The name/synonym for ligand DHB (curated from ChEBI, PubChem, and PDB databases):

13,4-DIHYDROXYBENZOIC ACID
23,4-DIHYDROXY-BENZOIC ACID
34-CARBOXY-1,2-DIHYDROXYBENZENE
44,5-DIHYDROXYBENZOIC ACID
5PROTOCATECHUIC ACID
6PROTOCATEHUIC ACID