In Vitro Characterization, Modelling, and Antioxidant Properties of Polyphenon-60 from Green Tea in Eudragit S100-2 Chitosan Microspheres.

Eliana B Souto,Conrado Marques,Patricia Severino,Raquel Da Da Ana,Massimo Lucarini,Ettore Novellino,Luciana N Andrade,Amélia M Silva,Antonello Santini,Aleksandra Zielińska,Atanas G Atanasov,Selma B Souto,Olaf K Horbańczuk,Alessandra Durazzo

doi:10.3390/nu12040967

Abstract

Eudragit S100-coated chitosan microspheres (S100Ch) are proposed as a new oral delivery system for green tea polyphenon-60 (PP60). PP60 is a mixture of polyphenolic compounds, known for its active role in decreasing oxidative stress and metabolic risk factors involved in diabetes and in other chronic diseases. Chitosan-PP60 microspheres prepared by an emulsion cross-linking method were coated with Eudragit S100 to ensure the release of PP60 in the terminal ileum. Different core–coat ratios of Eudragit and chitosan were tested. Optimized chitosan microspheres were obtained with a chitosan:PP60 ratio of 8:1 (Ch-PP608:1), rotation speed of 1500 rpm, and surfactant concentration of 1.0% (m/v) achieving a mean size of 7.16 µm. Their coating with the enteric polymer (S100Ch-PP60) increased the mean size significantly (51.4 µm). The in vitro modified-release of PP60 from S100Ch-PP60 was confirmed in simulated gastrointestinal conditions. Mathematical fitting models were used to characterize the release mechanism showing that both Ch-PP608:1 and S100Ch-PP60 fitted the Korsmeyers–Peppas model. The antioxidant activity of PP60 was kept in glutaraldehyde-crosslinked chitosan microspheres before and after their coating, showing an IC50 of 212.3 µg/mL and 154.4 µg/mL, respectively. The potential of chitosan microspheres for the delivery of catechins was illustrated, with limited risk of cytotoxicity as shown in Caco-2 cell lines using the 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The beneficial effects of green tea and its derivatives in the management of metabolic disorders can be exploited using mucoadhesive chitosan microspheres coated with enteric polymers for colonic delivery.

Highlights

Green tea is obtained from the fresh leaves of Camellia sinensis, a plant from the Theaceae family which has been used for centuries as a natural antioxidating beverage
The microspheres produced by emulsion cross-linking between chitosan and glutaraldehyde to load PP60 were yellowish because of the natural color of the active ingredient
After 24 h of assay, the cumulative amount reached 88.56 ± 1.24% and 79.54 ± 0.52% when released from non-coated and Eudragit S-100 coated microspheres, respectively. These results demonstrate that S100-coated chitosan microspheres (S100Ch)-PP60 was effectively coated with polyacrylic polymer and this is able to ensure an enteric resistance of the microspheres until they reach the colon

Summary

Introduction

Green tea is obtained from the fresh leaves of Camellia sinensis, a plant from the Theaceae family which has been used for centuries as a natural antioxidating beverage. Rich in antioxidant polyphenols (e.g., epigallocatechin-3-gallate), have been reported for reducing lipid peroxidation, oxidized low-density lipoproteins (LDL), cholesterol levels, and anti-hypertensive effects, factors that are relevant to reduce cardio-metabolic disease risk [7]. The role of green tea polyphenon-60 (PP60) in decreasing metabolic risk factors, oxidative stress, inflammation, and in the amelioration of cardiac apoptosis in experimentally induced diabetes has been described [9]. Among the naturally derived catechins (flavonoids composing the majority of soluble solids of green tea extracts), epigallocatechin gallate (EGCG) has already been proposed as active ingredient in polymeric nanoparticles for oral administration [10], and as lipid nanoparticles for ocular administration [11,12]

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