Characterization of volatile and polar compounds of jiaogulan tea [Gynostemma pentaphyllum (Thunb.) Makino] by hyphenated analytical techniques

Abstract

Jiaogulan [Gynostemma pentaphyllum (Thunb.) Makino] is a Chinese medicinal plant from southern Asia that has rapidly gained popularity and interest for its health-promotive and therapeutic properties. The volatile composition of jiaogulan tea was analyzed by using headspace-solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). A total of 29 volatile components were detected in the jiaogulan tea, with major compounds being benzaldehyde (15.3 %), 1,8-cineole (8.7 %), 6-methyl-5-hepten-2-one (7.8 %), (Z)-3-hexenal (7.6 %) and α-ionone (6.3 %). The chemical characterization of methanolic extract and 5 % infusion from the G. pentaphyllum leaves was determined by using LC-ESI-MS/MS systems. Chlorogenic acids, flavonoids and gypenosides were determined. The compounds quercetin 3-O-hexoside, isorhamnetin rutinoside and kaempferol dimethyl ether were identified in the extracts for the first time. Phenolic content was determined by gallic acid equivalents and antioxidant activity of the extracts was evaluated by DPPH, β-carotene/linoleic acid and ABTS radical scavenging assays. Both extracts showed weak antioxidant activity.