The role of rat liver microsomal enzymes in the metabolism of the fungal metabolite fusarin C.

The metabolic activation of fusarin C by a rat liver microsomal monooxygenase resulted in the formation of a water-soluble mutagenic metabolite. However, fusarin C incubated in the presence of a microsomal preparation, but in the absence of an NADPH-generating system, led to the formation of fusarin PM1, a highly water-soluble compound which, like fusarin C, requires metabolic activation to be mutagenic. Enzyme studies using as substrates fusarins A and D, compounds structurally related to fusarin C, together with structural studies of fusarin PM1 indicated that fusarin PM1 was formed by the action of carboxylesterase which hydrolyses the C-20 methyl ester group to a free carboxylic acid.