Study On The α-glucosidase Inhibitory Activity From Luculia Pinciana Hook And Rubia Cordifolia L.

This paper is composed of three chapters to screenα-glucosidase inhibitory activity of the constituents from plants. Chapter I, theα-glucosidase inhibitory activity of forty two kinds of medicinal plants was screened in vitro. In addition, theα-glucosidase of mammalian sources was also assayed, and compare with the inhibitory activity against the yeastα-glucosidase. Chapter II, theα-glucosidase inhibitory compounds from Luculia pinciana and Rubia cordifolia by the bioassay-guided method were isolated and identified in vitro. Chapeter III,α-glucosidase inhibitors from plant sources were summarized.Chapter Iα-glucosidase inhibitory activity of forty-two kinds of medicinal plantsThis chapter includes four parts. First, some majorα-glucosidase inhibitor screening methods was summarized. Then the microplate screening model ofα-glucosidase inhibitor with PNPG as substrate was established. In the third part, theα-glucosidase inhibitory activity of the one hundred and thirty-three kinds of extracts from forty-two kinds of medicinal plants in thirty-seven generaes and twenty-four families were assayed. And inhibition rate of eighty-five samples were higher than that of Acarbose as positive control, IC50 values of seventy-four samples were less than that of Acarbose. Strongα-glucosidase inhibitory activity extracts were mainly from Rubiaceae, Gesneriaceae, Ranunculaceae, Leguminosae, Oleaceae, Polygonaceae, and Primulaceae. The relationship between concentration and inhibitory activity of three plants of Gesneriaceae, two plants of Labiatae and the extracts by different solvent from the different parts of Coptis was assayed, and all the samples had different degrees of dose-dependent. The inhibited kinetics of Chirita eburnea Hance, Sophora japonica L. and Caragana sinica (Buchoz) Rehd. were non-competitive inhibition type with some shown competitive inhibition type. The last part, the rat intestinalα-glucosidase inhibition was assayed compared with the yeastα-glucosidase inhibitory activity. Chapter II Active compounds on inhibiton ofα-glucosidase activityThis chapter is composed of three parts. The first part,α-glucosidase inhibitors from L. pinciana and R. cordifolia by the bioassay-guided fraction. Five active compounds were isolated and identified from L. pinciana as scopletin (1), 5-methoxy-8-hydroxycoumarin (2), 1α, 3β, 24-trihydroxyursolic acid (3), ursolic acid (4) and oleanolic acid (5). The IC50 values of all compounds were lower than that of acarbose, in which compound 4 (IC50 = 3.3μg/mL) and 5 (IC50 = 2.88μg/mL) were the best. Four of them showed noncompetitive type manner onα-glucosidase inhibition except that compound 3 was competitive type manner. The second part, three active compounds from R. cordifolia were isolated and identified as 3-dihydroxy-2-methylanthra-quinone (6), 1-hydroxy-2-methylanthra- quinone (7), 2-dihydroxyanthraquinone (8). The IC50 values of compound 6, 7, 8 were all lower than that of acarbose, in which compound 8 was the best. Compound 6 and 7 showed competitive type manner onα-glucosidase, where as compound 8 showed noncompetitive type model.Chapter III Progress ofα-glucosidase inhibitors from medicinal plantsThis chapter summaried one hundred and thirty-nine compounds from medicinal plants which hadα-glucosidase inhibitory activity. Theses compounds were terpenes , alkaloids, flavonoids, quinones, phenols and other types of compounds. Flavonoids and phenylpropanoid compounds were main.