In 1940, a Vietnamese scientist Sang Dinh Bui extracted an alkaloid from the root of Stephania rotunda with the yield of 1.2 - 1.5% and he named this compound rotundine. From 1950 to 1952, two Indian scientists studied and extracted from Stephania glabra another alkaloid named hyndanrine. In 1965, the structure of rotundine and hyndarin was proved to be the same as tetrahydropalmatine. The pharmaceutical industry has synthetically produced the more potent enantiomer Levo-tetrahydropalmatine (Levo-THP), which has been marketed worldwide under different brand names as an alternative to anxiolytic and sedative drugs of the benzodiazepine group and analgesics such as opiates. It is also sold as a dietary supplement.

Tetrahydropalmatine (THP) is an isoquinoline alkaloid found in several different plant species, mainly in the genus Corydalis (Yan Hu Suo)and Stephania rotunda.

Common drug name for this is Rotundine and Hyndarine. For centuries, Corydalis Rhizoma has been used in Korean traditional medicine. Tetrahydropalmatine is an alkaloid compound and a prominent anti-inflammatory agent found in plants.

The traditional uses of Stephania rotunda were recorded in countries throughout Southeast Asia (Cambodia, Vietnam, Laos, and India). Different parts of Stephania rotunda were used in traditional medicine to treat about twenty health disorders. Phytochemical analyses identified forty alkaloids. The roots primarily contain l-tetrahydropalmatine (l-THP), whereas the tubers contain cepharanthine and xylopinine.

Tetrahydropalmatine has been demonstrated to possess analgesic effects and may be beneficial in the treatment of heart disease and liver damage.It is a blocker of voltage-activated L-type calcium channel active potassium channels. It is a potent muscle relaxant. It has also shown potential in the treatment of drug addiction to both cocaine and opiates, and preliminary human studies have shown promising results.

Clinical trials where L-THP was used for the treatment of cocaine and heroin addiction have promising results.

Chemical investigation of Stephania rotunda Lour growing in Vietnam in 2005 led to the isolation and structural elucidation of three new alkaloids, 5-hydroxy-6,7-dimethoxy-3,4-dihydroisoquinolin-1(2H)-one, thaicanine 4-O-beta-D-glucoside, as well as (−)-thaicanine N-oxide (4-hydroxycorynoxidine), along with 23 known alkaloids.

When the name Rotundin is used it almost allways means Rotundine. For the sake of clarity also information about Rotundin is present in the pages even though this is different chemical compound. Rotundin is sometimes also used to market Rotundine.