ABSTRACT
This study aimed to assess the hypoglycemic activity, and in vitro inhibition of α-glucosidase, inhibition of the advanced glycation end products (AGEs), and total antioxidant capacity were used to clarify its bioactivity. Furthermore, the potential hypoglycemic active chemical constituents in the aqueous extract of Osmanthus fragrans var. thunbergii flower were characterized using high performance liquid chromatography-electrospray ionization-quadruple time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS) method. The result showed that in vitro inhibition of α-glucosidase of the extract (IC50 = 2.11 ± 0.26 mg·mL-1) were similar to acarbose (IC50 = 2.88 ± 0.32 mg·mL-1), and it inhibited the AGEs formation and the total antioxidant capacity in a certain extent. Based on the MS fragmentation pathway analysis of reference chemical acteoside contained in this extract, and related references, 73 constituents were tentatively identified from the aqueous extract of Osmanthus fragrans var. thunbergii flower, including 58 phenylethanoids, 8 caffeoylquinic acids, 1 flavonoid vicenin-2, and 6 common organic chemicals in plant. Furthermore, 8 unknown alkaloids were characterized in this work. Among of these chemicals, 61 phenylethanoids were supposed to be detected for the first time. In conclusion, this work disclosed the potential hypoglycemic active constituents of Osmanthus fragrans var. thunbergii flower.
ABSTRACT
The chemical constituents were isolated and purified by column chromatography and semi-preparative reversed-phase high performance liquid chromatography with silica gel, MCI and polyamide in order to study the chemical constituents of dried flowers of Osmanthus fragrans var. aurantiacus. Their structures were identified by the physical and chemical properties and one-dimensional nuclear magnetic resonance (1H-, 13C-NMR, DEPT), two-dimensional nuclear magnetic resonance (1H-1H COSY, non-decoupled HSQC, HSQC, HMBC), UV, IR and high resolution mass spectrometry data. One new compound (1) and five known compounds (2-6) were isolated from 95% ethanol extract of dried broccoli. They were identified as (9S)-9-hydroxymengastigm-5-en-4-one-9-O-primeveroside (1), oleanolic acid (2), forsythiaside (3), 2-(4-hydroxyphenethyl)-ethanol-(6-acetyl)-β-D-glucopyranoside (4), salidroside (5), and acteoside (6). Compounds (2-6) were isolated from this plant for the first time.