Identification of Polyphenol Glucuronide Conjugates in Glechoma hederacea var. longituba Hot Water Extracts by High-Performance Liquid Chromatography-Tandem Mass Spectrometry (HPLC-MS/MS).

Glechoma hederacea var. longituba (GHL) is one of many herbal plants distributed worldwide and is known to contain various biologically useful antioxidant constituents. GHL has been used in folk remedies for various treatments and as favorable tea beverages. However, research on the precise analysis of ingredients in GHL extracts remains insufficient. In this study, compositional analysis has been conducted on polyphenolic ingredients in GHL hot water extracts. GHL samples collected from growing regions were incubated in hot water at 100 °C for 1 h. The polyphenolic constituents in the hot water extracts were analyzed using high performance liquid chromatography-high resolution mass spectrometry (HPLC-HR MS) and tandem mass spectrometry (HPLC-MS/MS) in negative ion mode. As a result, a total of seven compounds were identified as the major polyphenolic constituents. Interestingly, four constituents out of the identified substances were confirmed to be polyphenol glucuronide conjugates, in which glucuronidation was known to be an important metabolic process in polyphenol aglycone along with methylation and sulphation. This study can be applied for the quality control and standardization of GHL herbal samples and the monitoring of metabolic processes involved in the polyphenolic conjugates.