Targeting Catechol Oxidation via Boron Complexation: From Chemistry to Biology

Catechol (benzene-1,2-diol) is a highly versatile chemical motif that plays a central role in both terrestrial and marine systems, where its reactivity is governed by a combination of enzymatic oxidation and non-enzymatic interactions. This review examines the diverse enzymatic pathways responsible for catechol oxidation, including polyphenol oxidases, laccases, peroxidases, and microbial dioxygenases, and highlights how these conserved systems are adapted to distinct ecological functions such as plant defense, carbon cycling, bioadhesion, and material formation. A key focus is placed on the non-enzymatic formation of boron–catechol complexes, which can significantly modulate catechol reactivity. These complexes, formed through reversible interactions between boron species and the 1,2-diol group, can act as inhibitors of catechol oxidation by limiting substrate availability and altering redox behavior. Importantly, the extent of this inhibition is strongly dependent on pH, which governs both the speciation of boron (e.g., boric acid vs. borate) and the stability of borate esters, as well as the activity of oxidative enzymes. In terrestrial systems, variable pH conditions and soil chemistry influence the balance between oxidation, complexation, and degradation, whereas in marine environments, relatively stable and slightly alkaline conditions favor distinct modes of regulation. By integrating enzymatic and non-enzymatic perspectives, this review underscores the importance of boron–catechol interactions as a previously underappreciated control on catechol oxidation across ecosystems, with implications for biogeochemical cycling and the design of bioinspired materials.