Optimization of the ultrasonic-assisted extraction of the total methoxyflavones content from black ginger Kaempferia parviflora rhizomes

Abstract

The well-known black ginger Kaempferia parviflora (KP) has been proven to possess many health benefits. However, the optimization of bioactive compounds extraction from this medicinal plant was limited, despite its various applications in the functional food industry. In the current study, response surface methodology (RSM) using Box-Behnken Design (BBD) was employed to optimize both the extraction efficiency and the total content of six methoxyflavones in KP rhizomes harvested in Viet Nam. The extraction yield was maximized at 229.13 mg/g dried sample after 23 min extraction at 75 °C with an ultrasonic power of 46 %, a solid-liquid ratio of 1:60 g/mL, and an ethanol concentration of 42 % (v/v). Meanwhile, the highest amount of methoxyflavones (58.38 mg/g) was achieved with 40 % ultrasonic power, 1:40 g/mL solid-liquid ratio, 23 minutes extraction, and 99 % ethanol (v/v). These extraction conditions were applied to KP samples collected from five different cultivation regions, including Dak Lak, Gia Lai, Nghe An, Hung Yen, and Yen Bai. The results indicated that KP rhizomes in Yen Bai province yielded the highest efficiency (236.78 mg/g) and also contained the highest total methoxyflavone content (76.29 mg/g) compared to other locations (p < 0.05). In addition, 5,7,4'-trimethoxyflavone was consistently found to be the most abundant methoxyflavonein all five ginger samples. This is the first time the optimal extraction for maximizing the total amount of six major methoxyflavones from KP was assessed. The findings in this study can support the exploration of K.parviflora as a great source for further applications in the production of methoxyflavones-rich food supplements.