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- Title
Antioxidant and α-glucosidase inhibitor activities of natural compounds isolated from Quercus gilva Blume leaves.
- Authors
Indrianingsih, Anastasia Wheni; Tachibana, Sanro; Dewi, Rizna Triana; Itoh, Kazutaka
- Abstract
Objective To isolate and investigate antioxidant and α-glucosidase inhibitor compounds in the leaves of Quercus gilva Blume ( Q. gilva ). Methods Dry leaves of Q. gilva were extracted with methanol and the methanolic extract was further separated by silica gel column chromatography using several solvents with increasing polarity. The antioxidant activities of the isolated compounds were evaluated using various in vitro assays: 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, hydrogen peroxide radical scavenging activity, β-carotene bleaching assay, and reducing power assay. The α-glucosidase inhibitory assay was conducted against α-glucosidase from Saccharomyces cerevisiae . Results Three compounds were isolated and their structures were identified as catechin (1), epicatechin (2), and tiliroside (3) using an instrumental analysis. Compound 2 had higher antioxidant activity with inhibitory concentrations (IC 50 ) of (22.55 ± 2.23) μmol/L than that of quercetin, which was used as the standard, with an IC 50 of (28.08 ± 2.39) μmol/L, followed by compound 1 with IC 50 of (40.86 ± 3.45) μmol/L. On the other hand, compound 3 had the lowest antioxidant activity with an IC 50 of (160.24 ± 8.15) μmol/L. However, compound 3 had the highest α-glucosidase inhibitory activity with an IC 50 of (28.36 ± 0.11) μmol/L, followed by compounds 1 and 2 with (168.60 ± 5.15) and (920.60 ± 10.10) μmol/L, respectively. Conclusions The results obtained for the antioxidant activities and α-glucosidase inhibitory activities in a methanolic extract from the leaves of Q. gilva confirmed the potential of this plant as a source of natural antioxidants and antidiabetic medicine.
- Subjects
ANTIOXIDANTS; GLUCOSIDASE inhibitors; OAK; CAROTENES; BLEACHING (Chemistry)
- Publication
Asian Pacific Journal of Tropical Biomedicine, 2015, Vol 5, Issue 9, p748
- ISSN
2221-1691
- Publication type
Article
- DOI
10.1016/j.apjtb.2015.07.004