Piperonylic acid is a member of the class of benzodioxoles that is 1,3-benzodioxole substituted by a carboxy group at position 5. It is a natural product isolated from several plant species. It is a selective mechanism-based inactivator of the trans-cinnamate 4-hydroxylase enzyme and exhibits antifungal and skin wound healing properties. It has a role as an EC 1.14.14.91 ( trans-cinnamate 4-monooxygenase) inhibitor, an antifungal agent, a vulnerary and a plant metabolite. It is a monocarboxylic acid, an aromatic carboxylic acid and a member of benzodioxoles. It is a conjugate acid of a piperonylate.