5 research outputs found
Application of Residual Dipolar Couplings and Selective Quantitative NOE to Establish the Structures of Tetranortriterpenoids from <i>Xylocarpus rumphii</i>
Nine triterpenoid derivatives were
isolated from the heartwood
of <i>Xylocarpus rumphii</i> and were identified as xylorumphiins
E (<b>1</b>), C (<b>2</b>), L (<b>3</b>), and M–R
(<b>4</b>–<b>9</b>). Compounds <b>4</b>–<b>9</b> have a hemiacetal group in the triterpenoid side chain,
making them impossible to purify. Purification was achieved after
acetylation and subsequent separation of the epimeric mixtures of
acetates; however differentiaition of the <i>R</i> and <i>S</i> epimers was not possible using standard NMR techniques.
In one case, the relative configuration of a remotely located stereocenter
with respect to the stereocenters in the main skeleton was unambiguously
determined using residual dipolar couplings. Dipolar couplings were
collected from the sample oriented in compressed polyÂ(methyl methacrylate)
gels swollen in CDCl<sub>3</sub>. In another case, the relative configuration
was determined using 1D selective quantitative NOE experiments. Xylorumphiin
K (<b>10</b>), xyloccensin E, taraxer-14-en-3β-ol, (22<i>S</i>)-hydroxytirucalla-7,24-diene-3,23-dione, and 25-hydroxy-(20<i>S</i>,24<i>S</i>)-epoxydammaran-3-one were isolated
from the bark of the same plant. Compounds <b>3</b>–<b>10</b> are new compounds. Compounds <b>1</b>–<b>6</b> and xyloccensin E were tested at one concentration, 1 ×
10<sup>–5</sup> M, in the NCI59 cell one-dose screen but did
not show significant activity
Application of Residual Dipolar Couplings and Selective Quantitative NOE to Establish the Structures of Tetranortriterpenoids from <i>Xylocarpus rumphii</i>
Nine triterpenoid derivatives were
isolated from the heartwood
of <i>Xylocarpus rumphii</i> and were identified as xylorumphiins
E (<b>1</b>), C (<b>2</b>), L (<b>3</b>), and M–R
(<b>4</b>–<b>9</b>). Compounds <b>4</b>–<b>9</b> have a hemiacetal group in the triterpenoid side chain,
making them impossible to purify. Purification was achieved after
acetylation and subsequent separation of the epimeric mixtures of
acetates; however differentiaition of the <i>R</i> and <i>S</i> epimers was not possible using standard NMR techniques.
In one case, the relative configuration of a remotely located stereocenter
with respect to the stereocenters in the main skeleton was unambiguously
determined using residual dipolar couplings. Dipolar couplings were
collected from the sample oriented in compressed polyÂ(methyl methacrylate)
gels swollen in CDCl<sub>3</sub>. In another case, the relative configuration
was determined using 1D selective quantitative NOE experiments. Xylorumphiin
K (<b>10</b>), xyloccensin E, taraxer-14-en-3β-ol, (22<i>S</i>)-hydroxytirucalla-7,24-diene-3,23-dione, and 25-hydroxy-(20<i>S</i>,24<i>S</i>)-epoxydammaran-3-one were isolated
from the bark of the same plant. Compounds <b>3</b>–<b>10</b> are new compounds. Compounds <b>1</b>–<b>6</b> and xyloccensin E were tested at one concentration, 1 ×
10<sup>–5</sup> M, in the NCI59 cell one-dose screen but did
not show significant activity
Application of Residual Dipolar Couplings and Selective Quantitative NOE to Establish the Structures of Tetranortriterpenoids from <i>Xylocarpus rumphii</i>
Nine triterpenoid derivatives were
isolated from the heartwood
of <i>Xylocarpus rumphii</i> and were identified as xylorumphiins
E (<b>1</b>), C (<b>2</b>), L (<b>3</b>), and M–R
(<b>4</b>–<b>9</b>). Compounds <b>4</b>–<b>9</b> have a hemiacetal group in the triterpenoid side chain,
making them impossible to purify. Purification was achieved after
acetylation and subsequent separation of the epimeric mixtures of
acetates; however differentiaition of the <i>R</i> and <i>S</i> epimers was not possible using standard NMR techniques.
In one case, the relative configuration of a remotely located stereocenter
with respect to the stereocenters in the main skeleton was unambiguously
determined using residual dipolar couplings. Dipolar couplings were
collected from the sample oriented in compressed polyÂ(methyl methacrylate)
gels swollen in CDCl<sub>3</sub>. In another case, the relative configuration
was determined using 1D selective quantitative NOE experiments. Xylorumphiin
K (<b>10</b>), xyloccensin E, taraxer-14-en-3β-ol, (22<i>S</i>)-hydroxytirucalla-7,24-diene-3,23-dione, and 25-hydroxy-(20<i>S</i>,24<i>S</i>)-epoxydammaran-3-one were isolated
from the bark of the same plant. Compounds <b>3</b>–<b>10</b> are new compounds. Compounds <b>1</b>–<b>6</b> and xyloccensin E were tested at one concentration, 1 ×
10<sup>–5</sup> M, in the NCI59 cell one-dose screen but did
not show significant activity
Antiangiogenic Pterocarpan and Flavonoid Constituents of <i>Erythrina lysistemon</i>
The roots of Erythrina lysistemon, growing
in
Egypt, yielded 24 flavonoid compounds, including 17 pterocarpans,
two isoflavanones, one flavanone, two isoflavans, one 2-arylbenzofuran,
and an isoflava-3-ene. Nine pterocarpans have not been reported previously
(7–9, 11–14, 19, and 20), and 11 are reported
here for the first time from this species. Structures were established
using HRESIMS, NMR, and circular dichroism techniques. Selected compounds
were tested for their ability to block the growth of human retinal
endothelial cells and antiangiogenic activity in vitro. The isoflavonoids 5 and 6, and the pterocarpans 1, 2, 4, 20, and 22 demonstrated
selective antiproliferative activities on endothelial cells compared
to a nonendothelial cell type, with concentration-dependent antiangiogenic
effects in vitro against HRECs, a cell type relevant to neovascular
eye diseases
Phytochemical Investigations of Three <i>Rhodocodon</i> (Hyacinthaceae Sensu APG II) Species
The
genus <i>Rhodocodon</i> (Hyacinthaceae sensu APG II) is
endemic to Madagascar, and its phytochemistry has not been described
previously. The phytochemistry of three species in this genus has
been investigated, and eight compounds, including three bufadienolides
(compounds <b>1</b>, <b>4</b>, and <b>5</b>), a
norlignan (<b>2</b>), and four homoisoflavonoids (compounds <b>3</b> and <b>6</b>–<b>8</b>), have been isolated
and identified. Compounds <b>1</b>–<b>3</b> and <b>6</b>–<b>8</b> have not been described previously.
The COX-2 inhibitory activity of compound <b>6</b> and compound <b>7</b> acetate (compound <b>7A</b>) was investigated on isolated
colorectal cancer cells. Compounds <b>6</b> and <b>7A</b> inhibited COX-2 by 10% and 8%, respectively, at a concentration
of 12.5 μM compared to 12% for 1 mM aspirin (the positive control)