Immunomodulatory Effects of Green Tea Catechins and Their Ring Fission Metabolites in a Tumor Microenvironment Perspective

Abstract

Green tea is the second most consumed beverage following water, and the health benefits provided by its consumption have been well established from research in recent decades. The main bioactive compounds found in all Camellia sinensis-based teas are catechins, which have been reported to have antioxidant, anticancer, anti-inflammatory, and immunomodulatory properties. Although most of the health benefits are well established, studies show that the intact catechins as found in tea are poorly absorbed in the digestive tract. These compounds are degraded and undergo ring fission by the gut microbiota, increasing their absorption. In this review, we gather knowledge of the health benefits of green tea catechins and their metabolites, with a particular emphasis on the immunomodulatory effects in a cancer microenvironment scenario.

Keywords: catechin metabolites; green tea catechins; immune response; tumor microenvironment.

Figure 3

Chemical structures of EGCG metabolites derived from data provided by Takagaki et al. EGC-M5 is described as the major metabolite produced [37].

Figure 1

The main catechins in green tea.

Figure 2

Schematic diagram of EGCG catechin metabolism in the human body.

Figure 4

Schematic representation of green tea catechins’ and metabolites’ potential effects on immune cells in the tumor microenvironment.