292
J. C. Pardo-Novoa and C. M. Cerda-García-Rojas
4.1 Calculation of the Flack Parameter
Two new sesquiterpenoids with a unique structure, named dendrowardols A (223)
and B (224), were isolated from the stems of Dendrobium wardianum, a species of the
Orchidaceae family that mainly grows in the south of China and some Southeast Asian
countries, such as Myanmar, Bangladesh, and Thailand. Their structures were established based on extensive spectroscopic analysis including the 1D and 2D NMR data
[103]. The absolute configuration of 223 was assigned as (1S,4R,5R,6R,7S,10R,11S)
by X-ray diffraction analysis using the anomalous scattering of Cu Kα radiation that
allowed the calculation of the Flack parameter with a significant value of 0.09(19).
The relative configuration of the diastereomer 224 was determined by single-crystal
X-ray diffraction analysis that was carried out using Mo Kα radiation, thus limiting
the Flack analysis. Dendrowardol B (224) was evaluated by an MTT assay showed
a promoting effect on the proliferation of human lens epithelial cells induced by
d-galactose [103].
OH
OH
OH
OH
OH
OH
1
2
3
4
5
6
7
8
9
10
11
12
13
14
223 (dendrowardol A)
224 (dendrowardol B)
Two new plant metabolites of the aristolane-type sesquiterpenoid, designated as
nardoaristolone A (225) and B (226), were isolated from the underground parts of
Nardostachys chinensis, a medicinal species of the family Valerianaceae that generally grows in the Himalayan mountains [104]. Nardoaristolone A (225) contains a
chalcone derivative, while nardoaristolone B (226) possesses a nor-aristolane hydrocarbon skeleton with an unusual 3/5/6 tricyclic ring system. A biogenetic pathway
was proposed to explain the formation of both metabolites, for which their structures
were elucidated by spectroscopic measurements. The absolute configurations were
established by single-crystal X-ray diffraction analysis as (1R,4R,5R,6S,7R,10S)-225
and (4R,5R,6S,7R)-226 with Flack parameters of 0.0(3) and −0.03(19), respectively
[104].
1
2
3
4
5
6
7
8
9
10
11
12
13
14
O
O
O
OH
O
O
O
15
1'
2'
3'
4'
5'
6'
7'
8'
9'
1''
2''
3''
4''
5''
6''
O
O
1
2
3
4
5
10
14
15
6
7
9
11
12
13
225 (nardoaristolone A)
226 (nardoaristolone B)
J. C. Pardo-Novoa and C. M. Cerda-García-Rojas
4.1 Calculation of the Flack Parameter
Two new sesquiterpenoids with a unique structure, named dendrowardols A (223)
and B (224), were isolated from the stems of Dendrobium wardianum, a species of the
Orchidaceae family that mainly grows in the south of China and some Southeast Asian
countries, such as Myanmar, Bangladesh, and Thailand. Their structures were established based on extensive spectroscopic analysis including the 1D and 2D NMR data
[103]. The absolute configuration of 223 was assigned as (1S,4R,5R,6R,7S,10R,11S)
by X-ray diffraction analysis using the anomalous scattering of Cu Kα radiation that
allowed the calculation of the Flack parameter with a significant value of 0.09(19).
The relative configuration of the diastereomer 224 was determined by single-crystal
X-ray diffraction analysis that was carried out using Mo Kα radiation, thus limiting
the Flack analysis. Dendrowardol B (224) was evaluated by an MTT assay showed
a promoting effect on the proliferation of human lens epithelial cells induced by
d-galactose [103].
OH
OH
OH
OH
OH
OH
1
2
3
4
5
6
7
8
9
10
11
12
13
14
223 (dendrowardol A)
224 (dendrowardol B)
Two new plant metabolites of the aristolane-type sesquiterpenoid, designated as
nardoaristolone A (225) and B (226), were isolated from the underground parts of
Nardostachys chinensis, a medicinal species of the family Valerianaceae that generally grows in the Himalayan mountains [104]. Nardoaristolone A (225) contains a
chalcone derivative, while nardoaristolone B (226) possesses a nor-aristolane hydrocarbon skeleton with an unusual 3/5/6 tricyclic ring system. A biogenetic pathway
was proposed to explain the formation of both metabolites, for which their structures
were elucidated by spectroscopic measurements. The absolute configurations were
established by single-crystal X-ray diffraction analysis as (1R,4R,5R,6S,7R,10S)-225
and (4R,5R,6S,7R)-226 with Flack parameters of 0.0(3) and −0.03(19), respectively
[104].
1
2
3
4
5
6
7
8
9
10
11
12
13
14
O
O
O
OH
O
O
O
15
1'
2'
3'
4'
5'
6'
7'
8'
9'
1''
2''
3''
4''
5''
6''
O
O
1
2
3
4
5
10
14
15
6
7
9
11
12
13
225 (nardoaristolone A)
226 (nardoaristolone B)