a-glucosidase Inhibitors From Paraguayan Natural Medicine, Ñangapiry, The Leaves Of Eugenia Uniflora

Abstract

The water-soluble extract from a Paraguayan natural medicine, Nangapiry, the leaves of Eugenia uniflora L. (Myrtaceae), which has been used as an antidiabetic agent, was found to show inhibitory activities on the increase of plasma glucose level in the sucrose tolerance test (STT) conducted with mice. The portion adsorbed on a cation exchange resin was also found to inhibit a-glucosidases. From the active portion, two new active compounds named uniflorines A ( 1 ) and B ( 2 ) and known (+)-(3a, 4a, 5ß)-1-methylpiperidine-3, 4, 5-triol ( 3 ) were isolated. The structures of uniflorines A and B were determined as (-)-(1S, 2R, 6S, 7R, 8R, 8aR)-1,2,6,7,8-pentahydroxyindolizidine and (+)-(1S, 2R, 5R, 7R, 8S, 8aS)-1,2,5,7,8-pentahydroxyindolizidine by spectral means, respectively.

Synthetic and spectroscopic studies on the structures of uniflorines A and B: structural revision to 1,2,6,7-tetrahydroxy-3-hydroxymethylpyrrolizidine alkaloids

“…b Original assignments based on an indolizidine structure. 1 Further support for this structure came from the results of the reported NOE studies and 13 C NMR data of uniflorine A. 1 The original paper reported NOE correlations for uniflorine A between H-…”

“…The structure of uniflorine A was deduced from NMR analysis to be that shown as structure 1. 1 The proposed structure of uniflorine A is similar to that of castanospermine 2, except for the stereochemistry at C-1 and the extra hydroxyl substitution at C-2. As part of our program concerned with the synthesis of polyhydroxylated indolizidine and pyrrolizidine alkaloids [4][5][6][7][8][9][10][11] we reported an efficient 9-step synthesis of purported uniflorine A from L-xylose.…”

“…1 c Both signals were assigned as C-3 in the original paper. 1 The 13 C NMR chemical shifts of the methylene carbons reported for uniflorine A at  65.3 and  60.0 correspond more closely to C-3 and C-5, respectively, of a 1,2,6,7-tetrahydroxy-3-hydroxymethylpyrrolizidine (c.f. casuarine C-3 ( 70.0) and C-5 ( 58.0), Table 2) than to C-3 and C-5 of a 1,2,6,7,8-pentahydroxyindolizidine (the methylene resonances in 1 are at C-3 ( 59.2) and C-5 ( 55.4)) Thus it would be reasonable to assume that uniflorine A, like uniflorine B, is also a 1,2,6,7-tetrahydroxy-3-hydroxmethylpyrrolizidine alkaloid.…”

“…The alkaloid uniflorine A was isolated in 2000 from the leaves of the tree Eugenia uniflora L. [1][2][3] The watersoluble extract of these leaves has been used as an antidiabetic agent in Paraguayan traditional medicine.…”

Influence of foliar nutrients on phenol levels in leaves of Eugenia uniflora

“…Its leaves have been used in folk medicine for the treatment of diarrhea (Brandelli et al, 2009), inflammation (Schapoval et al, 1994), hyperglycemia, hyperlipidemia, hypertriglycemia (Arai et al, 1999;Matsumura et al, 2000) and hypertension (Consolini et al, 1999). In addition, they have been used as an antimalarial and spasmolytic agent (Wazlawik et al, 1997;Morioka et al, 2000) as well as an inhibitor of DNA polymerase, maltase, sucrase, and α-glucosidase (Lee et al, 2000;Matsumura et al, 2000).…”