The determination of antidiabetic, anticholinesterase and antioxidant properties of ethanol and water extracts of blackberry (Rubus fruticosus L.) fruits at different maturity stages
Mehmet Akyüz
Abstract
The aim of the current study is to investigate the antidiabetic, anticholinesterase and antioxidant properties of Rubus fruticosus L. at the different of maturity stages (immature, intermediate and ripening). For this purpose, the inhibitory effects of the ethanol and water extracts of the samples on acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-glucosidase and α-amylase enzyme activities were tested to evaluate their antidiabetic and neuroprotective potentials. The inhibitory activities of the extracts were also compared with that of antidiabetic drug, acarbose and, neuroprotective drugs, neostigmine and galanthamine. In addition to antioxidant activities, three stages of both extracts were evaluated with three antioxidant methods including 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) scavenging activities and reducing power activity. The antioxidant activities of all samples were compared with standard antioxidant molecules butylated hydroxyanisole (BHA) and Trolox. On the other hand, the amounts of total phenolic compounds in both extracts were determined as mgGAE/g extract. The ethanol and water extracts of immature, intermediate and ripening stages of R. fruticosus L. exhibited antidiabetic properties by inhibiting α-glucosidase and α-amylase enzymes at different rates. The ethanol extract of intermediate (IC50=0.019 mg/ml), immature (IC50=0.021 mg/ml) and ripening (IC50=0.520 mg/ml) stages and the water extracts of immature (IC50=0.014 mg/ml), intermediate (IC50=0.014 mg/ml) and the ripening stages (IC50=0.136 mg/ml) were determined as the most potent inhibitors against α-glucosidase. The inhibition effects of both extracts of the three stages were found to be many times higher than acarbose (IC50=14.45 mg/ml) against α-glucosidase enzyme. The water extracts of intermediate (IC50=0.54 mg/ml), immature (IC50=1.52 mg/ml) and ripening (IC50=4.17 mg/ml) stages were determined as powerful inhibitory effects against α-amylase enzyme compared to acarbose (IC50=0.11 mg/ml). The ethanol and water extracts of fruit at different maturity stages acted as rather weak inhibitors against AChE and BChE compared to neostigmine and galanthamine. DPPH radical scavenging activity of ethanol extracts of intermediate (IC50=0.01 mg/ml), ripening (IC50=0.05 mg/ml) and immature (IC50=0.06 mg/ml) stages were higher than Trolox (IC50=0.12 mg/ml) and BHA (IC50=0.16 mg/ml), whereas the DPPH radical scavenging activity of the water extracts were relatively lower. ABTS radical scavenging powers of ethanol extracts of immature (IC50=0.002 mg/ml), intermediate (IC50=0.004 mg/ml) and ripening (IC50=0.028 mg/ml) stages were higher compared to BHA (IC50=0.05 mg/ml) and Trolox (0.072 mg/ml). ABTS radical scavenging power of water extracts of immature (IC50=0.021 mg/ml) stage was higher compared to BHA (IC50=0.05 mg/ml) and Trolox (IC50=0.072 mg/ml) and was lower than that of intermediate (IC50=0.20 mg/ml) and ripening (IC50=0.32 mg/ml) stages. The reducing power activities of all ethanol and water extracts of the fruit were lower compared to Trolox and BHA at 200 µg/ml concentration. Total phenolic content of ethanol extracts of immature, intermediate and ripening stages were found as 275.93±3.96, 168.17±3.13 and 49.78 ±5.20 mgGAE/g extract, whereas for water extracts were found as 86.79±2.48, 74.25±3.18 and 41.83±5.27 mg GAE/g extract, respectively.