Epigallocatechin-3-gallate loaded-zein nanoparticles: Molecular interaction, antioxidant, antienzimatic, hemolytic and cytotoxic activities

Epigallocatechin-3-gallate (EGCG) has demonstrated remarkable antioxidant and antienzymatic activities. Nonetheless, its therapeutic use is limited due to its biopharmaceutical characteristics. Zein has become a prominent material for nano delivery systems, providing stability, biocompatibility and biodegradability for therapeutic agents. In this study, zein nanoparticles loaded with EGCG at 288 µg/ml (ZNp-EG288), produced by nanoprecipitation, were characterized and evaluated regarding their antioxidant (DPPH), antielastase, anticollagenase, anti-hyaluronidase and cytotoxicity activities. An EGCG solution prepared in the same conditions (EGCG288) was used for comparison purposes. Molecular Docking was performed to understand the mode of interaction between EGCG and zein to form the nanoparticles and also to evaluate the binding affinity over elastase, collagenase and hyaluronidase, while NMR techniques were used to experimentally confirm the binding and to study the hydration of EGCG in its complexes with zein. Also, the hemolytic potential and the cytotoxicity were evaluated over erythrocytes, immortal human keratinocyte (HaCaT) and squamous carcinoma (A431) cells. The obtained ZNp-EG288 nanoparticles (251.8 nm) were spherical, monodisperse and positively charged (+27.4 mV). ZNp-EG288 presented an encapsulation efficiency and loading of 98.6% and 28.4%, respectively, together with a sustained release over 48h. Both ZNp-EG288 and EGCG288 demonstrated high antioxidant activity, with an IC50 of 8.26 and 12.34 μg/mlL after 48 h, respectively. The EGCG nanoencapsulation resulted in a good anticollagenase activity (44.44%) and enhanced the antielastase (94.08 %) and antihyaluronidase (22.09%) activities compared to EGCG288 (74.02 and 13.03 %, respectively). The interaction studies both in silico and by NMR reinforced these results and demonstrated that the activity of EGCG was increased due to selective interactions to zein. Finally, ZNp-EG288, BZNp and EGCG288 were found non-hemolytic, while the treatment with ZNp-EG288 was less cytotoxic than EGCG288 in both cell lines studied (∼27%). Therefore, the nanoencapsulation in zein nanoparticles decreased the cytotoxicity of EGCG. Accordingly, EGCG-loaded zein nanoparticles improved key biological properties related to the skin's antiaging and repairing mechanisms and could become a good stretegy for pharmaceutical and/or skin care products.