Experimental and calculation study of co-delivery of insulin and nitric oxide carriers for diabetes and cardiovascular diseases

The co-delivery of cardiovascular nitric oxide donors to reduce heart complications in diabetic patients has been addressed recently. This study used experimental and theoretical methods to examine the co-delivery of insulin protein and cardiovascular nitric oxide donors. Nitrosobenzene (C-NO, NB), 1-nitroso-2-naphthol (C-NO, NNP), N-nitrosopyrrolidine (N-NO, NPY), and N-nitrosodiphenylamine (N-NO, NDP) NO donors were used. Experimental studies using UV–visible spectroscopy, fluorescence quenching, and X-ray photoelectron spectroscopy (XPS) confirm that insulin can effectively bind with these NO donors. Among the donors studied, NDP (4.438 × 10⁻¹ M⁻¹) and NNP (2.209 × 10⁻¹ M⁻¹) exhibit the highest binding affinities with insulin, demonstrating the potential of these interactions. XPS survey spectrum showed C, N, and O peaks originating from the NO functional group and the coexistence of additional S2p peaks from insulin. Theoretical calculations carried out using molecular docking, molecular dynamics simulations, cluster analysis, and the Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) method further confirm the stability of the insulin-NO donor complexes. Results reveal strong hydrophobic and hydrogen bonding interactions with the key residues Ile10 and Leu13 from chain A and Leu27, Ala35, Leu38, and Val39 from chain B, with a binding free energy value of −42.2 kJ/mol for NDP with insulin. These observations highlight the possibility of using insulin as a carrier for cardiovascular NO donors to tackle the heart complications associated with diabetes because of the deficiency of vasodilator NO.