Catecholic compounds are ubiquitous in nature and play a variety of critical roles in the human body. We have recently reviewed their widespread endogenous functions, including neurotransmission and neuromodulation, hormonal signaling, metabolic regulation, and antioxidant defense. These compounds are also emerging as promising therapeutics due to their biochemical versatility and bioactive properties . Recent studies highlight the potential of catecholic compounds as chemotherapeutic and radiotherapeutic enhancers , intranasal chemotherapeutic nanoparticles for glioblastomas 2022), anti-inflammatories for pulmonary fibrosis , dietary anti-diabetics , and novel antibacterials for antibiotic-resistant bacteria , among others. Substantial groundwork has been laid for understanding catecholic chemistry and its potential transformations. Among the most studied and biologically significant catecholic compounds in humans is L-3,4-dihydroxyphenylalanine (L-DOPA, or levodopa), a key biosynthetic precursor derived from L-tyrosine via the enzyme tyrosine hydroxylase (Fig. ). The catechol group in L-DOPA is preserved as it is enzymatically converted into neurotransmitters such as dopamine, and subsequently into epinephrine and norepinephrine, along with other bioactive catecholic compounds. However, oxidation of the catechol group is common in many biosynthetic pathways; for instance, L-DOPA can also undergo oxidation, catalyzed by tyrosinase, to form Ldopaquinone, characterized by an o-quinone functional group. L-dopaquinone can then cyclize and rearomatize into L-leucodopachrome, which undergoes further oxidation, catalyzed by dopachrome tautomerase, to form L-dopachrome -another compound with an o-quinone functional group. Notably, each transformation from a catechol group to an o-quinone group in these pathways is enzyme-catalyzed, highlighting the regulation of catecholic oxidation in biological systems . In non-biological systems, catecholic functional groups can be oxidized through various chemical processes , but these reactions require precise control to avoid the formation of runaway polymers or supramolecular structures .