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      Novel Flavonoid Glycosides of Quercetin from Leaves and Flowers of Gaiadendron punctatum G.Don. (Violeta de Campo), used by the Saraguro Community in Southern Ecuador, Inhibit α-Glucosidase Enzyme

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          Abstract

          Gaiadandendron punctatum G.Don. (violeta de campo) is a plant used in traditional medicine by the Saraguro people, an ancient indigenous group that lives in southern Ecuador. From samples collected in the region, six glycoside flavonoids, five with quercetin and one with kaempferol as aglycon, were isolated and characterized from hydroalcoholic extracts of leaves and flowers. Rutin ( 2) was found in flowers and leaves, nicotiflorin ( 1) was found in flowers, artabotryside A ( 3) was found in leaves, and three novel quercetin flavonoid glycosides were isolated, elucidated, and characterized via 1D and 2D NMR experiments ( 1H, 13C, COSY, DEPT, HMBC, HSQC, TOCSY, NOESY, ROESY), acid hydrolysis–derivatization–GC-MS analysis, HPLC-MS, IR, UV, and optical rotation. The new quercetin flavonoid glycosides were named hecpatrin ( 4) (isolated from leaves), gaiadendrin ( 5) (isolated from leaves), and puchikrin ( 6) (isolated from flowers). The hydroalcoholic extracts of the leaves presented antimicrobial activity against Micrococcus luteus, Staphylococcus aureus, and Enterococcus faecalis and the hydroalcoholic extract of the flowers was active against Micrococcus luteus. However, glycoside flavonoids presented scarce antimicrobial activity against bacteria. Hydroalcoholic extracts from leaves and flowers and their secondary metabolites showed inhibition against the α-glucosidase enzyme at different concentrations. Rutin, gaiadendrin, and nicotiflorin showed competitive α-glucosidase inhibition, while hecpatrin presented non-competitive inhibition.

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          Most cited references 43

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          Progress in antifungal susceptibility testing of Candida spp. by use of Clinical and Laboratory Standards Institute broth microdilution methods, 2010 to 2012.

           D Diekema,  M Pfaller (2012)
          Antifungal susceptibility testing of Candida has been standardized and refined and now may play a useful role in managing Candida infections. Important new developments include validation of 24-h reading times for all antifungal agents and the establishment of species-specific epidemiological cutoff values (ECVs) for the systemically active antifungal agents and both common and uncommon species of Candida. The clinical breakpoints (CBPs) for fluconazole, voriconazole, and the echinocandins have been revised to provide species-specific interpretive criteria for the six most common species. The revised CBPs not only are predictive of clinical outcome but also provide a more sensitive means of identifying those strains with acquired or mutational resistance mechanisms. This brief review serves as an update on the new developments in the antifungal susceptibility testing of Candida spp. using Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) methods.
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            NMR spectroscopy in the structural elucidation of oligosaccharides and glycosides.

            The potential of one- and two-dimensional NMR techniques for the identification of individual sugar residues, their anomeric configuration, interglycosidic linkages, sequencing and the site of any appended group, in establishing the structures of naturally occurring oligosaccharides and glycosides is presented.
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              Inhibitory effect of pine extract on alpha-glucosidase activity and postprandial hyperglycemia.

              This study investigated the inhibitory effect of pine bark extract (PBE) and needle extract on carbohydrate-hydrolyzing enzymes and the hypoglycemic effect in diabetic mice (Lep(ob) [ob/ob]). Pine bark and needle were dried and then placed in ethanol, and the extracts were assayed for the measurement of inhibition mode of PBE against alpha-amylase (EC 3.2.1.1) and alpha-glucosidase (EC 3.2.1.20). We also investigated the effect of long-term treatment with extracts on levels of postprandial blood glucose, body weight, food efficiency ratio, and gene expression of glucose transporter-4 in quadriceps muscle in diabetic mice (Lep(ob) [ob/ob]). The PBE showed competitive inhibition against salivary alpha-amylase and the combination of non-competitive and uncompetitive inhibition against yeast alpha-glucosidase. In animal experiments, PBE effectively suppressed the increase of postprandial blood glucose level by delaying absorption of diet, and body weights of the group that received PBE were significantly lower than that in the group administered 0.5% carboxylmethyl cellulose (control) 21 d after administration. PBE can be used to suppress postprandial hyperglycemia of diabetic patients. It also can be applied for control of obesity by decreasing the food efficiency ratio, especially carbohydrates.
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                Author and article information

                Journal
                Molecules
                Molecules
                molecules
                Molecules
                MDPI
                1420-3049
                22 November 2019
                December 2019
                : 24
                : 23
                Affiliations
                Departamento de Química, Universidad Técnica Particular de Loja (UTPL), Loja 1101608, Ecuador; hpcedeno@ 123456utpl.edu.ec (H.C.); ssespinosa@ 123456utpl.edu.ec (S.E.); jmandrade@ 123456utpl.edu.ec (J.M.A.); lecartuche@ 123456utpl.edu.ec (L.C.)
                Author notes
                [* ]Correspondence: omalagon@ 123456utpl.edu.ec
                Article
                molecules-24-04267
                10.3390/molecules24234267
                6930599
                31771116
                © 2019 by the authors.

                Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( http://creativecommons.org/licenses/by/4.0/).

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