Severalα-glucosidase inhibitory constituents were isolated from the methanolic extract of the leaves of Quercus phillyraeoides A.Gray(Q.phillyraeoides)using a bioassay-guided fractionation technique.Further separatio...Severalα-glucosidase inhibitory constituents were isolated from the methanolic extract of the leaves of Quercus phillyraeoides A.Gray(Q.phillyraeoides)using a bioassay-guided fractionation technique.Further separation and purification of the methanol-soluble fraction led to the isolation of constituents with moderate and strong inhibitory activities againstα-glucosidase:α-sitosterol-d-glucoside(1)and condensed tannin fractions(2,3,4,5,and 6).Compound 1 and fractions 2-6 had inhibitory concentration(IC50)values againstm-glucosidase from Saccharomyces cerevisiae of 118.8,2.79,2.78,3.10,2.60,and 3.14μg/mL,respectively,while quercetin as the standard had an IC50 value of 4.80mg/mL.Furthermore,the significant antioxidant activities were evaluated using several assays,such as the DPPH radical scavenging,hydrogen peroxide radical scavenging,reducing power,andβ-carotene-linoleate bleaching assays,and the results suggested that the isolated constituents showed their possible application for treating the hyperglycemia-induced oxidative stress.The results of the present study showed the potential of Q.phillyraeoides as a rich source of natural antidiabetic medicine.展开更多
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 e...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 identii ed as catechin(1), epicatechin(2), and tiliroside(3) using an instrumental analysis. Compound 2 had higher antioxidant activity with inhibitory concentrations(IC50) of(22.55 ± 2.23) μmol/L than that of quercetin, which was used as the standard, with an IC50 of(28.08 ± 2.39) μmol/L, followed by compound 1 with IC50 of(40.86 ± 3.45) μmol/L. On the other hand, compound 3 had the lowest antioxidant activity with an IC50 of(160.24 ± 8.15) μmol/L. However, compound 3 had the highest α-glucosidase inhibitory activity with an IC50 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 coni rmed the potential of this plant as a source of natural antioxidants and antidiabetic medicine.展开更多
文摘Severalα-glucosidase inhibitory constituents were isolated from the methanolic extract of the leaves of Quercus phillyraeoides A.Gray(Q.phillyraeoides)using a bioassay-guided fractionation technique.Further separation and purification of the methanol-soluble fraction led to the isolation of constituents with moderate and strong inhibitory activities againstα-glucosidase:α-sitosterol-d-glucoside(1)and condensed tannin fractions(2,3,4,5,and 6).Compound 1 and fractions 2-6 had inhibitory concentration(IC50)values againstm-glucosidase from Saccharomyces cerevisiae of 118.8,2.79,2.78,3.10,2.60,and 3.14μg/mL,respectively,while quercetin as the standard had an IC50 value of 4.80mg/mL.Furthermore,the significant antioxidant activities were evaluated using several assays,such as the DPPH radical scavenging,hydrogen peroxide radical scavenging,reducing power,andβ-carotene-linoleate bleaching assays,and the results suggested that the isolated constituents showed their possible application for treating the hyperglycemia-induced oxidative stress.The results of the present study showed the potential of Q.phillyraeoides as a rich source of natural antidiabetic medicine.
文摘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 identii ed as catechin(1), epicatechin(2), and tiliroside(3) using an instrumental analysis. Compound 2 had higher antioxidant activity with inhibitory concentrations(IC50) of(22.55 ± 2.23) μmol/L than that of quercetin, which was used as the standard, with an IC50 of(28.08 ± 2.39) μmol/L, followed by compound 1 with IC50 of(40.86 ± 3.45) μmol/L. On the other hand, compound 3 had the lowest antioxidant activity with an IC50 of(160.24 ± 8.15) μmol/L. However, compound 3 had the highest α-glucosidase inhibitory activity with an IC50 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 coni rmed the potential of this plant as a source of natural antioxidants and antidiabetic medicine.
