Identification of purine-derived compounds, ustilagomaydisin A-C, from the plant pathogen Ustilago maydis and their modulating effects on multidrug-resistant (MDR) tumors

Three new purine-derived compounds, named ustilagomaydisin A-C (1-3), together with 16 known compounds, were isolated from Ustilago maydis, a pathogen fungus associated with the worldwide distributed crop disease corn smut. The structural characterization of compounds was carried out by spectroscopic methods. In addition, compounds 1-7 were evaluated for multidrug-resistance reversing activity by using the doxorubicin resistant K562/A02 human leukemia cells. Compounds 4-7 (5 mu M) overcame the multidrug-resistance (MDR) with the reversal fold (RF) values ranging from 1.56 to 2.68 for K562/A02 cells, respectively, while compounds 1-3 were weakly active. (C) 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.