Characterization of UV-Sensitive Marker Constituents of Polygala Root for TLC: Applications in Quality Control of...

Polygala Root (the root of Polygala tenuifolia WILLDENOW; Japanese name "Onji"), a well-known crude drug, traditionally used as an expectorant and sedative, has been attracting increased interest in recent years owing to its newly found pharmacological effect related to neuroprotection. However, there is no specific method for identifying and estimating the quality of this crude drug in the Japanese Pharmacopoeia, 17th edition. Therefore, in order to develop a TLC-based simple and convenient identification method using characteristic chemical marker(s) for the drug and its extract products, UV-sensitive constituents of Polygala Root were first investigated. A total of 23 aromatic compounds were isolated and characterized. Two new compounds, namely, polygalaonjisides A (1) and B (2), were characterized as syringic acid 4-O-(2'-O-β-D-apiosyl)-β-D-glucoside and 2-O-(β-D-glucosyl)-3'-O-benzoylsucrose, respectively. Based on these phytochemical results, a TLC method focusing on three marker spots with Rf value of approximately 0.4-0.5 due to tenuifolisides A and B and 3,6'-di-O-sinapoylsucrose was proposed as a simple and convenient test to identify Polygala Root or its single-extract products on the market. The data presented in this paper could be useful in stipulating a confirmation test to identify Polygala Root.