Acid esters of triterpenoids and steroid glycosides from Gambeya africana

Article abstract of DOI:10.1055/s-2002-34416

Chemical studies of the CH₂Cl₂-MeOH extract of the seeds of Gambeya africana (Baker) Pierre led to the isolation of 15 compounds. Their structures were established on the basis of spectroscopic methods and chemical reactions. They co

Full text of DOI:10.1055/s-2002-34416

Jean Wandji1
Francois Tillequin2
Dulcie A Mulholland3
Jean-Duplex Wansi1
Tanee Z. Fomum1
Victorine Fuendjiep4
Francine Libot2
Fatty Acid Esters of Triterpenoids and Steroid
Glycosides from Gambeya africana
Nole Tsabang4
Abstract
ol], one new steroidal glycoside, [3b-O-b-xylopyranosylchon-
drillasterol] and nine known compounds, (3b-octadecanoyloxy-
Chemical studies of the CH2Cl2-MeOH extract of the seeds of 12-oleanene, 3b-eicosanoyloxy-12-oleanene, 3b-docosanoyloxy-
Gambeya africana (Baker) Pierre led to the isolation of 15 com- 12-oleanene, 3b-acetoxy-12-oleanene, erythrodiol, 28-hydroxy-
pounds. Their structures were established on the basis of spec- b-amyrone, chondrillasterol , chondrillasterone and 3b-O-b-glu-
troscopic methods and chemical reactions. They comprised five copyranosylchondrillasterol).
new fatty acid esters of erythrodiol, [3b-octacosanoyloxy-12-
oleanen-28-ol, 3b-triacontanoyloxy-12-oleanen-28-ol, 3b-do- Key words
triacontanoyloxy-12-oleanen-28-ol, 3b-tetratriacontanoyloxy- Gambeya africana ´ Sapotaceae ´ seeds ´ fatty acid esters ´ erythro-
12-oleanen-28-ol and 3b-hexatriacontanoyloxy-12-oleanen-28- diol ´ triterpenoids ´ chondrillasterol ´ steroid glycosides
Introduction
Materials and Methods
822
The genus Gambeya belongs to the Sapotaceae family and com- General experimental procedures
prises many species widely distributed in West and Central Melting points were determined on a Kofler microhotstage appa-
Africa. It is related to Chrysophyllum Linn, a pantropical genus ratus and are uncorrected. Optical rotations were determined on
of about 80species [1]. The plants are used in folk medicine
a Perkin-Elmer 241 polarimeter. IR spectra were measured on a
for the treatment of various diseases including sterility and va- JASCO IR-810spectrometer. 1H- and 13C-NMR, 13C-DEPT, 1H-1H
ginal infections; some of them possess anti-tumoral and anti- COSY, HSQC and HMBC spectra were recorded on Bruker AC-300
inflammatory properties [2], [3], [4]. To the best of our knowl- and Gemini 400 instruments. DCI/NH3 MS and ES-MS were re-
edge, a chemical study has not yet been reported on Gambeya corded on a Nermag R10-10C instrument. GC-MS analyses were
africana, synonym of Chrysophyllum delevoyi De Wild. This carried out in a GC chromatograph coupled with an ion trap mass
present report on G. africana from Cameroon describes the iso- detector, using a DB5-MS column (30m ” 0.32 mm ” 1 mm). TLC
lation of six new compounds (1±5 and 14) along with nine analyses were performed on precoated aluminium sheets (silica
known compounds (6±13 and 15) isolated for the first time gel 60F 254, 0.25 mm). Column chromatography was performed
from the species (Fig.1).
over silica gel 60(70±230mesh and 230±400mesh) at normal
Affiliation
1 Department of Organic Chemistry, University of Yoaunde-1, Cameroon
2 Laboratoire de Pharmacognosie, UMR/CNRS No-8638, UniversitØ RenØ-Descartes, FacultØ de Pharmacie, Paris,
France
3 Department of Chemistry, Natural Products Research Group, University of Natal, Durban, Republic of South
Africa
4 Centre de recherche en plantes mØdicinales et mØdecine traditionnelle, IMPM, YaoundØ, Cameroun
Correspondence
Prof. Dr. Jean Wandji ´ Department of Organic Chemistry ´ University of Yaounde-1 ´ Faculty of Science ´
PO.Box 812 Yaounde ´ Cameroon ´ E-Mail: jeanwandji@yahoo.fr ´ Fax: +237-223 53 86
Received December 21, 2001 ´ Accepted February 24, 2002
Bibliography
Planta Med 2002; 68: 822±826 ´ ꢀ Georg Thieme Verlag Stuttgart ´ New York ´ ISSN 0032-0943

Fig. 1 Structures of compounds 1±15.
pressure, and 60C (20±40 mm), 60H (5±40 mm) under compress- 100 ml each were eluted over silica gel 60H [5±40 mm] (75 g)
ed air (300 mbar).
using CH2Cl2-MeOH (49:1) to yield erythrodiol 10 (133 mg),
chondrillasterol 12 (90mg) and chondrillasterone 13 (25 mg).
Further chromatography of the combined fractions [33±40] (10 g)
Plant material
The mature fruits of G. africana (Baker) Pierre were collected over silica gel 60H [5±40 mm] (75 g) eluted with CH2Cl2-MeOH
from Eloundem forest, around Yaounde, Cameroon in March (47:3) yielded quercetin (75 mg) and taxifolin (35 mg) in agree-
1997. A voucher specimen documenting the collection has been ment to authentic compounds with reference [11]. Combined
deposited in the National Herbarium Yaounde, Cameroon, (ref. fractions [41±46] (20g) were further subjected to column chro-
56550HNC).
matography over silica gel 60C [20±40 mm] (100 g); fractions of
100 ml each eluted with CH2Cl2-MeOH (9:1) provided chondril-
lasterol xylopyranoside 14 (30mg) and chondrillasterol gluco-
823
Extraction and isolation procedures
The seeds of G. africana were separated, air-dried and ground. pyranoside 15 (150mg).
The powder (3.0kg) was extracted with CH Cl2-MeOH (1:1) at
2
room temperature. The extract was filtered and evaporated un- Chemical derivatives
der reduced pressure. The residue (500 g) was partitioned into Transesterification: Compounds 1±5 (75 mg) were refluxed at
n-hexane- and EtOAc-soluble fractions. The EtOAc-soluble frac- 70 8C in dry MeOH (25 ml) with NaOMe (25 mg) for 2 h. The re-
tion (200 g) was subjected to column chromatography over silica action mixture was extracted successively with H2O and CHCl3.
gel (600 g). A total of 52 fractions were eluted with mixtures of The chloroform phase was dried over Na2SO4 and evaporated to
hexane-CH2Cl2 (400ml each from 100:0 to 0:100) and CH 2Cl2- give the methylalkanoates 1a±5a (34.5 mg). Addition of HCl
MeOH (400ml each from 100:0 to 50:50). The elutes were mon-
(1%) to the water phase following by extraction with CHCl3 affor-
itored using TLC and viewed under UV light (254/365 nm) and by ded erythrodiol 10 (26.7 mg).
spraying with 1% vanillin/ 5% H2SO4/EtOH reagent followed by
heating at 100 8C. The fractions were combined on the basis of Acid hydrolysis of sterol glycosides: Each compound, 14 (10mg)
similar TLC profiles. Further chromatography of the combined and 15 (10mg), was heated at reflux with 10ml of 2 N HCl-
fractions [4±7] (20g) over silica gel 60C [20±40
mm] (100 g) MeOH (1:1) for 1.5 h. The MeOH was evaporated and the aqu-
eluted with hexane-CH2Cl2 (9:1) yielded one spot for a mixture eous solution was extracted with CHCl3. The aglycone in the
of [b-amyrin stearate 6, b-amyrin eicosanoate 7, and b-amyrin chloroform layer was analysed by TLC [CH2Cl2-MeOH, 19:1].
docosanoate 8, 300 mg]. Further column chromatography of the The remaining aqueous phase was evaporated to dryness and
combined fractions [8±12] (15 g) over silica gel 60C [20±40 mm] monosaccharides (xylose from 14 and glucose from 15) were
(75 g) using hexane-CH2Cl2 (4:1) afforded b-amyrin acetate 9 identified by comparison with authentic samples on TLC [i-
(105 mg). Recrystallization of the combined fractions [13±20] PrOH-H2O, 17:3], after detection with p-anisidine phthalate.
(25 g) from acetone furnished one TLC spot containing esters of
erythrodiol with fatty acids 1±5 (200 mg). Combined fractions Physical and spectroscopic data
[21±25] (15 g) were recrystallized from hexane to give 28-hydro- Fatty acid esters of erythrodiol 1±5: White powders (acetone). IR
xy-b-amyrone 11 (20mg). Combined fractions [26±32] (12 g)
(KBr): n
max = 3450, 1730, 1518, 830 cm±1. ES-MS m/z (rel.
were further subjected to column chromatography; fractions of int.) = 871 [M1 + Na]+ (7.46) (C58H104O3Na), 899 [M2 + Na]+
Wandji J et al. Fatty Acid Esters¼ Planta Med 2002; 68: 822±826

(23.46) (C60H108O3Na), 927 [M3 + Na]+ (20.67) (C62H112O3Na), H-3¢), 3.52 (1H, m, H-4¢), 3.22 (1H, dd, J = 12.0; 9.5 Hz, H-5¢), 3.87
955 [M4 + Na]+ (22.66) (C64H116O3Na), 983 [M5 + Na]+ (7.74) (1H, dd, J = 12.0 ; 5.2 Hz, H-5¢). 13C-NMR (100 MHz, CD3OD/TMS),
(C66H120O3Na). 1H-NMR (300 MHz, CDCl3 /TMS): d = 0 .84 (6H, see Table 1.
s, CH3 ±23 and CH3 ±24), 0 .86 (3H, s, CH±30), 0.87 (3H, s,
3
CH3 ±29), 0 .92 (3H, s, CH ±25), 0 .94 (3H, s, CH ±26), 1.14 (3H, 3-O-b-D-Glucopyranosylchondrillasterol 15: Colorless crystals; m.p.
3
3
s, CH3 ±27), 3.20and 3.55 (2H, d, J = 10 .9 Hz, CH±28), 4.50 292±294 8C. [a]D22: ±43.508 (MeOH, c 0.647). IR (KBr): nmax = 3460,
2
(1H, dd, J = 6.0; 10.0 Hz, H-3), 5.17 (1H, t, J = 3.7 Hz, H-12). 2950, 1650, 1110, 970, 840 cm±1. DCI/NH3 MS: m/z = 592 [M +
Long chain; d = 0 .83 (3H, m, terminal CH), 1.23 [br s, (CH2)n], NH4]+, 575 [M + H]+. EI-MS: m/z (rel. int.): = 574 [M]+ (9.2)
3
2.27 (2H, t, J = 7.5 Hz, -CH2-CO2). 13C-NMR (75 MHz, CDCl3): (C35H58O6), 412 [M - Glc]+, 395 (93.5), 311 (14.1), 255 (100.0), 229
d = 15.5 (C-24), 16.7 (C-25), 16.8 (C-26), 18.2 (C-6), 22.0(C-16),
(34.5), 213 (25.8), 187 (17.5), 173 (15.5), 161 (24.5), 147 (34.6), 133
23.5 (C-23), 23.6 (C-30), 25.5 (C-15), 25.9 (C-27), 28.0 (C-2), (30.4), 109 (22.9). 1H-NMR (400 MHz, CD3OD/TMS): d = 0.43 (3H,
29.1 (C-23), 31.0(C-22), 31.9 (C-20), 32.5 (C-7), 33.2 (C-29),
34.0(C-21), 36.8 (C-17), 36.9 (C-10), 37.7 (C-1), 37.7 (C-4), 39.7
s, CH3-18), O.57 (3H, s, CH3±19), 0 .73 (3H, d,J = 6.6 Hz, CH3-26),
0.76 (3H, t, J = 7.1 Hz, CH3-29), 0.80 (3H, d, J = 6.6 Hz, CH3-27),
(C-8), 41.7 (C-14), 42.8 (C-18), 46.4 (C-19), 47.5 (C-9), 55.2 (C-5), 0.94 (3H, d, J = 7.5 Hz, CH3-21), 3.86 (1H, m, H-3), 4.90(1H, ddd,
69.7 (C-28), 80.5 (C-3), 122.3 (C-12), 144.2 (C-13). Long chain; J = 16.0; 7.0 and 7.0 Hz, H-23), 4.95 (1H, dd, J = 16.0and 7.0Hz,
d = 14.1 (terminal CH3), 29.7 [(CH2)n], 36.8 (CH2-CO2), 173.7 H-22), 5.10(1H, t, 8.6 Hz, H-7). Glucose; d = 4.47 (1H, d, J = 7.5
(R-COO).
Hz, H-1¢), 3.28 (1H, dd, J = 9.5; 7.5 Hz, H-2¢), 3.36 (1H, t, J = 9.9
Hz, H-3¢), 3.70(1H, m, H-4 ¢), 3.32 (1H, m, H-5¢), 3.69 (1H, dd,
Methylalkanoates 1a±5a: White powders. GC-MS; (70eV): m/z
+
(rel. int.) = Rt1a 16: 56, 438 [M1a]+ (12.5); Rt2a 17: 58, 466 [M2a
]
(11.2); Rt3a 18: 60, 494 [M3a]+ (9.7); Rt4a 19: 62, 522 [M4a]+ (8.9)
and Rt5a 20: 64, 550 [M5a]+ (7.5).
Table 1 13C-NMR chemical shifts of compounds 12, 13, 14 and 15
No.
12 (DCCl3)
13 (CDCl3)
14 (CD3OD)*
15 (CD3OD)*
b-Amyrin fatty acid esters 6±8: White powders (CDCl3). ES-MS:
m/z (rel. int.) = 743 [M6 + Na]+ (8.5), 771 [M7 + Na]+ (24.3), 799
[M8 + Na]+ (48.5). 1H-NMR (CDCl3/TMS), in accordance to refer-
ence [5].
1
2
3
4
5
6
7
37.1
26.1
38.1
38.8
211.4
44.2
43.0
30.1
117.0
140.4
48.9
34.4
21.7
39.4
43.3
55.0
23.0
28.5
55.9
13.1
12.5
38.2
29.8
79.5
35.2
41.0
30.0
118.7
140.4
50.4
35.6
22.6
40.4
44.3
55.2
24.2
29.8
56.856.8
13.2
13.9
38.2
29.7
79.8
35.3
41.1
30.4
118.8
71.0
34.2
40.2
b-Amyrin acetate 9: Colorless crystals; m.p. 242±2448C; DCI/
1
NH3 MS: m/z = 486 [M + NH4]+; H- and 13C-NMR (CDCl3/TMS),
29.6
117.4
139.5
49.4
see literature [6].
8139.6
Erythrodiol 10: Colorless crystals; m.p. 2378C. [a] 22: + 768
9
50.4
35.7
22.6
40.4
44.4
55.3
24.5
29.8
D
824
10
34.2
(CHCl3, c 0.75). DCI/NH3 MS: m/z = 442 [M + NH4]+. 13C-NMR
11
21.5
(CDCl3), in accordance to reference [7].
12
39.4
13
43.3
28-Hydroxy-12-oleanen-3-one 11: White powder, m.p. 199 8C.
[a]D22:738 (CHCl3, c 1.00). DCI/NH3 MS: m/z = 458 [M + NH4]+.
1H- and 13C-NMR (CDCl3), see literature [8].
14
55.1
15
23.0
16
28.5
17
55.9
Chondrillasterol 12: Colorless crystals; m.p. 163 8C. [a]D22: + 1.78
(CHCl3, c 0.5). DCI/NH3 MS: m/z = 430[M + NH 4]+, 413 [M + H]+.
13C-NMR (CDCl3) (Table 1), in agreement with reference [9].
1812.0
19
12.1
13.0
13.9
20
40.840.840.5
21.1
40.5
21
21.1
138.0
129.6
51.2
22.5
139.6
130.5
52.3
22.5
139.7
130.5
52.5
Chondrillasterone 13: White powder; m.p. 170 8C. [a] 22: + 2.58
22
138.2
129.4
51.2
D
(CHCl3, c 0.8). 13C-NMR (CDCl3), (Table 1); IR, 1H-NMR (CDCl3/
23
TMS), see literature [10].
24
25
31.9
31.9
30.9
30.9
26
19.0
19.0
20.1
20.2
3b-O-b-Xylopyranosylchondrillasterol 14: Colorless crystals; m.p.
282±283 8C. [a]D22: -25.608 (MeOH, c 0.506). IR (KBr): nmax = 3450,
2950, 1645, 1110, 970, 840 cm±1. DCI/NH3 MS: m/z = 562 [M +
NH4]+, 545 [M + H]+. EI-MS: m/z (rel. int.) = 544 [M]+ (11.2)
(C34H56O5), 412 [M - Xyl]+, 395 (90.5), 255 (100.0), 229 (32.5), 213
(25.5),187 (17.5),149 (15.5), 133 (35.4). 1H-NMR (400 MHz, CD3OD/
TMS): d = 0 .44 (3H, s, CH 18), 0 .58 (3H, s, CH ±19), 0.74 (3H, d,
J = 6.6 Hz, CH3 ±26), 0.76 (3H, t, J = 7.1 Hz, CH3 ±29), 0.81 (3H, d,
J = 6.Hz, CH3 ±27), 0.94 (3H, d, J = 7.5 Hz, CH3 ±21), 3.84 (1H, m,
H-3), 4.91 (1H, ddd, J = 16.1; 7.1 and 7.1 Hz, H-23), 4.94 (1H, dd,
J = 16.1 and 7.1 Hz, H-22), 5.10 (1H, t, 8.6 Hz, H-7). Xylose;
d = 4.52 (1H, d, J = 7.0 Hz, H-1¢), 3.34 (1H, m, H-2¢), 3.46 (1H, m,
27
21.4
21.4
22.2
22.3
2825.4
29
25.4
26.6
26.6
12.2
12.4
13.4
13.3
Glucose
103.1
76.1
Sugars
1'
Xylose
105.1
75.1
2'
3±
3
3'
77.0
77.9
4'
70.1
72.6
5'
66.9
76.3
6'
63.7
*Attributions based on DEPT, HSQC and HMBC experiments.
Wandji J et al. Fatty Acid Esters¼ Planta Med 2002; 68: 822±826

J = 12.0 ; 4.5 Hz, H-6¢), 3.79 (1H, dd, J = 12.0; 2.0 Hz, H-6¢). 13C- NMR spectrum as erythrodiol 10 [7]. Its EI-mass spectrum exhi-
NMR (100 MHz, CD3OD/TMS), see Table 1.
bited the molecular peak at m/z = 442 and two others at m/z = 234
and 20 3 (234 ± CHOH), due to the retro-Diels-Alder cleavage in
2
ring C, in agreement with literature [13]. The GC-MS of the methyl
ester mixture exhibited five peaks at m/z = 438, 466, 494, 522 and
550, identified as: methyl octacosanoate 1a (C29H58O2), methyl tria-
Results and Discussion
Air-dried and powdered seeds of G. africana were extracted with contanoate 2a (C31H62O2), methyl dotriacontanoate 3a (C33H66O2),
CH2Cl2-MeOH (1:1) at room temperature and the extract was methyl tetatriacontanoate 4a (C35H70O2), and methyl hexatriacon-
evaporated using a vacuum pump. The residue was partitioned tanoate 5a (C37H74O2), respectively. Therefore, compounds 1±5
into n-hexane- and EtOAc-soluble fractions. Repeated column were identified as a mixture of five fatty esters of erythrodiol, of
chromatography of the EtOAc fraction yielded fifteen compounds which the fatty acids corresponded to 28, 30, 32, 34 and 36 carbons,
1±15. Spectroscopic analyses including 1D- and 2D-NMR, MS, respectively. These erythrodiol ester derivatives are reported for the
GC-MS, in addition to chemical reactions led to the determina- first time.
tion of their structures.
Compound 14 gave a positive Liebermann-Burchard reaction, as
The structures of the nine known compounds 6±13 and 15 a steroidal glycoside. Its DCI/NH3 mass spectrum exhibited pseu-
(Fig.1) were elucidated by comparison of their physical data domolecular peaks at m/z = 562 [M + NH4]+ and 545 [M + H]+
(m.p., [a]D) and spectroscopic data (1H-, 13C-NMR) with literature implying the molecular formula C34H56O5. The IR spectrum re-
data. All of them are reported here for the first time from G. vealed a strong hydroxy group band at 3450and glycosidic bands
africana.
(C-O) at 1110cm ±1. The 13C-NMR DEPT spectrum of 14 revealed a
total of 34 carbon resonances, namely, 6 CH3-, 10CH 2-, 15 CH-
Compounds 1±5 were obtained as white powder, showing a and 3 C-. The 1H-NMR spectrum (see experimental) showed the
single rose TLC-spot by spraying with the 5%H2SO4/1%vanillin/ presence of six methyl groups (dH = 0.44, 0.58, 0.74, 0.76, 0.81
EtOH reagent. They gave positive Liebermann-Burchard reac- and 0.94), one oxymethine proton (dH = 3.84) and three olefinic
tion, as usual for a triterpenoid. The ES-mass spectrum exhib- protons (dH = 4.91, 4.94 and 5.10). In the 13C-NMR spectrum (Ta-
ited five sodiated molecular peaks at m/z = 871 [M1 + Na]+, 899 ble 1), four olefinic carbon resonances at dC = 118.7, 130.5, 139.6
[M2 + Na]+, 927 [M3 + Na]+, 955 [M4 + Na]+, and 983 [M5 + Na]+, and 140.4 could be recognized readily. The above information
showing clearly that compounds 1±5 were a mixture of five was consistent with a C-29 sterol possessing a pentosyl moiety
constituents corresponding to the respective molecular formu- at the C-3 position. The 1H- and 13C-NMR data of the aglycone
lae: C58H104O3 (MW1 = 848), C60H108O3 (MW2 = 876), C62H112O3 pattern were closely related with those reported for the 24-
(MW3 = 90 4), C H116O3 (MW4 = 932) and C66H120O3 (MW5
=
ethyl-D-7,22(E)-sterol nucleus. The chemical shifts and coupling
64
960). Their IR spectrum showed characteristic absorption bands constants in the side chain matched with published data for
at 3450(OH), 1730(ester function), and 1518 (C = C) cm ±1. The chondrillasterol in the 24b-configuration [9], [14]. The anomeric
13C-NMR spectrum of 1±5 (see experimental) exhibited reso- proton appears as a doublet at dH = 4.52 (J = 7.0Hz), implying
nance signals at dC = 122.3 and 144.2, characteristic of the 12- the b-configuration of the pentose. The anomeric carbon reso-
oleanene triterpene type, in agreement with literature [8]. The nance at d = 105.1 and four other signals at d = 77.1, 75.1, 70.1
1H-NMR spectrum of 1±5 (see experimental) exhibited two and 66.9 in the 13C-NMR spectrum were attributed to xylose in
825
1
doublets of the AB system at dH = 3.20 and 3.55 (J = 10.9 Hz) as- agreement with literature [15]. Assignments of the H- and 13C-
cribed to one hydroxymethylene group in the structure. The NMR signals of compound 14 were accomplished from the 1H-
presence of one olefinic proton was confirmed by the triplet at 1H COSY, HSQC and HMBC experiments. The EI-MS of 14 dis-
dH = 5.17 (J = 3.7 Hz) assigned to H-12. The 13C-NMR DEPT played a peak at m/z = 412 corresponding to the aglycone ion.
spectrum displayed seven resonance peaks at dC = 15.5, 16.7, This information was confirmed by the DCI/NH3 MS in which an
16.8, 23.6, 25.9, 29.1 and 33.2 assigned to the seven methyl additional peak was observed at m/z = 413 [Aglyc + H]+. Acid hy-
groups in the triterpene pattern, one peak at dC = 80.5 (C-3) drolysis of 14 afforded xylose that was identified by TLC compar-
and one hydroxymethylene carbon at dC = 69.7. Furthermore, ison with authentic sample. On the basis of the above discussion,
the 1H-NMR spectrum of 1±5 exhibited series of resonance compound 14 was identified as a new chondrillasterol xyloside:
peaks at dH = 0 .85 (t,J = 6.0Hz), 1.23 (brs) and 2.24 (t, J = 7.5 3b-O-b-xylopyranosylchondrillasterol.
Hz) assigned to the long chain protons. In addition, it showed a
doublet of doublet at dH = 4.50 (J = 10.0; 6.3 Hz) attributed to Compound 15 gave a positive Liebermann-Burchard reaction, as
H-3, confirming therefore the location of the ester function at a steroidal glycoside. Its DCI/NH3 mass spectrum showed pseu-
the C-3 position, in agreement with reported data [12]. The 13C- domolecular peaks at m/z = 592 [M + NH4]+ and 575 [M + H]+
NMR spectrum also confirmed the presence of the long chain es- corresponding to the molecular formula C35H58O6. The IR spec-
ter with the resonance peaks at dC = 173.3 (RCOO), 29.7 [(CH2)n] trum revealed characteristic absorption bands at 3460(OH),
1
and 14.3 (CH3). Assignments of the H- and 13C-NMR signals of 1650(C = C) and 1110(glycosidic bands C±O) cm ±1. The 13C-NMR
1±5 were accomplished from the 1H-1H COSY and HSQC experi- spectrum of 15 (Table 1) exhibited 35 carbon resonance peaks, of
ments. Thus, compounds 1±5 were established as a mixture of which 29 were similar to those of the aglycone pattern in com-
fatty acid esters of a 12-oleanene triterpene type.
pound 14. The hexosyl moiety at the C-3 position was established
as glucose: the H-NMR spectrum showed the anomeric proton
1
Transesterification of 1±5 yielded the genin and a mixture of resonance at dH = 4.47 as a doublet (J = 7.5 Hz), implying the
methyl esters of fatty acids. The genin was identified by the 13C- (b-configuration. The signals at dH = 3.69 (dd, J = 12.0; 4.5 Hz)
Wandji J et al. Fatty Acid Esters¼ Planta Med 2002; 68: 822±826

and 3.79 (dd, J = 12.0; 2.0 Hz) were assigned to the hydroxyme- References
thylene protons. In the 13C-NMR spectrum, the anomeric carbon
1
Keay RWJ. Trees of Nigeria. Clarendon Press, Oxford: 1989: 387±99
resonance at dC = 103.1 and five other signals at dC = 77.9, 76.1,
76.3, 72.6 and 63.7 could be recognized readily. The EI-mass spec-
trum of 15 showed a peak at m/z = 412 corresponding to the loss
of the hexosyl moiety. Acid hydrolysis of 15 yielded glucose that
was identified by TLC comparison with authentic sample. Ac-
cordingly, compound 15 was established as a chondrillasterol
glucoside, 3b-O-glucopyranosylchondrillasterol isolated for the
first time from G. africana. Its isomer, the 3-O-b-glucoside of a-
spinasterol has been reported from Pithecellobium cauliflorum
[16].
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Acknowledgements
The authors thank Dilip Jagjivan, University of Natal, Durban, for
recording some of the NMR spectra, Prof.H.Budzkiewicz of Insti-
tut fuer Organische Chemie, Cologne, Germany for recording
some of the mass spectra. Jean Wandji deeply acknowledges the
financial support from the Organisation for the Prohibition of
Chemical Weapons (OPCW), The Netherlands, for Internship at
the University of Natal, Durban, South Africa. He also wishes to
thank International Foundation for Science (Sweden) and the
ªUniversitØ RenØ-Descartes, Paris-5º (France) for supporting
parts of this work.
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