A new lupane-type triterpenoid fatty acid ester and other isolates from Ophiorrhiza shendurunii

Article abstract of DOI:10.1080/14786419.2016.1160232

A new pentacyclic triterpenoid fatty acid ester, lupan-20-ol-3(β)-yl hexadecanoate (1), together with lupan-20-ol-3(β)-yl acetate (2), olean-18-en-3(β)-yl hexadecanoate (3), dotriacontanoic acid (4), stigmasterol (5), rubiadin (6), nonadecanoic acid (7), palmitic acid (8) and camptothecin (9) were isolated from the hexane and chloroform extracts of Ophiorrhiza shendurunii from South India. Structures of the isolates were determined by¹H,¹³C,¹³C DEPT,¹H–¹H COSY, HMBC, HSQC, NOESY NMR, FT-IR, DART-MS, ESI-MS, alkaline hydrolysis, derivatisation, GC–MS and HPTLC analyses. O. shendurunii hexane and chloroform extracts showed significant activities against Candida albicans and Fusarium oxysporum. Compounds 1 to 3 showed only moderate antiyeast/antifungal activities.

Full text of DOI:10.1080/14786419.2016.1160232

Natural Product Research
Formerly Natural Product Letters
ISSN: 1478-6419 (Print) 1478-6427 (Online) Journal homepage: http://www.tandfonline.com/loi/gnpl20
A new lupane-type triterpenoid fatty acid ester
and other isolates from Ophiorrhiza shendurunii
Renjith Rajan, Ramaswamy Venkataraman & Sabulal Baby
To cite this article: Renjith Rajan, Ramaswamy Venkataraman & Sabulal Baby (2016): A new
lupane-type triterpenoid fatty acid ester and other isolates from Ophiorrhiza shendurunii,
Natural Product Research, DOI: 10.1080/14786419.2016.1160232
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Date: 02 April 2016, At: 18:22

Natural Product research, 2016
http://dx.doi.org/10.1080/14786419.2016.1160232
A new lupane-type triterpenoid fatty acid ester and other
isolates from Ophiorrhiza shendurunii
Renjith Rajana, Ramaswamy Venkataramanb and Sabulal Babya
aPhytochemistry and Phytopharmacology division, Jawaharlal Nehru tropical Botanic Garden and research
b
Institute, thiruvananthapuram, India; department of chemistry, sri Paramakalyani college, Manonmaniom
sundaranar university, tirunelveli, India
ARTICLE HISTORY
ABSTRACT
received 8 august 2015
accepted 13 February 2016
A new pentacyclic triterpenoid fatty acid ester, lupan-20-ol-3(β)-yl
hexadecanoate (1), together with lupan-20-ol-3(β)-yl acetate (2),
olean-18-en-3(β)-yl hexadecanoate (3), dotriacontanoic acid (4),
stigmasterol (5), rubiadin (6), nonadecanoic acid (7), palmitic acid (8)
and camptothecin (9) were isolated from the hexane and chloroform
extracts of Ophiorrhiza shendurunii from South India. Structures of the
KEYWORDS
Ophiorrhiza shendurunii;
pentacyclic triterpenoid fatty
acid ester; lupan-20-ol-3(β)-
yl hexadecanoate; antifungal
activity
1
1
isolates were determined by H, 13C, 13C DEPT, H–1H COSY, HMBC,
HSQC, NOESY NMR, FT-IR, DART-MS, ESI-MS, alkaline hydrolysis,
derivatisation, GC–MS and HPTLC analyses. O. shendurunii hexane
and chloroform extracts showed significant activities against Candida
albicans and Fusarium oxysporum. Compounds 1 to 3 showed only
moderate antiyeast/antifungal activities.
1. Introduction
Genus Ophiorrhiza (Rubiaceae) is represented by 47 species and 9 varieties in the Indian
subcontinent (Deb & Mondal 2001). Sixteen species and three varieties occur in the southern
Western Ghats region in India. Plants in genus Ophiorrhiza are used as antitussive, analgesic
and for the treatment of ulcers, gastropathy, leprosy and amenorrhoea in traditional medi-
cines (Rajan et al. 2013). Moreover, genus Ophiorrhiza is a promising source of the anticancer
CONTACT sabulal Baby
sabulal@jntbgri.res.in
supplemental data for this article can be accessed at http://dx.doi.org/10.1080/14786419.2016.1160232.
© 2016 taylor & Francis

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R. RAjAN ET AL.
drug camptothecin along with other phytochemicals (Rajan et al. 2013). Ophiorrhiza shen-
durunii, A.E.S. Khan & al, is one of the species screened for camptothecin by us recently
(Rajan et al. 2013). O. shendurunii is an undershrub with subfruticose stem endemic to the
southern Western Ghats (Shanavas Khan et al. 1998). High degree of endemicity of O. shen-
durunii to southern Western Ghats prompted us to choose it for our studies. Here we report
phytochemical investigation of hexane and chloroform extracts of O. shendurunii which
led to the isolation of one new pentacyclic triterpenoid fatty acid ester, lupan-20-ol-3(β)-yl
hexadecanoate (1), along with eight known compounds (2 to 9). Antifungal/antiyeast activ-
ities of O. shendurunii hexane, chloroform extracts and the major isolates (1), (2), (3) and (6)
were also tested.
2. Results and discussion
Lupan-20-ol-3(β)-yl hexadecanoate (1) was isolated as a white, waxy solid from the hexane
1
1
extract of O. shendurunii (Figure 1). H NMR and H–1H COSY data showed eight tertiary
methyls at δH 1.22 (H30, 3H, s), 1.12 (H29, 3H, s), 0.81 (H28, 3H, s), 0.95 (H27, 3H, s), 1.06 (H26,
(1)
(2)
(3)
(5)
(6)
(9)
Figure 1. lupan-20-ol-3(β)-yl hexadecanoate (1), lupan-20-ol-3(β)-yl acetate (2), olean-18-en-3(β)-yl
hexadecanoate (3), stigmasterol (5), rubiadin (6) and camptothecin (9) isolated from O. shendurunii.

NATuRAL PRODuCT RESEARCH
3
3H, s), 0.86 (H25, 3H, s), 0.84 (H24, 3H, s), 0.84 (H23, 3H, s), one secondary methyl at δ 0.88
(H′16, 3H, t, J = 6.4 Hz), 10 methylenes at δ 0.99/1.68, 1.60/1.28, 1.49/1.39, 1.40/1.48, 1.28/1.49,
1.12/1.79, 1.32/1.62, 1.49/1.35, 1.87/1.62, 1.12/1.30 and six methine multiplets at δ 4.48 (H3,
dd, J = 10.0 Hz, 6.0 Hz), 0.80, 1.28, 1.71, 1.33, 1.80. 13C NMR and DEPT spectra showed 46
carbon atoms corresponding to nine methyls at δC 27.97, 16.59, 16.21, 16.16, 14.82, 19.21,
24.82, 31.56, 14.12, 24 methylenes at δ 38.36, 23.73, 18.22, 34.49, 21.41, 27.56, 28.73, 35.57,
28.99, 40.19, 34.87, 25.18, 29.18, 29.27, 29.47, 29.60–29.69, 29.37, 31.93, 22.70, six methines
at δ 80.60, 55.27, 50.18, 37.45, 48.31, 49.97, six quaternary carbon atoms at δ 37.83, 41.37,
37.00, 43.52, 44.64, 73.46 and one carbonyl carbon atom at δ 173.68. NOE correlations were
found between H-3/H3–23, H-1α and H-5α in (1) indicating relative stereochemistry of the
side chain at C3 as β (Figure S1). J values of H at C3 in (1) δH 4.48 dd (J = 6 Hz, J = 10 Hz) were
also matching with β configuration (Thibeault et al. 2007). Other important NOE correlations
in (1) were H-5α/H3–23, H-3, H-9; H-9/H3–27; H3–27/H-18; H-18/H-16; H-16/H3–29; H3–24/
H3–25; H3–25/H3–26; H26/H3–13; H-13/H3–28 (Figure S1) (Abdel Bar et al. 2008). DART-MS
of (1) showed (M + H)+ signal at m/z 683.46 corresponding to the molecular formula, C46H82O3
(Figure S1). IR absorptions at 3513 and 1729 cm−1 in (1) showed the presence of hydroxyl and
carbonyl groups. NMR data of the triterpenoid skeleton (1) were matching with compound
(2) (lupan-20-ol-3(β)-yl acetate).
Alkaline hydrolysis of (1) (HPTLC, Rf 0.55) and subsequent methylation yielded the fatty
acid methyl ester of its side chain and the terpenoid alcohol. Terpenoid alcohol (Rf 0.13) was
acetylated using pyridine-acetic anhydride to yield its monoacetylated derivative, which
showed same Rf value (0.40) on HPTLC as lupan-20-ol-3(β)-yl acetate (2). Fatty acid methyl
ester was identified by GC–MS (molecular ion peak 270, base peak 74) as hexadecanoic acid
methyl ester (Figure S1). From these data, the structure of (1) isolated from O. shendurunii
was elucidated as lupan-20-ol-3(β)-yl hexadecanoate (Figure 1).
Lupan-20-ol-3(β)-yl acetate (2), olean-18-en-3(β)-yl hexadecanoate (3), dotriacontanoic
acid (4) and stigmasterol (5) were also isolated from the hexane extract of O. shendurunii
(Figure 1, Supplementary material). Rubiadin (6), nonadecanoic acid (7), hexadecanoic acid
(palmitic acid) (8) and camptothecin (9) were isolated from the chloroform extract of O.
shendurunii whole plant (Figure 1, Supplementary material). Compound (10) isolated from
the chloroform extract was same as (3), olean-18-en-3(β)-yl hexadecanoate, obtained from
the hexane extract. This study is the first report of compounds (1) to (9) from O. shendurunii.
Hexane extract of O. shendurunii on agar well diffusion assay showed significant anti-
yeast/antifungal activities against Candida albicans (MTCC 3017) (22/28 mm) and Fusarium
oxysporum (MTCC 3075) (18/26 mm) but no antibacterial activity against Escherichia coli
(MTCC 2622, gram -ve) (no zone) and Bacillus subtilis (MTCC 2756, gram +ve) (no zone).
Antiyeast activities of compounds 1 to 3 were tested against C. albicans, Leucosporidium
frigidum (MTCC 3537), Rhodotorula rubra (MTCC 1446) and Saccharomyces cerevisiae (MTCC
3196) and antifungal activities against Aspergillus fumigatus (MTCC 3376), Aspergillus niger
(MTCC 3496), Penicillium expansum (MTCC 2006) and F. oxysporum. Compounds 1, 2 and 3 at
10 μg/μL in 3:7 CHCl3:MeOH (100 μL each) showed moderate activities with inhibition zones
of 15 (1), 10 (2), 16 mm (3) against C. albicans and 10 (1), 8 (2), 8 mm (3) against F. oxysporum,
compared to inhibition zones of standard ketoconazole (0.15 μg/μL in 1% DMSO, 100 μL) 28
(C. albicans) and 26 mm (F. oxysporum), respectively. 1, 2 and 3 did not show considerable
antiyeast or antifungal activities against other tested strains.

4
R. RAjAN ET AL.
O. shendurunii chloroform extract on agar well diffusion assay showed significant
antibacterial activity against B. subtilis (22/18 mm) and E. coli (19/23 mm) with ampicillin
(0.1 μg/μL) as control. Chloroform extract also showed significant antiyeast/antifungal
activities against C. albicans (28/28 mm) and F. oxysporum (24/26 mm) with ketoconazole
(0.15 μg/μL) as control. Rubiadin (6) isolated from the chloroform extract of O. shendurunii
did not show any antiyeast/antifungal or antibacterial activities in agar well diffusion assay.
3. Experimental
3.1. General
1H NMR (400 MHz), 13C NMR (100 MHz) and 2D NMR (COSY, HSQC, HMBC, NOESY) spectra
were recorded at room temperature on a 400 MHz FT-NMR spectrometer (Bruker, Germany) in
CDCl3 usingTMS as internal standard. IR spectra were recorded on a FT-IR spectrophotometer
(PerkinElmer, uSA). DART-MS analyses were carried out on an AccuTOF jMS-T100LC Mass
Spectrometer with a DART (jEOL, uSA). Mass spectra in positive ion mode were recorded
on an ESI-MS (Thermo, uSA). GC–MS analysis was performed on a Gas Chromatograph 6890
(Agilent Technologies, uSA), fitted with an HP-5 (5% phenyl 95% dimethyl polysiloxane,
non-polar, 30 m × 0.32 mm i.d., 0.25-μm film thickness) capillary column, coupled with a
Model 5973 Mass Detector; operation conditions: injection mode – split, injector temper-
ature 250 °C, oven temperature programme 60–246 °C (3 °C/min), carrier gas He 1.4 mL/
min. HPTLC experiments were performed on a HPTLC system (CAMAG, Switzerland) with
pre-coated silica gel plates (60F-254, 8 × 10 cm, 0.2-mm thickness) (E. Merck, Germany).
Rotary evaporator (Buchi, Switzerland) was used for the removal of solvents from extracts.
Column chromatography was performed with 60–120 and 100–200 mesh silica gel (Central
Drug House Pvt. Ltd., New Delhi). Pre-coated silica gel plates (60 F254, 10 × 10-cm plates,
0.2-mm thickness) (E. Merck, Germany) were used for TLC. Distilled solvents were used for
chromatographic separations.
3.2. Plant material
O. shendurunii (whole plant) was collected from Shenduruny Wildlife Sanctuary of the Kerala
region of southern Western Ghats in India in january 2011. Plant specimen was authenticated
by Dr E.S. Santhosh Kumar of jNTBGRI and a voucher specimen was kept at the Institute
Herbarium (TBGT 69911).
3.3. Extraction, isolation
O. shendurunii (whole plant) was shade dried and powdered. Powdered plant material (1.2 kg)
was Soxhlet extracted using 4 L of hexane for 18 h. The plant powder was subsequently
extracted with 4 L of chloroform for 18 h. Solvents were fully removed using a rotary evap-
orator to yield 64 g of hexane and 15 g of chloroform extracts.
Hexane extract (60 g) was fractionated by silica gel column chromatography (5.5 × 90 cm)
using 100% hexane, followed by increasing polarities of hexane-CHCl3, CHCl3-MeOH and
100% MeOH. These fractions were pooled to five final fractions (Hfr 001 to 005) based on
TLC profiles. Repeated column chromatography of Hfr 001 with hexane:ethyl acetate led to

NATuRAL PRODuCT RESEARCH
5
a subfraction with compound (3) as its major constituent. Subsequent purification of this
subfraction by preparative TLC in 20 × 10-cm plates using hexane:ethyl acetate (9.5:0.5)
yielded compound (3) (250 mg). Compound (4) was precipitated as a white powder from Hfr
002, which was further purified by recrystallisation in hot chloroform (40 mg). Compound
(1) was obtained as a crude oily mixture from Hfr 003, further purified by column chroma-
tography in hexane:ethyl acetate (in gradient) and by preparative TLC in 20 × 10-cm plates
using hexane:ethyl acetate (9.5:0.5) (150 mg). Compound (5) was isolated from Hfr 004 by
repeated column chromatography using hexane:chloroform (20 mg). Compound (2) was iso-
lated from Hfr 005 as a white solid by repeated column chromatography using hexane:ethyl
acetate and hexane:chloroform (90 mg).
Chloroform extract (14 g) was fractionated by silica gel column chromatography
(5.5 × 90 cm) using 100% hexane, followed by increasing polarities of hexane-CHCl3, CHCl3-
MeOH and 100% MeOH. These fractions were pooled to six final fractions (Cfr 001 to 006)
based on their TLC profiles. Cfr 001 appeared as a waxy material and GC–MS confirmed it as a
mixture of hydrocarbons with major components as octadecane, hexadecane and eicosane.
Cfr 002 on repeated column chromatography and purification by preparative TLC resulted
in a white waxy compound (10, 22 mg). Cfr 003 on repeated column chromatography and
recrystallisation yielded a white solid (7, 31 mg). Compound (8, 18 mg) was isolated as a
white solid from Cfr 004 by repeated column chromatography and recrystallisation. Cfr 005
on column chromatography and recrystallisation yielded a yellow-coloured solid (6, 15 mg).
Cfr 006 on repeated column chromatography and preparative TLC yielded a fluorescent
compound (9, 10 mg). The purity of all isolates was confirmed by HPTLC and melting point
1
measurements. Compounds 1 to 10 were identified by H, 13C NMR, 2D NMR and mass
spectral analyses (Figure 1, Figure S1).
3.4. Lupan-20-ol-3(β)-yl hexadecanoate (1)
White waxy solid; m.p. 72 °C; αD25: + 10.098 (c = 0.1, CHCl3); IR λmax cm−1: 3513, 2920, 2849,
1729, 1713, 1466, 1379, 1264, 1245, 1224, 1182, 1102; 1H NMR (CDCl3, 400 MHz): δ = 0.99, 1.68
(2H, m, H-1), 1.28, 1.60 (2H, m, H-2), 4.48 (1H, dd, J = 6, 10 Hz, H-3), 0.79 (1H, t, J = 8.8 Hz, H-5),
1.49, 1.39 (2H, m, H-6), 1.40, 1.48 (2H, m, H-7), 1.28 (1H, m, H-9), 1.28, 1.49 (2H, m, H-11), 1.12,
1.79 (2H, m, H-12), 1.71 (1H, m, H-13), 1.32, 1.62 (2H, m, H-15), 1.49, 1.35 (2H, m, H-16), 1.33
(1H, m, H-18), 1.80 (1H, m, H-19), 1.62, 1.86 (2H, m, H-21), 1.12, 1.30 (2H, m, H-22), 0.84 (3H,
s, H-23), 0.84 (3H, s, H-24), 0.86 (3H, s, H-25), 1.06 (3H, s, H-26), 0.95 (3H, s, H-27), 0.81 (3H, s,
H-28), 1.12 (3H, s, H-29), 1.22 (3H, s, H-30), 2.29 (2H, t J = 7.6 Hz, H-2′), 1.60 (2H, m, H-3′), 1.25
(2H, br, s, H-4′-13′), 1.25 (2H, m, H-14′), 1.28 (2H, m, H-15′), 0.88 (3H, t, J = 6.4 Hz, H-16′); 13
C
NMR (CDCl3, 100 MHz): δ = 38.4 (CH2, C-1), 23.7 (CH2, C-2), 80.6 (CH, C-3), 37.8 (C, C-4), 55.3
(CH, C-5), 18.2 (CH2, C-6), 34.5 (CH2, C-7), 41.4 (C, C-8), 50.2 (CH, C-9), 37.0 (C, C-10), 21.4 (CH2,
C-11), 27.6 (CH2, C-12), 37.5 (CH, C-13), 43.5 (C, C-14), 28.7 (CH2, C-15), 35.6 (CH2, C-16), 44.6
(C, C-17), 48.3 (CH, C-18), 50.0 (CH, C-19), 73.5 (C, C-20), 29.0 (CH2, C-21), 40.2 (CH2, C-22),
28.0 (CH3, C-23), 16.6 (CH3, C-24), 16.2 (CH3, C-25), 16.2 (CH3, C-26), 14.8 (CH3, C-27), 19.2 (CH3,
C-28), 24.8 (CH3, C-29), 31.6 (CH3, C-30), 173.7 (C, C-1′), 34.9 (CH2, C-2′), 25.2 (CH2, C-3′), 29.2
(CH2, C-4′), 29.3 (CH2, C-5′), 29.5 (CH2, C-6′), 29.6 (CH2, C-7′-12′), 29.4 (CH2, C13′), 31.9 (CH2,
C-14′), 22.7 (CH2, C-15′), 14.1 (CH3, C-16′); HMBC correlations: H-1/C-3, C-12, C-25, H-2/C-4′,
C-3,C-1, H-3/C-1′, C-23, C-24, H-5/C-27, H-7/C-5, C-27, H-9/C-26, C-29, H-11/C-9, H-12/C-26,
H-18/C-19, C-28, H19/C-20,C-21, C-28, H-21/ C-20, H-22/C-17,C-20, C-28, H-23/C-3, C-4, C-5,

6
R. RAjAN ET AL.
C-24, H-24/C-3, C-4, C-5, C-23, H-25/C-1, C-5, C-9, H-26/C-7, C-8, C-9, C-14, H-27/C-28, C-14,
C-15, H-28/C-16, C-17, C-18, C-22, H-29/C-19, C-20, C-30, H-30/C-19, C-20, C-29, H-2′/C-1′, C-3′,
C-4′, H-3′/C-1, C-4′, H-14′/C-13′, C-15′, H-15′/C-14′, H-16′/-14′, C-15′; DART-MS m/z: 683.46
(M + H)+ (Figure 1, Figure S1).
3.5. Alkaline hydrolysis of (1)
Compound 1 (15 mg) was dissolved in 3 mL of benzene, 12 mL 3% of KOH/MeOH was added,
reaction mixture was kept at room temperature for 15 min, then neutralized with 1 N HCl/
MeOH and extracted with chloroform. Triterpenoid alcohol (lupan-3,20-diol) and methyl
ester of the fatty acid (hexadecanoic acid methyl ester) were separated from the residue by
column chromatography (Al-Musayeib et al. 2013). Methyl ester of hexadecanoic acid was
identified by GC–MS (Figure S1).
3.6. Acetylation of lupan-3,20-diol, HPTLC analysis
Lupan-3,20-diol (5 mg) obtained from alkaline hydrolysis of (1) was dissolved in pyridine,
1 mL of acetic anhydride was added and kept at room temperature overnight. Reaction
mixture was diluted with ethanol and evaporated under vacuum to obtain the monoacetate
derivative (Chakrabartty et al. 1982). Rf values of (1), monoacetate derivative and lupan-20-
ol-3(β)-yl acetate (2) were compared by HPTLC.
3.7. Antimicrobial activities
O. shendurunii hexane and chloroform extracts were tested for antiyeast/antifungal and
antibacterial activities by agar well diffusion assay (Zhang et al. 2010). Potato dextrose agar
(Hi media) medium (1 L) prepared in distilled water was poured onto 90-mm petri plates
(25–30 mL/plate). Petri plates containing the medium were seeded with 24-h culture of
microbial strains (bacteria, yeast/fungi). Wells (5-mm diameter) were cut on these plates
and the hexane (50 μg/μL in 1:1 hexane-CHCl3, 100 μL) and chloroform (50 μg/μL in DMSO,
100 μL) extracts were repeatedly applied. The plates were then incubated at 37 °C for 24 h
(bacteria) or 72 h (yeast/fungi). Antiyeast/antifungal and antibacterial activities were assayed
by measuring the diameters of the inhibition zones formed around the well. Ketoconazole
(0.15 μg/μL in 1% DMSO, 100 μL) and ampicillin (0.1 μg/μL in 1% DMSO, 100 μL) were used
as antifungal/antiyeast and antibacterial standard drugs, respectively. One set of control
experiment was also performed with pure solvent, DMSO. Compounds 1, 2, 3 and 6 isolated
from the hexane and chloroform extracts of O. shendurunii were also screened for their
antiyeast and antifungal activities using the same protocol. Test compounds (10 μg/μL in
3:7 CHCl3:MeOH, 100 μL each) and ketoconazole (control, 0.15 μg/μL in 1% DMSO, 100 μL)
were repeatedly applied on potato dextrose agar medium, incubated at 37 °C for 72 h and
inhibition zones were measured.
4. Conclusion
A new pentacyclic triterpenoid fatty acid ester, lupan-20-ol-3(β)-yl hexadecanoate (1),
together with eight known molecules were isolated from the hexane and chloroform extracts

NATuRAL PRODuCT RESEARCH
7
of O. shendurunii from South India. Several lupane-type terpenoids were isolated from plants
and they are known for various biological activities, including antibacterial/antifungal/anti-
yeast activities (Abad et al. 2007; Nguyen & Nguyen 2013; Hill & Connolly 2015). O. shenduru-
nii hexane and chloroform extracts showed significant activities against C. albicans and F.
oxysporum on agar well diffusion assay. Isolated compounds 1 to 3 showed only moderate
antiyeast and antifungal activities.
Acknowledgements
R.R. is a doctoral student registered at MS university, Tirunelveli.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This work was supported by the Board of Research in Nuclear Sciences, Department of Atomic Energy,
Government of India [grant number 2010/35/4/BRNS/1278 dated 11/08/2010].
References
Abad Mj, Ansuategui M, Bermejo P. 2007. Active antifungal substances from natural sources. Arkivoc.
vii:116–145.
Abdel Bar FM, Zaghloul AM, Bachawal SV, Sylvester PW, Ahmad KF, El Sayed KA. 2008. Antiproliferative
triterpenes from Melaleuca ericifolia. j Nat Prod. 71:1787–1790.
Al-Musayeib NM, Mohamed GA, Ibrahim SR, Ross SA. 2013. Lupeol-3-O-decanoate, a new triterpene
ester from Cadaba farinosa Forssk. growing in Saudi Arabia. Med Chem Res. 22:5297–5302.
Chakrabartty T, Poddar G, Pyrek jS. 1982. Isolation of dihydroxylupene and dihydroxylupane from the
bark of Lawsonia inermis. Phytochemistry. 21:1814–1816.
Deb DB, Mondal DC. 2001. Taxonomic revision of the genus Ophiorrhiza L. (Rubiaceae) in Indian
subcontinent. Bull Bot Surv Ind. 39:1–148.
Hill RA, Connolly jD. 2015. Triterpenoids. Nat Prod Rep. 32:273–327.
Rajan R, Varghese S, Kurup R, Gopalakrishnan R, Venkataraman R, Satheeshkumar K, Baby S. 2013.
Search for camptothecin-yielding Ophiorrhiza species from southern Western Ghats in India: a
HPTLC-densitometry study. Ind Crops Prod. 43:472–476.
Shanavas Khan AE, Santhosh Kumar ES, Pushpangadan P. 1998. A new species of Ophiorrhiza L.
(Rubiaceae) from Kerala, India. j Bombay Nat Hist Soc. 95:317–318.
Nguyen MT, Nguyen NT. 2013. A new lupane triterpene from Tetracera scandens L., xanthine oxidase
inhibitor. Nat Prod Res. 27:61–67.
Thibeault D, Gauthier C, Legault j, Bouchard j, Dufour P, Pichette A. 2007. Synthesis and structure-
activity relationship study of cytotoxic germanicane- and lupane-type 3β-O-monodesmosidic
saponins starting from betulin. Bioorg Med Chem. 15:6144–6157.
Zhang H, Xu Y, Wu L, Zheng X, Zhu S, Feng F, Shen L. 2010. Anti-yeast activity of a food-grade dilution-
stable microemulsion. Appl Microbiol Biotechnol. 87:1101–1108.