Indirect inactivation of tyrosinase in its action on 4- tert

Under anaerobic conditions, the o-diphenol 4-tert-butylcatechol (TBC) irreversibly inactivates met and deoxytyrosinase enzymatic forms of tyrosinase. However, the monophenol 4-tert-butylphenol (TBF) protects the enzyme from this inactivation. Under aerobic conditions, the enzyme suffers suicide inactivation when it acts on TBC. We suggest that TBF does not directly cause the suicide inactivation of the enzyme in the hydroxylase activity, but that the o-diphenol, which is necessary for the system to reach the steady state, is responsible for the process. Therefore, monophenols do not induce the suicide inactivation of tyrosinase in its hydroxylase activity, and there is a great difference between the monophenols that give rise to unstable o-quinones such as L-tyrosine, which rapidly accumulate L-dopa in the medium and those like TBF, after oxidation, give rise to a very stable o-quinone

In vitro effect of DNA topoisomerase inhibitors on Candida albicans

In this paper we report the results of the study of the in vitro effect of eight anticancer DNA topoisomerase inhibitors on the growth of Aspergillus fumigatus, A. niger, Candida glabrata and Cryptococcus neoformans. Only one compound, idarubicin, displayed promising antifungal activity against A. niger, C. glabrata and C. neoformans with MIC(50) values varying between 3.6 and 14.2 μM (1.8-7.1 μg/ml). Three other compounds, aclarubicin, doxorubicin and mitoxantrone, showed some antifungal activity against C. glabrata and C. neoformans with MIC(50) values in the mid micromolar range. The data of this study indicate that selected DNA topoisomerase inhibitors are a promising class of compounds for the development of new antifungal agents