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 evaluate the antioxidant activity of extracts of dried flowers of Tithonia diversifolia(Hemsl) A.Gray(T.diversifolia) dry flower-a slirubby plant belonging to the Asteraceac family and very common in Braz...Objective:To evaluate the antioxidant activity of extracts of dried flowers of Tithonia diversifolia(Hemsl) A.Gray(T.diversifolia) dry flower-a slirubby plant belonging to the Asteraceac family and very common in Brazil,providing data to help prevent premature aging skin.Methods:The tests of phytochemical screening included total phenols,tannins,flavonoids,alkaloids and saponins.The active antioxidant was determined by 2,2-diphenyl-1-picrylhydrazyl method.Results:The phytoehemical screening of T.diversifolia dry flowers revealed the presence of phenolic compounds(tannins,flavonoids and total phenolsi,while alkaloids and saponins were not detected.The IC_(50) values showed a strong antioxidant activity of the plant extracts.Conclusions:Therefore,this study suggests the possibility of using dry flowers extracts of T.diversifolia for the prevention of cell aging,as was shown to have significant antioxidant activity.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.
基金Supported by Pro-Saude Ⅱ,Fundacao do ABC(Grant No.2261/2008)
文摘Objective:To evaluate the antioxidant activity of extracts of dried flowers of Tithonia diversifolia(Hemsl) A.Gray(T.diversifolia) dry flower-a slirubby plant belonging to the Asteraceac family and very common in Brazil,providing data to help prevent premature aging skin.Methods:The tests of phytochemical screening included total phenols,tannins,flavonoids,alkaloids and saponins.The active antioxidant was determined by 2,2-diphenyl-1-picrylhydrazyl method.Results:The phytoehemical screening of T.diversifolia dry flowers revealed the presence of phenolic compounds(tannins,flavonoids and total phenolsi,while alkaloids and saponins were not detected.The IC_(50) values showed a strong antioxidant activity of the plant extracts.Conclusions:Therefore,this study suggests the possibility of using dry flowers extracts of T.diversifolia for the prevention of cell aging,as was shown to have significant antioxidant activity.
