Catalyzes the non-heme iron(II)-dependent oxidative cleavage of 2,3-dihydroxyphenylpropionic acid and 2,3-dihydroxicinnamic acid into 2-hydroxy-6-ketononadienedioate and 2-hydroxy-6-ketononatrienedioate, respectively. Also catalyzes the cleavage of catechol. 3-(2,3-dihydroxyphenyl)propanoate + O2 = (2Z,4E)-2-hydroxy-6-oxonona-2,4-dienedioate + H(+) (2E)-3-(2,3-dihydroxyphenyl)prop-2-enoate + O2 = (2Z,4E,7E)-2-hydroxy-6-oxonona-2,4,7-trienedioate + H(+) Aromatic compound metabolism; 3-phenylpropanoate degradation. Homotetramer. Belongs to the LigB/MhpB extradiol dioxygenase family.