Sophora flavescens is a shrubby member of the pea family that grows on hillsides and grasslands across China, Japan and Korea. Its long yellow root, known in Chinese as ku shen, meaning bitter root, has been part of traditional Chinese practice for more than two thousand years and is recorded in the classic herbal text Shennong Bencao Jing.
In Chinese practice sophora root is traditionally used for skin and scalp, often in washes and topical preparations as well as in herbal formulas. Today it appears mainly in hair and skin care. On an ingredient list you may see Sophora flavescens root extract, and it is often blended with other Asian botanicals such as chrysanthemum and sappanwood in scalp formulas.
The root contains two main groups of active compounds, alkaloids such as matrine and oxymatrine, and prenylated flavonoids such as kurarinone. Laboratory studies have investigated their antioxidant, anti-inflammatory and antimicrobial activity. Most of this research is at the laboratory and animal stage, and studies in people are limited.