Alpha-glucosidase Inhibition Activity of Methanol Extracts Obtained from Nine Pteridophyte Species Native to Korea

Abstract

This study was conducted not only to analyze α-glucosidase inhibition activity with fronds and rhizomes of nine Pteridophyte species, but also to select the plant materials suitable for natural α-glucosidase inhibitor. Harvested rhizomes and fronds were washed, freeze-dried and grinded. After conducting ultrasonification extraction for 30 minutes in ultrasonic water tank with 100% methanol solvent, and vacuum filtration, α-glucosidase inhibition activity was measured. Acarbose was used as the positive control. After mixing 100 μL of 0.7 unit α-glucosidase enzyme solution into 50 μL of extract and reacting them at 37℃ for 10 minutes, 50 μL of 1.5 mM ρ-NPG solution was taken and reacted at 37℃ for 20 minutes. The reaction was stopped with 1 mL of 1 M Na2CO3 and absorbance was measured in 405 nm. With the regression analysis, the content of solubility solids (the value of IC50) which can inhibit 50% of 0.7 unit α-glucosidase solution’s activity was investigated. The frond (IC50 = 14.00∼913.33 μg･mL-1) and rhizome extracts (IC50 = 12.93∼205.84 μg･mL-1) of nine Pteridophyte species showed higher α-glucosidase inhibition activity in comparison with acarbose (IC50 = 1413.70 μg･ mL-1). The extracts of fronds and rhizomes showed higher value than acarbose by 1.55∼100.98 and 6.87∼109.33 times each. Especially, α-glucosidase inhibition activities of Pyrrosia lingua in fronds and Osmunda cinnamomea var. fokiensis in rhizomes were the highest. The necessary biomass of fronds and rhizomes for inhibiting 50% of α-glucosidase activity showed the lowest value, 0.35, 0.27 mg each, in O. cinnamomea var. fokiensis. IC50 value of P. lingua was the highest among fronds of nine Pteridophyte species, but content of soluble solids was 2.4 times less than O. cinnamomea var. fokiensis. So frond of O. cinnamomea var. fokiensis is more economic in comparison with P. lingua. As the result of this study, O. cinnamomea var. fokiensis showed high α-glucosidase inhibition activity even with small biomass. Therefore it was considered to be high-valued economic material as natural α-glucosidase inhibitor