Preparation of flavonoids from Amomum tsaoko and evaluation of their antioxidant and α-glucosidase inhibitory activities

<i>Amomum tsaoko</i> is an important homologous medicinal and food plant, and its fruit is rich in flavonoids. However, few studies have reported the preparation and bioactivity of flavonoids in <i>A. tsaoko</i> (ATF). In this study, the optimal conditions for ultrasound-assisted extraction of ATF were identified through response surface optimization. HPD300 was identified as the best resin for the purification of ATF, as it exhibited a Freundlich model-conformative adsorption isotherm. Among the different concentrations of ethanol, 20 % and 30 % resulted in higher flavonoid purity (>90 %) and stronger antioxidant and α-glucosidase inhibition activities. A widely targeted metabolomics assay revealed that the relative abundance of flavonoids in a mixture of 20 % and 30 % ethanol eluates was greater than 73 %, which mainly contained (+)-epicatechin, isoquercitrin, astragalin kaempferol-3-O-rutinoside, and procyanidin B2. These findings provide a theoretical basis for the in-depth development and potential use of ATF in the functional food, cosmetic and pharmaceutical industries.