extracts towards B[a]P was weaker than that tow ards IQ. For a direct mutagen, 4-nitroquinoline-N-oxide (NQNO), only the So l extracts showed strong inhibitory effects in the TA100 system. The antimu tagenic activity of water extracts of Sec was partly reduced by heating at 100 degreesC for 20 min. The heat-stable antimutagens in Sec extracts could be produced in the plant extract preparation process. Fractions with molec ular weights above 30,000 showed the strongest antimutagenicity and peroxid ase activity in all the fractions of the Sec extracts. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.