New cucurbitane type triterpenes from Momordica foetida Schumach. (Cucurbitaceae)

Article abstract of DOI:10.1016/j.phytol.2020.05.010

Phytochemical studies on Momordica foetida led to the isolation and characterization of Momordin (23,24,25,26,27-pentanorcucurbitacin) (3), a new pentanor cucurbitane along with the known β-sitosterol 3-O-β-D-glucopyranoside (4), β-sitosterol (5) and kaempferol-7-O-?-D-glucopyranoside (6). In adition to those components, two previously unreported cucurbitane glucosides, namely 3β-hydroxy-7-oxo-23(R)-cucurbita-5,24-diene-23-O-β-D-glucopyranoside (Momordiside A) (1) and 3β-hydroxy-7β-methoxy-23(R)-cucurbita-5,24-diene-23-O-β-D-glucopyranoside (Momordiside B) (2) were also obtained. The structures were elucidated by HR-ESI-MS and spectroscopic analysis including 1D- and 2D-NMR. Compounds 1 and 2 showed significant antioxidant potential in DPPH radical scavenging assay. In addition, compound 2 further revealed significant inhibitory potential against the enzyme urease in vitro as well as moderate activity against oral cancer cell line CAL-27.

Full text of DOI:10.1016/j.phytol.2020.05.010

Phytochemistry Letters 38 (2020) 90–95
Contents lists available at ScienceDirect
Phytochemistry Letters
journal homepage: www.elsevier.com/locate/phytol
New cucurbitane type triterpenes from Momordica foetida Schumach.
(
Cucurbitaceae)
a,b,c,e,
c
c
Désiré Soh
*, Bruno Tchebemou Bakang , Ernestine Nkwengoua Tchouboun ,
c,d c e,f,g
h
Yves Oscar Ditchou Nganso , Ulrich Dzo Defokou , Lazare Sidjui Sidjui , Ayaz Ahmed ,
i
j
e
c
Rémy Bertrand Teponno , Mehreen Lateef , Muhammad Shaiq Ali , Barthélemy Nyassé
a
b
c
d
e
f
g
h
Department of Chemistry, Higher Teacher Training College, University of Bamenda, P.O. Box 39 Bambili, Cameroon
TWAS Research Unit (TRU) of The University of Bamenda, Bamenda, Cameroon
Laboratory of Medicinal Chemistry & Pharmacognosy, Department of Organic Chemistry, Faculty of Science, University of Yaoundé I, P.O. Box 812 Yaounde, Cameroon
Department of Chemistry, Faculty of Science, University of Maroua, P.O. Box 814, Maroua, Cameroon
H. E. J. Research Institute of Chemistry, International Centre for Chemical & Biological Sciences (ICCBS), University of Karachi, Karachi, 75270 Pakistan
Institute of Medical Research and Medicinal Plant Studies, Yaounde, Cameroon
Faculty of Sciences, Department of Organic Chemistry, TWAS Research Unit (TRU) of University of Yaounde I, Yaounde, Cameroon
Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270,
Pakistan
i
j
Department of Chemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon
Multidisciplinary Research Lab., Bahria University Medical and Dental College, Karachi, Pakistan
A R T I C L E I N F O
A B S T R A C T
Keywords:
Phytochemical studies on Momordica foetida led to the isolation and characterization of Momordin
(23,24,25,26,27-pentanorcucurbitacin) (3), a new pentanor cucurbitane along with the known β-sitosterol 3-O-
β-D-glucopyranoside (4), β-sitosterol (5) and kaempferol-7-O-ß-D-glucopyranoside (6). In adition to those
components, two previously unreported cucurbitane glucosides, namely 3β-hydroxy-7-oxo-23(R)-cucurbita-
Momordica foetida
Cucurbitaceae
Cucurbitane type triterpenes
Antioxidant activity
Urease inhibition
5
,24-diene-23-O-β-D-glucopyranoside (Momordiside A) (1) and 3β-hydroxy-7β-methoxy-23(R)-cucurbita-5,24-
diene-23-O-β-D-glucopyranoside (Momordiside B) (2) were also obtained. The structures were elucidated by HR-
ESI-MS and spectroscopic analysis including 1D- and 2D-NMR. Compounds 1 and 2 showed significant anti-
oxidant potential in DPPH radical scavenging assay. In addition, compound 2 further revealed significant in-
hibitory potential against the enzyme urease in vitro as well as moderate activity against oral cancer cell line
CAL-27.
1
. Introduction
et al., 1992; Froelich et al., 2007; Rosaria et al., 2013; Nantia Akono et al.,
2
018). Pharmacological studies have indicated antidiabetic, antilipogenic,
The genus Momordica (Cucurbitaceae) comprises about 60 species of
antiplasmodial, antimalarial, antioxidant activities of crude extracts
(Froelich et al., 2007; Rosaria et al., 2013; Nantia Akono et al., 2018),
providing scientific support of its indigenous use. Phytochemical in-
vestigations led to the isolation of curcubitane triterpenoids, poly-
phenolics, alkaloids and glycosides (Rosaria et al., 2013). The chemo-
taxanomic and ethnopharmacological significance of the genus Momordica
sparked the investigation of the secondary metabolites of M. foetida.
Herein we report the isolation of two previously unreported cucurbitane
glycosides, named momordisides A (1) and B (2) along with momordin
(3), a previously undescribed pentanortriterpene. In addition, three known
secondary metabolites namely β-sitosterol 3-O-β-D-glucopyranoside, β-si-
tosterol and kaempferol-7-O-ß-D-glucopyranoside were also isolated.
annual, perennial climbers herbaceous or rarely small shrubs native of
tropical and subtropical Africa, Asia and Australia. They grow in rain-
forest, deciduous forests, bushlands, savannas, or grasslands (Hanno and
Susanne, 2010). Momordica foetida Schumach. is a perennial herbaceous
climbing vine native of tropical Africa (Mulholland et al., 1997). Synonym
names are M. cordifolia E. Mey. ex Sond., M. mannii Hook. f. and M.
morkorra A. Rich. (The Plant List, 2013). The leaf is used in traditional
medicine for treatment of a wide range of diseases and disorders including
stomach troubles, as an emetic, as a vermifuge, against smallpox, chick-
enpox, measles, body swellings, oedema and gout, as antidote for veno-
mous stings such as bee stings and also as a pain-killer (Hakizamungu
⁎
Corresponding author.
E-mail address: desiresoh75@gmail.com (D. Soh).
https://doi.org/10.1016/j.phytol.2020.05.010
Received 31 December 2019; Received in revised form 13 May 2020; Accepted 25 May 2020
1874-3900/ © 2020 Phytochemical Society of Europe. Published by Elsevier Ltd. All rights reserved.

D. Soh, et al.
Phytochemistry Letters 38 (2020) 90–95
Fig. 1. Structures of compounds 1-6 isolated from M. foetida.
downfield signals at δ
2
. Results and discussion
C
205.8 could be attributed to conjugated ketone
carbonyl functionality while the olefinic carbons resonated at δ 174.1,
C
2.1. Isolation and structure elucidation
132.9, 126.0 and 123.5. Acid hydrolysis of 1 with 5% HCl/MeOH,
provided the sugar residue which was identified as D-glucose by gas
chromatography of its TMS ethers and the sign of its optical rotation.
The sugar moiety was located at C-23 on the basis of the HMBC cor-
The air-dried whole plant and fruit of M. foetida were extracted
separately with MeOH at room temperature. The whole plant extract
(
75.8 g) was subjected to column chromatography on silica gel yielding
relation between H-23 at δ
H
3.64 and the anomeric carbon at δ 102.6.
C
compounds 1, 2,.4, 5 and 6 (Fig. 1). The methanol extract of the fruit
was suspended in water and extracted with hexane, ethyl acetate and n-
butanol. The n-butanol extract (20.52 g) was subjected to column
chromatography over silica gel to afford compound 3. The known
compounds were characterized as β-sitosterol 3-O-β-D-glucopyranoside
The cumulative spectral data were similar to those reported for ku-
guaglycoside A (Chen et al., 2008), which has previously been reported
from the roots of Momordica charantia. However, the notable difference
was the presence of a carbonyl functionality at C-7 in momordiside A
(1). This was further confirmed by the HMBC correlation depicted be-
(
(
4) (Huh et al., 2011; Cho et al., 2012; Lee et al., 2013), β-sitosterol (5)
Rubinstein et al., 1976; Lee et al., 2013) and kaempferol-7-O-ß-D-
tween the proton at δ
H
2.37 (s, H-8) and the carbon at δ 205.2 (C-7).
C
The HMBC spectrum of 1 (Fig. 2) further showed correlations of H-3 (δ
H
glucopyranoside (6) (Froelich et al., 2007).
3.60) with C-1 (δ
C
22.1), C-5 (δ
C
174.1) and C-29 (δ
C
28.5) confirming
2
5
Momordiside A (1) was obtained as a white powder; [ ] = +
the location of hydroxyl group at C-3. The olefinic proton H-6 (δ 6.03)
D
H
1
7.72. The molecular formula was deduced as C36
H
58
O
8
, through HR-
also exhibited HMBC correlations with C-4 (δ 44.0), C-5 (δ 174.1), C-
C
C
+
ESI-MS which showed an ion cluster at m/z [M+H] peak at m/z
19.4205 (calcd. for C36 Na. 641.4024) implying 8 degrees of
unsaturation. The UV spectrum showed absorption bands at λmax (log ε)
05 (0.724), 248 (1.259) nm suggesting the presence of an α, β-un-
saturated ketone chromophore (Chang et al., 2008). The IR spectrum
8 (δ 61.2) and C-10 (δc 41.7). Correlations were also observed between
C
6
H
58
O
8
H-8 (δ 2.37) and C-7 (δ 205.2), C-6 (δ 126.0), C-13 (δ 49.2), C-14
H
C
C
C
(δ 47.1), C-15 (δc 35.9), C-19 (δ 28.2), C-30 (δ 17.9). The olefinic
C
C
C
2
proton H-24 (δ 5.33) also showed HMBC correlations with C-26 (δc
H
18.8) and C-27 (δc 25.9). The α-orientation of the glucose moiety at C-
-
1
showed absorptions for hydroxyl group (3416 cm ), the conjugated
23 was determined by the cross-peaks between H-23 (δ 3.64), H-20
H
-
1
-1
ketone (1685 cm ), olefinic (1652 cm ) and conjugated olefin
(δ 2.16), H-18 (δ 0.92) and H-19 (δ 0.95), respectively, in the
H
H
H
-
1
(
1600 cm ) functionalities.
NOESY spectrum of 1 (Fig. 3) (Liu et al., 2009). The structure of
compound 1 was finally concluded as 3β-hydroxy-7-oxo-23(R)-cu-
curbita-5,24-diene-23-O-β-D-glucopyranoside to which the trivial name
momordiside A was given.
1
In the H NMR spectra of 1 (Table 1) the aglycone showed typical
signals for five tertiary methyl groups at δ
H
0.84, 0.92, 0.95, 1.15, 1.22
(
3H each, s), one secondary methyl as doublet at δ
H
0.94 (3H, d, J
2
5
=
6.0 Hz), two allylic methyls at 1.61, 1.66 (3H, s), two oxymethines at
Compound 2 was isolated as a white powder; [ ] = + 31.46. The
D
3
5
.60 (1H, m, H-3), 3.64 (1H, m H-23) and two olefinic protons at δ
H
molecular formula C37
H
62
O was deduced from the molecular ion peak
8
.33 (1H, t, H-24) and 6.03 (1H, s, H-5). The anomeric proton was
at m/z 634.44320 in the HR-EI-MS (calcd for C37
H
62
8
O 634.4445). Acid
observed as doublet at δ
H
4.66 (d, J = 7.5 Hz). The larger coupling
hydrolysis furnished D-glucose which was identified as described for
compound 1. The UV spectrum showed absorption bands at λmax (log ε)
213 (0.0.324) nm. The IR spectrum exhibited absorptions bands for
constant allowed us to assign β and axial configuration of the-gluco-
pyranosyl moiety.
1
3
-1
-1
-1
The C (broadband and DEPT) and HSQC NMR spectra data of 1
hydroxyl (3414 cm ), C = C (1650 cm ) and methoxyl (1250 cm )
functionalities. The main difference between compounds 1 and 2 was
replacement of the carbonyl group of compound 1 by a methoxyl
moiety. This was confirmed by HMBC correlation of methoxyl protons
(
Table 1) showed 30 signals of triterpene moiety and a further six
signals of a sugar unit including eight methyl (δc 13.8, 15.7, 17.9, 18.8,
2
3
4
8
5.4, 25.9, 28.2 and 28.5), seven methylene (δ 22.1, 28.0, 29.1, 29.6,
C
0.9, 32.2, 35.9), one oxymethylene (δc 63.1), four methine (δ
C
41.7,
at δ
H
3.49 with C-7 (δ
C
78.9) as well as correlations of H-8 (δ
H
2.05)
1
2.2, 47.9 and 61.2), seven oxymethine (δ
4.7, 102.6), five quaternary carbons (δ
C
C
68.9, 72.6, 72.9, 75.1, 77.4,
with C-6 (δ
C
120.2) and C-7 (δ
C
78.9). Careful comparison of the H and
1
3
36.9, 44.0, 47.1, 49.2); the
C NMR data of 2 (Table 1) with those of kuguaglycoside A (Chen
91

D. Soh, et al.
Phytochemistry Letters 38 (2020) 90–95
Table 1
1
H and 13C NMR data of compounds 1–3 in CD
3
OD.
Position
1
2
3
δ
c
δ
H
(m; J in Hz)
δ
c
δ
H
(m; J in Hz)
δ
c
H
δ (m; J in Hz)
1
2
22.1
29.6
1.76 (m)
22.3
30.0
1.75 (m)
1.81 m)
1.69 (m)
1.94 (m)
-
24.1
39.0
1.74 (m)
1
.80 (m)
2.17 (m)
1.76 (m)
2.61 (m)
2
.09 (m)
2.95 (m)
3
4
5
6
7
8
9
77.4
44.0
174.1
126.0
205.0
61.2
36.9
41.7
29.1
3.60 (m)
77.5
42.4
149.4
120.2
78.9
49.5
35.2
40.2
27.9
211.3
50.3
70.8
56.7
208.4
52.2
40.1
37.2
26.2
-
-
-
-
-
-
-
6.03 (s)
5.78 (d, J = 5)
3.49 (m)
2.05 (s)
–
3.57 (s)
-
-
2.37 (s)
3.61 (d, J = 4.5)
-
-
1
1
0
1
2.82 (d, J = 11)
2.35(d, J = 9.5)
1.54 (m)
1.79 (m)
1.48 (m)
1.69 (m)
-
3.05 (dd, J = 2.5, 2.5)
1.55 (m)
1.61 (m)
1.54 (m)
1.74 (m)
-
2.08 (m)
2
.18 (m)
1
2
28.0
1.54 (m)
33.7
29.7
1
-
.75 (m)
1
1
1
3
4
5
49.2
47.1
35.9
48.6
47.5
35.9
45.7
49.0
35.5
-
-
-
1.01 (d, J = 11)
1.34 (m)
1.38 (m)
1.53 (m)
1.67 (m)
1.61 (m)
0.97 (s)
0.96 (s)
1.30 (m)
1.86 (m)
1.67 (m)
2.12 (m)
2.24 (m)
1.14 (s)
1
.52 (m)
1
6
32.2
1.48 (m)
31.3
27.0
1
.88 (m)
1
1
1
7
8
9
47.9
15.7
28.2
1.61 (m)
0.92 (s)
0.95 (s)
48.3
15.8
29.3
47.4
16.0
65.0
3.51 (d, J = 10.5)
4
.13 (d, J = 10.5)
2
2
2
0
1
2
42.2
13.8
30.9
2.16 (m)
0.94 (s)
1.61 (m)
42.2
13.8
29.1
2.14 (m)
0.94 (s)
2.09 (m)
2.21 (m)
3.66
43.5
17.9
179.1
2.74 (m)
1.37 (d, J = 10.5)
-
1
.80 (m)
2
2
2
2
2
2
2
3
3
4
5
6
7
8
9
0
84.7
123.5
132.9
25.9
18.8
25.4
28.5
17.9
3.64
84.8
123.6
132.8
25.9
17.9
25.9
28.7
18.8
15.1
25.3
20.9
1.1 (s)
5.33 (t)
-
5.33 (t)
-
1.43 (s)
1.02 (s)
1.66 (s)
1.61 (s)
1.22 (s)
1.15 (s)
0.84 (s)
-
1.67 (s)
1.62 (s)
1.17 (s)
1.03 (s)
0.72 (s)
Glucose
1
2
3
4
5
6
’
’
’
’
’
’
4.66 (d, J = 7.5)
3.61 (m)
102.6
75.1
4.67 (d, J = 8.0)
3.64 (m)
102.2
75.1
72.9
69.0
72.6
63.2
4.03 (m)
72.9
4.02 (m)
3.50 (dd, J = 2.5, 2.5)
3.27(d, J = 2.5)
3.67, 3.80 (d, J = 10.0)
68.9
3.51 (m)
72.6
3.27(d, J = 3)
3.67, 3.80(d, J = 9.5)
63.1
Fig. 2. Key HMBC and COSY correlations compound 1.
Fig. 3. Key NOESY correlations of compound 1.
et al., 2008) revealed that
compound 2 had similar structure except for the stereochemistry at
C-23. The ROESY (Fig. 4) correlations between H-23 (δ 3.66), H-20
2.14), H-18 (δ 0.97) and H-19 (δ 0.96) revealed R configuration
H
gave brisk effervescence with dilute sodium bicarbonate revealing the
presence of a free carboxylic group. Its positive HR-FABMS showed a
pseudomolecular ion peak [M+H] at m/z 433.2244, (calcd. for
(
δ
H
H
H
for C-23.
2
5
Compound 3 was isolated as a colorless powder; [ ] = -15.69. It
D
C H
25 36
O 433.2226) corresponding to the molecular formula C
6
H
25 37
6
O ,
92

D. Soh, et al.
Phytochemistry Letters 38 (2020) 90–95
Table 2
IC50 values of compounds 1 and 2 in Urease inhibition and antioxidant activity.
Compound
Antioxidant
IC50 (μM)
Urease Inhibition
IC50 (μM)
1
45.1 ± 0.49
59.2 ± 0.28
44.2 ± 0.06
Nil
2
32.5 ± 0.45
BHA
Thiourea
21.6 ± 0.12
aldehyde at C-19. It was finally elucidated to 23,24,25,26,27-penta-
norcucurbitacin to which we gave the trivial name momordin.
2.2. In vitro biological screening of isolated compounds
Fig. 4. Key ROESY correlations of compound 2.
The new compounds isolated from Momordica foetida were eval-
uated for their therapeutic potential against various enzymes as well as
antioxidant activity and antiproliferative activity against oral cancer
cell line. The compound 1 showed significant antioxidant and urease
inhibitory potential (Table 2) while 2 showed only promising anti-
oxidant activity.
which indicated eight degrees of unsaturation. The UV spectrum
showed absorption bands at λmax (log ε) 230 (1.433). The IR spectrum
-
1
displayed absorptions for hydroxyl group (3409 cm ), in addition to
-
1
those of carbonyl and carboxylic groups (1708 cm ).
1
The H NMR spectrum of 3 showed singlets for four tertiary methyls
Compounds 1 and 2 were found to be cytotoxic against cancer cells
at low doses i.e. IC50 60.68 and 10.69, respectively (Table 3). These
compounds were noncytotoxic against normal cells as the higher con-
centration. The activity of compound 1 was very near to the value of
standard drug i.e. cisplatin.
at δ
H
1.02, 1.10, 1.14, 1.43, doublet for a secondary methyl at δ 1.37
H
(
d, J =7 Hz), oxymethylene protons at δ
H
4.13 and 3.51 (d, J
=
10.5 Hz, 1H each) and an oxymethine proton at δ 3.57 (s, 1 H). The
H
1
3
C (broadband and DEPT) and HSQC NMR spectra data of 3 displayed
15.1(C-23) 16.0(C-18), 17.9(C-
1), 20.9(C-25) and 25.3(C-24)), an oxymethylene carbon (δc 65.1),
56.7), seven methylenes (δ 24.1, 26.2, 27.0,
9.7, 35.5, 39.0, 65.1), five methines (δ 37.2, 43.5, 47.4, 52.2, 56.7)
and eight quaternary carbons. The carbonyl carbons resonated at δ
79.1, 208.4, 211.3 while an oxygenated quaternary carbon appeared
70.8. Its HMBC spectrum revealed correlations between H-1 (δ
.17), C-3 (δ 211.3) and C-5 (δ 70.8); between H-2 (δ 2.61/2.94), C-
(δ 211.3), C-10 (δ 37.2); H-23(δ 1.10), H-24(δ 1.43) with C-3 (δ
11.3), C-4 (δ 50.3), C-5 (δ 70.8) and C-6 (δ 56.7), providing evi-
2
5 signals including five methyls (δ
C
2
3
. Experimental
oxymethine carbons (δ
C
C
2
C
3
.1. General experimental procedures
C
1
Column chromatography was carried out on silica gel (70-230 and
30-400 mesh, E. Merck, Darmstadt, Germany). Thin layer chromato-
at δ
C
H
2
2
3
2
C
C
H
graphy was performed on percolated 0.5 mm thick aluminium sheets
C
C
H
H
C
(
Merck Silica gel 60, F254) and visualised by spraying with ceric sul-
C
C
C
phate solution followed by heating at 120 °C on a hot plate. The mass
spectra were recorded on a JEOL MS Route instrument and nuclear
magnetic resonance (NMR) spectra were recorded on a Bruker DPX-400
dence for the presence of a carbonyl group at C-3. Further HMBC cor-
relations of H-6 (δ
H
3.57) with C-4 (δ
C
50.3), C-5 (δ
C
70.8), C-7 (δ
C
2
08.4); H-8 (δ
H
3.61) to C-6 (δ
C
56.7), C-7 (δ
C
208.4), C-19 (δ
C
65.1), C-
1
13
instrument, H and C NMR probes operating at 500 and 125 MHz,
respectively, with tetramethylsilane as an internal standard. Optical
rotations were recorded on a JASCO P-2000, polarimeter (Japan). The
UV spectra were measured on a HP 8451A diode array spectro-
photometer.
9
(δ 40.1), C-10 (δ
C
C
37.2), C-14 (δ 49.0) enabled us to locate the
C
carbonyl group at C-7, the oxymethine at C-6 and the oxygenated
quaternary carbon at C-5. The NOESY correlations (Fig. 5) of H-8 to H-
1
8, H-19; H-24; H-17 to H-25 established the stereochemistry of H-8β,
H-10β, H-19β, H-24β and H-17α. The β-orientation of H-6 was sug-
gested by the correlations between H-6 and H-24. These data showed
that compound 3 is virtually the same as kuguacin K (Chen et al., 2009)
and differs only by the presence of a hydroxyl group instead of an
3
.2. Plant material
The whole plant and fruits of Momordica foetida were collected in
August 2015 in Awae, in the Centre region of Cameroon and identified
at the National Herbarium of Cameroon by comparison with a voucher
specimen number 52290 HNC.
3.3. Extraction and isolation
The whole plant and fruits of Momordica foetida (Cucurbitaceae)
were air dried and ground into fine powders. The powder from whole
plant (2.25 kg) and fruits (1.42 kg) were macerated with methanol for
Table 3
IC50 values of compound 1 and 2 against cell lines NIH-3T3 and CAL-27.
Compound
NIH-3T3
CAL-27
IC50 (μM)
IC50 (μM)
1
82.92 ± 2.15
18.45 ± 0.96
2.41μM/ml
60.68 ± 0.31
10.69 ± 1.36
2
Standard Drug: Cisplatin
Fig. 5. Key HMBC, COSY and NOESY correlations of compound 3.
93

D. Soh, et al.
Phytochemistry Letters 38 (2020) 90–95
7
2 h. The extracts were filtered and concentrated with the rotary eva-
3.7. Anticancer activity
porator to obtain crude extracts with 158.8 g and 123.25 g respectively.
The crude extract of whole plant (80.8 g) was subjected to column
chromatography over silica gel (230–400 mesh) and eluted with
hexane, hexane/ EtOAc (7.5:2.5), hexane/ EtOAc (7:3), hexane / EtOAc
The cytotoxic capability of compounds was evaluated on oral cancer
(CAL-27) and normal mouse fibroblast (NIH-3T3) cells as described
previously (Farooq et al., 2017). Cells were seeded at density 15,000
cells per well in 96 well microtiter plate and incubated overnight. After
24 hours of incubation, cells were treated with compounds at different
concentrations in the range of 1.95 – 250 μg and incubated for 48 h.
After incubation, 10 μL MTT dye was added in each well and incubated
for further 4 h to evaluate metabolically active cells. The formazan
crystals were then solubilized in DMSO and absorbance was measured
at 570 nm. Percent inhibition of cells was calculated by using the fol-
lowing equation:
(
1:1), EtOAc, EtOAc /MeOH (9:1) and MeOH to afford seven fractions
which were combined on the basis of their TLC profile into two batches
F
1
(26.52 g) and F
2
(31.25 g), respectively. The f batch F (26.52 g) was
1
subjected to column chromatography over silica gel (230–400 mesh)
and eluted with n-hexane/ EtOAc (15:5), to afford β-sitosterol (5). The
batch F (31.25 g) was also subjected to column chromatography with
2
mixtures of n-hexane/EtOAc in increasing order of polarity. The frac-
tion which eluted with n-hexane/EtOAc (12:8) afforded β-sitosterol-3-
O-β-D-glucoside (4) (25.03 mg). Further elution with increasing ethyl
acetate concentration afforded momordiside A (1) (56.01 mg) and
momordiside B (2) (65.08 mg). The crude extract of fruits (100.85 g)
was suspended in water and extracted successively with ethyl acetate
and n-butanol to afford two major sub-fraction MFF1(45.25 g) and
MFF2 (23.83 g) respectively. MFF2 (23.83 g) was subjected to column
cell proliferation inhibition (%) = 100 - [(OD compound - OD
Blank) / (OD Control - OD Blank) x100] IC50 of the compounds were
calculated by using software (EZ-Fit Enzyme Kinetics; Perrella
Scientific).
4. Conclusion
chromatography over silica gel (230-400 mesh) with CH
tures of CH Cl /MeOH in increasing order of polarity to provide com-
pound 3 (8.52 mg) on elution with CH Cl /MeOH (15:5).
2
2
Cl and mix-
2
2
As a result of the phytochemical studies on the whole plant of and
fruits of Momordica foetida, three previously unreported cucurbitane
triterpenes, have been isolated along with three known secondary
metabolites and their biological activities have also been evaluated.
Among these, compound 1 is found to be active against enzyme urease
besides being significantly antioxidative and also showed anti-
proliferative activity indicating its role as therapeutic against cancer
and therefore suggested to conduct further pharmacological studies for
its use in future for drug development.
2
2
3.4. Acid hydrolysis
The solutions of 1 and 2 (3 mg) in methanol (4 mL) containing 1 N
HCl (2 mL) were refluxed for 4 h The mixture was concentrated, diluted
with water, and extracted with ethyl acetate. The aqueous phase was
concentrated to obtain the sugar residue which was identified to -
D
23
glucopyranose based on its optical rotation ([α] =51.9) the GC re-
D
tention time of its Me
3
Si ether (α anomer t
R
4.2, β anomer t
R
7.9) when
Declaration of Competing Interest
None
compared with that of a standard sample.
.5. Determination of DPPH radical scavenging activity
The free radical scavenging activity was measured by 1,1-diphenyl-2-
3
Acknowledgements
picryl-hydrazil (DPPH) activity using a method previously described
Gulcin et al., 2005). The solution of DPPH of 0.3 mM was prepared in
ethanol. Five microlitres of each sample of different concentration
62.5 μg – 500 μg) was mixed with 95 μL of DPPH solution in ethanol.
The mixture was dispersed in a 96 well plate and incubated at 37 °C for
The author DS is grateful to The World Academy of Sciences (TWAS)
and the International Centre for Chemical and Biological Sciences for
the award of ICCBS-TWAS fellowship 2016 (Fr. 3240293185).
(
(
Appendix A. Supplementary data
3
0 min. The absorbance at 515 nm was measured by microtitre plate
reader (Spectramax plus 384 Molecular Device, USA) and the percent
radical scavenging activity was determined in comparison with the me-
thanol treated control (Basar et al., 2015). BHA (Butylhydroxyanisol)
was used as standard.
Supplementary material related to this article can be found, in the
online version, at doi:https://doi.org/10.1016/j.phytol.2020.05.010.
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