Evaluation of antimutagenic and desmutagenic effects of humic and fulvic acids on root tips of Vicia faba

Humic acids (HA) and fulvic acids (FA) of different origin were evaluated f or their antimutagenic and/or desmutagenic activity on Vicia faba germinati ng seeds treated with the mutagen compound maleic hydrazide (MH). Both HA a nd FA were tested at two different concentrations. 20 and 200 mg L-1, eithe r alone or together with 10 mg L-1 of MH. Two experimental procedures were used to investigate the occurrence and nature of the antimutagenic or desmu tagenic activity. In procedure 1, HA or FA and MH were interacted for 24 h and then added to the seeds. In procedure 2, the seeds were first treated w ith HA or FA for 6 days and then transferred to plates containing the MH so lution, so that no interaction occurred between HA or FA and MH outside the seeds. The evaluation of the genotoxic activity was done by counting both micronuclei and aberrant anatelophases in root tip cells. Results obtained by using procedure 1 showed a clear desmutagenic action of HA and FA used a t both concentrations, whereas results of procedure 2 indicated no antimuta genic effect of HA or FA. (C) 2000 by John Wiley & Sons, Inc.