Antioxidant Activity and α-Glucosidase Inhibitory Activity of Red Kale (Brassica oleracea L. var. acephala) Extract according to the Extraction Methods Used

Kim, M.R.; Kim, M.H.; Han, Y.S.

Antioxidant Activity and α-Glucosidase Inhibitory Activity of Red Kale (Brassica oleracea L. var. acephala) Extract according to the Extraction Methods Used

2022

Kim, M.R. | Kim, M.H. | Han, Y.S.

The purpose of this study was to measure the antioxidant activity and α-glucosidase inhibitory activity of red kale using three different extraction methods, namely reflux extraction (RE), ultrasonic extraction (USE), and stirrer extraction (SE). The yield of red kale with different extraction methods was as follows: RE (40.51%), USE (45.22%), and SE (38.56%). Among the methods, the extract obtained through the USE method showed the highest total polyphenol content (76.63 mg GAE/g), total flavonoid content (64.12 mg RE/g), and total anthocyanin content (787.07 mg/100 g). While analyzing The DPPH radical scavenging activity, ABTS⁺ radical scavenging activity, nitrite scavenging activity, and SOD activity were assessed as half-maximal inhibitory concentration (IC50). The values for the extract obtained through the USE method were 39.35 μg/mL, 86.12 μg/mL, 4,715.10 μg/mL, and 610.67 μg/mL respectively. The reducing power proportionally increased with concentration, and at a concentration of 100~1,000 μg/mL, the extract obtained through USE showed the highest absorbance of 0.09～1.05. The ORAC was measured at a concentration of 125～500 μg/mL and the USE extract showed the highest content at 130.22～419.48 μM TE/g. The α-glucosidase inhibitory activity as IC50 of the red kale extract for each method was as follows: RE (3,060.41 μg/mL), USE (2,772.03 μg/mL), and SE (2,835.47 μg/mL). Thus, the results of this study showed that red kale extracted by USE had the highest antioxidant and α-glucosidase inhibitory activities. Given its excellent physiological activity, it could, therefore, be used as a natural functional substance.

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