Epigallocatechin-3-gallate loaded-zein nanoparticles: Characterization, stability and associated antioxidant, anti-tyrosinase and sun protection properties

Abstract

Epigallocatechin-3-gallate (EGCG) is an active polyphenol which has demonstrated interesting biological properties, such as antioxidant and anti-tyrosinase activities. Nonetheless, its therapeutic use is limited due to its cost, instability and low bioavailability. In the skin aging process, the search for delaying/masking the elderly signs has increased greatly in the last years, boosting the skin care industry. Zein is a natural polymer whose biological features gained attention recently. It has demonstrated the ability to entrap bioactive molecules, improve their stability and also their biological activities. This study aimed to develop and characterize zein nanoparticles containing EGCG (ZNp-EG) and evaluate the antioxidant, anti-tirosinase activities as well as the associated sun protection factor (SPF), in view of improving the skin aplicability. ZNp-EG were prepared by nanoprecipitation and appreciated morphologically by transmission electronic microscopy, characterized in terms of size, zeta potential, polydispersity index, pH, encapsulation efficacy (EE) and drug loading (DL). Finally the zein-EGCG association was evaluated by Fourier transformed infrared (FT-IR) and fluorescence spectroscopy. The antioxidant activity was determined using the ABTS radical scaverging method. The anti-tyrosinase and photoprotective activities were enumerated spectrophotometrically. The ZNp-EG nanoparticles showed an average size of 251.8 nm, EE and DL up to 98.43% and 28.35%, respectively. The ZNp-EG at 288 µg / mL remained stable up to 365 days under different storage conditions (5 °C, 25° and 40 °C). The interaction between zein and EGCG was confirmed by FT-IR and steady-state fluorescence. Both ZNp-EG and EGCG solution showed high antioxidant activity, with IC50 of 84.08 and 69.86 µg / mL after 48 h, respectively. The nanoencapsulation of EGCG enhanced the anti-tyrosinase activity (64.59%) compared to its solution (34.29%). Finally, BZNp, ZNp-EG and EGCG at 144 µg/mL presented SPF of 26.13, 29.71 and 15.69, respectively. In this context, our results demonstrate that zein nanoparticles were able to improve key biological properties related to the skin pigmentation and sun protection, where EGCG can be used in a nanodelivery system for pharmaceutical and/or cosmetic applications.