Antioxidant and inhibitory activities of α-amylase, α-glucosidase, and G۶Pase from Smallanthus sonchifolius tuber extract as a potential antidiabetic agent

Introduction: Diabetes mellitus (DM) is a chronic condition with free radicals and carbohydrate-hydrolyzing enzymes playing key roles in its progression. Yacon or Smallanthus sonchifolius (Poepp.) H.Rob, a low-sugar crop, has shown promising bioactivities. This research aimed to explore the antidiabetic and antioxidant potential of yacon tuber extract (YTE). Methods: YTE’s antioxidant and enzyme inhibitory activities were assessed using ۲,۲-diphenyl-۱-picrylhydrazyl (DPPH) at concentrations of ۶.۲۵, ۱۲.۵, ۲۵, ۵۰, ۱۰۰, ۲۰۰ µg/mL, hydrogen peroxide (H₂O₂) scavenging activity at ۱۲.۵, ۲۵, ۵۰, ۱۰۰, ۲۰۰, ۴۰۰ µg/mL, ۳-ethylbenzothiazoline-۶-sulfonic acid (ABTS) and ferric reducing antioxidant power (FRAP) at ۱.۵۶, ۳.۱۳, ۶.۲۵, ۱۲.۵, ۲۵, ۵۰ µg/mL. The inhibition of α-amylase, α-glucosidase (۶.۲۵, ۱۲.۵, ۲۵, ۵۰, ۱۰۰, ۲۰۰ µg/mL), and glucose ۶-phosphatase (G۶Pase) (۵.۵۱, ۱۱.۰۳, ۲۲.۶, ۴۴.۱۲, ۸۸.۲۴, ۱۷۶.۴۷ µg/mL) was also assessed. Phytochemical analysis identified key bioactive compounds, and IC₅₀ values were determined to quantify YTE’s antioxidant and antidiabetic potentials. Results: YTE contained flavonoids, terpenoids, triterpenoids, and phenolic compounds. It showed highest antioxidant activity (P<۰.۰۵) in DPPH, ABTS, H₂O₂, and FRAP assays at ۲۰۰, ۵۰, ۴۰۰, and ۵۰ µg/mL, respectively, compared to the other concentrations. In DPPH, H₂O₂, and ABTS assays, the IC₅₀ values were ۱۰۵.۷۷ μg/mL, ۷۲۶.۶۴ μg/mL, and ۶۱.۰۳ μg/mL, respectively. FRAP activity was ۳۳۸.۶۸ μM/μg Fe (II) at ۵۰ µg/mL. YTE also inhibited α-amylase, α-glucosidase, and G۶Pase with IC₅₀ values of ۱۷۴.۹۵ μg/mL, ۲۲۲.۱۷ μg/mL, and ۱۱۲.۵۱ μg/mL, respectively. Conclusion: YTE exhibited significant antioxidant properties and inhibited carbohydrate-hydrolyzing enzymes, indicating its potential as an antidiabetic agent.