A series of novel dibenzo[b,d]furan mono-carboxylic acid derivatives were synthesized, characterized and evaluated for their ability to inhibit Protein Tyrosine Phosphatase 1B (PTP1B) in vitro in order to use them as potential anti-diabetic agents. Structure–activity relationship study led to the identification of potent compound 5E which inhibited PTP1B with IC50 value of 82 ± 0.43 nM. Compound 5E