**1. Introduction**

According to WHO, stroke is a focal or global neurological deficit that more than 24 hours or dies before 24 hours, caused by vascular disorders in the brain [1–3]. There are three types of strokes: ischemic stroke, intracerebral hemorrhage, and spontaneous subarachnoid hemorrhage. Ischemic stroke is the most common type in about 70−80% of stroke cases [4]. Stroke is the second leading cause of death in the world and caused the death of 5.7 million people in 2005 [2, 5, 6]. Around 69% of stroke cases occur in low- and middle-income countries, about 71% of the 5.9 million stroke cases [7–9]. Most stroke patients will have a residual disability, although about 50−70% return to functional independence [10]. Based on this, it is necessary to understand the pathogenesis so that an acute ischemic stroke therapy approach can be carried out [6, 11].

The current standard of treatment for acute ischemic stroke is thrombolysis. However, only 2−8.5% of stroke patients can undergo thrombolysis in America, and less than 2% in the world undergo thrombolysis [2, 3, 12]. During 1995−2015, 430 candidates for stroke therapy were divided into two categories, namely thrombolytic agents and neuroprotectants [13–15]. One of the popular neuroprotectants used in stroke therapy is Citicholin. However, recent studies have shown that Citicholin is less effective as stroke therapy, so it is necessary to develop a new approach to protective therapy for ischemic stroke patients [16–20].

Acute stroke is caused by decrease blood flow, a decrease in the amount of Adenosine triphosphate (ATP). This event will cause lactic acidosis and loss of ion homeostasis in neuronal cells [21]. In addition, disruption of ion homeostasis will cause high levels of calcium and Adenosine diphosphate (ADP) in the cells, which will stimulate mitochondrial reactive oxygen species (ROS) and other sources of free radicals [22–24].

Green tea (*C. sinensis*) is the most consumed beverage in the world and is a source of polyphenols known as catechins, including epigallocatechin-3-gallate (EGCG), which is 63% of total catechins [25–31]. A meta-analysis showed that individuals who consumed 3 cups a day had a 21% lower risk of stroke than those who consumed <1 cup of tea daily [26, 32]. Many studies in animal models have shown that administering EGCG to ischemia–reperfusion brain tissue will reduce the expansion of ischemia [33, 34]. EGCG is also a potent free radical scavenger and can protect neuronal cells from oxidative damage induced by prooxidants [35]. Green tea with the active ingredient EGCG has a role in preventing neuronal cell death in ischemic conditions by inhibiting oxidative stress and improving mitochondrial function [25, 27, 28, 36]. Many studies explain that green tea consumption will decrease stroke risk, but not many studies explain the benefit of green tea in the treatment of acute stroke. This chapter will discuss the benefit of green tea in acute stroke [33, 37].
