Polygala is a large genus of flowering plants distributed widely in temperate zones throughout the world. The genus name Polygala comes from the ancient Greek word meaning “much milk” as many milkwort species are in this genus. Polygala tenuifolia is a well-known traditional medicinal herb in Korea and China. The root is used as one of the 50 fundamental herbs used in Traditional Chinese Medicine. P. tenuifolia, also called ‘Yuan Zhi’ in China and ‘Wonji’ in Korea, has been known for its anti-inflammatory effects and mainly used for the treatment of various brain inflammatory diseases, insomnia, and amnesia. Many bioactive chemical compounds such as xanthones, triterpenoid saponins and oligosaccharide esters were isolated from the root. Tenuifoliside A, one of the phenylpropanoids isolated from P. tenuifolia, exhibited anti-inflammatory effects in LPS-stimulated macrophages by down-regulating the expression of inflammatory mediators and cytokines through the inhibition of NF-κB activation as well as the JNK/MAPK signaling pathway.