Natural Resources, 2011, 2, 167-172
doi:10.4236/nr.2011.23022 Published Online September 2011 (http://www.SciRP.org/journal/nr)
167
Isolation, Identification and Tyrosinase Inhibitory
Activities of the Extractives from Allamanda
cathartica
Kosei Yamauchi1, Tohru Mitsunaga1, Irmanida Batubara2
1Faculty of Applied Biological Science, Gifu university, Gifu, Japan; 2Department of Chemistry, Faculty of Mathematics and Natural
Sciences, Biopharmaca Research Center, Bogor Agricultural University, Bogor, Indonesia.
Received April 19th, 2011; revised May 12th, 2011; accepted June 4th, 2011.
ABSTRACT
Tyrosinase inhibitory activity of the extractives from A. cathartica was examined and their new bioactivity and potent
active compounds were identified. Five compounds, glabridin, new lignan, kaempferol, naringenin, and allamandicin,
were isolated by a series of chromatography, and identified by NMR and LC-MS. Among them, glabridin had the high-
est tyrosinase inhibitory activity (IC50:2.93 μM) which is 15 times stronger than that of kojic acid used as positive con-
trol (IC50:43.7 μM). Moreover the lignan was indentified as 1-[3-(4-allyl-2,6-dimethoxyphenoxy)-4-methoxyphenyl] pro-
pane-1,2,diol which was a novel lignan.
Keywords: Allamanda c athartica, Tyrosinase, Glabridin, Kaempferol, Naringenin, Allamandicin
1. Introduction
Allamanda cathartica is a plant cultivated in tropical area.
It is used as decoction in various areas and is used in
numerous ways. For instance, the extract is used as
cathartic in South America and the stem extract is used
as antihypertensive in Bangladesh [1-3]. However, the
studies of components which have potent bioactivity in
this plant are very few, and the mechanisms of the bioac-
tivity have not been done sufficiently. Therefore, the aim
of this study is to search active compounds from extract
of this plant, and reveal the bioactive mechanism. We
have been interesting to find the bioactive compounds
from tropical plant extracts, and have identified some
kinds of natural products relating to health and beauty so
far. The present study examined tyrosinase inhibitory
activity of the extractives from A. cathartica.
Melanin is a pigment which is biosynthesized from
tyrosine by enzymatic oxidation of tyrosinase. Melanin is
widely distributed in body surface, retina, nigra of brain,
adrenal medullae, and so on. Moreover, it is thought to
play an important role in skin cancer prevention by pro-
tection of cells from ultraviolent rays. While, it is said
that melanin is a reason of sunburn and mottle. Therefore,
compounds inhibiting melanin are expected to applica-
tion of cosmetic as whitening agent. Melanin is biosyn-
thesized in cells called melanocyte, and the starting ma-
terial of biosynthesis is L-tyrosin. The key enzyme of
melanin synthesis is tyrosinase which contains copper,
and catalyzes two reactions in the melanin biosynthesis.
In the cell, first key step of melanin biosynthesis is the
oxidation of L-tyrosine to L-DOPA and second step is
L-DOPA to L-DOPA quinine, which are catalyzed by
tyrosinase. As the result, pheomelanin and eumelanin are
produced. Pheomelanin is red-orange color and eumela-
nin is blackish brown.
Then, tyrosinase inhibitior makes melanin production
diminishing, because the activity of this enzyme is
rate-controlling step of melanin synthesis. We found that
A. cathartica stem extract has tyrosinase inhibitory activity,
and tried to search the center active compound. Some kind
of tyrosinase inhibitors have been already found from
plant extract [4-9]. We isolated 5 compounds (Figure 1)
from extract of A.cathartica, and glabridin had the highest
tyrosinase inhibitory activity among the compounds.
2. Materials and Methods
2.1. Materials
The sample was identified by Herbarium Bogoriense,
Cibinong, Indonesia and deposited in Biopharmaca Re-
search Center, Bogor Agricultural University no.

Isolation, Identification and Tyrosinase Inhibitory Activities of the Extractives from Allamanda cathartica 168
OO
OH
OH
3
5
6
89
10 1'
2'
3'
5'
6'
1"
4"
5"
4
7
2"
3"
2
4'
O
O
1
2
3
4
6
7
8
9
1'
2' 3' 4'
5' 6' 7'
8'
9'
O
O
HO
OH
O
O
OH
OH
HO
OH
2
3
45
6
7
8
9
10
1'
2'
3'
4'
5'
6'
O
OH
OOH
HO 2
3
4
5
6
79
10
1'
2'
3' 4'
5'
6'
8
O
O
O
O
O
O
OH
1
3
4
5
6
7
8
9
10
11
12 13
14
H
H
A: glabridinB: new lignan
(1-(3-(4-allyl-2,6-dimethoxyphenoxy)
-4-methoxyphenyl)propane-1,2,diol )
C: kaempferol
D: naringeniE: allamandicin
Figure 1. Structure of compound A-E.
1002002.
2.2. Extraction and Fractionation of A. cathartica
Stem Powder
A. cathartica stem powder (385.4 g) was extracted with
methanol. The methanol extract was fractionated with
ethyl acetate. The ethyl acetate soluble fraction was
separated with silica gel column chromatography (69 mm
φ × 510 mm L). Eluted with n-hexane, EtOAc, MeOH to
obtain Fr.1-Fr.8. The Fr.3 was separated with preparative
HPLC[ODS-3 (20 mm φ × 250 mm L) (MeOH/0.05%
TFA aq.soln. = 10/90 (0 min), 100/0 (60 min), 100/0 (80
min)] to obtain Fr.3-1-Fr.3-4. Finally, compound A, B, C,
D, and E were isolated from Fr.3-3, Fr.3-1, Fr.3-4, Fr.3-4,
and Fr.3-4 respectively by preparative HPLC [ODS-3 (10
mm φ × 250 mm L) (MeOH/0.05% TFA aq.soln. = 10/90
(0 min), 100/0 (60 min), 100/0 (80 min)] (Figure 2).
2.3. Tyrosinase Activity Assay
The tyrosinase activity method performed based on Ba-
tubara et al. (2010) [10]. Briefly, sample 70 μl was put in
96-well plate. Tyrosinase 30 μl (333 unit/ml in phosphate
buffer 50 mM pH 6.5) and 110 μl of substrates (L-tyro-
sine 2mM or L-DOPA 12mM) were added. After incuba-
tion at 37˚C for 30 min, the absorbance at 510 nm was
determined using a micro plate reader. Moreover IC50
value (concentration of inhibitor showing 50% inhibition)
was calculated.
2.4. Identification of Compounds
Compound A-E were identified by 1H-NMR, 13C-NMR,
1H-1H-COSY, HMQC, HMBC, and LC-MS. Aceton-d6
was used as the solvent for all compounds. These NMR
measurements were performed by using JEOL EC600-
NMR.LC-MS measurements (Waters Waters®XevoTM
QTof MS) was performed using column C18 (2.1 × 100
mm) with MeOH/water = 60/40 (0 min), 100/0 (10 min),
100/0 (13 min) as eluent.
The NMR data of compounds isolated from A. cathar-
tica stem is shown in Table 1. LC-MS: ES－data of
Compoun A, B, C, D, and E were m/z: 323 (M-1), 373,
285, 271, 307 respectively.
3. Results and Discussion
3.1. Compounds Identification
Allamanda cathartica contains hydrocarbons(long chain
esters), e.g. 1-triacontanol, 1-dotriacontanol, docosanoic-,
tetracosanoic- and hexacosanoic acid in the root; β-si-
tosterol and triterpenes e.g. ursolic acid and β-amyrin in
the leaves or stem, and lupeol in the roots [1-3]. Other
components isolated from the roots include series of iri-
doid lactones: allamadin, allamandicin, plumericin, iso-
plumericin, plumeieride and fluvoplumierin [11,12].
Compound A concluded as glabridin, while compound
C, D and E was kaempferol, naringenin, and alla-
mandicin respectively. Interestingly, Kaempferol have

Isolation, Identification and Tyrosinase Inhibitory Activities of the Extractives from Allamanda cathartica 169
P-HPLC
Preparative HPLC( P-HPLC)
P-HPLC
P-HPLC
Stem powder of A .catharitica (385.4 g)
Insoluble fraction
Extracting with EtOAc 12 h ×3
Residue
MeOH extract (ASM)(29.9 g)
Soluble fraction
Silicagelcolumn chromatography
( 69 mmφ×510 mm L)
Fr.3-1 Fr.3-2 Fr.3-3 Fr.3-4
Fr.1 Fr.2 Fr.3 Fr.4 Fr.5 Fr.6 Fr.7 Fr. 8
Extracted with MeOH12 h ×3
Compound B Compound A Compound C,D,E
Figure 2. Isolation scheme of the c ompounds from A. catharitica stem powder.
been found in petals of this plant, and allamandicin have
been found in roots[4]. However, it was revealed that the
two compounds are also contained in stem. Moreover,
glabridin and naringenin are found the first time in this
plant.
NMR spectrum of glabridin was also searched, and
tried to compare to data of compound A and glabridin.
The NMR spectrum data from glabridin was similar to
that of compound A. Equally, compound C, D, E were
identified as keampferol, naringenin, allmandicin respec-
tively [13-15].
Compound B was found to be a novel compound. Ac-
cording to NMR data for compound B, 5.11 and 5.07ppm
protons were geminal and alkene protons because of
chemical shift and HMQC data. The two protons of 6.55
ppm peeks were equivalen in aromatic ring protons, be-
cause it appeared as singlet proton. The three protons of
6.72, 6.94, 6.68 ppm were also the aromatic protons in-
dicating ortho-metha, ortho, and metha coupling. Ac-
cording to the HMBC spectrum of compound B (Figure
3), long-range correlations were observed between H-1
and C-2, H-2 and C-1, C-3, C-4, H-3 and C-1, C-2, C-4,
H-5 and C-3, C-4, C-6, 6-OMe and C-6, 8-OMe and C-8,
H-9 and C-8, C-4, C-3, H3-1’ and C-2’, C-3’, H-2’ and
C-3’, H-3’ and C-4’, C-9’, H-5’ and C-3’, C-4’, C-6’,
C-7, 7’-OMe and C-7’, H-8’ and C-7’, C-9’ and between
H-9’ and C-8’, C-3’, C-4’. These NMR and MS data
showed us the compound B is lignan 1-[3-(4-allyl-2,
6-dimetoxyphenoxy)-4-methoxyphenyl]propane-1,2,diol
shown Fi gure 1.
3.2. Tyrosinase Inhibitory Activity
Allamanda crude extract and the fractions were analyzed
for their activity against tyrosinase. The IC50 values of
MeOH extract and fractions are shown in Table 2. Kojic
acid is used as a positive control, because kojic acid is
included in whitening agent of cosmetic products. Table
1 shows that IC50 value of MeOH extract is 98.4 μg/ml,
and that of Fr.3 is 8.35 μg/ml. Thus, tyrosinase inhibition
is becoming strong with following fractionation. Among
to Fr.3-1 till Fr.3-4, Fr.3-3 had the strongest activity (IC50
0.589 μg/ml).
From Fr.3-3, glabridin was isolated. Moreover, from
Fr.3-1, lignan was isolated and from Fr.3-4, naringenin,
kaempferol, and allamandicin were isolated. Their ty-
rosinase inhibitory activity are shown in Table 3. Ac-
cording to Ta ble 3, only glabridin has potent activity.
The tyrosinase inhibitory activity of glabridin is shown in
Figure 4 for L-tyrosine as substrate and Figure 5 for
L-DOPA as substrate. According to Figure 4, glabridin
had about 93% of tyrosinase inhibition at concentration
19.3 μM for reaction with L-tyrosine as substrate. While,
Kojic acid had only about 28% inhibition at 54.9 μM con-
centration. IC50 value of glabridin was 2.93 μM, and this
value was lower than that of Kojic acid value (43.7 μM).
Moreover, in Figure 5 (tyrosinase inhibitory activity
using DOPA as the substrate), IC50 value of glabridin
was 25.5 μM, and this value was lower than that of Kojic
O
O
H3C
H3C
OCH3
OH
HO
H3C
O
H
H
H
H
HH
H
H
H
H
H
H
Figure 3. Key HMBC correlations of compound B.

Isolation, Identification and Tyrosinase Inhibitory Activities of the Extractives from Allamanda cathartica 170
Table 1. 1H-NMR and 13C-NMR data of compound A-E.
Position Compound A δH J(Hz) δC Position compound B δHJ(Hz) δC
2
3
4
5
6
7
8
9
10
1’
2’
3’
4’
5’
6’
1”
2”
3”
4”
5”
4.31 m
3.97 t
3.47 m
2.95 dd
2.77 ddd
6.81 d
6.25 d
6.45 d
6.31 dd
6.93 d
6.68 d
5.57 d
1.33 s
1.35 s
10.3
15.8,10.9
15.7,5.7,1.8
8.05
8.55
2.3
8.3,1.75
15.5
10.2
10.3
70.1
31.7
30.4
129.3
108.4
152.0
109.6
149.8
114.8
118.4
156.1
102.8
157.4
106.7
128.7
116.9
127.8
75.1
27.0
27.1
1
2
3
4
5
6
7
8
9
OMe
1’
2’
3’
4’
5’
6’
7’
8’
9’
OMe
5.11 dd
5.01 dd
5.97 m
3.34 d
6.55 s
6.55 s
3.83 s (6H)
1.00 d
4.29 m
4.70 s
6.72 d
6.94 d
6.68 dd
3.78 s (3H)
17.2, 2.10
10.3, 2.04
6.90
6.18
8.22
1.38
8.22, 1.38
115.1
137.7
40.2
137.7
105.8
153.7
136.0
153.7
105.8
55.7
12.6
82.1
73.0
145.4
114.5
133.4
147.3
109.7
118.6
55.4
Position Compound C δH J(Hz) δC Position Compound D δHJ(Hz) δC
2
3
4
5
6
7
8
9
10
1’
2’
3’
4’
5’
6’
6.23 s
6.50 s
8.11 d
6.98 d
6.98 d
8.11 d
8.28
8.22
8.22
8.28
146.2
135.8
175.8
161.5
98.4
164.2
93.7
157.0
103.3
122.5
123.0
115.5
159.4
115.5
123.0
2
3
4
5
6
7
8
9
10
1’
2’
3’
4’
5’
6’
5.42 dd
2.70 dd
3.20 m
5.93 d
5.94 s
7.36 d
6.87 d
6.87 d
7.36 d
2.76,13.1
2.5,17.1
2.04
8.28
8.28
8.28
8.28
79.1
42.7
196.4
164.2
96.0
166.6
95.0
163.6
102.3
129.9
128.2
115.3
157.9
115.3
128.2
Position Compound E δH J(Hz) δC
1
3
4
5
6
7
8
9
10
11
12
13
14
CO
OMe
5.67 d
7.40 s
3.92 m
5.92 dd
5.79 dd
3.46 dd
4.70 s
2.70 d
4.33 m
1.32 d
3.69 s(3H)
6.18
2.04,5,46
2.10,5.52
6.18,9.60
1.18
6.18
102.0
152.6
109.2
38.2
140.0
127.9
106.5
53.6
83.6
55.2
175.9
66.0
21.5
166.4
50.9

Isolation, Identification and Tyrosinase Inhibitory Activities of the Extractives from Allamanda cathartica 171
Table 2. Tyrosinase inhibitory activity of extract and fractions from A. cathartic a stem.
Kojic
acid
MeOH
extract Fr.1 Fr.2 Fr.3 Fr.4 Fr.5 Fr.6 Fr.7 Fr.8
IC50(μg/ml) 6.18 98.4 100< 95.7 8.35 89.1 100< 100< 100< 100<
Fr.3-1 Fr.3-2 Fr.3-3 Fr.3-4
IC50(μg/ml) 100< 56.6 0.589 100<
Table 3. Tyrosinase inhibitory activity of compounds isolated from A. cathartic a stem.
compounds Kojic acid Glabridin Lignan Kaempferol Naringenin Allmandicin
IC50(μM) 43.7 2.93 100< 100< 100< 100<
Figure 4. Tyrosinase inhibitory activity of glabridin using tyrosine as the substrate.
Figure 5. Tyrosinase inhibito ry activity of glabridin using DOPA as the substrate.
acid value 298 μM. Tyrosinase inhibitory activity of
glabridin was more than 10 times stronger than that of
kojic acid. Thus, glabridin is the center active compound,
and possibly has a potent activity for cosmetic as whit-
ening agent.
4. Conclusions
In this study, 5 compounds were newly found in A. ca-
tharitica stem, namely glabridin, new lignin, naringenin,
kaempferol and allamandicin. Among all the isolated
compounds, glabridin has the most potent tyrosinase in-
hibitory activity.
REFERENCES
[1] J. L. C. H. van Valkenburg and N. Bunyapraphatsara,
(Eds.), “Plant Resources of South-Ease Asia No 12(2)

Isolation, Identification and Tyrosinase Inhibitory Activities of the Extractives from Allamanda cathartica 172
Medicinal and Poisonous Plants 2,” Plant Resources of
South-East Asia (PROSEA), Bogor, 2002, pp. 49-52.
[2] P. A. Akah and V. N. Offiah, “Gastrointestinal Effects of
Allamanda Cathartica Leaf Extracts,” International
Journal of Pharmacognosy, Vol. 30, No. 3, 1992, pp. 213-
217. doi:10.3109/13880209209054001
[3] M. J. Balunas and A. D. Kinghorn, “Drug Discovery from
Medicinal Plants,” Life Sciences, Vol. 78, No. 5, 2005, pp.
431-441. doi:10.1016/j.lfs.2005.09.012
[4] S. Khatib, O. Nerya, R. Musa, M. Shmuel, S. Tamir and J.
Vaya, “Chalcones as Potent Tyrosinase Inhibitors: The
Importance of a 2,4-Substituted Resorcinol Moiety,”
Bioorganic & Medicinal Chemistry, Vol. 13, No. 2, 2005,
pp. 433-441. doi:10.1016/j.bmc.2004.10.010
[5] O. Nerya, R. Musa, S. Khatib, S. Tamir and J. Vaya,
“Chalcones as Potent Tyrosinase Inhibitors: The Effect of
Hydroxyl Positions and Numbers,” Phytochemistry, Vol.
65, No. 10, 2004, pp. 1389-1395.
doi:10.1016/j.phytochem.2004.04.016
[6] Z.-P. Zheng, K.-W. Cheng, J. Chao, J. Wu and M. Wang,
“Tyrosinase Inhibitors from Paper Mulberry (Broussone-
tia Papyrifera),” Food Chemistry, Vol. 106, No. 2, 2008,
pp. 529-535. doi:10.1016/j.foodchem.2007.06.037
[7] C. Okunji, S. Komarnytsky, G. Fear, A. Poulev, D. M.
Ribnicky, P. I. Awachie, Y. Ito and I. Raskin, “Prepara-
tive Isolation and Identification of Tyrosinase Inhibitors
from the Seeds of Garcinia Kola by High-Speed Counter-
Current Chromatography,” Journal of Chromatography A,
Vol. 1151, No. 1-2, 2007, pp. 45-50.
doi:10.1016/j.chroma.2007.02.085
[8] Azhar-ul-Haq, A. Malik, M. T. H. Khan, Anwar-ul-Haq,
S. B. Khan, A. Ahmad and M. I. Choudhary, “Tyrosinase
Inhibitory Lignans from the Methanol Extract of the
Roots of Vitex Negundo Linn. and Their Structure-Acti-
vity Relationship,” Phytomedicine, Vol. 13, No. 4, 2006,
pp. 255-260. doi:10.1016/j.phymed.2004.09.001
[9] M.-H. Lee, Y.-P. Lin, F.-L. Hsu, G.-R. Zhan and K.-Y.
Yen, “Bioactive Constituents of Spatholobus Suberectus
in Regulating Tyrosinase-Related Proteins and mRNA in
HEMn Cells,” Phytochemistry, Vol. 67, No. 12, 2006, pp.
1262-1270. doi:10.1016/j.phytochem.2006.05.008
[10] I. Batubara, L. K. Darusman, T. Mitsunaga, M. Rah-
miniwati and E. Djauhari, “Potency of Indonesian Me-
dicinal Plants as Tyrosinase Inhibitor and Antioxidant
Agent,” Journal Biological Sciences, Vol. 10, No. 2,
2010, pp. 138-144. doi:10.3923/jbs.2010.138.144
[11] S. M. Kupchan, A. L. Dessertme, B. T. Blaylock and R. F.
Bryan, “Isolation and Structural Elucidation of Alla-
mandin, and Antileukemic Iridoid Lactone from Alla-
manda Cathartica,” The Journal of Organic Chemistry,
Vol. 39, No. 17, 1974, pp. 2477-2482.
doi:10.1021/jo00931a001
[12] J. J. W. Coppen and A. L. Cobb, “The Occurrence of Iri-
doids in Plumeria and Allamanda,” Phytochemistry, Vol.
22, No. 1, 1983, pp. 125-128.
doi:10.1016/S0031-9422(00)80071-0
[13] J. J. W. Coppen, “Iridoids with Algicidal Properties from
Allamanda Cathartica,” Phytochemistry, Vol. 22, No. 1,
1983, pp. 179-182. doi:10.1016/S0031-9422(00)80083-7
[14] R. Singh, B. Singh, S. Singh, N. Kumar, S. Kumar and S.
Arora, “Anti-Free Radical Activities of Kaempferol Iso-
lated from Acacia nilotica (L.) Willd. Ex. Del.,” Toxicol-
ogy in Vitro, Vol. 22, No. 8, 2008, pp. 1965-1970.
doi:10.1016/j.tiv.2008.08.007
[15] A.-R. S. Ibrahim, “Sulfation of Naringenin by Cunning-
hamella Elegans,” Phytochemistry, Vol. 53, No. 2, 2000,
pp. 209-212. doi:10.1016/S0031-9422(99)00487-2