全 文 ：书天然产物研究与开发 Nat Prod Ｒes Dev 2015，27:1843-1846
文章编号:1001-6880(2015)11-1843-04
Ｒeceived:July 28，2015 Accepted:September 21，2015
Foundation item:This work was supported by the National Natural Sci-
ence Foundation of China (21432010);The Science Foundation of
Yunnan (2014A050) ;The Technological leading talent project of Yun-
nan，and the Xibuzhiguang Project (grant to Y． T． D．)
* Corresponding Author Tel:86-871-5223070;E-mail:diyt@ mail． kib．
ac． cn;haoxj@ mail． kib． ac． cn
长序三宝木中的降二萜成分研究
唐贵华1，2，苑春茂1，张 于1，李顺林1，邸迎彤1* ，郝小江1*
1中国科学院昆明植物研究所 植物化学与西部植物资源持续利用国家重点实验室，昆明 650201;
2中山大学药学院，广州 510006
摘 要:从长序三宝木(Trigonostemon howii)茎的化学成分研究中发现 4 个降二萜化合物，其中新化合物 trigo-
howilone A(1)经波谱数据包括核磁、质谱、比旋光等鉴定为 trigoxyphin P 的对映异构体。已知化合物结构确定
为 trigoxyphin Q(2)，trigohowilol H(修订后的俗名)(3)和 9-O-demethyltrigonostemone(4)。所有化合物均为首次
从该植物中分离得到。
关键词:大戟科;长序三宝木;降二萜;trigohowilone A;(－)-trigoxyphin P
中图分类号:Ｒ284． 1;Q946． 91 文献标识码:A DOI:10． 16333 / j． 1001-6880． 2015． 11． 001
Degraded Diterpenoids from Trigonostemon howii
TANG Gui-hua1，2，YUAN Chun-mao1，ZHANG Yu1，LI Shun-lin1，DI Ying-tong1* ，HAO Xiao-jiang1*
1State Key Laboratory of Phytochemistry and Plant Ｒesources in West China，Kunming Institute of Botany，Chinese Academy of Sciences，
Yunnan Kunming 650201，China;2School of Pharmaceutical Sciences，Sun Yat-sen University，Guangdong Guangzhou 510006，China
Abstract:Phytochemical investigation on the stems of Trigonostemon howii resulted in the isolation of four degraded
diterpenoids． A new compound，trigohowilone A (1)，was defined as the enantiomer of trigoxyphin P based on the analy-
ses of its spectroscopic data including NMＲ，MS，and the specific rotation data． The structures of known compounds were
identified as trigoxyphin Q (2) ，trigohowilol H (revised trivial name) (3) ，and 9-O-demethyltrigonostemone (4)． All
compounds were obtained from the plant for the first time．
Key words:Euphorbiaceae;Trigonostemon howii;degraded diterpenoids;trigohowilone A;(－)-trigoxyphin P
Introduction
Trigonostemon howii Merrill ＆ Chun (Euphorbiace-
ae)，an evergreen shrub growing in dense montane for-
ests，is distributed in Hainan Province of China and Vi-
etnam ［1］． Previous research on this plant collected in
China has revealed the occurrence of 14 daphnane-type
diterpenoids ［2］ and 10 degraded diterpenoids ［3］，while
phytochemical investigation of the Vietnamese plant
species T． howii only obtained a tigliane diterpenoid，
four coumarins，and two penylpropanoids ［4］． As a part
of our ongoing research on this plant ［3］，four degraded
diterpenoids (Fig． 1)，including the enantiomer of trig-
oxyphin P，trigohowilone A (1) ，and three known
ones，trigoxyphin Q (2) ，trigohowilol H (3) ，and 9-O-
demethyltrigonostemone (4) were isolated from the
stems of T． howii collected from Hainan Province of
China． Compounds 1-4 were obtained from T． howii for
the first time．
Materials and Methods
Instruments
1D and 2D NMＲ spectra were recorded on Bruker AM-
400 and Bruker DＲX-600 spectrometers using TMS as
an internal standard． ESI-MS analyses were carried out
on an API Qstar Pulsar 1 instrument． HＲ-EI-MS analy-
ses were carried out on a Waters Autospec Premier
P776 mass spectrometer． Silica gel (80-100 and 300-
400 mesh，Qingdao Makall Group Co．，Ltd．)，C8 silica
gel (20-45 μm，Fuji Silysia Chemical Ltd．)，and Seph-
adexLH-20 (GE Healthcare Bio-Xciences AB)were
used for column chromatography (CC)and silica gel
GF254(Qingdao)was used for preparative TLC in the
form of precoated plates． TLC spots were visualized un-
der UV light and by dipping into 5% H2SO4 in EtOH
followed by heating．
Plant material
The stems of T． howii were collected from Sanya，Hain-
an Province，China，in October 2011． The plant was i-
dentified by one of the authors (Gui-hua Tang)，and a
voucher specimen (H20101201) was deposited at
State Key Laboratory of Phytochemistry and Plant Ｒe-
sources in West China，Kunming Institute of Botany．
Extraction and isolation
The air-dried stems of T. howii (32. 0 kg)were pow-
dered and extracted with MeOH for three times (4，3，
and 3 h，respectively)under reflux. After evaporating
the solution under reduced pressure，the crude residue
was re-suspended in water and then partitioned succes-
sively with EtOAc and n-BuOH to give two correspond-
ing portions. The EtOAc extract (196. 6 g)was subjec-
ted to CC over silica gel (80-100 mesh)using petrole-
um ether (PE)-Me2CO (50 ∶ 1→0 ∶ 1)to yield five
fractions (A-E). Fr. B was subjected to CC over C8 sil-
ica gel eluting with a gradient of increasing MeOH in
H2O (30% -100%) to gain 10 fractions (B1-B10)
. Subsequently，Fr. B2 was chromatographed on a Seph-
adex LH-20 column (MeOH)and a silica gel column
(300-400 mesh，CHCl3-Me2CO，20 ∶ 1 + 1% formic
acid)to obtain 3 (5. 6 mg). Fr. D was subjected to CC
over C8 silica gel eluting with a gradient of increasing
MeOH in H2O (50% -100%) to gain nine fractions
(D1-D9). Fr. D8 was chromatographed on a Sephadex
LH-20 column (MeOH)to gain four subfractions (D8a-
B8d). After filtration the insoluble material from sub-
fraction D8b，the stock was subjected to CC over a silica
gel column (300-400 mesh，CHCl3-Me2CO，10∶ 1)and
a Sephadex LH-20 column (Me2CO)to afford 1(4. 5
mg). Subfraction D8d was purified by a silica gel col-
umn (300-400 mesh，CHCl3 – Me2CO，15∶ 1)to get 2
(1. 3 mg)and 4 (11. 8 mg).
Trigohowilone A (1) Yellow amorphous powder;
［α］25D － 21. 5 (c 0. 27，CHCl3);UV (MeOH)λmax
(logε)366 (3. 77)，312 (3. 99) ，283 (4. 08) ，208
(4. 51)nm;IＲ (KBr)υmax 3442，1707，1689，1657，
1640，1629，1549，1511 cm-1;1H NMＲ (CD3OD，600
MHz)δ 7. 86 (1H，s，H-14)，6. 44 (1H，s，H-6) ，
6. 27 (2H，s，H-2and H-6) ，4. 56 (1H，br. s，H-7) ，
3. 67 (6H，s，3-and 5-OMe) ，3. 17 (1H，q，J = 7. 2
Hz，H-8) ，2 37 (3H，s，H-17) ，1. 35 (3H，s，H-18) ，
1. 33 (3H，s，H-19) ，1. 27 (3H，d，J = 7. 2 Hz，H-
9) ;13 C NMＲ (CD3OD，150 MHz)δ 207. 9 (C，C-
3)，187. 2 (C，C-7) ，159. 9 (C，C-12) ，159. 6 (C，C-
5) ，150. 2 (C，C-8) ，149. 1(C × 2，C-3 and C-5) ，
143. 9 (C，C-1) ，135. 8 (C，C-4) ，135. 4 (C，C-1) ，
131. 8 (C，C-13) ，128. 9 (CH，C-14) ，128. 0 (C，C-
9) ，124. 1 (C，C-11) ，123. 4 (C，C-10) ，121. 1 (CH，
C-6) ，105. 2 (CH × 2，C-2 and C-6) ，56. 6 (CH3 ×
2，3-and 5-OMe)，48. 2 (C，C-4) ，46. 4 (CH，C-
7) ，36. 7 (CH，C-8) ，24. 4 (CH3，C-19)，22. 6
(CH3，C-18)，20. 7 (CH3，C-9)，17. 7 (CH3，C-17);
ESI-MS m/z 469 ［M + Na］+，HＲ-EI-MS m/z
446. 1715［M］+(calcd for C27H26O6，446. 1729).
Trigoxyphin Q (2) Yellow amorphous powder;UV
(MeOH)λmax(logε)542 (3. 30)，408 (2. 97) ，373
(3. 02) ，317 (3. 62) ，291 (3. 65) ，208 (4. 11)nm;
IＲ (KBr)υmax 3442，1711，1689，1630，1552 cm
-1;1H
NMＲ (CD3OD，400 MHz)δ 8. 26 (1H，s，H-14)，
6. 89 (1H，s，H-6) ，6. 53 (2H，s，H-2 and H-6) ，
3. 84 (6H，s，3-and 5-OMe) ，2. 47 (3H，s，H-19) ，
2，20 (3H，s，H-17) ，1. 47 (6H，s，H-18 and H-19) ;
13C NMＲ (CD3OD，100 MHz)(seven carbon reso-
nances not visible)δ 209. 0 (C，C-3) ，156. 3 (C，C-
5) ，150. 3(C × 2，C-3 and C-5) ，148. 2 (C，C-1) ，
136. 4 (C，C-4) ，135. 3 (C，C-7) ，135. 2 (CH，C-
14) ，132. 7 (C，C-8) ，126. 3 (C，C-9) ，118. 5 (CH，
C-6) ，106. 5 (CH × 2，C-3 and C-5) ，57. 0 (CH3 ×
2，3-and 5-OMe)，50. 3 (C，C-4) ，24. 4 (CH3 × 2，C-
18 and C-19)，17. 7 (CH3，C-17)，15. 1 (C，C-9) ;
ESI-MS m/z 467［M + Na］+，911 ［2M + Na］+，HＲ-
EI-MS m/z 444. 1581 ［M］+ (calcd for C27 H24 O6，
446. 1573).
Trigohowilol H (3) Yellow amorphous powder;UV
(MeOH)λmax(logε)434 (4. 27)，305 (3. 97) ，293
(3. 90) ，248 (4. 10) ，220 (4. 30) ，201 (4. 24)nm;
IＲ (KBr)υmax 3428，1734，1662，1626，1574，1446，
1403，1344，1300 cm-1;1H NMＲ (acetone-d6，600
MHz)δ 8. 36 (1H，s，H-11)，8. 04 (1H，s，H-14) ，
6. 69 (1H，s，H-6) ，2. 34 (3H，s，H-11) ，1. 41 (6H，
s，H-18 and H-19) ;13 C NMＲ (acetone-d6，150 MHz)
4481 Nat Prod Ｒes Dev Vol. 27
δ 207. 9 (C，C-3)，184. 0 (C，C-7) ，166. 9 (C，C-1) ，
166. 2 (C，C-5) ，161. 4 (C，C-12) ，133. 5 (C，C-9) ，
129. 0 (C，C-13) ，126. 4 (CH，C-14) ，124. 5 (C，C-
8) ，119. 5 (C，C-10) ，101. 9 (CH，C-6) ，107. 6 (CH，
C-11) ，43. 9 (C，C-4) ，25. 0 (CH3 × 2，C-18 and C-
19)，17. 0 (CH3，C-17);ESI-MS m/z 293 ［M +
Na］+，563［2M + Na］+ .
9-O-Demethyltrigonostemone (4) Yellow amor-
phous powder;1H NMＲ (acetone-d6，400 MHz) δ
9. 22 (1H，s，7-OH)，8. 00 (1H，s，H-14) ，7. 58 (1H，
s，H-11) ，7. 56 (1H，s，H-1) ，6. 94 (1H，s，H-5) ，
4. 02 (3H，s，12-OCH3)，3. 84 (3H，s，2-OCH3)，2. 34
(3H，s，H-17) ，1. 43 (6H，s，H-18 and H-19) ;13 C
NMＲ (acetone-d6，100 MHz) δ 198. 7 (C，C-3)，
158. 9 (C，C-12) ，153. 9 (C，C-7) ，148. 5 (C，C-2) ，
144. 0 (C，C-5) ，132. 6 (C，C-9) ，127. 4 (C，C-13) ，
124. 4 (CH，C-14) ，119. 7 (C，C-8) ，115. 4 (C，C-
10) ，113. 5 (CH，C-1) ，105. 9 (CH，C-6) ，101. 0
(CH，C-11) ，55. 9 (CH3，2-OCH3)，55. 8 (CH3，12-
OCH3)，49. 6 (C，C-4)，28. 4(CH3 × 2，C-18 and C-19)，
16. 8 (CH3，C-17);ESI-MS m/z 335［M + Na］
+ .
Fig. 1 Chemical structures of compounds 1-4
Structural identification
Trigohowilone A (1)，yellow amorphous powder，had
the molecular formula C27H26O6 with 15 degrees of un-
saturation based on the［M］+ at m/z 446. 1715 (calcd
446. 1729) in its HＲ-EI-MS. The IＲ absorptions at
3442，1707，1689，1657，1640，1629，1549，1511 cm-1
indicated the presence of hydroxyl，carbonyl and phenyl
functionalities. The 1H NMＲ spectrum showed four aro-
matic or olefinic protons ［δH 7. 86 (1H，s)，6. 27
(2H，s) and 6. 44 (1H，s) ］，two methine protons
［4. 55 (1H，br. s)and 3. 17 (1H，q，J = 7. 2 Hz) ］，
three singlet methyls［δH 2. 36 (3H，s)，1. 35 (3H，s)
and 1. 32 (3H，s) ］，one methyl［δH 1. 26 (1H，d，J =
7. 2 Hz)］ coupled with the proton at 3. 17 ppm，and
two O-methyl groups ［δH 3. 67 (6H，s)］. 27 signals
consistent with six methyls，six methines，and 15 qua-
ternary carbons were observed in the 13C NMＲ and
DEPT spectra.
Fig. 2 Key 2D correlations of trigohowilone A (1)
Preliminary analyses of 2D NMＲ data showed that two
singlet methyls at δH 1. 35 (H-18)and 1. 32 (H-19)
were the gem-dimethyl groups located at the quaternary
carbon at δC 48. 2 (C-4)，and the methyl at δH 2. 36
(H-17)was the aromatic methyl group. These informa-
tion together with two ketone carbonyl［δC 207. 9 (C-
3)and 187. 2 (C-7)］ indicated that 1 possessed a
moiety resembled the skeleton of trigohowilol H
(3)［5］，which was confirmed by the HMBC and ＲOE-
SY correlations (Fig. 2). In addition，analyses of 2D
NMＲ data determined the presence of a symmetrical
phenylpropanoid moiety ［δH 6. 27 (H-2 /6)，4. 55
(H-7) ，3. 17 (H-8) ，1. 26 (H-9) ，3. 67 (3 /5-
OCH3);δC 149. 1 (C-3 /5)，135. 7 (C-4) ，135. 4
(C-1) ，105. 2 (C-2 /6) ，46. 4 (C-7) ，36. 7 (C-
8) ，20. 7 (C-9) ，56. 6 (3 /5-OCH3)］. HMBC cor-
relations of H-9 /C-1，H-8 /C-3，C-10，and C-11，and
H-7 /C-1，C-9，and C-12 (Fig. 2)confirmed the two
above-mentioned moieties via C-1 – C-8and C-11 –
C-7carbon bonds to construct the planar structure of
1，which was identified as trigoxyphin P，isolated from
the same genus species T. xyphophylloides ［6］. The rela-
tive configuration of 1 was also determined as the same
as trigoxyphin P by analyses of the coupling constant of
H-7and H-8 and the ＲOESY correlation of H-2or H-
6 /H-8(Fig. 2). However，the specific rotation of 1
(［α］20D = － 21. 5)was opposite to that of trigoxyphin
P(［α］20D = + 32. 6)，which indicated that 1 and trig-
oxyphin P were a pair of enantiomers. Thus，the struc-
ture of compound 1 was defined as shown and named
5481Vol. 27 TANG Gui-hua，et al:Degraded Diterpenoids from Trigonostemon howii
trigohowilone A or (－)-trigoxyphin P.
Analyses of the 2D NMＲ spectra of compounds 2 and 3
determined their structures，which were identical to
trigoxyphin Q ［6］ and trigoxyphin U ［5］，
respectively. However，there is another different struc-
ture named trigoxyphin U ［7］，so the trivial name of
compound 3 was revised as trigohowilol H. Moreover，
the known compound，9-O-demethyltrigonostemone (4)
［8］，was identified by comparison of its spectroscopic
data with literature data.
Fig. 3 Scheme 1 Proposed biogenetic pathways of compounds 1-4
The intriguing discovery of these four degraded diterpe-
noids (1-4)in the same plant led us to further study
the possible biogenetic relationships among these com-
pounds. As shown in Scheme 1，the postulated precur-
sor (i)could be modified through different biosynthetic
pathways involving ring contraction based on the rear-
rangement of α，β-epoxyketone［9］ and oxidation to form
the intermediates ii and vii，respectively. Oxidative de-
carboxylation of the intermediate (ii)would yield iii，
which was then converted into iv or vi by keto-enol
tautomerism. The heterodimers，compounds 1 and 2，
could be visualized as cycloadducts of iv and phenyl-
propanoid via intermolecular Diels-Alder reaction，
whereas 3 could be derived from the oxidation of
vi. Oxidation of the intermediate (i)followed by meth-
yl esterification would produce compound 4.
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