title: Stability of (-)-epigallocatechin gallate and its activity in liquid formulations and delivery systems.
abstract: (-)-Epigallocatechin gallate (EGCG) has become a popular disease-preventive supplement worldwide because it may aid in slowing down the onset of age-related diseases such as cancer, diabetes and tissue degeneration. As largely demonstrated in cell culture studies, EGCG possesses antioxidant properties and exhibits favorable effects on gene expression, signal transduction and other cell functions. However, only limited effects have been observed in experimental animals and human epidemiological studies. The inconsistency between the biological activity of EGCG in cell cultures and in vivo can be attributed to its low stability, which not only decreases its bioavailability but also leads to the formation of degradation products and prooxidant molecules with possible side-effects. Understanding EGCG degradation kinetics in solution and in vivo is crucial for its successful clinical application. Ambient conditions (pH, temperature, oxygen) can either enhance or decrease the stability of EGCG, thus influencing its biological activity. Usage of stabilizers and/or encapsulation of EGCG into particulate systems such as nanoparticles or microparticles can significantly increase its stability. In this review, the effects of ambient conditions, stabilizers and encapsulation systems on EGCG stability, activity and degradation rate are illustrated.
authors: Institute for Biomechanics, ETH Zurich, Hoenggerbergring 64, 8093, Zurich, Switzerland. Electronic address: okrupkova@ethz.ch.
authors: Olga
authors: O
authors: Krupkova
authors: Institute for Biomechanics, ETH Zurich, Hoenggerbergring 64, 8093, Zurich, Switzerland; Competence Center for Applied Biotechnology and Molecular Medicine, University of Zurich, Winterthurerstr. 190, 8057, Zurich, Switzerland. Electronic address: sferguson@ethz.ch.
authors: Stephen J
authors: SJ
authors: Ferguson
authors: Institute for Biomechanics, ETH Zurich, Hoenggerbergring 64, 8093, Zurich, Switzerland; Competence Center for Applied Biotechnology and Molecular Medicine, University of Zurich, Winterthurerstr. 190, 8057, Zurich, Switzerland. Electronic address: kwuertz@ethz.ch.
authors: Karin
authors: K
authors: Wuertz-Kozak
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000737:chemistry* / Q000378:metabolism / Q000627:therapeutic use; D016588:Anticarcinogenic Agents / Q000008:administration & dosage / Q000737:chemistry* / Q000378:metabolism / Q000627:therapeutic use; D000975:Antioxidants / Q000008:administration & dosage / Q000737:chemistry* / Q000378:metabolism / Q000627:therapeutic use; D002392:Catechin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000627:therapeutic use; D019587:Dietary Supplements / Q000009:adverse effects / Q000032:analysis; D016503:Drug Delivery Systems / Q000009:adverse effects; D004355:Drug Stability; D005519:Food Preservation; D005520:Food Preservatives / Q000009:adverse effects / Q000737:chemistry; D006801:Humans; D008081:Liposomes; D053758:Nanoparticles / Q000009:adverse effects / Q000737:chemistry; D010084:Oxidation-Reduction; D011310:Preservatives, Pharmaceutical / Q000009:adverse effects / Q000737:chemistry; D012995:Solubility; D013237:Stereoisomerism
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D016588:Anticarcinogenic Agents; D000975:Antioxidants; D005520:Food Preservatives; D008081:Liposomes; D011310:Preservatives, Pharmaceutical; D002392:Catechin; C045651:epigallocatechin gallate
keywords: Activity; Degradation; Encapsulation; Epigallocatechin gallate; Stability