Screening of different fruit extracts from Viburnum opulus L. as inhibitors of key enzymes linked to type 2 diabetes and antioxidants: a comparative evaluation

In this study, the inhibiting effect on α-amylase and α-glucosidase, the antioxidant activity of different fruit extracts from V. opulus and the chemical compounds in most active extract were investigated. The antioxidant activity was tested with DPPH⋅, ABTS⋅+ and FRAP tests and the phytochemical analyses of the active extract was determined by LC–MS/MS. According to the results, the highest α-glucosidase and α-amylase activity even from positive control acarbose were found in ethanol extract (IC50 = 3.671 ± 0.016 µg/mL and 601.667 ± 0.015 µg/mL, respectively). Also, the highest TPC (96.000 ± 0.001 mgGAE/gextract) and TFC (69.327 ± 0.693 mgCA /gextract) was found in the same extract and this extract showed the highest antioxidant activity on DPPH⋅ (%34), FRAP (at a concentration of 1 mg/mL equivalent to 1521.527 ± 1.528 mmol Fe2+) and ABTS+⋅ (at a concentration of 0.5 mg/mL equivalent to 0.43 ± 0.002 µM Trolox) tests. Organic and phenolic acids and triterpenic compounds were identified in V. opulus ethyl acetate extract by LC–MS/MS analysis. In conclusion, this study may be supported with detailed investigation on different pathways in anti-diabetic activity and could contribute to the advanced studies of this species.