Development of a UPLC-ESI-MS method for simultaneous determination of flavonoids and diterpenes in Egletes viscosa (L.) Less herbal products

Abstract

Egletes viscosa (L.) Less (Asteraceae) is a tropical aromatic herb whose flower buds are used for gastrointestinal disorders. Its gastroprotective properties have been attributed to the flavonoid ternatin and the furan diterpenes tanabalin and centipedic acid. The aim of this study was to develop a method of ultra-performance liquid chromatography coupled to electrospray ionization and mass spectrometry (UPLC-ESI-MS) for identifying the constituents from E. viscosa flower buds as well as quantifying its bioactive compounds in herbal products. Infusions and tincture from wild and commercial E. viscosa materials were directly injected on a UPLC-quadrupole-time-of-flight system (UPLC-q-TOF). Afterwards, reference standards were used to quantify ternatin, tanabalin and centipedic acid in these samples, employing a UPLC-single quadrupole system set up for positive mode and Selected Ion Monitoring (SIM). Seventeen compounds were identified, including caffeic acid derivatives, flavonoids and diterpenes, from which seven have been reported for the first time in this specie. The quantification method showed good linearity (R > 0.99), accuracy, precision and sensitivity. The intra-day and inter-day precisions presented relative standard deviations inferior to 6.04 and 8.78%, respectively. The recoveries of all the analytes varied 82.25–117.87%. The limits of detection and quantification ranged between 10–25 μg/L and 25–75 μg/L, respectively. For the samples, the contents of ternatin, tanabalin and centipedic acid ranged from 0.89 to 8.03 mg/L, 0.84–16.8 mg/L and 3.21–16.8 mg/L, respectively. The method demonstrated to be rapid, sensitive and reliable for the quality control of E. viscosa-based products, besides being applicable to other plant extracts containing flavonoids and diterpenes.