Polymeric Nanoparticles Encapsulating White Tea Extract for Nutraceutical Application Vanna Sanna,* ,†,‡ Giuseppe Lubinu, † Pierluigi Madau, † Nicolino Pala, † Salvatore Nurra, † Alberto Mariani, † and Mario Sechi †,‡ † Department of Chemistry and Pharmacy, University of Sassari, Via Vienna 2, 07100 Sassari, Italy ‡ Laboratory of Nanomedicine, Department of Chemistry and Pharmacy, University of Sassari, c/o Porto Conte Ricerche, Tramariglio, 07041 Alghero, Italy ABSTRACT: With the aim to obtain controlled release and to preserve the antioxidant activity of the polyphenols, nanoencapsulation of white tea extract into polymeric nanoparticles (NPs) based on poly(ε-caprolactone) (PCL) and alginate was successfully performed. NPs were prepared by nanoprecipitation method and were characterized in terms of morphology and chemical properties. Total polyphenols and catechins contents before and after encapsulation were determined. Moreover, in vitro release profiles of encapsulated polyphenols from NPs were investigated in simulated gastrointestinal fluids. The antioxidant activity and stability of encapsulated extract were further evaluated. Interestingly, NPs released 20% of the polyphenols in simulated gastric medium, and 80% after 5 h at pH 7.4, showing a good capacity to control the polyphenols delivery. Furthermore, DPPH • assay confirmed that white tea extract retained its antioxidant activity and NPs protected tea polyphenols from degradation, thus opening new perspectives for the exploitation of white tea extract-loaded NPs for nutraceutical applications. KEYWORDS: white tea extract, nanoparticles, controlled release, antioxidant activity ■ INTRODUCTION The health benefits associated with tea consumption have been attributed to the major polyphenolic constituents, the flavan-3- ols, also known as catechins, which include (+)-epigalloca- techin-3-gallate (EGCG), (+)-epigallocatechin (EGC), (+)-epi- catechin-3-gallate (ECG), and (+)-epicatechin (EC) (Figure 1). 1 Despite the promising results in preclinical studies as chemopreventive agents, the extensive use of catechins has met only limited success, mostly due to their instability to oxygen, change in pH, temperature, and light, as well as their inefficient systemic delivery and low bioavailability. 2,3 In this context, the encapsulation of catechins into micro- and nanosystems is emerging as a useful strategy to protect these bioactive compounds from undesirable effects of environmental conditions, thus retaining the structural integrity until the time of consumption or administration. 4 Moreover, this approach provides carriers able to prevent the degradation during digestion, thus enhancing subsequent bioactivity and bioavailability, and to promote a controlled release as well as targeted delivery. 5,6 The individual tea catechins are not equally chemically or biologically active. However, it has been reported that an unfractionated green tea extract has a synergistic and therefore more antioxidant effects than any single component. 7 There- fore, it is interesting to explore the behavior of tea extracts encapsulated into nanosystems in terms of effective antioxidant activity and improved controlled delivery and stability of bioactive polyphenols. Despite the numerous nanoformulations containing the active ingredient EGCG, 8-11 only few examples have been described for the encapsulation of green tea extract. 12,13 Recently, several papers suggested that white tea presents higher levels of antioxidants than green tea because it contains the most pharmacologically active catechin deriva- tives. 14-16 Regardless of the valuable data reported so far from green tea, few investigations have been generated from white tea, and there are no publications on white tea extract encapsulation into nanoparticles (NPs). Because of their attractive bioactive properties, the present study aims to formulate the white tea extract into novel polymeric NPs for nutraceutical applications to control the tea polyphenols release in gastrointestinal fluids and to preserve the antioxidant activity. Moreover, the influence of encapsulation on the storage stability of extract was investigated. ■ MATERIALS AND METHODS Materials. White tea (Pai Mu Tan) leaves were kindly provided from Erboristeria Ghinato (Sassari, Italy). Poly(ε-caprolactone) (PCL), alginic acid, sodium salt from brown algae (Alg, low viscosity), pluronic F-127 (a block copolymer of poly(ethylene oxide)-poly- (propylene oxide)-poly(ethylene oxide), Folin-Ciocalteu’s reagent, and 2,2-diphenyl-1-picryl hydrazyl (DPPH) were purchased from Sigma-Aldrich (Steinheim, Germany). (-)-Epigallocatechin gallate (EGCG) (98%), (-)-epigallocatechin (EGC) (98%), (-)-epicatechin gallate (ECG) (98%), and epicatechin (EC) (98%) were supplied by Zhejiang Yixin Pharmaceutical Co., Ltd. (Lanxi, Zhejiang, China). Preparation of Tea Extract. Tea extract was prepared by infusion of 1.0 g of leaves in 20 mL of distilled water at 60 °C for 30 min and then filtering through Whatman No. 1. Received: September 9, 2014 Revised: January 19, 2015 Accepted: January 19, 2015 Published: January 19, 2015 Article pubs.acs.org/JAFC © 2015 American Chemical Society 2026 DOI: 10.1021/jf505850q J. Agric. Food Chem. 2015, 63, 2026-2032