Abstract

[2,2-azino-bis(3-ethylbenzothiazoline)-6-sulphonic acid] Diammonium salt (ABTS) radical scavenging and ferric reducing antioxidant power (FRAP) assay were used to analyze the antioxidant activity of red raspberry (Harrywaters, HW) fruits with 2,6-Di-tert-butyl-4-methylphrnol (BHT) as positive controls and α-glucosidase inhibitory activity of HW extracts with acarbose as positive control in vitro. HW fruits had free radical scavenging activity and iron-reduction activity. ABTS radical scavenging activity of petroleum ether extract (HWPE), ethyl acetate extract (HWEA) and n-butanol extract (HWBU) with IC₅₀ values of 54.09, 57.88 and 47.74 µg/mL, respectively, were weaker than that of BHT (IC₅₀ = 7.72 µg/mL). HWPE exhibited higher ferric reducing antioxidant power with 367.57 ± 2.77 μmol/g as Trolox equivalent than that of HWEA and HWBU, but weaker than that of BHT with1581.68 ± 97.41 μmol/g as Trolox equivalent. HWEA (IC₅₀ = 67.7 μg/mL) had the best α-glycosidase inhibitory activity, followed by HWPE (IC₅₀ = 163.1 μg/mL) and HWBU (IC₅₀ = 292.2 μg/mL). Their α-glycosidase inhibitory activity were far higher than that of acarbose (IC₅₀ = 1103.01 µg/mL) as positive control. Results indicated that HW had a certain extent antioxidant activity and good α-glycosidase inhibitory activity in vitro, and active compounds should be isolated and identified in the next work.

Keywords: Red raspberry (Harrywaters), antioxidant activity, α-glucosidase inhibitory activity.