Abstract

Tea is a well-known beverage in the world due to its aroma and health benefits. Many reports indicated that tea contains more than 500 components that display several activities. Catechins are the most important component in a tea leaf. They present a great deal of health advantages by scavenging free radicals and retarding extracellular matrix degradation induced by UV radiation and pollution. Furthermore, catechins also directly affect the skin by activating collagen synthesis and inhibiting matrix metalloproteinase enzyme production. Although catechins have been of interest in dermatological product development, they have limitations in skin permeation. Cutaneous metabolism and physicochemical properties of the molecules, such as hydrophilicity, partition coefficient, and chemical structure are the major factors influencing catechin skin permeation. Moreover, the distribution within skin layers of the gallate containing catechins also depends on cutaneous metabolism. Pharmaceutical technology offers a promising solution for improving catechin skin permeation.

INTRODUCTION

Catechin is a member of the polyphenol compound found in many medicinal plants. The major sources of catechin are Camellia sinensis and Camellia assumica. Their leaves are fermented in various conditions for producing different types of tea beverage. Tea polyphenols include groups of compounds of different chemical structures with variable biological properties. They are (+)-catechin, (-)-epicatechin (EC), gallocatechin (GC), (-)-epicatechin gallate (ECG), (-)-epigalocatechin (EGC), and (-)-epigalocatechin gallate (EGCG). However, the major compounds of catechins that are of interested include EGC, EC, EGCG, and ECG because they are prominently present in tea beverages (1-4).
The four catechins: epigallocatechin (EGC), epicatechin (EC), epigallocatechin gallate (EGCG), and epicatechin gallate (ECG) (Figure 1) are the most important constituents in tea extract due to their health benefits, such as antioxidant, antibacterial, anti-inflammatory, anti-obesity, and anti-arteriosclerosis. Due to minimum oxidation during the fermentation process in green tea production, EGCG and ECG always present the highest amount among all tea types (5) ...