Coumarins are a large group of natural substances with diverse pharmacological properties that may predetermine some of them for the prevention and/or treatment of
cardiovascular diseases and also other pathologies. Free
iron participates in the production of
reactive oxygen species (ROS) and plays an important role in the pathogenesis of
cardiovascular diseases. Therefore, chelation of
iron may attenuate some ROS consequences, but on the other hand, reduction of ferric
ions to ferrous ones is unfavourable and leads to intensification of ROS production. In this study, we have examined the interaction of
iron with
coumarins which has been rarely analyzed. A series of naturally occurring and chemically synthesized 4-methylcoumarins were analyzed for their ferrous and total
iron-chelating properties and compared with standard
iron chelator deferoxamine. The
iron chelation activity was assessed by a simple spectrophotometric approach based on the specific
indicator for ferrous
ions--
ferrozine. The methodology was also extended for the measurement of total
iron. Among the tested
coumarins, ortho-dihydroxyderivatives were the most potent
iron chelators and
7,8-dihydroxy-4-methylcoumarin even reached the efficiency of
deferoxamine in neutral pH. However, these ortho-dihydroxycoumarins did not bind
iron firmly in acidic conditions (e.g., in acute
myocardial infarction) and, moreover, they reduced ferric
ions that could lead to intensification of the Fenton chemistry. Other tested
coumarins did not substantially chelate
iron with the exception of ortho-diacetoxycoumarins. Conclusively, the use of
iron-chelating
coumarins in acidic conditions may be disadvantageous in contrast to neutral conditions.