Fabrication of BSA-Green Tea Polyphenols-Chitosan Nanoparticles and Their Role in Radioprotection: A Molecular and Biochemical Approach Sumit Kumar, † Ramovatar Meena, ‡ and Paulraj Rajamani* ,‡ † School of Life Science and ‡ School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India * S Supporting Information ABSTRACT: Normal tissue damage from ionizing radiation during radiotherapy is a major concern in cancer treatment. Tea polyphenols (TPs) have been shown to reduce radiation-induced damage in multiple studies, but their pharmacological application is still limited due to poor bioavailability. The present study was aimed at to increase the TPs bioavailability by nanoformulation by using BSA as the matrix and chitosan as the external shell. Encapsulated TPs nanoparticles were spherical in size and promoted TPs stability in normal and gastrointestinal conditions without losing antioxidant activity. Oral administration of nanoparticles for 3 days prior to irradiation exposure has been shown to protect mice from hematological injuries that result in the reduction of radiation-induced lethality. TPs reduce radiation-induced oxidative damage and apoptosis by restoring the redox status through the Nrf2-ERK pathway and reducing Bax expression, respectively. Regarding potency, encapsulated TPs have shown a significantly higher level of radioprotection than TPs, suggesting that TP nanoparticles can be explored as valuable radioprotective and pharmacotherapeutic agent. KEYWORDS: tea polyphenols, nanoparticle, antioxidants, free-radical scavenging, radiation protection ■ INTRODUCTION Ionizing radiation (IR) exposure can inflict cellular injuries as a manifestation of reactive oxygen species (ROS) such as superoxide anions (O 2 · - ), hydroxyl radical (HO·), and hydrogen peroxide (H 2 O 2 ), etc., thus causing tumor-cell killing during radiotherapy. 1 However, despite being targeted in nature, radiotherapeutic radiation also causes serious injuries to normal tissues due to undefined boundaries and uncleared location of tumor, thus reducing the benefit of radiotherapy. 1,2 Radioprotectors are compounds that reduce radiation-induced damage to normal tissues. 1 In the last few decades, multiple investigations have been performed, but the ideal radio- protector remains elusive. 1 Furthermore, many diseases such as aging, diabetes, arthritis, coronary disease, cancer, etc. are also known to be mediated by free radicals; hence, finding a good radioprotector may also help in treating these pathological conditions. 2 Tea infusion, prepared from the dried leaves of Camellia sinensis, is the second most popular beverage around the world after water. 3 Green tea is produced from the unfermented leaves of C. sinensis, demonstrated to be rich in health- promoting compounds 4,5 such as catechins (epigallocatechin gallate (EGCG), epigallocatechin, etc.). 3 Previously, EGCG has shown to reduce the radiation-induced esophagitis in non- small-cell lung-cancer patients in the phase II clinical trial 1 and enhance the tumor radiosensitivity in breast-cancer patients. 6 However, the utility of tea polyphenols (TPs) in radio- protection or in other therapeutic applications is severely limited due to rapid degradation (80% in 1 h at physiological pH) and poor bioabsorption (0.1-1.1%). 7,8 Nanostructure- based drug-delivery systems is one of the fastest-emerging area in enhancing the bioavailability of different drugs. 9-11 The coating of chitosan or polylactic co-glycolic acid over TPs has been shown to improve the stability of TPs in addition to improving the transcellular delivery of TPs. 7,8 However, despite enhancement in the stability and bioavailability of TPs in vitro, 7,8 its nanoparticle (NP) efficacy in the in vivo model system is yet to be tested. Furthermore, the choice of material in nanoparticle formulation is also quite important. Previously, many biodegradable materials such chitosan, BSA, polylactic co- glycolic acid, cyclodextrin, etc. have been used for the drug entrapment. However, due to the remarkable efficacy of BSA 12 resulted in the FDA approval of BSA for drug formulation and delivery. 12,13 Thus, the present study aimed at synthesizing tea polyphenol (TP) nanoparticles (NPs) using BSA as the matrix and chitosan as the covering shell and investigate the physicochemical properties and stability of TP NPs in the gastric environment. Furthermore, we also tested whether the improved stability of TPs does translate into any enhanced radioprotective activity in the murine model system. ■ MATERIALS AND METHODS Tea Polyphenol Extraction. Fresh-dried Darjeeling variety green tea (C. sinensis) leaves were purchased locally (TATA Tetley, Tata Global Beverages; Kolkata, India), crushed, mixed with hot distilled water (DW; 80 °C) in a 1:20 ratio and incubated for 20 min in a water bath at 80 °C. The infusion was collected by filtration (0.45 μm membrane filter), and the process was repeated once with residue. The infusion was cooled at room temperature (RT) and extracted with an Received: May 6, 2016 Revised: July 6, 2016 Accepted: July 7, 2016 Published: July 7, 2016 Article pubs.acs.org/JAFC © 2016 American Chemical Society 6024 DOI: 10.1021/acs.jafc.6b02068 J. Agric. Food Chem. 2016, 64, 6024-6034