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A guaianolide from Amberboa tubuliflora
Phytochemistry, Vol. 29, No. 12, pp. 3946-3947, 1990 Printedin Great Britain.
A GUAIANOLIDE AHMED
Institute
A. AHMED,*
for Organic
Chemistry,
0031.9422/90 $3.00+0.00 :c? 1990 PergamonPressplc
FROM AMBERBOA
M. ABOU EL-ELA,
Technical
J. JAKUPOVIC, A. A. SEIF
University
of Berlin, D-1000
Alexandria,
Alexandria,
TUBULIFLORA EL-DIN? and M.
Berlin 12, F.R.G.; tFaculty
EL-GHAZOULYt
of Pharmacy,
University
of
Egypt
(Received in reuised form10 April 1990) Key Word Index--Amberboa derivative.
tubulifora; Compositae;
sesquiterpene
lactone;
guaianolide;
tetrahydro-zaluzanin
Abstract-The reinvestigation of the aerial parts of A. tubulijora afforded a new sesquiterpene lactone together with four known compounds. The structure of the new compound was established by high field ‘H NMR spectroscopic methods.
INTRODUCTION
Amberboa (Compositae, tribe Cynareae) with ca six species. Dittrich [l] placed
is a small genus the genus in the subtribe Centaureinae close to the genus Centaurea although some botanists consider it as a member of the genus Centaurea [2]. Cynaropicrin and desacylcynaropicrin were reported from most Amberboa species [3, 43, and in addition, A. muricata DC. (= Centaurea muricata L.) gave isolippidiol and muricatin [S], A. lippii gave grosheimin, amberboin, lippidiol and isolippidiol [6]. We have now re-investigated A. tubuliJlora. RESULTS AND DISCUSSION
The extract of the aerial parts of A. tub&Jot-a afforded, in addition to cynaropicrin and desacylcynaropicrin [3], a new guainolide 1, aguerinj? [7], trachelogenin [S], filifolide A [9] and loliolide [lo]. The ‘HNMR spectrum of 1 (Table 1) indicated the presence of a guaianolide skeleton, which contained only one exomethylene group. The two exomethylene protons appeared as two signals at 65.14 and 4.80 and the nature of these signals suggested that a 10(14)-double bond was present. On the other hand, the two doublets at 6 1.33 and 1.18 proved a 11,13- and 4,15-dihydro derivative. However, the signal for H-l 1 overlapped with that of H-7 and the couplings could not be detected. In deuteriobenzene H-l 1 was a clear dq at 62.69. The coupling J,, 1iand the chemical shift of H-13 indicated an lip-proton. Two free hydroxyl groups were deduced from the downfield shift of the signals at 63.65 and 4.42. This was supported by the IR spectrum. Spin decoupling allowed the assignments of all signals and located the hydroxyl groups at C-8 and C-9. The formation of the acetonide derivative 2 confirmed the presence of vicinal hydroxyl groups. Additionally, a pair of double doublets at 62.45 and 2.40 indicated a neighbouring keto group. The two protons and the keto group are placed at C-2 and C-3, respectively. The ’ 3C NMR spectrum of compound 1 exhibited *Permanent address: Department of Chemistry, Science, El-Minia
University,
El-Minia,
Faculty
of
Egypt. 3946
signals for carbonyl carbon at 6219.3, for lactone carbony1 at 179.5, for exo-methylene carbons at 6 147.5 and 114.9 as well as for three carbons bearing oxygen at 6 72.3, 77.4 and 83.2 (Table 1). Finally, the stereochemistry of 1 was established by NOE difference spectroscopy experiments. Saturation of H-8 showed effects on H-9 (8.5%) and H-6 (4%) while H-4 enhanced H-6 (5%) and H-7 enhanced H-13 (1%). Furthermore, saturation of H-15 showed an effect on H-5 (5%). Thus, compound 1 was identified as 8a,9a-dihydroxy-4b,l5,1 lb,l3-tetrahydrodehydrozaluzanin. EXPERIMENTAL
The air-dried aerial parts of A. tubul$ora Murb. (800 g, collected from Alexandria, Egypt, in March 1987, voucher A 126, deposited in the Department of Botany, El-Minia University, Egypt) were extracted with Et,O-MeOH-petrol (1: 1: 1). The extract was sepd as reported previously [ 1 I]. The fraction eluted with Et,O-petrol (1: 1) was further sepd by TLC followed by HPLC (RP 8, MeOH-H,O, l:l, ca 100 bar, flow rate, 3 ml min- ‘) to give 20 mg tilfolide-A and 10 mg aguerin-B. The second fraction which eluted with Et, O-petrol (3: 1) was purified by TLC to give 8 mg trachelogenin, 10 mg lolioiide. The polar fraction eluted with Et,O-MeOH (9: 1) purified by HPLC (MeOH-H,O, 2:3) gave 15 mg 1. 8a,9a-Dihydroxy-4~,15,111(,13-tetrahydro-dehydrozaluzanin (1). IR Y:!:‘~ cm-‘: 3420 (OH), 1770 (p-lactone), 1610; MS m/z (rel. int.): 280 [M]+ (8). 262 [M - H,O]+ (4), 252 [M-CO]’ (22) 96 (100).
3941
Short Reports Table 1. ‘HNMR spectra1 data of compounds 1 and 2 (400 MHz, CDCI,, &values) and *sC NMR spectral data of compound 1 H
1
1
3.67 br ddd (2.5, 9, 9) 2.54 dd (9, 18) 2.40 ddd (1, 2.5, 18)
2
2 4 5
2
2.26 m 2.22 m
6 I
8 9
11 13 14 15
4.02 dd (9, 10) 2.85 ddd (11, 10, 10) 3.65 dd (6, 10) 4.42 d (6) 2.82 dq (11, 7.5) 1.33 d (7.5)
5.14 s 4.80 s 1.18 d (7.5)
C
Acknowledgement-A.
Humboldt-Stiftung
A. Ahmed thanks the Alexander von for a fellowship.
1
3.57
1
38.4 d
2.58 2.49 2.25 2.15
2 3 4 5
43.1 t 219.3 s 30.5 d 50.9 d
3.95
6
2.83 4.21
7 8
4.68
9
11.4 d 44.4 d 72.3 d 83.2 d
2.88 1.35 5.40 4.97 1.23
10 11
147.5 s 47.5 d
12
179.5 s
13 14 15
11.1 q 114.9 t 14.3 q
REFERENCES
1. Dittrich, M. (1977) 7’heBiology and Chemistry of Compositae (Heywood, V. H., Harborne, J. B. and Turner, B. L., eds), p. 1011. Academic Press, New York. 2. TLckholm, V. (1974) Students’ Flora of Egypt p. 542. Cairo University. 3. Omar, A., El-Ghazouly, M., Seif El-Din, A. A. and Khafagy, S. (1983) Acta Pharm. Jugosl. 33, 233. 4. Harrision, D. A. and Kulshreshta, D. K. (1984) Fitoterapia 35, 189. 5. Gonzales. A. G. Bermeio, J., Massanet, G. and Perez, J. (1973) An. Quim. 69, 1333. 6. Gonzalez, A. G., Garcia, B. M. and Breton, J. L. (1970) An.
Quim. 66, 799. 7. Gonzalez, A. G., Bermejo, J., Cabrera, I., Massanet, G. M., Mansilla, H. and Galindo, A. (1978) Phytochemistry 17,955. R. (1975) Phyto8. Vanhaelen, M. and Vanhaelen-Fastre, chemistry 14, 2709.
The acetonide deriuatioe (2). Compound
solved in dry Me&O CuSO, and one drop filtered and the product m/z (rel. int.): 320 [M]’
1 (10 mg) was dis(1 ml) followed by the addition of dry cone H,SO,. After 2 hr the mixt. was extracted with Et,0 to give 7 mg 2. MS (64), 305 [M-Me] + (78), 84 (100).
9. Torrance, S. J. and Steelink, C. C. (1974) J. Org. Chem. 39, 1068. 10. Holub, M. and Samek, 2. (1975) Phytochemistry 14, 1659. 11. Bohlmann, F., Zdero, C., King, R. M. and Robinson, H. (1984) Phytochemistry 23, 1979.
A GUAIANOLIDE AHMED
Institute
A. AHMED,*
for Organic
Chemistry,
0031.9422/90 $3.00+0.00 :c? 1990 PergamonPressplc
FROM AMBERBOA
M. ABOU EL-ELA,
Technical
J. JAKUPOVIC, A. A. SEIF
University
of Berlin, D-1000
Alexandria,
Alexandria,
TUBULIFLORA EL-DIN? and M.
Berlin 12, F.R.G.; tFaculty
EL-GHAZOULYt
of Pharmacy,
University
of
Egypt
(Received in reuised form10 April 1990) Key Word Index--Amberboa derivative.
tubulifora; Compositae;
sesquiterpene
lactone;
guaianolide;
tetrahydro-zaluzanin
Abstract-The reinvestigation of the aerial parts of A. tubulijora afforded a new sesquiterpene lactone together with four known compounds. The structure of the new compound was established by high field ‘H NMR spectroscopic methods.
INTRODUCTION
Amberboa (Compositae, tribe Cynareae) with ca six species. Dittrich [l] placed
is a small genus the genus in the subtribe Centaureinae close to the genus Centaurea although some botanists consider it as a member of the genus Centaurea [2]. Cynaropicrin and desacylcynaropicrin were reported from most Amberboa species [3, 43, and in addition, A. muricata DC. (= Centaurea muricata L.) gave isolippidiol and muricatin [S], A. lippii gave grosheimin, amberboin, lippidiol and isolippidiol [6]. We have now re-investigated A. tubuliJlora. RESULTS AND DISCUSSION
The extract of the aerial parts of A. tub&Jot-a afforded, in addition to cynaropicrin and desacylcynaropicrin [3], a new guainolide 1, aguerinj? [7], trachelogenin [S], filifolide A [9] and loliolide [lo]. The ‘HNMR spectrum of 1 (Table 1) indicated the presence of a guaianolide skeleton, which contained only one exomethylene group. The two exomethylene protons appeared as two signals at 65.14 and 4.80 and the nature of these signals suggested that a 10(14)-double bond was present. On the other hand, the two doublets at 6 1.33 and 1.18 proved a 11,13- and 4,15-dihydro derivative. However, the signal for H-l 1 overlapped with that of H-7 and the couplings could not be detected. In deuteriobenzene H-l 1 was a clear dq at 62.69. The coupling J,, 1iand the chemical shift of H-13 indicated an lip-proton. Two free hydroxyl groups were deduced from the downfield shift of the signals at 63.65 and 4.42. This was supported by the IR spectrum. Spin decoupling allowed the assignments of all signals and located the hydroxyl groups at C-8 and C-9. The formation of the acetonide derivative 2 confirmed the presence of vicinal hydroxyl groups. Additionally, a pair of double doublets at 62.45 and 2.40 indicated a neighbouring keto group. The two protons and the keto group are placed at C-2 and C-3, respectively. The ’ 3C NMR spectrum of compound 1 exhibited *Permanent address: Department of Chemistry, Science, El-Minia
University,
El-Minia,
Faculty
of
Egypt. 3946
signals for carbonyl carbon at 6219.3, for lactone carbony1 at 179.5, for exo-methylene carbons at 6 147.5 and 114.9 as well as for three carbons bearing oxygen at 6 72.3, 77.4 and 83.2 (Table 1). Finally, the stereochemistry of 1 was established by NOE difference spectroscopy experiments. Saturation of H-8 showed effects on H-9 (8.5%) and H-6 (4%) while H-4 enhanced H-6 (5%) and H-7 enhanced H-13 (1%). Furthermore, saturation of H-15 showed an effect on H-5 (5%). Thus, compound 1 was identified as 8a,9a-dihydroxy-4b,l5,1 lb,l3-tetrahydrodehydrozaluzanin. EXPERIMENTAL
The air-dried aerial parts of A. tubul$ora Murb. (800 g, collected from Alexandria, Egypt, in March 1987, voucher A 126, deposited in the Department of Botany, El-Minia University, Egypt) were extracted with Et,O-MeOH-petrol (1: 1: 1). The extract was sepd as reported previously [ 1 I]. The fraction eluted with Et,O-petrol (1: 1) was further sepd by TLC followed by HPLC (RP 8, MeOH-H,O, l:l, ca 100 bar, flow rate, 3 ml min- ‘) to give 20 mg tilfolide-A and 10 mg aguerin-B. The second fraction which eluted with Et, O-petrol (3: 1) was purified by TLC to give 8 mg trachelogenin, 10 mg lolioiide. The polar fraction eluted with Et,O-MeOH (9: 1) purified by HPLC (MeOH-H,O, 2:3) gave 15 mg 1. 8a,9a-Dihydroxy-4~,15,111(,13-tetrahydro-dehydrozaluzanin (1). IR Y:!:‘~ cm-‘: 3420 (OH), 1770 (p-lactone), 1610; MS m/z (rel. int.): 280 [M]+ (8). 262 [M - H,O]+ (4), 252 [M-CO]’ (22) 96 (100).
3941
Short Reports Table 1. ‘HNMR spectra1 data of compounds 1 and 2 (400 MHz, CDCI,, &values) and *sC NMR spectral data of compound 1 H
1
1
3.67 br ddd (2.5, 9, 9) 2.54 dd (9, 18) 2.40 ddd (1, 2.5, 18)
2
2 4 5
2
2.26 m 2.22 m
6 I
8 9
11 13 14 15
4.02 dd (9, 10) 2.85 ddd (11, 10, 10) 3.65 dd (6, 10) 4.42 d (6) 2.82 dq (11, 7.5) 1.33 d (7.5)
5.14 s 4.80 s 1.18 d (7.5)
C
Acknowledgement-A.
Humboldt-Stiftung
A. Ahmed thanks the Alexander von for a fellowship.
1
3.57
1
38.4 d
2.58 2.49 2.25 2.15
2 3 4 5
43.1 t 219.3 s 30.5 d 50.9 d
3.95
6
2.83 4.21
7 8
4.68
9
11.4 d 44.4 d 72.3 d 83.2 d
2.88 1.35 5.40 4.97 1.23
10 11
147.5 s 47.5 d
12
179.5 s
13 14 15
11.1 q 114.9 t 14.3 q
REFERENCES
1. Dittrich, M. (1977) 7’heBiology and Chemistry of Compositae (Heywood, V. H., Harborne, J. B. and Turner, B. L., eds), p. 1011. Academic Press, New York. 2. TLckholm, V. (1974) Students’ Flora of Egypt p. 542. Cairo University. 3. Omar, A., El-Ghazouly, M., Seif El-Din, A. A. and Khafagy, S. (1983) Acta Pharm. Jugosl. 33, 233. 4. Harrision, D. A. and Kulshreshta, D. K. (1984) Fitoterapia 35, 189. 5. Gonzales. A. G. Bermeio, J., Massanet, G. and Perez, J. (1973) An. Quim. 69, 1333. 6. Gonzalez, A. G., Garcia, B. M. and Breton, J. L. (1970) An.
Quim. 66, 799. 7. Gonzalez, A. G., Bermejo, J., Cabrera, I., Massanet, G. M., Mansilla, H. and Galindo, A. (1978) Phytochemistry 17,955. R. (1975) Phyto8. Vanhaelen, M. and Vanhaelen-Fastre, chemistry 14, 2709.
The acetonide deriuatioe (2). Compound
solved in dry Me&O CuSO, and one drop filtered and the product m/z (rel. int.): 320 [M]’
1 (10 mg) was dis(1 ml) followed by the addition of dry cone H,SO,. After 2 hr the mixt. was extracted with Et,0 to give 7 mg 2. MS (64), 305 [M-Me] + (78), 84 (100).
9. Torrance, S. J. and Steelink, C. C. (1974) J. Org. Chem. 39, 1068. 10. Holub, M. and Samek, 2. (1975) Phytochemistry 14, 1659. 11. Bohlmann, F., Zdero, C., King, R. M. and Robinson, H. (1984) Phytochemistry 23, 1979.