Effect of catechins and high-temperature-processed green tea extract on scavenging reactive oxygen species and preventing Aß1-42 fibrils' formation in brain microvascular endothelium.

ABSTRACT

The present study investigated the effect of high-temperature-processed green tea extract (HTP_GTE) and its bioactive components on the reduction of reactive oxygen species (ROS) and amyloid-beta (Aß) protein in human microvascular endothelial cells. Compared to Aß1-42-only treatment, pretreatment of HTP_GTE was revealed to effectively inhibit ROS generation (P<0.05). HTP_GTE and catechins not only inhibit Aß1-42 fibril formation but also destabilize preformed Aß1-42 fibrils. The presence of HTP_GTE, Aß1-42 fibril formation was significantly inhibited in a dose-dependent manner at 12.5-100 µg/ml of HTP_GTE, showing 86-56%, respectively. Treatment of various concentrations of HTP_GTE and catechins steadily destabilized the preformed Aß1-42 fibrils for 24 h in a dose-dependent manner. It was observed that the gallated groups such as epigallocatechin gallate, epicatechin gallate, gallocatechin gallate, and catechin gallate more effectively disturbed Aß1-42 fibril formation and destabilized the preformed Aß1-42 fibrils than the non-gallated group. Taken together, these findings supported that sterilized green tea could be promising natural anti-amyloidogenic agents associated with therapeutic approaches in Alzheimer's disease by scavenging ROS generation and Aß fibril in the brain tissue.