REVIEW - STUDY ON BENZOPYRANS AND OTHER ISOLATED COMPOUNDS FROM MALLOTUS APELTA

111
Journal of Chemistry, Vol. 45 (Special issue), P. 111 - 121, 2007
REVIEW:
STUDY ON BENZOPYRANS AND OTHER ISOLATED
COMPOUNDS FROM MALLOTUS APELTA
Received 15 October 2007
NGUYEN HOAI NAM
1
, NGUYEN HAI DANG
1
, PHAN VAN KIEM
1
, LUU VAN CHINH
1
,
PHAN THI BINH
2
, LA DINH MOI
3
, AND CHAU VAN MINH
1
1
Institute of Natural Products Chemistry, VAST
2
Institute of Chemistry, VAST
3
Institute of Ecology and Biological Reources, VAST

SUMMARY
During the last decades, dozens of compounds have been isolated from Mallotus apelta.
These compounds which are classified under the categories viz. terpenoids, steroids, flavonoids,

cumarino-lignoids, cembrane diterpenoids, and benzopyranoids. They were known to exhibit
interesting biological activities. The phytochemical investigations revealed that malloapelta B
which was the major component of M. apelta, showed strong NF-

B and NFAT transcription
factor inhibitory and cytotoxic activities. Numerous studies on the synthesis of some derivatives of
malloapelta B were carried out. This paper reviews the progress on the isolation, structure
elucidation and biological activities of secondary metabolites from M. apelta, especially, the new
structures of benzopyrans. Chemical modifications of malloapelta B and structure-activity
relationship were also discussed.
Keywords: Mallotus, mallotus apelta, benzopyran, malloapelta b.

I - INTRODUCTION
Ba bet (Mallotus) genus comprises about
140 species, distributed in regions from South to
South-East Asia, such as in Malaysian region
(about 75 species), in China (about 40 species)
and in Vietnam (about 40 species) [1]. Mallotus
species have been used in traditional medicine
to treat various diseases. For example Mallotus
apelta has been used to treat chronic hepatitis,
hepatalgia, enteritis, diarrhea, lymphopathy,
Mallotus repandus has been used to treat
influenza and fever, Mallotus barbatus has been
used in both Vietnamese and Chinese folk
medicine as antipyretic, diuretic, relieving pain
and curing cholera, Mallotus macrostachyus has
been used to treat wounds and pimple, Mallotus
paniculatus has been used to treat traumatic
injuries and swelling [2, 3]. To improve the

efficiency of using Mallotus species in
traditional medicine, it is neccesary to know
their chemical components and pharmaceutical
activity. However, herbal medicine and its
extracts contain hundreds of unknown
components, which are often only present in a
low amount. Moreover, variability usually exists
within the same herbal materials [4, 5]. The
chemical components may vary depending on
harvest seasons, plant origins, drying processes
and other factors [6]. Therefore, investigation on
the chemical components of the plant is
important for pharmaceutical studies. Since the
112
last decades the scientists have been searching
for the chemical components, pharmaceutical
activity of Mallotus species and synthesizing
derivatives from isolated compounds from these
species. The purpose of this review is to present
an overview of the studies on M. apelta
including the isolation and structure elucidation
of bioactive compounds, chemical modifications
and synthetic processes.
II - PHYTOCHEMISTRY
The chemistry of M. apelta has been widely
examined and the biological activity
investigations were carried out from all over of
the world. The efforts have led to the isolation
of a number of physiologically active
compounds viz. terpenoids, steroids, flavonoids,

cumarino-lignoids, cembrane diterpenoids,
benzopyranoids. We are actively working on the
synthesis of some new derivatives of
malloapelta B, a major component of M. apelta,
with an aim to find new derivatives having
stronger bioactivity. Various compounds
isolated from M. apelta in different areas have
been classified under the categories terpenoids,
steroids, flavonoids, cumarino-lignoids,
cembrane diterpenoids, benzopyranoids and
miscellaneous compounds as listed in figures 1-
5.

R
R
HO
R
1
R
2
H
O
O
R
1
H
3
CR
3
R

2
1. CH
3
(CH)CH
2
OH H
2. H CH
3
(CH)CH
2
3. CH
2
(C)CH
2
OH H
4. O
5. 3 - OH, 3-H
6. 3 - OH, 3-H
R
1
R
2
7. OH H CH
3
8. COOH CH
3
H
R
1
R

2
R
3
R
2
R
1
R
HO
HH
R
9. 3-OH -(CH
2
)
2
CH(C
2
H
5
)CH(CH
3
)
2
10. 3-OGla -(CH
2
)
2
CH(C
2
H

5
)CH(CH
3
)
2
11. 3 -OH -CH
2
=CH-CH(C
2
H
5
)CH(CH
3
)
2
R
1
R
2
12. O
13. 3-OH, 3-H
14

Figure 1: Terpenoids and steroids isolated from M. apelta
113
Terpenoids and steroids
The phytochemistry of M. apelta has been
extensively studied since the early 1980s. One
of the earlier phytochemical reports was
published in 1985, it described the isolation of

four triterpenes 3, 29-dihydroxylupane (1),
erythrodiol-3-acetate (7), acetylursolic acid (8)
and -sitosterol (9) from the roots of this plant
[7]. This plant also contains a variety of other
pentacyclic terpenoids. Based on the spectral
and chemical evidence, their structures were
determined to be hennadiol (3), friedelin (4),
friedelanol (5), epifriedelanol (6), taraxerone
(12), and epitaraxerol (13) [14, 16] and a new
pentacyclic triterpene, named malloapelta A (2)
[15, 16, 19]. From the methanol extract of M.
apelta, daucosterol (10), stigmasterol (11), and
ergosterol (14) were isolated and purified using
column chromatography over silica gel [19].
Flavonoids
Two flavonoids quercitrin (15) and astilbin
(16) were identified from M. apelta collected in
Vietnam [19].

O
H
OH
OH
HO
O
O
O
CH
3
OH

HO
O
H
O
15
OH
OH
OH
HO
O
O
O
CH
3
OH
HO
OH
O
16

Figure 2: Flavonoids isolated from M. apelta
Cumarino-lignoids
A method for the isolation and purification
of three coumarino-lignoids aquillochin (17),
cleomiscosin A (18) and 5’-demethylaquillochin
(19) from M. apelta has been reported by Cheng
et al [12].
Cembrane diterpenoids
Recently, several cembrane diterpenoids 10-
hydroxycembren-5-one (20), 6-

hydroxycembrene-5,10-dione (21) [9] 10,14-
Dihydroxy-5-isopropenyl-2,8,12-trimethyl-
cyclotetradeca-2,8,12-trienone (22) [10,11] have
been isolated from M. apleta.

OO
O
CH
2
OH
H
3
C
O
O
R
2
R
3
R
1
R
1
R
2
R
3
17. OCH
3
OH OCH

3
18. OCH
3
OH H
19. OCH
3
OH OH
R
1
O
R
2
R
1
R
2
20. OH,H H
21. O OH
22 OH,H OH

Figure
3:
Cumarino
-
lignoids and
cembrane diterpenoids isolated from
M. apelta
114
Benzopyranoids
In 2001, An et al have isolated seven

benzopyran derivatives 4-hydroxy-2,6-dimethyl-
6-(3,7-dimethyl-2,6-octadienyl)-8-(3-methyl-2-
butenyl)-2H-1-benzopyran-5,7(3H,6H)-dione
(23), 4-hydroxy-2,6,8-trimethyl-6-(3,7-
dimethyl-2,6-octadienyl)-2H-1-benzopyran-
5,7(3H,6H)-dione (24), 5-hydroxy-2,8-
dimethyl-6-(3-methyl-2-butenyl)-8-(3,7-
dimethyl-2,6-octadiennyl)-2H-1-benzopyran-
4,7(3H,8H)-dione (25), 5-hydroxy-2,8,6-
trimethyl-8-(3,7-dimethyl-2,6-octadiennyl)-2H-
1-benzopyran-4,7-(3H,8H)-dione (26), 2,3-
dihydro-5,7-dihydroxy-2,6-dimethyl-8-(3-
methyl-2-butenyl)-4H-1-benzopyran-4-one (27),
2,3-dihydro-5,7-dihydroxy-2,8-dimethyl-6-(3-
methyl-2-butenyl)-4H-1-benzopyran-4-one (28),
and 2,3-dihydro-5,7-dihydroxy-2,6,8-trimethyl-
4H-1-benzopyran-4-one (29) from the leaves of
M. apelta [13].

O
OH
O
O
R
1
CH
3
R
2
CH

3
23. CH
2
-CH=C(CH
3
)-(CH
2
)
2
-CH=C(CH
3
)
2
CH
2
-CH=C(CH
3
)
2
24. CH
2
-CH=C(CH
3
)-(CH
2
)
2
-CH=C(CH
3
)

2
CH
3
OO
O
CH
3
OH
R
2
R
1
25. CH
2
-CH=C(CH
3
)
2
CH
2
-CH=C(CH
3
)-(CH
2
)
2
-CH=C(CH
3
)
2

26. CH
3
CH
2
-CH=C(CH
3
)-(CH
2
)
2
-CH=C(CH
3
)
2
O
OH O
R
1
HO R
2
R
3
27. CH
2
-CH=C(CH
3
)
2
CH
3

CH
3
28. CH
3
-CH
2
-CH=C(CH
3
)
2
CH
3
29. CH
3
CH
3
CH
3
O
CH
3
CH
3
R
1
H
3
CO
OCH
3

R
2
30. -CO-CH=CH-CH
3
H
31. -CO-CH
2
-CH(OH)-CH
3
H
32. -CO-CH
2
-CH(CH
3
)-OCOCH
3
H
33. H -CO-CH=CH-CH
3
34. H -CO-CH
2
-CH(OH)-CH
3
35. H -CO-CH
2
-CH(CH
3
)-OCH
3
36. H

HC CH
O
H
CCH
3
O
R
1
R
2
R
2
R
1
R
1
R
2
R
3
R
1
R
2
Figure 4: Benzopyranoids isolated from M. apelta

In recent years, a number of biologically
active secondary metabolites have been isolated
from M. apelta which is widely distributed in
the northern areas of Vietnam. From the

methanol extract of the M. apelta, a new
chromene derivative with benzopyran skeleton
was isolated and identified as 1-(5,7-dimethoxy-
2,2-dimethyl-2H-chromen-8-yl)-but-2-en-1-one
or malloapelta B (30) with high yield. Different
chromatographic techniques were applied to
purify compounds 8-(1’-oxo-3’(R)-hydroxy-
butyl)-5,7-dimethoxy-2,2-dimethyl-2H-1-
115
benzopyran (31), 8-(acetic acid 1’-oxo-3’(R)-
hydroxy-butyl ester)-5,7-dimethoxy-2,2-
dimethyl-2H-1-benzopyran (32); 6-(1’-oxo-2’-
en-butyl)-5,7-dimethoxy-2,2-dimethyl-2H-1-
benzopyran (33), 6-[1'-oxo-3'(R)-hydroxy-
butyl]-5,7-dimethoxy-2,2-dimethyl-2H-1-
benzopyran (34), 6-[1'-oxo-3'(R)-methoxy-
butyl]-5,7-dimethoxy-2,2-dimethyl-2H-1-
benzopyran (35), and 6-(1’-oxo-2’,3’-epoxy-
butyl)-5,7-dimethoxy-2,2-dimethyl-2H-1-
benzopyran (36) from the leaves of M. apelta
which were named as malloapelta C, D, E, F, G,
and H, respectively [17, 18]. These compounds
were evaluated their NF-B inhibitory, NFAT
transcription factor inhibitory and cytotoxic
activities (The cytotoxic assay was evaluated on
two cancer cell lines (Human hepatocellular
carcinoma, Hep-G2) and rhabdosarcoma, RD).
Interestingly, malloapelta B showed strong NF-
B inhibitory activity, NFAT transcription
factor inhibitory and cytotoxic activities, the

other compounds showed significant cytotoxic
activities against the two mentioned human
cancer cell lines [17, 18].
Miscellaneous compounds
Recently, the Chinese scientists carried out
an extensive screening for effective anti-HIV
natural products. Notably, the extract of the roots
of M. apelta showed significant activity [8].
Based on the bioassay guided fractionation,
malloapeltine (37), 4-methoxy-3-cyano-pyridine
1-oxide (38), along with 4,5,4’-trimethyl-ellagic
acid (39) were purified from the roots of this
plant [9]. These compounds were evaluated for
their anti-HIV activity, among them 37
demonstrated a significant inhibitory activity [9].
The following phytochemical examination of the
M. apelta by Cheng et al led to the isolation of
two compounds named as 2,4,15,16-tetrahy-
droxydolabradan (40), malloapeltin (37) [10,11].
By repeated chromatography on silicagel column,
isopimpinellin (41), -tocopherol (42), trans-
phytol (43), squalene (44) -carotene (45), lutein
(46), and betulaprenol 10 (47) were isolated from
the methanol extract of this plant which were
identified by comparison with the spectral data
reported in the literatures [15, 16, 19].
N
OCH
3
CN

O
N
+
N
O
O
-
O
O
OHH
3
CO
OCH
3
H
3
CO
O
O
OH
OH
OH
HO
37
38
39
40
O
O
O

OCH
3
OCH
3
41
OH
3
CH
2
OH
nn=9
O
H
OH
2
2
2
2
44
45
46
O
HO
42
43
4
7
Figure 5: Other compounds isolated from M. apelta
116
III - CHEMICAL MODIFICATIONS AND SYNTHESES

To investigate the relationship between the structure and their bioactivity as well as to find
new derivatives having stronger effect, Binh et al synthesized the derivatives of malloapelta B by
using electro organic synthetic method (see scheme 1). As a result, a new compound named as
bimalloapelta (48) and a known compound 8-[1’-oxo-3’(R)-methoxy-butyl]-5,7-dimethoxy-2,2-
dimethyl-2H-1-benzopyran (49) were afforded (see scheme 2) [22, 23].
O
CH
3
H
3
C
H
3
C
O
H
3
CO OCH
3
O
CH
3
H
3
C
O
CH
3
H
3

C
O
CH
3
H
3
C
O
O
CH
3
H
3
C
+ClO
3
-
+
ClO
4
-
+
2e
-
-e
-
2
48
Scheme 1: Modifications of malloapelta B to produce 48 [22]
O

CH
3
H
3
C
H
3
C
O
H
3
CO OCH
3
O
C
H
3
H
3
C
H
3
C
O
H
3
CO OCH
3
O
C

H
3
H
3
C
H
3
C
O
H
3
CO OCH
3
H
3
CO
-e
-
CH
3
OH, -H
+
4
9
Scheme 2: Modifications of malloapelta B to produce 49 [23]
OH
3
CO
OCH
3

O
+ROH
+ROH
(C
2
H
5
)
2
NH
OH
3
CO
OCH
3
O
OR
CH
3
(C
2
H
5
)
2
NH
O
C
H
H

2
C
H
3
CO
OCH
3
O
CH
3
49. R=CH
3
50. R=CH
2
CH
3
51. R=CH
2
CH
2
CH
3
52. R=CH(CH
3
)
2
Scheme 3: Modifications of malloapelta B to produce 49 - 52 [25]
OH
3
CO

OCH
3
O
HNO
3
/H
2
SO
4
CHCl
3
OH
3
CO
OCH
3
O
NO
2
5
3
Scheme 4: Modification of malloapelta B to produce 53 [25]
117
As part of our ongoing studies to look for new derivatives having stronger bioactivities, nine
benzopyrans 8-[1’-oxo-3’(R)-methoxy-butyl]-5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (49),
8-[1’-oxo-3’(R)-ethoxy-butyl]-5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (50), 8-[1’-oxo-3’(R)-
propoxy-butyl]-5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (51), 8-[1’-oxo-3’(R)-isopropoxy-
butyl]-5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (52), 8-[1’-oxo-2’-en-butyl]-5,7-dimethoxy-3-
nitro-2,2-dimethyl-2H-1-benzopyran (53), 8-[1’-oxo-3’(R)-methyl-4’-acetyl-5’-oxo-hexyl]-5,7-
dimethoxy-2,2-dimethyl-2H-1-benzopyran (54), 8-(1’-oxo-3’(R)-methyl-4’(S/R)-(methylformiate)-

5’-oxo-hexyl)-5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (55), 8-(1’-oxo-3’(R)-methyl-4’(S/R)-
(ethylformiate)-5’-oxo-hexyl)-5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (56), and 1-(5,7-
dimethoxy-2,2-dimethyl-2H-chromen-8-yl)butan-1-one (57) were synthesized by addition, nitration
and Michael reactions from malloapleta B [24, 25, 26].
O
H
3
CO
OCH
3
O
CH
3
COCH
2
R
Michael reaction
OCH
3
CH
3
O
O
CH
3
CH
3
O
O
OH

3
CO
OCH
3
O
R
H
3
C
OCH
2
CH
3
CH
3
O
O
55. R=
54 R=
56. R=

Scheme 5: Modifications of malloapelta B to produce 54 - 56 [24]
O
CH
3
CH
3
OCH
3
H

3
CO
O
C
O
O
C
H
3
COOCH
3
O
CH
3
CH
3
OCH
3
H
3
CO
O
O
C
H
3
CH
3
CH
3

OCH
3
H
3
CO
O
CH
3
CH
3
CH
3
OCH
3
H
3
CO
HO
O
CH
3
CH
3
CH
3
OCH
3
H
3
CO

O
O
CH
3
CH
3
CH
3
OCH
3
H
3
CO
O
O
CH
3
CH
3
CH
3
OCH
3
H
3
CO
H
3
CO
O

CH
3
CH
3
CH
3
OCH
3
H
3
CO
O
H
2
/Pd-C
30 psi
H
2
/Pd-C
15 psi
Dimethyl malonate
NaOCH
3
1) CH
3
CH
2
MgBr
2) NH
4

Cl/H
2
O
1) LiAlH
4
2) H
2
O/MeOH
NaBH
4
/M eOH
10-15
0
C
5
7
58
59
60
61
62
63

Scheme 6: Modifications of malloapelta B to produce 57 - 63 [26]
118
The other method for synthesizing of malloapelta B’s derivatives has been reported by Chinh
et al [26]. Compounds 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)butan-1-one (57) was
produced by reducing malloapelta B in sodium borohydride environment (see scheme 6), 1-(5,7-
dimethoxy-2,2-dimethylchroman-8-yl)butan-1-one (58), 8-butyl-5,7-dimethoxy-2,2-
dimethylchroman (59) were produced by reducing malloapleta B in catalytic hydrogenation (see

Scheme 6). The other compounds 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)-3-methoxy-1-
butene (60), 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)-3-hydroxy-1-butene (61), 1-(5,7-
dimethoxy-2,2-dimethyl-2H-chromen-8-yl)-3-methylpentan-1-one (62), and 2-(4-(5,7-dimethoxy-
2,2-dimethyl-2H-chromen-8-yl)-4-oxobutan-2-yl)malonate (63) were synthesized from malloapelta
B by addition reaction (see Scheme 6). By applying this method we also obtained the same
compounds. The summary of synthesized compounds from malloapelta B by these methods is
exhibited in Figure 6.
O
CH
3
CH
3
O
O
R
CH
3
H
3
CO
OCH
3
R
49. CH
3
50. CH
2
CH
3
51. CH

2
CH
2
CH
3
52. CH(CH
3
)
2
O
CH
3
CH
3
O
R
CH
3
H
3
CO
OCH
3
CH
3
CH
3
O
O
R=

OCH
3
CH
3
O
O
OCH
2
CH
3
CH
3
O
O
5
4
55 56
OO
O
CH
3
H
3
C
CH
3
H
3
C
CH

3
H
3
C
O
O
OCH
3
H
3
CO
H
3
CO
OCH
3
HH
H
48
OH
3
CO
OCH
3
O
NO
2
O
OH
3

CO
OCH
3
O
OH
3
CO
OCH
3
53
57
58
OH
3
CO
OCH
3
5
9
OH
3
CO
OCH
3
OCH
3
OH
3
CO
OCH

3
OH
O
OH
3
CO
OCH
3
O
O
-
OO
-
OO
OCH
3
H
3
CO
60
61
62
63

Figure 6: Synthesized compounds from malloapelta B

119
IV - STRUCTURES AND BIOLOGICAL
ACTIVITIES OF SYNTHESIZED
COMPOUNDS

It is well-known that LPS or TNF induced
NF B activation are related to septic shock,
autoimmune disorders, and inflammatory
diseases [27,28]. It is also agreed that
compounds containing , -unsaturated carbonyl
moiety usually exhibit good inhibitory activity
against these factors [26, 27]. Interestingly,
benzopyrans, with ,-unsaturated carbonyl
group, also display this characteristic [20, 21].
Malloapleta B with ,-unsaturated
carbonyl motiety in side chain presented a
potent NF B inhibitory activity (IC
50
= 5.0
µM), and NFAT transcription factor inhibitory
(IC
50
= 2.48 µM) and cytotoxic activity against
two human cancer cell lines (Hep-G2 and KB
with IC
5
0
= 0.49 µg/ml and 0.54 µg/ml,
respectively) [20, 21]. Therefore, malloapelta B
were selected for studying the relationship
between structure and biological activity. In the
structure of malloapelta B (see Figure 7) we
proposed three positions A, B, C which seem to
be active in organic reaction. To investigate the
relationship between structure and biological

activity of this compound, we modified its
structure by changing individual A, B, C
position or both A and B, A and C, B and C to
produce some derivatives. Then the biological
activity of the derivatives were retested by the
same method applied for malloapelta B [18, 20,
21, 25]. The relationship studies between
structure and biological activity of the
derivatives and malloapleta B were carried out
by comparing their biological activity with that
of malloapelta B.
Binh et al [22] modified the structure of
malloapelta B by using cyclic voltammetry to
oxidize the C position, in this method, a
mechanism of electro organic oxidation of
malloapelta B was proposed as shown in scheme
1. Firstly, malloapelta B transferred one electron
to convert into corresponding cation radical,
which was further oxidized by LiClO
4
then
converted into 48. This compound was tested on
Hep-G2 and RD cells. As a result, 48 exhibited
strongly cytotoxic activity on both tested cell
lines with the IC
50
values of 0.46 µg/ml and 0.33
µg/ml, respectively.

OH

3
CO
OCH
3
O
2
3
45
6
7
8
9
10
11
12
1'
2
'
3'
4'

Figure 7: Three positions A, B, C in the
structure of malloapelta B
Comparing these results with those of
malloapelta B, the IC
50
values of both
compounds were similar and that the oxidation
of double bond at C-3/C4 (C position) did not
affect to their cytotoxic activity. The other

method [25] to modify the C position (double
bond at C-3/C4) of the structure of malloapelta
B was applied by using nitration reaction (see
scheme 3) to produce 53. In this method the
hydrogen atom (H-3) of the C position on
structure of malloapleta B was replaced by the
NO
2
group. This compound also exhibited
strongly cytotoxic activity on both tested cell
lines Hep-G2 and RD with the IC
50
values of
0.87 µg/ml and 0.62 µg/ml, respectively.
Comparing these resutls with those of
malloapelta B, the IC
50
values of this compound
was slightly higher. The observed result
suggested that the addition of NO
2
group into
the position C in the structure of malloapelta B
was not affect the cytotoxic activities. The
decreasing cytotoxic activity of this compound
due to NO
2
group obstructed the access into the
C position of structure of malloapelta B [25].
The B position on the structure of malloapelta B

was also modified by an electro organic
oxidation method to produce compound 49 (see
scheme 2) [23]. The B position was made partial
changes by an addition reaction and Michael
reaction with different reagents to produce
A
B
C
120
compounds 49-52, 54-57, 62-63 (see scheme
3,5,6) [24,25,26]. The reduction of double bond
(B position) and carbonyl group (A position)
was attempted by catalytic hydrogenation of
malloapelta B at 30 psi of H
2
gas in the presence
of 10% Pd/C resulted in the conversion of ,-
unsaturated carbonyl to butyl yielded compound
59 (see scheme 6). However, by carrying out the
same reaction at 15 psi of H
2
gas in the presence
of 10% Pd/C, this reaction reduced the double
bond (B position) and saturation of 3,4 double
bond (C position) in the pyran ring to yield
compound 58 (see scheme 6). Compound 60
and 61 were produced by treating malloapelta B
with lithium aluminum hydride. The results are
much complicated with the formation of
isomerizied products 60 and 61 as showed in the

scheme 6 [26]. Those compounds above were
assayed for their inhibitory activity on TNF-
induced, NF B using transfected Hela cell and
the results are described in the literature [26].
The authors concluded that only 59 showed the
slightly decreased inhibitory activity. The rest of
compounds showed the NF-B inhibitory
activity at nearly the same concentration of cell
cytotoxicity. Thus these compounds are
considered to be inactive. The results revealed
that ,-unsaturated carbonyl moiety and the
C=C double bond plays an important role to the
activity of malloapelta B. According to the
discussion above, mallotapelta B still showed
the most interesting biological activities.
V - CONCLUDING REMARKS
Numerous compounds have been isolated
and identified from Mallotus apelta since the
last two decades. They were classified under the
categories triterpenoids, steroids, flavonoids,
cumarino-lignoids, cembrane diterpenoids,
benzopyranoids and miscellaneous compounds.
Among them, benzopyranoids were known to be
the most identified components from this plant.
Interestingly, the results of biological activity
assay showed that malloapelta B, a major
component of M. apelta, exhibited considerable
NF-B and NFAT transcription factor inhibitory
and cytotoxic activities. Consequently, great
efforts have been made to modify the structure

of malloapelta B for pharmaceutical tests. As a
result, sixteen derivatives were obtained.
Structure-activity relationship studies on the
synthesized compounds revealed that ,-
unsaturated carbonyl moiety and the C=C
double bond plays an important role to the
activity of malloapelta B. It is clear that for a
number of studies on the synthesis of some new
derivatives, malloapelta B presented the most
interesting biological activities.
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