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 for their antimutagenic and/or desmutagenic activity on Vicia faba germinating seeds treated with the mutagen compound maleic hydrazide (MH). Both HA and FA were tested at two different concentrations, 20 and 200 mg L-1, either 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 desmutagenic 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 with HA or FA for 6 days and then transferred to plates containing the MH solution, 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 at both concentrations, whereas results of procedure 2 indicated no antimutagenic effect of HA or FA.