Optimization of ultrasonic extraction of bioactive components from Alpiniae oxyphyllae Fructus using response surface methodology

Alpinia oxyphylla Miq. (A. oxyphylla) is a favorable medicinal and edible plant and its fructus has various biological activities. In the present study, ultrasonic extraction (UE) of the active constituents from Alpiniae oxyphyllae Fructus (A. oxyphyllae Fructus) was optimized using central composite design and the extract was characterized for its activities. The results of the study suggested that under optimum UE conditions (ethanol concentration (60%, v/v), solid-liquid ratio (1:40), and number of extractions (4)), the total phenolic content (TPC), total flavonoid content (TFC), and total triterpene content (TTC) were 11.92 mg GAE/g DW, 15.37 mg RE/g DW, and 58.04 mg UAE/g DW, respectively. The 8 major compounds in the extract of A. oxyphyllae Fructus were identified and quantified by ultra-performance liquid chromatography tandem electrospray ionization time-of-flight mass spectrometry (UPLC-ESI-QTrap-MS) and high performance liquid chromatography (HPLC-DAD). The extract of A. oxyphyllae Fructus obtained by UE based on optimal parameters had higher TPC, TFC and TTC, better antioxidant activities, antibacterial activities and enzyme inhibitory activities as compared to boiling water extraction (BWE) and maceration extraction (ME).