New Acylated Saponins from Polygala myrtifolia

Abstract

The ten new acylated presenegenin ( (2b,3b,4a)-2,3,27-trihydroxyolean-12-ene-23,28-dioic acid) glycosides 1 ± 10 have been isolated by successive MPLC from the roots of Polygala myrtifolia L. as five inseparable mixtures of the trans-and cis-4-methoxycinnamoyl derivatives, i.e., myrtifoliosides A 1 /A 2 (1/2), B 1 /B 2 (3/4), C 1 /C 2 (5/6), D 1 /D 2 (7/8), and E 1 /E 2 (9/10). Their structures were elucidated mainly by extensive spectroscopic experiments, including 2D NMR techniques, as 3- (7) and its cis-isomer 8, and (9) and its cis-isomer 10.Introduction. ± The Polygalaceae is a cosmopolitan plant family, consisting of approximately 1000 species in 15 genera. Polygala myrtifolia L., a South African medicinal herbaceous plant, is used by indigenous people to treat tuberculosis symptoms such as fever, blood in the septum, and cough [1]. Bacteriological tests showed that aqueous extracts of the green parts of the plant give doubtfully positive tests against Staphylococcus aureus and negative tests against Escherichia coli [2]. Polygala species have already been investigated, resulting in the isolation of presenegenin glycosides [3 ± 6] but no previous phytochemical study has been undertaken on P. myrtifolia. Herein we report the isolation and structure elucidation of ten new triterpene glycosides named myrtifoliosides A 1 /A 2 , B 1 /B 2 , C 1 /C 2 , D 1 /D 2 , and E 1 /E 2 (1 ± 10), which were obtained as five inseparable mixtures of the trans-and cisacyl derivatives from the EtOH extract of the roots of P. myrtifolia.

Triterpene Saponins from Four Species of the Polygalaceae Family

“…This indicated that 1/2 was a mixture of (E)-and (Z)-4-methoxycinnamoyl triterpene glycosides. Such an (E)/(Z)-isomer behavior of the 4-methoxycinnamoyl moiety in MeOH solutions under light has often been described in many saponins from the Polygalaceae like P. arenaria [5] or P. myrtifolia [6]. (2)) revealed the (1 !…”

“…After extensive 2D-NMR spectroscopic analysis and subtraction of the signals of the glucopyranosyl moiety of the prosapogenin, the signals of six sugar units linked to C(28) of the presenegenin remained, which were identified as Fuc, Rha, Xyl, Gal, Ara, and apiofuranosyl (Api). This latter was determined to be in the b-anomeric form by comparing its spectroscopic data with literature values [6]. Furthermore it was assumed to have the D-configuration normally found in nature.…”

“…One of them (300 mg), rich in saponins, was fractionated by successive MPLC (silica gel, CHCl 3 / MeOH/H 2 O 13 : 7 : 2, lower phase): C-NMR ((D 5 )pyridine): for aglycon, see [3]; for sugars and acyl groups, see Tables 1 -3. (5 (6). White amorphous powder.…”

A new oleanane glycoside from the roots of Astragalus caprinus

“…8,9 Correlations observed in the HMBC spectrum between signals at υ H 4.85 (1H, d, J D 7.6 Hz, GlcA-1) and υ C 90.2 (C-3), and in the NOESY spectrum between υ H 4.85 (GlcA-1) and υ …”

Triterpene Saponins from Polygalaceae

“…3)-a-L-arabinopyranosyl-and is substituted by the same acyl residues as in 32/33 and 34/35, respectively. The five pairs of presenegenin glycosides from P. myrtifolia (40/41-48/49) (Haddad et al, 2003) are substituted at the position 4 of the fucopyranosyl unit by a E/Z-4-methoxycinnamoyl group whereas the glycosides of Carpolobia alba (50-52) are substituted at the positions 3 and 4 by one acetyl group (Mitaine-Offer et al, 2002). Compounds 50 and 51 are common to both species C. alba and C. lutea.…”