Providing a compound capable of continuously taking and having a vascular endothelial function improving effect by enhancing NO function from the vascular endothelial cells. A compound represented by Formula (I) wherein R 1 , R 2 , R 3 and R 4 are each independently H or a gallate group, a vascular endothelial function improving agent, food and drink or pharmaceutical composition containing the compound.本發明係提供可持續攝取,且具有藉由增強來自血管內皮細胞的NO之作用等,而改善血管內皮功能的作用之化合物。本發明係有關以式(I)(式中R1、R2、R3及R4係分別為H或沒食子酸酯基)所示之化合物或其鹽,以及含該化合物之血管內皮功能改善劑、飲食品或醫藥組成物。
