Antioxidant and Alpha-Glucosidase Inhibitory Activities of

Flavonoids Extracted from Euphorbia thymifolia Linn.

The flavonoids isolated from EtOAc extract of Euphorbia thymifolia Linn. were assayed for antioxidant and alpha-glucosidase inhibitory activity. Antioxidant property was determined by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) while inhibition of alpha-glucosidase was screened using yeast alpha-glucosidase enzyme. Luteolin and quercetin-3-O-arabinofuranoside isolated from EtOAc extract were subjected to bioactivity screening. The results showed that these flavonoids played a crucial role in antioxidant activity and inhibition of alpha-glucosidase; of which, quercetin-3-O-arabinofuranoside demonstrated a powerful antioxidant activity with IC50 value of 0.013±0.05 µg/mL compared to that of luteolin with IC50 value of 3.04±0.04 µg/mL while IC50 value of the positive control (ascorbic acid) was 0.097±0.29 µg/mL. Similarly, alpha-glucosidase inhibitory activity of quercetin-3-O-arabinofuranoside was recorded with low IC50 of 11.76±0.18 µg/mL compared to that of luteolin with IC50 value of 263±0.01 µg/mL, almost the same as IC50 value resulting from the positive control, Acarbose (250.4±0.01 µg/mL).

Keywords: Alpha-glucosidase, Antioxidant, EtOAc extract, E.  thymifolia, Flavonoids.

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