High-resolution alpha-glucosidase inhibition profiling combined with HPLC-HRMS-SPE-NMR for identification of anti-diabetic compounds in Eremanthus crotonoides (Asteraceae)

Type 2 Diabetes (T2D) is a chronic metabolic disorder, that is expected to affect more than 500 million people worldwide in 2030 [1]. α-Glucosidase slows down the cleavage and absorption of monosaccharides from complex dietary carbohydrates, and represents therefore an important class of drugs for management of T2D [2]. In this study, crude ethanol extract of Eremanthus crotonoides leaves was investigated by high-resolution α-glucosidase inhibition profiling combined with HPLC-HRMS-SPE-NMR [3,4]. The HPLC chromatogram (in blue) and the α-glucosidase inhibition profile (in red) is shown in the figure below – and this shows a series of HPLC peaks in the retention time range 40 – 65 min associated with α-glucosidase inhibitory activity. The region from 40 – 48 min were reseparated using a pentafluorophenyl HPLC column for a complementary separation method compared to C18 This led to identification of six α-glucosidase inhibitors, i.e., quercetin (16), trans-tiliroside (17), luteolin (19), quercetin-3-methyl ether (20), 3,4-dicaffeoylquinic acid n-butyl ester (26), and 3,5-dicaffeoylquinic acid n-butyl ester (29).