Comparative analysis of the inhibitory effects of aloin on tyrosinase supported by Fe3O4@rGO: investigation of interaction mechanisms, inhibitory activity, and conformational changes†

Tyrosinase is a key enzyme that regulates the rate of melanin synthesis, thereby modulating both food browning and skin pigmentation. It has been found that aloin is an effective inhibitor of tyrosinase activity and Fe₃O₄@rGO has remarkable drug-loading capability. In this study, enzyme inhibition kinetics and multispectral techniques were employed to investigate the enzyme inhibitory effect of Fe₃O₄@rGO-aloin nanocomposites and evaluate their anti-browning effect and safety. The binding ability of tyrosinase and aloin was further enhanced by the addition of Fe₃O₄@rGO. The IC₅₀ value of Fe₃O₄@rGO-aloin against tyrosinase was determined to be 2.26 ± 0.15 × 10⁻⁵ mol L⁻¹ with a typical anticompetitive inhibition. The findings suggest that Fe₃O₄@rGO-aloin exhibits a more potent inhibitory effect on tyrosinase compared to aloin. Furthermore, three-dimensional fluorescence, Fourier transform infrared and circular dichroism experiments demonstrated that aloin-loaded Fe₃O₄@rGO nanoparticles induce alterations in the secondary structure and conformation of tyrosinase. This indicates the potential of Fe₃O₄@rGO nanocomposites as candidates for the development of novel tyrosinase inhibitors for the treatment of hyperpigmentation disorders.