Metallofullerenol Gd@C(OH) preserves human erythrocyte plasma membrane integrity from AAPH-induced oxidative stress: Molecular mechanisms and antioxidant activity.

Metallofullerenols and fullerenols have attracted attention due to their remarkable ability to interact with various biologically relevant molecules, paving the way for biomedical applications, ranging from medical imaging techniques to drug carriers, acting with increased efficiency and reduced side effects. In this work, we investigated the effects of two fullerene derivatives, Gd@C(OH) and C(OH), on erythrocyte membrane components under oxidative stress conditions induced by 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) as a source of peroxyl radicals. The results demonstrated that gadolinium encapsulation within the fullerene cage enhanced the electron affinity of Gd@C(OH), resulting in stronger antioxidant activity. Gd@C(OH) formed a protective hydrophilic layer at the lipid-water interface, effectively preventing lipid peroxidation, oxidative protein damage, and potassium leakage, outperforming C(OH). Both compounds improved membrane fluidity, but Gd@C(OH) exhibited superior preservation of the erythrocyte lipid bilayer and protein function. Additionally, Gd@C(OH) maintained the anion exchange function of band 3 protein, which is critical for ionic homeostasis, by preventing oxidation-induced aggregation and preserving thiol groups. Despite its limited membrane penetration, Gd@C(OH) stabilized membrane components through hydrogen bonding, which indirectly enhanced membrane stiffness and fluidity under oxidative stress. This external protection of membrane integrity reduced the risk of lipid peroxidation and oxidative damage to erythrocyte proteins. In contrast, C(OH), while effective in protecting membrane lipids, was less effective in preserving protein structure. These findings highlight the unique protective properties of Gd@C(OH), attributed to polarization effects induced by the encapsulated Gd atom. This study indicates that metallofullerenols, such as Gd@C(OH), may have therapeutic potential in mitigating oxidative damage.