Seven undescribed steroids from the leaves of Datura metel L.

Article abstract of DOI:10.1016/j.steroids.2021.108877

Extraction of Datura metel L. leaves with ethanol as a solvent gave a group of steroids, including two unique 1,10-seco-withanolides (1, 4), an unusual nitrogen-containing withanolides (2), one undescribed saponin (3), two withanolides with a carbohydrate (5, 6), and one C₂₁ steroid (7). These compounds' structures were identified based on HR-ESI-MS and ¹H, ¹³C NMR data analyses, also compared with data from the document. Some compounds showed moderate inhibition on NO production in lipopolysaccharide-stimulated RAW 264.7 cells.

Full text of DOI:10.1016/j.steroids.2021.108877

Steroids 173 (2021) 108877
Contents lists available at ScienceDirect
Steroids
journal homepage: www.elsevier.com/locate/steroids
Seven undescribed steroids from the leaves of Datura metel L.
Yan Liua, Jin-yan Tanb, Hai-dan Zoua, Zi-Tang Qia, Anam Naseema, Juan Pana, Wei Guana,
,
,*
Bing-you Yanga *, Hai-xue Kuanga
a Key Laboratory of Chinese Materia Medica, Ministry of Education of Heilongjiang University of Chinese Medicine, Harbin 150040, China
b Shanxi University of Chinese Medicine, Jingzhong 030619, China
A R T I C L E I N F O
A B S T R A C T
Keywords:
Extraction of Datura metel L. leaves with ethanol as a solvent gave a group of steroids, including two unique 1,10-
seco-withanolides (1, 4), an unusual nitrogen-containing withanolides (2), one undescribed saponin (3), two
withanolides with a carbohydrate (5, 6), and one C21 steroid (7). These compounds’ structures were identified
based on HR-ESI-MS and 1H, 13C NMR data analyses, also compared with data from the document. Some
compounds showed moderate inhibition on NO production in lipopolysaccharide-stimulated RAW 264.7 cells.
Leaves of Datura metel L.
1, 10-seco-withanolide
Nitrogenous steroids
C21-steroid
1. Introduction
2. Experimental
Withanolides are a series of oxygenated C28 ergostane-type steroidal
lactones, founded primarily in several genus of Solanaceae which
include Acnistus, Datura, Dunalia, Jaborosa, Physalis and Withania.
Recently, due to the varied structures and broadly biological activities
withanolides have attracted increasing attentions. Moreover, recent
pharmaco-logical researches have illustrated that withanolides show
anti-inflammatory, antimicrobial, immunomodulatory, and cytotoxic
activities [1,2].
2.1. General experimental procedures
NMR spectra were indicated on Bruker DRX 400-MHz. The internal
standard was TMS. Semi-preparative HPLC was recorded on Shimadzu
CBM-20A semi-preparative machine with a Waters SunFire™ C18 col-
umn (4.6 × 150 mm, 5 μm, 10 × 250 mm, 5 μm). X-ray data were ob-
tained on a Bruker D8 Venture instrument. Optical rotations were
obtained on a Jasco P-2000 digital polarimeter. Silica gel (200–300
mesh, 80–100 mesh, Qingdao Marine Chemical Ltd., Qingdao, China),
and octadecylsilyl silica gel (ODS, YMC Company Ltd., Japan) were used
for column chromatography.
The genus Datura contains 14 species that belong to the Solanaceae
family [3,4]. In general, Datura has been applied for mystery and reli-
gious stuff and to cure asthma as a crude drug [5]. The phytochemical
research conducted on different Datura species has led to the isolation
and identification of several groups of phytochemical constituents, such
as steroids [6–8], alkaloids [9], phenolic acid. Steroids from genus
Datura plant were reported to possess a diversity of structures and potent
biological activities [11–14].
2.2. Collection, extraction, and isolation
The leaves of Datura metel L. were matured in September 2017 in the
Shuangcheng region, Heilongjiang Province of China, which were
authenticated by Prof. Rui-Feng Fan. A voucher specimen (Herbarium
No. 20170901) was preserved at the School of Pharmacy, Heilongjiang
University of Chinese Medicine, Harbin, China.
In this research, seven unknown steroids from the leaves of Datura
metel L. were elucidated (Fig. 1), including two unique 1,10-seco-with-
anolides (1, 4), an unusual nitrogen-containing withanolides (2), one
undescribed saponin (3), two withanolides with a carbohydrate (5, 6),
and one C21 steroid (7).
Air-dried D. metel leaves (20.0 kg) were extracted with 70% EtOH
under reflux for eightfold (3 h each). The resulted solutions were filtered
and concentrated under reduced pressure to give the EtOH extract (4.82
kg). The crude extraction was eluted through HP-20 macroporous
adsorption resin by column chromatography at the flow rate of 1BV⋅hꢀ 1
(bed volume⋅hourꢀ 1) with water (2BV), 30% EtOH (2BV), 95% EtOH
* Corresponding authors at: College of Pharmacy, Heilongjiang University of Chinese Medicine, 24 Heping Road, Xiangfang District, Harbin 150040, China.
E-mail addresses: ybywater@163.com (B.-y. Yang), hxkuang@yahoo.com (H.-x. Kuang).
https://doi.org/10.1016/j.steroids.2021.108877
Received 5 March 2021; Received in revised form 21 May 2021; Accepted 8 June 2021
Available online 13 June 2021
0039-128X/© 2021 Elsevier Inc. All rights reserved.

Y. Liu et al.
Steroids 173 (2021) 108877
Fig. 1. Chemical structures of compounds 1-7.
Table 1
Table 2
NMR data of compound 1 (CD3OD, δ in ppm, J in Hz).
NMR data of compound 2 (CD3OD, δ in ppm, J in Hz).
No.
δH
δC
1H–1H COSY
HMBC
1,3,4
NOESY
No.
δH
δC
1H–1H COSY
HMBC
NOESY
1
2
–
174.0
35.0
–
1
2
–
199.0
151.1
–
2.94 d (7.3)
3,4
4
–
–
–
3
5.78 m
125.3
129.7
125.6
158.4
60.2
43.8
40.3
145.3
27.0
41.1
44.3
50.6
24.0
28.4
53.2
12.2
18.3
40.4
13.7
80.1
30.7
–
3
6.43 d (10.0)
6.30 d (10.0)
–
134.6
125.3
144.2
131.8
64.7
38.1
34.9
54.5
23.1
40.5
43.8
50.5
25.0
28.2
53.2
12.1
18.4
40.4
13.7
80.2
30.8
–
1
4
6.10 d (11.0)
5,10
6,8
4
2,5
5
–
5
6
–
6
5.99 d (5.5)
3.95 t (4.4)
1.56 m
7,8
5
5
7
5.03 d (2.3)
7
9,10
8
1.38 m
8
18
9
2.28 m
12,11
8,9
9
2.19 m
12,11
8,9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
–
10
11
12
13
14
15
16
17
18
19
20
21
22
23
–
2.07 m; 1.39 m
1.88 m; 1.42 m
1.99 m; 1.37 m
–
2.10 m; 1.39 m
–
1.65 m
15,16
17
1.59 m
1.85 m; 1.26 m
1.85 m; 1.23 m
1.84 m; 1.38 m
1.29 m
1.85 m; 1.45 m
22
23
1.33 m
0.79 s
12,13,14,17
5,9,10
0.81 s
12,17
1,9
8
1.75 s
1.34 s
1.98 m
22
23
1.99 m
21
22
20
22
1.05 d (6.7)
1.06 d (6.6)
4.49 m
4.48 dt (13.2, 3.4)
2.55 m
2.20 m
–
2.59 dd (18.0, 13.2)
2.22 dd (18.0, 3.2)
–
24
25
26
157.8
126.4
168.5
–
24
25
26
27
160.4
123.7
168.6
63.6
–
–
–
–
–
–
4.63 d (11.2)
4.47 d (11.2)
2.14 s
24,25,26
27
4.38 m
4.32 m
2.11 s
3.64 s
56.4
–
24,25,26
28
1’
2’
3’
4’
5’
6’
20.8
104.0
75.0
78.0
71.6
78.0
62.8
–
23,24,25
27
28
20.2
52.2
23,24,25
1
4.32 d (7.8)
3.16 dd (8.7, 7.8)
3.36 m
OMe
3.30 m
3.26 m
(4BV), respectively. The corresponding eluent was collected and
concentrated at reduced pressure to obtain 930 g (19.3%), 1195 g
(24.8%), and 1894 g (39.3%) of the eluent components eluted with
water, 30% ethanol, and 95% ethanol respectively.
3.86 dd (12.0, 2.1)
3.67 dd (12.0, 5.3)
2

Y. Liu et al.
Steroids 173 (2021) 108877
Fig. 2. Key HMBC and 1H–1H COSY of compounds 1-7.
Fig. 3. NOESY of compounds 1-7.
The 30% EtOH extract (400 g) was subjected to column chroma- 2.2.2. Daturmetelide Y (2)
White amorphous powder, positive Molish reaction, [α D
]
21.02+145 (c
tography over silica gel and eluted with a gradient elution program of
dichloromethane-methanol (1:0–0:1, v/v) to obtain nine fractions (Fr.
1–9). Fr. 2-Fr. 8 were disposed by silica gel, ODS and other column
chromatography and semi-preparative HPLC and finally received com-
pound 3 (8.4 mg).
0.1, CH3OH) HR-ESI-MS: m/z 644.3071 for [Mꢀ H]ꢀ (calcd. 644.3071),
corresponding to C34H47NO11; 1H NMR (400 MHz) and 13C NMR (100
MHz) data, showing in Tables 1 and 2.
The 95% EtOH isolation (400 g) was subjected to column chroma-
tography over silica gel and eluted with a gradient elution program of
dichloromethane-methanol (1:0–0:1, v/v) to obtain nine fractions (Fr.
1–6). Fr. 2-Fr. 6 were disposed by silica gel, ODS and other column
chromatography, as well as semi-preparative HPLC and received com-
pound 1 (5.9 mg), 2 (0.9 mg), 4 (1.2 mg), 5 (1.1 mg), 6 (35.6 mg), 7 (9.8
mg).
2.2.3. Meteloside J (3)
White amorphous powder, positive Molish reaction, [α D23.26
﹣30 (c 0.1,
]
CH3OH) HR-ESI-MS: m/z 1118.5387 for [M+HCOO]ꢀ (calcd.
1118.5383), corresponding to C52H83NO22; 1H NMR (400 MHz) and 13
NMR (100 MHz) data, showing in Tables 1 and 2.
C
2.2.4. Daturmeteside F (4)
White amorphous powder,[α D23.39
﹣20 (c 0.1, CH3OH) HR-ESI-MS: m/z
]
2.2.1. Daturmetelide X (1)
479.3372 for [Mꢀ H]ꢀ (calcd. 479.3373), corresponding to C28H48O6;
1H NMR (400 MHz) and 13C NMR (100 MHz) data, showing in Tables 1
and 2.
White amorphous powder, [α D
]
21.02+182 (c 0.1, CH3OH) HR-ESI-MS:
m/z 560.2858 for [M+HCOO]ꢀ (calcd. 560.2860), corresponding to
C
29H41NO7; 1H NMR (400 MHz) and 13C NMR (100 MHz) data, showing
in Tables 1 and 2.
2.2.5. Daturmetelide Z (5)
White amorphous powder, positive Molish reaction, [α D20.74
﹣75 (c 0.1,
]
CH3OH) HR-ESI-MS: m/z 599.3213 for [Mꢀ H]ꢀ (calcd. 599.3220),
3

Y. Liu et al.
Steroids 173 (2021) 108877
Table 3
Table 4
NMR data of compound 3 (CD3OD, δ in ppm, J in Hz).
NMR data of compound 4 (CD3OD, δ in ppm, J in Hz).
No.
δH
δC
1H–1H COSY
HMBC
NOESY
No.
δH
δC
1H–1H COSY
HMBC
NOESY
1
2
1.88 m; 1.08 m
1.92 m
38.6
30.7
–
2,3
1,3
1
2
3.70 t (6.4)
1.66 m
1.77 m
3.90 m
2.35 m
2.26 m
–
60.3
40.9
–
1.61 m
3
4
3.60 m
79.3
39.5
–
4
3
4
70.9
41.8
–
2.30 br. t (11.9)
2.46 dd (13.1, 2.2)
5
5
5
5
5
141.9
122.7
33.2
32.8
51.7
38.0
22.0
40.9
41.4
57.8
32.7
82.5
63.5
16.8
19.8
42.8
14.8
112.5
31.9
29.6
35.5
78.6
17.2
–
5
144.3
129.3
65.6
38.3
42.4
71.9
21.8
40.7
43.6
50.5
25.1
29.0
54.4
12.0
25.0
43.7
13.0
72.7
35.7
–
6
5.39 br. s
2.01 m; 1.55 m
1.66 m
7,8
6
5.76 m
3.84 m
1.61 m
1.57 m
–
7,8
7
9,10
7
9,10
8
8
9
0.97 m
12,11
8,9
12
9
12,11
8,9
19
10
11
12
13
14
15
16
17
18
19
20
21
22
23
10
11
12
13
14
15
16
17
18
19
20
21
22
23
1.54 m
1.65 m; 1.72 m
1.26 m; 2.07 m
–
1.76 m; 1.20 m
9,14
12
1.14 m
1.46 m
1.19 m; 1.81 m
1.42 m; 1.89 m
1.26 m
0.78 s
2.01 m; 1.29 m
4.61 q (7.5)
1.75 m
0.81 s
12,13,17
1,9,10
12,17
1.05 s
1.29 s
5,9,10
9
1.91 m
1.77 m
1.01 m
3.85 m
2.28 m
1.96 m
–
0.97 d (6.9)
–
20,22
22
1.70 m
24,25,26
1.56 m
24
25
26
1.70 m; 1.59 m
1.47 m
25,26,27
24,25,26
24,25,27
24
25
26
131.0
131.5
64.1
–
–
5.11 d (9.9)
–
4.05 d (11.4)
4.13 d (11.4)
1.77 s
27
0.87 d (6.5)
–
–
23,24,25,26
27
28
17.1
18.5
24,25,26
23,24,25
1.77 s
NHCO
CH3
Glc 1’
2’
–
173.5
22.8
100.3
78.5
77.5
80.9
76.4
61.8
102.0
72.2
72.4
73.9
69.7
17.9
102.5
83.1
78.2
71.2
77.9
62.4
106.3
75.9
77.7
71.1
67.2
1.96 s
NHCO
3
4.52 m
MHz) data, showing in Tables 1 and 2.
3.41 m
3’
3.68 m
4’
3.52 t (9.2)
3.37 m
2.3. Acid hydrolysis and GC analysis
5’
6’
3.91 m; 3.63 m
5.24 br. s
3.89 m
The extraction with glycosyl groups (2, 3, 5, 6, each 2 mg) were acid
hydrolysed and then the hexane layer (reaction products) were analysed
by an Agilent 7890 A GC system using a DM-5 column (30 m × 0.25 mm,
Rha 1’’
2’’
2’
3’’
3.67 m
4’’
3.39 m
0.25
μm). The absolute configurations were obtained by comparing
5’’
4.14 m
retention times with standard sugars (China Institute for the Control of
Pharmaceutical and Biological Products) which were derivatives pre-
pared in the same way.
6’’
1.24 d (6.2)
4.51 m
Glc 1’’’
2’’’
4’
3.42 m
3’’’
3.58 m
4’’’
3.31 m
3. Results and discussion
5’’’
3.33 m
6’’’
3.87 m; 3.64 m
4.57 d (7.6)
3.24 m
Xyl 1’’’’
2’’’’
3’’’’
4’’’’
5’’’’
2’’’
3.1. New compounds structure elucidation
3.33 m
The molecular formula of daturmetelide X (1) was assigned as
3.48 m
C
29H41NO7, HR-ESI-MS at m/z 560.2858 [M+HCOO]ꢀ , corresponding
3.86 m; 3.17 m
1
to ten degrees of unsaturation. The H NMR spectrum of 1 (Table. 1)
revealed the presence of four methyl groups [δ 0.78 (3H, s, CH3-18),
1.75 (3H, s, CH3-19),1.05 (3H, d, J = 6.7 Hz, CH3-21), 2.11 (3H, s, CH3-
28)], two olefin hydrogens [δ 5.78 (1H, m, H-3), 6.10 (1H, d, J = 11.0
Hz, H-4)], and a signal of methoxy protons δ 3.69 (3H, s, H-OCH3). The
13C NMR spectrum of 1 (Table 2), coupled with the DEPT spectrum,
revealed 29 carbon signals, including four methyl carbons, seven
methylene carbons (one oxygenated), nine methine carbons (one
oxygenated), eight quaternary carbons, and one methoxy group. But as
the ten degrees of unsaturation were accounted for by two carbonyl
groups (C-1, δc 174.0, C-26, δc 168.5), one hydroxyimino group (C-6, δc
158.4), and three olefinic bonds, the remaining four degrees of unsa-
turation indicated that 1 was tetracyclic withanolide. That means one
corresponding to C34H48O9; 1H NMR (400 MHz) and 13C NMR (100
MHz) data, showing in Tables 1 and 2.
2.2.6. Daturmetefoside A (6)
White amorphous powder, positive Molish reaction, [α D20.74
﹣88 (c 0.1,
]
CH3OH) HR-ESI-MS: m/z 631.3125 for [Mꢀ H]ꢀ (calcd. 631.3119),
corresponding to C34H48O11
;
1H NMR (400 MHz) and 13C NMR (100
MHz) data, showing in Tables 1 and 2.
2.2.7. 6β,7
α
,15β-Trihydroxy-pregna-2,4-diene-1,20-dione (7)
White amorphous powder, positive Molish reaction, [α D
]
23.26+66 (c
0.1, CH3OH) HR-ESI-MS: m/z 359.1845 for [Mꢀ H]ꢀ (calcd. 359.1859),
ring (except for
α,β-unsaturated δ lactone) of common withanolide-
corresponding to C21H28O5; 1H NMR (400 MHz) and 13C NMR (100
skeleton was opened.
The flat structure of 1 was judged by elucidation of the 2D NMR,
4

Y. Liu et al.
Steroids 173 (2021) 108877
Table 5
Table 6
NMR data of compound 5 (CD3OD, δ in ppm, J in Hz).
NMR data of compound 6 (CD3OD, δ in ppm, J in Hz).
No.
δH
δC
1H–1H
HMBC
NOESY
No.
δH
δC
1H–1H COSY
HMBC
NOESY
COSY
1
–
207.8
80.3
129.4
142.0
83.3
121.5
143.1
39.2
42.3
49.0
23.6
41.0
45.2
54.2
24.9
28.3
52.9
12.4
18.0
40.4
13.8
80.0
30.8
1
2
3
–
206.9
128.2
148.2
2
4.52 dd (6.3, 1.2)
6.77 dd (8.3, 6.3)
6.83 dd (8.3, 1.2)
3,4
2,4
2,3
5.83 dd (10.0, 2.5)
6.91 ddd (10.0, 4.6,
2.5)
3,4
2,4
1
1
3
1
2
4
5
4
3.35 m
34.5
2,3
5
6
5.58 dd (9.8, 1.7)
6.12dd (9.8, 2.8)
2.13 m
7,8
2.88 dd (21.2, 4.6)
7
9,10
5
137.3
125.7
31.9
34.4
44.5
51.8
24.8
41.0
43.7
57.5
25.4
28.1
53.3
12.3
19.5
40.4
13.7
80.1
30.8
8
15
17
6
5.63 d (5.6)
2.02 m; 1.58 m
1.45 m
7,8
5
9
2.27 m
12,11
8,9
7
9,10
14
7
10
11
12
13
14
15
16
17
18
19
20
21
22
23
8
1.77 m; 1.64 m
2.08 m; 1.33 m
9
1.82 m
12,11
8,9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
2.18 m; 1.59 m
2.03 m; 1.33 m
1.37 m
1.77 m; 1.36 m
1.86 m; 1.45 m
1.31 m
8
9
1.28 m
1.68 m; 1.23 m
1.84 m; 1.42 m
1.28 m
0.84 s
12,17
1,9
1.03 s
1.99 m
21
22
20
0.80 s
12,17
1,9
1.06 d (6.7)
4.50 m
1.26 s
1.98 m
21
22
20
22
2.57 dd (17.9, 13.5)
2.24 m
1.06 d (6.6)
4.48 m
24
25
26
27
–
160.3
123.6
168.5
63.6
2.58 dd (18.1, 13.4)
2.22 dd (18.1, 3.1)
–
–
–
24
25
26
160.3
123.7
168.7
4.63 d (11.2)
4.47 d (11.2)
2.14 s
24,25,26
–
–
28
1’
2’
3’
4’
5’
6’
20.9
104.0
75.0
78.0
71.6
78.0
62.8
23,24,25
27
–
4.34 d (7.8)
3.18 dd (8.9, 7.8)
3.36 m
27
4.63 d (11.1
4.47 d (11.1)
2.14 s
63.4
24,25,26
28
Allo 1’
2’
20.7
101.4
72.3
72.9
68.8
75.5
63.1
23,24,25
27
3.31 m
4.68 d (7.9)
3.30 m
3.27 m
3.81 dd (11.9, 2.0)
3.63 dd (11.9, 5.5)
3’
4.04 t (2.8)
3.49 dd (9.2, 2.8)
3.67 m
4’
5’
6’
3.85 m
3.67 m
Table 7
NMR data of compound 7 (CD3OD, δ in ppm, J in Hz).
No.
δH
δC
1H-1H COSY
HMBC
NOESY
including HSQC, 1H–1H COSY, and HMBC spectra (Fig. 2). The 1H–1H
COSY correlations of H2-12/H2-11/H-9/H-8/H-14/H2-15/H2-16/H-17
and H2-2/H-3/H-4 showed the C-2/C-3/C-4 and C-12/C-11/C-9/C-8/C-
14/C-15/C-16/C-17 section (Fig. 2, red bold lines). The HMBC corre-
lations from CH3-19 to C-5, C-9, and C-10; from H-7 to C-6 and C-8
which indicated the oximido was attached on C-6; from CH3-18 to C-12,
C-13, C-14, and C-17 constructed the rings B-D of withanolide-skeleton.
Other HMBC correlations from H2-2 to C-1, C-3, and C-4 and correlations
from H-4 to C-5 and C-10 arranged one entire carbon chain connected to
ring B at C-5. Finally, the remaining one methoxy group was attached at
C-1 based on key HMBC correlation from H-OCH3 to C-1 (Fig. 3).
The small coupling of H-7 with H-8 (J = 2.3 Hz) indicated an
1
–
208.5
126.7
142.4
122.1
157.2
79.4
72.5
33.0
42.8
55.4
22.4
40.9
44.6
56.0
70.8
36.8
64.8
16.3
19.8
211.3
31.5
2
6.00 dd (9.7, 0.8)
7.09 dd (9.7, 6.0)
6.26 d (6.0)
–
1
5
5
3
4
5
6
4.26 d (3.3)
4.12 t (2.8)
2.47 td (11.4, 2.4)
1.68 m
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
2.02 m; 1.56 m
2.00 m; 1.36 m
18
12
1.46 m
4.39 m
2.21 m
2.58 t (9.3)
0.95 s
1.47 s
–
equatorial position of H-7 and the α-stereochemistry for the hydroxyl at
that position [17], which was also supported by the significant NOESY
correlations of CH3-18/H-15β and H-15β/H-7. The 20S configurtion of 1
was elucidated by a NOESY experiment based on correlations from CH3-
21/ H-17 to H2-23, from H2-16 to H-22, and from H-20 to H-22 (Fig. 2).
The absolute configuration of C-22 was assumed as R because of a
double triplet at δH 4.48 (dt, J = 13.2, 3.4 Hz) corresponding to H-22
[18]. Furthermore, the Z geometry of Δ3 was deduced by analyzing
coupling constants (J = 11.0 Hz) [19]. All of the above data were
compatible with the structure of 1 is proposed as (3Z,20S,22R)-1,10-
12,17
1,19
2.15 s
17,20
based on HR-ESI-MS at m/z 644.3071 [Mꢀ H]ꢀ . The 1H NMR data
(Table 1) of 2 revealed the signals for four methyl groups [δ 0.81 (3H, s,
CH3-18), 1.34 (3H, s, CH3-19), 1.06 (3H, d, J = 6.6 Hz, CH3-21), 2.14
(3H, s, CH3-28)], three olefin hydrogens [δ 6.43 (1H, d, J = 10.0 Hz, H-
3), 6.30 (1H, d, J = 10.0 Hz, H-4), 5.98 (1H, d, J = 5.5 Hz, H-6)], a
glucosyl group [4.33 (1H, d, J = 7.8 Hz, H-1′)]. The 13C NMR spectrum
of 2 (Table. 2), coupled with the DEPT spectrum, revealed 34 carbon
seco-7α,27-dihydroxy-1-methoxyl-6-hydroxyimino-1-oxo-witha-3,5
(10),24-trienolide and named daturmetelide X, which having an unusual
framework (1,10-seco-withonlide) and this type of skeleton have not
been reported in natural products except physalinol A.
Daturmetelide Y (2) possessed a molecular formula of C34H47NO11
5

Y. Liu et al.
Steroids 173 (2021) 108877
signals, including six carbons of glucosyl group, four methyl carbons, six
mesomethylene carbons (one oxygenated), ten methine carbons (two
oxygenated), and eight quaternary carbons. The 1H NMR and 13C NMR
data of compound 2 were compared with the known compound datur-
ametelin I. They were very similar except that the methylene on the C-2
position on the A ring was replaced by oximido [20]. The correlation
between H-4 [6.43 (1H, d, J = 10.3 Hz)] and C-2 (151.1) in the HMBC
correlation spectrum further confirms this inference. The small coupling
constant (J = 2.3 Hz) between H-7 and H-8 in compound 2 indicated
that H-7 was β-configurational [17]. The absolute configurations of the
β-glucose were further determined to D after acid hydrolysis. The cor-
relation spectra of HSQC, 1H–1H COSY, and HMBC were comprehen-
configuration.
The correlation of HSQC, 1H–1H COSY, and HMBC was compre-
hensively analyzed, and all proton signals and carbon signals in 1H NMR
and 13C NMR spectra of compound 4 were fully assigned. According to
the above information, the structure of compound 4 was affirmed as
(20S,22R,24E)-1,10-seco-ergosta-5,24-diene-1,3,7α,10β,22α,26-hexol
(Fig. 1). A SciFinder structure search confirmed the novelty of this
compound which was named daturmeteside F.
The molecular formula of daturmetelide Z (5) was assigned as
C
34H48O9 by HR-ESI-MS at m/z 599.3213 [Mꢀ H]+. The 1H NMR spec-
trum of 5 revealed the presence of four methyl groups [δ 0.80 (3H, s,
CH3-18), 1.26 (3H, s, CH3-19), 1.06 (3H, d, J = 6.6 Hz, CH3-21), 2.14
(3H, s, CH3-28)], three olefin hydrogens [δ 5.83 (1H, dd, J = 10.0, 2.5
Hz, H-2), 6.91 (1H, ddd, J = 10.0, 4.6, 2.5 Hz, H-3), 5.63 (1H, d, J = 5.6
Hz, H-6)] and a signal of glycosides δ 4.68 (1H, d, J = 7.9 Hz, H-1′). The
13C NMR spectrum of 5 (Table 2), coupled with the DEPT spectrum,
revealed 34 carbon signals, including six carbons of glucosyl group, four
methyl carbons, six mesomethylene carbons (one oxygenated), eleven
methine carbons (two oxygenated), and seven quaternary carbons. The
1H NMR and 13C NMR data of 5 were compared with a known com-
pound, daturametelin A, and they were found to be similar, except for
the difference of the glycosyl group attached with C-27 [16]. The small
coupling constant of H-3′ (J = 2.9 Hz), the large coupling constant of H-
1′ (J = 7.9 Hz), and the coupling cleavage mode between H-2′ and H-5′
showed that C-27 in 5 was β-D allopyranoside [17]. The absolute
configuration of the β-allose was determined to be D by GC after acid
hydrolysis.
sively analyzed, and all hydrogen and carbon signals in 1H NMR and 13
C
NMR spectra of compound 2 were fully assigned. According to the above
information, the structure of compound 2 was determined as (20S,22R)-
7α,27-dihydroxy-2-hydroxy-imino-1-oxo-witha-3,5,24-trienolide-27-O-
β-D-glucopyranoside (Fig. 1). A SciFinder structure search confirmed the
novelty of this compound which was named daturmetelide Y.
The molecular formula of meteloside J (3) was assigned as
C
52H83NO22 HR-ESI-MS at m/z 1118.5387 [M+HCOO]ꢀ . The 1H NMR
spectrum of 3 (Table 1) revealed the presence of five methyl groups [δ
0.81 (3H, s, CH3-18), 1.05 (3H, s, CH3-19), 0.97 (3H, d, J = 6.9 Hz, CH3-
21), 0.87 (3H, d, J = 6.5 Hz, CH3-27), 1.96 (3H, s, H-CH3)], one olefin
hydrogen δ 5.39 (1H, br. s, H-6), four signals of saccharides [δ 4.52 (1H,
m, H-1′), 5.24 (1H, br. s, H-1′′), 4.51 (1H, m, H-1′′′), 4.57 (1H, d, J = 7.6
Hz, H-1′′′′)]. The 13C NMR spectrum of 3 (Table 2), coupled with the
DEPT spectrum, revealed 52 carbon signals, including 23 carbons of
saccharides, five methyl carbons, nine mesomethylene carbons, ten
methine carbons (three oxygenated), and five quaternary carbons. Ac-
cording to literature comparison, the carbon spectrum of 3 was similar
to meteloside G, except that there was an additional set of xylose carbon
signals [δ 106.3 (Xyl C-1′′′′), 75.9 (Xyl C-2′′′′), 77.7 (Xyl C-3′′′′),71.1 (Xyl
C-4′′′′), 67.2 (Xyl C-5′′′′)], while the chemical shift of C-2′′ moves to the
lower field to δ 83.1. It was speculated that xylose might be attached to
the second position of this glucose [15]. The correlation signal between
H-1′′ and C-2′′ was revealed in the HMBC spectrum of 3, which further
confirmed the inference. The absolute configurations of xylopyranosyl
and glucopyranosyl were determined as D while the absolute configu-
rations of rhamnopyranosyl was L by GC analysis.
The correlation of HSQC, 1H–1H COSY, and HMBC was compre-
hensively analyzed, and all proton signals and carbon signals in 1H NMR
and 13C NMR spectra of compound 5 were fully assigned. According to
the above information, the structure of compound 5 was affirmed as
(20S, 22R)-27-hydroxy-1-oxo-witha-2,5,24- trienolide-27-O-β-D-allo-
pyranoside (Fig. 1). A SciFinder structure search confirmed the novelty
of this compound which was named daturmetelide Z.
Daturmetefoside A (6) had the molecular formula of C34H48O11 as
deduced by analysis of HR-ESI-MS at m/z 631.3125 [Mꢀ H]+. The H
1
NMR spectrum of 6 (Table 1) revealed the presence of four methyl
groups [δ 0.84 (3H, s, CH3-18), 1.03 (3H, s, CH3-19), 1.06 (3H, d, J = 6.7
Hz, CH3-21), 2.14 (3H, s, CH3-28)], four olefin hydrogens [δ 6.77 (1H,
dd, J = 8.3, 6.3 Hz, H-3), 6.83 (1H, dd, J = 8.3, 1.2 Hz, H-4), 5.58(1H,
dd, J = 9.8, 1.7 Hz, H-6), 6.12(1H, dd, J = 9.8, 2.7 Hz, H-7)] and a
glucosyl group δ 4.34 (1H, d, J = 7.8 Hz, H-1′). The 13C NMR spectrum of
6 (Table 2), coupled with the DEPT spectrum revealed 34 carbon signals,
including six carbons of glucosyl group, four methyl carbons, six
mesomethylene carbons (one oxygenated), eleven methine carbons (two
oxygenated), and seven quaternary carbons. The 1H NMR and 13C NMR
data of 6 were compared with a known compound, acnistin H, and they
The 1D NMR data and NOESY correlation spectrum of compound 3
are very similar to those of meteloside G, so we speculated that the
relative configuration of the two compounds was consistent, and further
analysis of its NOESY spectrum could confirm the above inference. The
correlation of HSQC, 1H–1H COSY, and HMBC was comprehensively
analyzed, and all proton signals and carbon signals in 1H NMR and 13
C
NMR spectra of compound 3 were fully assigned. According to the above
information, the structure of 3 was affirmed as (25R,26R)-3-O-β-D-
xylopyranosyl-(1 → 2)-β-D-glucopyranosyl-(1 → 4)-[
α
-L-rhamnopyr-
were found to be similar, except for the difference of the α,β-unsaturated
anosyl-(1 → 2)]-β-D-glucopyranosyl-spir-ost-5-en-3β-ol-26 acetamide
(Fig. 1). A SciFinder structure search confirmed the novelty of this
compound which was named meteloside J.
lactone [18]. The absolute configuration of the β-glucopyranoside was
determined to be D by GC after acid hydrolysis.
The 1D NMR data and NOESY correlation spectrum of compound 6
was highly similar to acnistin H, so we conjectured that the relative
configuration of 6 was the same as acnistin H. The correlation of HSQC,
1H–1H COSY, and HMBC was comprehensively analyzed, and all proton
signals and carbon signals in 1H NMR and 13C NMR spectra of compound
6 were fully assigned. According to the above information, the structure
Daturmeteside F (4) possessed a molecular formula of C28H48O6
based on HR-ESI-MS at m/z 479.3372 [Mꢀ H]ꢀ . The 1H NMR data
(Table. 1) of 4 revealed the signals for five methyl groups [δ 0.78 (3H, s,
CH3-18), 1.29 (3H, s, CH3-19), 1.01 (3H, m, CH3-21), 1.77 (3H, s, CH3-
27), 1.77 (3H, s, CH3-28)], one olefin hydrogen δ 5.76 (1H, m, H-6). The
13C NMR spectrum of 4 (Table. 2), coupled with the DEPT spectrum,
revealed 28 carbon signals, including five methyl carbons, nine meso-
methylene carbons (two oxygenated), nine methine carbons (three
oxygenated), and five quaternary carbons (two oxygenated). The 1H–1H
COSY spectrum revealed that the H-1/H-2/H-3/H-4 formed a spin
coupling system, which constituted the structure to C-1 to C-4 pieces.
The correlation signals between H-4 (δ 2.35, 2.26) and C-5 (δ 144.3)
were observed in HMBC spectra, which connected the structural frag-
ments of C-1, C-4 to C-5. The correlation between CH3-19 and H-9 can be
observed in the NOESY spectrum, which showed that H-19 was β
of compound 6 was determined as (20S,22R)-2β,5α,27-trihydroxy-1-
oxo-witha-3,6,24-trienolide-27-O-β-D-glucopyranoside (Fig. 1). A Sci-
Finder structure search confirmed the novelty of this compound which
was named daturmetefoside A.
The molecular formula of 6β,7α,15β-trihydroxy-pregna-2,4-diene-
1,20-dione (7) was assigned as C21H28O5 HR-ESI-MS at m/z 359.1845
[Mꢀ H]ꢀ . The 1H NMR spectrum of 7 (Table 1) revealed the presence of
three methyl groups [δ 0.95 (3H, s, CH3-18), 1.47 (3H, s, CH3-19), 2.15
(3H, s, CH3-21)], three olefin hydrogens [δ 6.00 (1H, dd, J = 9.7, 0.8 Hz,
H-2), 7.09 (1H, dd, J = 9.7, 6.0 Hz, H-3), 6.26 (1H, d, J = 6.0 Hz, H-4)].
6

Y. Liu et al.
Steroids 173 (2021) 108877
The 13C NMR spectrum of 7 (Table 2), coupled with the DEPT spectrum
revealed 21 carbon signals, including two methyl carbons, three meso-
methylene carbons, ten methine carbons (three oxygenated), and five
(YQ2019H029); Heilongjiang Postdoctoral Science Foundation (LBH-
Z18245); National Key Research and Development Project
(2018YFC1707100).
quaternary carbons. In compound 7, α,β-unsaturated lactone ring was
replaced by a carbonyl group, and the correlation signals between CH3-
21 (δ 31.5), C-17 (δ 64.8), and C-20 (δ 211.3) were observed in HMBC
spectra. According to the NOESY spectrum, correlation signals between
Appendix A. Supplementary data
Supplementary data to this article can be found online at https://doi.
org/10.1016/j.steroids.2021.108877.
CH3-18/H-12β and H-12
was configuration.
According to the above information, the structure of compound 7
α/H-17 can be observed, revealing that H-17
α
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Acknowledgments
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7