Phytochemical profiles and screening of α-glucosidase inhibitors of four Acer species leaves with ultra-filtration combined with UPLC-QTOF-MS/MS

Understanding of the phytochemical profiles and bio-active compounds is extremely important for the application of new plant resources in health food and medicinal industry. This research was designed to elucidate the phytochemical profiles of Acer palmatum Thunb (APT), Acer truncatum Bunge (ATB), Acer mono Maxim. (AMM) and Acer buergerianum Miq. (ABM) leaf extracts by ultra-high performance liquid chromatography coupled to quadruple time-of-flight tandem mass spectrometry (UPLC-QTOF-MS/MS), content of polyphenols and α-glucosidase inhibition were measured, the α-glucosidase inhibitors (AGIs) were also screened by ultra-filtration combined with UPLC-QTOF-MS/MS. The similarity and variation in chemical components and AGIs profile were evaluated by principle component analysis. The richest total phenolics, total flavonoids and hydrolysable tannins content was found in APT, ATB and AMM leaf extract, respectively. The IC50 values of α-glucosidase inhibition in vitro were 167–433 fold of that of acarbose. In total, 80 compounds were identified, among which 48, 51, 41 and 32 compounds were proposed from APT, ATB, AMM and ABM leaf extract, respectively. A total of 39 potent AGIs including 28 flavonoids, 6 tannins, 2 phenolic acids and 3 others were screened. Glucosides of kaempferol, myricetin, quercetin and apigenin constituted the predominant AGIs. The major phytochemical and AGIs profiles of APT and ATB leaf extract were similar, but they distinguished greatly among AMM, ABM and APT/ATB extracts. Flavonoids were the predominant chemical components and AGIs of the four tested Acer species, tannins come to the second. This study can provide important chemical information for the application of APT, ATB, AMM and ABM leaf in health food and pharmaceutical industry, specially as an new source of natural AGIs.