Involved in the biosynthesis of UDP-glucuronic acid (UDP-GlcA), providing nucleotide sugars for cell-wall polymers. May be also involved in plant ascorbate biosynthesis. myo-inositol + O2 = D-glucuronate + H(+) + H2O Binds 2 iron ions per subunit. Polyol metabolism; myo-inositol degradation into D-glucuronate; D-glucuronate from myo-inositol: step 1/1. Expressed in flowers and siliques. Belongs to the myo-inositol oxygenase family.