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Acetogenins from root bark of Uvaria narum
Phytochemistry, Vol. 30,NO. 7, pp.2373-2377, 1991 Printedin Great Britam.
ACETQGENINS
0
0031-9422/w %3.00+0.00 1991PergamonPress ptc
FROM ROOT BARK OF UVARIA NARUM
A. HISHAM,* L. A. C. P~ETERS,M_ CLAEYS, H, VAN DEN HEUVEL, E. ESMANS,?R. DUMMISSE,J: and A. J. VLIETINCK Department of Pharmaceutical Sciences, University of Antwerp (UIA), Universiteitsplein 1, B-2610, Antwerp, Belgium; *Department of Organic Cbemistry, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2024 Antwerp, Belgium (Received in revised form 30 November 1990)
Key Word Index--Uuaria
narum;
Annonaceae; root bark; acetogenins; isodesacetyluvaricin; narumicins I and Ii.
Abstract-Three new acetogenins, isodesacetyluvaricin, narumicins f. and II were isolated fram hexane and ethyl acetate extracts of the root bark of Uvaria narum, in addition to the known compounds glutinone, glutinol, taraxerol, fi-sitosterol and benzyl benzoate.
INTRODUCTION
Our recent investigations on the root bark of Uuczria narum Bl. (Annonaceae) have led to the isolation of five new acetogenins [11 2f. Further studies on the hexane and ethyl acetate extracts of the root bark of the title plant resulted in the isolation of three more new acetogenins, isodesacetyluvaricin (I), narumicin I (2) and narumicin II (3) in addition to the known compounds glutinone, glutinol, taraxerol, p-sitosterol and benzyl benzoate. Acetugenins 2 and 3 were obtained as an equimixture of two diastereoisomers and could not be resolved by normal chromatographic techniques beoause of their identical R, values. Mass spectrometry established the identical carbon backbones of 2 and 3 in the racemic mixture while NMR spectroscopy including 2D NMR experiments and a thorough comparison of the diagnostic NMR chemical shifts of the similar known compounds led ta the assignments of their relative stereochemistry in the bis-tetrahydrofuranyl part. REsULTs AND DISCU~IUN
The known compounds benzyl benzoate, glutinone, glutinol, taraxerol and /3-sitosterol were eluted in the
OH R
1
H
2 OH 3 OH *Author to whom correspondence should be addressed. PflY
30+7-s
order of their increasing polarity from the hexane extract and identified from comparison of their spectral data and physical constants with those in the literature. Compound I was isolated from the chloroform fractions of the hexane extract whilst 2 and 3 were isulated as a homogeneous mixture from the ethyl acetate extract. Isodesacetyluvaricin (l), a low melting waxy solid, showed a [M +H]’ ion at m/z 607 in the FAB and CI(CH,) mass spectra indicating a M, of 606. The ‘H and 13C NMR spectra (Tables 1 and 2) showed the presence of an ct,@-unsaturated y-la&one, two THF rings, a long ahphatic chain and two hydruxyl groups. Compound I formed a diacetyl and a diTMSi derivative confirming two hydroxyl groups. The EI mass spectral fragmentation pattern of 1 and its derivatives established the carbon skeleton of 1 which was found to be identical with that of clesacetyluvaricin, a compound isolated from the roots of U. accuminata by Jolad et al. [3]. The differences in the ‘H and *3C NMR chemical shifts of the chiral centres in 1 and desacetyluvaricin indicated that they are diastereoisomers. The relative figuration in the bis-THF part in desaeetyluvaricin was previousIy determined as &reo, trans, ghreo, tram, erythro going frum C-15 to C-24 [4,5$ In the 13C NMR spectrum of desacetyluvaricin, C-15, C16, C-I9, C-20, C-23 and C-24 appeared as six distinct signals at 6’74.1 (C-15), 83.2, 82.4, 82.2, 82.9 and 71.6 (C24) (3). However, in the 13C NMR spectrum of 1,these six carbons appeared as only three peaks at S 74.1 (C-l 5 and C-24), 83.2 (C-I 6 and C-23) and 8 1.8 (C-I9 and C-20) as in the case of asimicin [6 and refs cited therein]. In the ‘H NMR spectrum of desacetyluvaricin, H-15 appeared at 63.39 and H-24 appeared between 63.8-3.93 together with the oxymethine protons of the THF rings. In 1, both H-15 and H-24 appeared at 63.40. In order to determine the relative stereochemistry in the bis-THF part in 1 we applied Hoye and Suhadolnik’s proton chemical shift correlation methodology [4, 51. The identical C-15 and C-24 acetyl methyl resonance at 82.077 in the ‘H NMR spectrum of the d&&ate of 1. (la) indicated that the C-15/C-16 and C-23/C-24 stereorelationships in 1 are threu. The chemical shifts of H- 19 and H-20 in la at 6 3.89 and H-16 and H-23 at 63.98 by comparison with the model compounds suggested a brans, threo, tram relationship for the THF rings [4,5]. From these data the relative
2373
A. HISHAM et
2374
al,
Table 1. ‘H NMR data of compounds 1, la, 2 and 3 (300 MHz, CDCI,) H
1
2
3
la
3 4 5 6 7-13 14 15 16 17,18 19,20 21,22 23 24 25 26-33 34 35 36 37 OAc OAc
2.26 t (7.8) 1.5 111 1.25 br 1.25 br 1.2s hr 1.35-1.40 m 3.39 m 3.82-3.87 m 1.5-2.0 m 3.82.-3.87 m 1.5-2.0 m 3.82-3.87 m 3.39 m 1.35-1.40 m 1.25 hr 0.88 t (6.8) 6.99 d (1.4) 4.99 dq (6.8, 1.4) 1.40 d (6.8) ..-
2.40 m 1.65 m 3.59 m 1.35-1.40 m 1.25 br 1.35-1.40 m 3.39 m 3.82-3.87 m 1.5-2.0 m 3.82-3.87 m 1.5-2.0 m 3.82-3.87 m 3.39 m 1.35-1.40 m 1.25 hr 0.88 t (6.8) 7.05 d (1.4) 5.0t dq (4.8, 1.4) 1.40 d (6.8)
2.40 m 1.65 m
2.26 L (7.8) 1.5 m 1.25 br 1.25 br 1.25 hr 1.5m 4.85 m 3.98 m 1.5-2.0 m 3.89 m 1.5-2.0 m 3.98 m 4.85 m 1.5 m 1.25 br 0.88 t (6.8) 6.99 d (1.4) 4.99 dq (6.8, 1.4) 1.40 d (6.8) 2.077 2.077
J (in Hz)
1
1.3.5-1.40 m 1.25 br 1.35-1.40 m 3.39 m 3.82..3.87 m 1.5-2.0 m 3.82-3.87 m 1.5-2.0 m 3.82-3.81 m 3.82-3.87 m 1.35-1.40 m 1.25 br 0.88 t (6.8) 7.05 d (1.5) 5.01 dq (6.8, 1.4) 1.40 d (6.8) -
in parentheses.
Table 2. 13C NMR data of compounds l-3 (75 MHz, CDCl,) C
3.59 m
2
3
1 2 3 4 5 6 7 8--12 13 14 15 16 17,18,21,22
173.9 134.3 25.2 27.2 29.7-29.2 29.7-29.2 29.7F29.2 29.7-29.2 25.7 33.5 74.1 83.2 28.9, 28.3
173.7 133.9 21.4 35.2 70.7 37.4 25.6 29.6-29.1 25.6 33.4 73.99 83.05 28.9, 28.3
173.7 133.9 21.4 35.2 70.7 37.4 25.6 29.6-29.1 25.9” 33.2’” 73KP 83.1eb 28.9,28.3,24.3
19 20 23 24 25 26 27-31 32 33 34 35 36 37
81.8 81.8 83.2 74.1 33.5 25.7 29.7-29.2 31.9 22.7 14.1 148.9 77.3 19.2
81.69 81.69 83.05 73.99 33.4 25.6 29.6-29.1 31.8 22.6 14.0 149.3 77.4 19.0
82.42’ 82.15” 82.6Tb 71.30’6 32.36’” 25.6’ 29.6-29.1 31.8 22.6 14.0 149.3 77.4 19.0
*Indicate low intensity signals. “-“May be reversed within column.
stereochemistry of the bis-THF part in 1 can be ascribed as threo, trans, three, trans, threo. The stereochemistry at C-36 is unknown. Narumicins I (2) and II (3), a stereoisomeric mixture, showed a [M-t-H]’ ion at m/-_ 623 in the FAB mass spectrum indicating a M, of 622. The EI mass spectrum of the product did not show a [M]’ but a series of peaks (m/z 604,586,568,550) arising from the loss of water were observed. The IR spectrum showed absorption bands for hydroxyl groups (3455 cm- ‘) and an a&unsaturated y-lactone (1755 cm I). The ‘H and 13C NMR spectra of the product exhibited typical signals for an cc& unsaturated y-lactone, hydroxyl groups, a long aliphatic chain and THF rings. The mixture formed a triacetate (EIMS m/z 688 (M - HOAc] ‘) and a triTMSi derivative (EIMS m/z 823 [M - Mej+) confirming the presence of three hydroxyl groups. The EIMS fragmentation pattern of the product and its triacetyl and triTMSi derivatives established the identical carbon skeletons of 2 and 3. The diagnostic fragment ions observed in the EI mass spectrum of the mixture and its derivatives are summarized in Scheme 1. The NMR spectral data showed that these two isomers differed only in the relative stereochemistry of the bis-THF portion. The remaining parts of the molecules were found to have identical chemical shifts. The El mass spectral ions at m/z 15.5 (15%) in the underivatized product and the corresponding trimethylsilylated ion at m/z 227 (72%) in the triTMSi derivative formed by the cleavage of the C-4/C-5 bond supported the position of a hydroxyl group at the C-5 position, as in the case of our previously reported compound panalicin [2] isolated from the root bark of U. narum. Even though a peak at m/z 497 was not observed in the EI mass spectrum of the underivatized product formed by the competitive
Acetogenins from Uoarianarum
m/z-
R H TMSi AC
241 313 283
;
; ,
I I I
‘$
TM% 52.5 AC 465
I I
I
0
I
R m/z .J-w TM% 243
R H TMSi AC
353 m/z 451 595 535
R H
m/z ,! 497’
Scheme 1. Diagnostic ions in EI mass spectrum of narumicins I (2) and II (3) and their triTMSi and triacetyl derivatives. *Peak not observed, corresponding peaks formed by consecutive loss of two molecules of water evident.
cleavage of the C-4/C-S bond, the peaks at m/z 479 (15%) [497 -H,O] and 461(10%) [497 - 2H,O] were observed which could be assigned for the ions formed by the C-4/C5 cleavage, followed by the loss of one and two molecules of water (Scheme 1). The presence of a hydroxyl group at the C-5 position was further confirmed by the ‘H-‘H COSY spectrum (3OOMHz, CDCl,) and the lH-13C HETCOR spectrum of the product. The two proton multiplet at 62.40 could obviously be attributed to the H-3 protons. In the ‘H--‘H COSY spectrum, these protons showed correlation with the H-36 proton at 65.01 (lH, dq) in the y-lactone ring. In the ‘H-13C HETCOR spectrum, the H-3 protons correlated with the methylene carbon signal at 621.4. In the ‘H-‘H COSY spectrum, the H-5 proton at 63.59 (lH, m) and the H-3 protons at 6 2.40 showed correlation with a proton multiplet at 61.65 which could clearly be assigned to the protons of the CH, group between C-3 and C-5. Furthermore, the hetero correlations (HETCOR) observed for the atoms in this region [(e.g. 6 1.65 (m) -35.4 (H-4-C4), 3.59 (lH, m)-+70.7 (H-5-&-5), 1.35-1.40 (m)+37.4 (H-6-X-6)] were also in agreement with the position of a hydroxyl group at C-5. Moreover, the ‘H and 13C NMR chemical shifts for the atoms at C-3, C-4, C-5 and C-6 in the narumicin stereoisomeric mixture were found to be different from the NMR chemical shifts reported for these atoms in other common compounds which possess either a hydroxyl group at C-4 or without any hydroxyl substitution in this region. As mentioned above, anomalies in the expected NMR signals as well as in the 13C NMR signal intensities of the chiral centres in the bis-THF portion, that is at C-15, C-16, C-19, C-20, C-23, and C-24, suggested that it was a stereoisomeric mixture of two compounds which differed in the relative configuration in this part. The ‘H and 13CNMR chemical shifts of the remaining parts of the molecules, that is, atoms 1-12, 2634 and 35-37, were quite agreeable with the expected values and were found to be identical for both isomers. A thorough comparison with the diagnostic NMR chemical shifts of the similar reported compounds as well as the application of the Hoye and Suhadolnik proton chemical shift correlation methodology [4, 51 enabled us to interpret the ‘H and
2315
’ 3C NMR spectra of the stereoisomeric mixture and led to the assignment of the relative stereochemistry in the bis-THF part in both isomers. A compilation of the NMR spectral data with the proposed stereochemistry for all the Annonaceous acetogenins reported until 1990 is presented in a recent review article published by Rupprecht et al. [6]. In the “C NMR spectra of the adjacent bis-THF ring-containing acetogenins with a three, trans, threo, trans, erythro (or erythro, trans, threo, trans, three) relative stereochemistry such as in bullatacin, bullatacinone, annonin I, annonin VI, and desacetyluvaricin C-16, C-19, C-20 and C-23 showed four distinct signals between 683.2,82.7,82.1 and 82.4 and the carbinol methine carbons at C-15 and C-24 showed two signals between 673.8-74.3 and 71.3-71.5 with a difference of ca 2.5 ppm. However, in the case of 1 and asimicin [6], two compounds with a three, trans, three, trans, three stereochemistry (which possess pseudosymmeteric stereochemistry), C-16, C-19, C-20 and C-23 showed only two signals at 683.1 (C-16 and C-23) and 81.7 (C-19 and C-20) and C-15 and C-24 also appeared as a single peak at ca 674. In the ‘H NMR of all known bis-THF acetogenins with one three and one erythro relationship for C-15/C-16 and C-23/C-24, one of the protons at either C-15 or C-24 appeared at ca 63.4 and the other proton was found to be merged with oxymethine proton multiplets of the THF rings which usually appear between 63.82 and 3.92. However, in 1 and asimicin, H- 15 and H-24 appeared at ca 6 3.4. These data, as well as the NMR chemical shifts reported for the two synthetic model compounds by Born et al. [7], indicate that a very reliable conclusion could be drawn about the stereorelationships between C-15/C-16 and C-23/C-24 in the adjacent bis-THF acetogenins from the following generalization: a C-15 or C-24 carbon chemical shift at ca 673.8-74.1 and a corresponding proton chemical shift at ca 63.38-3.41 can be ascribed for a three-relationship between the THF ring and the adjacent hydroxyl bearing carbon, and a C-15 or C-24 carbon chemical shift at ca 671.3-71.6 and a corresponding proton chemical shift at ca 63.8-3.9 can be ascribed for an erythro-relationship. This generalization can be validated from the chemical shift data of the mono THF-containing acetogenins cited in the review article [6]_ In the ‘%NMR spectrum of the mixture of 2 and 3, C-16, C-19, C-20 and C-23 showed six signals at 683.14, 83.05, 82.67, 82.42, 82.15 and 82.69 and C-15 and C-24 showed three signals at 673.99,73.90 and 71.30 with high and low intensities. Out of these, four oxymethine carbon signals of the THF rings at 683.14, 82.67, 82.42 and 82.15 and two of the carbinol methine carbon signals at 673.90 and 71.30 were low intensity signals compared with the remaining signals of the THF rings at 683.05 and 81.69 and the carbinol methine signal at 673.90, the signal intensity ratio between the two sets of signals was found to be 1: 2, respectively. In the ‘H NMR spectrum (300 MHz, CDCl,) of the equimixture of 2 and 3 signals of H-16, H-19, H-20 and H-23 in both isomers as well as one of the carbinol methine protons at either H-15 or H-24 in one of the isomers appeared as a multiplet between 63.82 and 3.89 which showed an integration for 4.5 protons. Similarly, the signals of both the H-15 and H-24 protons in one of the isomers as well as one of the protons at either H-15 or H-24 in the second isomer appeared as a multiplet at 63.39 which showed an integration for 1.5 protons. In the
2376
A. HISHAM et al.
lH-13C HETCOR spectrum of the mixture, all six oxymethine carbon signals which appeared for C-16, C-19, C20 and C-23, and one of the low intensity carbinol methine carbon signals at 671.30 which appeared for C15 or C-24 in one of the isomers showed correlation with the 4.5 proton multiplet as expected. Similarly, the high intensity carbinol methine carbon signal at 673.99 and the low intensity signal at 673.90 showed correlation with the 1.5 proton multiplet at 63.39. The chemical shifts of the low intensity signals of the THF portion in the narumicin stereoisomeric mixture were strikingly similar to those in the adjacent bis-THF acetogenins with a threo, trans, threo, tmns, erythro stereochemistry and the high intensity signals were identical with those in 1 and asimicin which possess a threo, trans, threo, trans, threo stereochemistry. This data led to the conclusion that the mixture contained a threo, trans, threo, trans, erythro isomer and a threo, trans, threo, trans, threo isomer in a 1: 1 ratio. A high field ‘H NMR spectrum (300 MHz, CDCl,) of the acetate of the mixture showed three acetyl methyl singlets at 62.077, 2.06 and 2.05 with considerable differences in their relative intensities (2.077 > 2.06 > 2.05). A two proton multiplet at 6 3.98 (H-16 and H-23) and a two proton multiplet at 63.89 (H-19 and H-20) suggested a trans configuration for both rings and a threo relationship between H-19/H-20 in both isomers according to Hoye and Suhadolnik’s methodology [S, 63. By taking all the above observations into consideration, the ‘H and 13CNMR spectra of the stereoisomeric mixture can be interpreted unambiguously. The isomer named narumitin I (2) was ascribed the relative stereochemistry threo, trans, threo, trans, threo and the second isomer named narumicin II (3) was ascribed threo, trans, threo, trans, erythro or erythro, trams, threo, trans, threo going from C-15 to C-24. The ‘H and 13C chemical shifts assigned for both the isomers are given in Table 1. The stereochemistries at C-36 and C-5 in 2 and 3 are unknown. The diagnostic oxymethine NMR shifts assigned for 2 in the bis-THF part are virtually identical with those signals of compound 1 and asimicin, and the chemical shifts assigned for 3 are identical with those of rolliniastatin II [6]. From the identical diagnostic oxymethine 13C NMR signals of the bis-THF part, it seems that rolliniastatin II, a stereochemically undefined compound, could probably have the identical relative stereochemistry in the bis-THF part to narumicin II.
EXPERIMENTAL
General. Instruments used, plant material, general isolation procedures and derivative preparations were the same as described previously 121. Isolation of benzyl benzoate, glutinone, glutinol, taraxerol and fl-sitosterol. These compounds were isolated from the hexane, toluene, toluene-CHCl, frs of the hexane extract as described in ref. [Z]. Isolation of isodesacetyluvaricin (l), narumicin, I (2) and II (3). Compound 1 was isolated from the initial CHCl, frs and purified by prep. TLC on silica gel using CH,Cl,-EtOAc (3:2). The homogeneous mixt. of 2 and 3 was isolated from the initial CHCl, frs of the EtOAc extract which was purified either by repeated CC or by prep. TLC using CHCl,-MeOH (9: 1). Benzyl benzoate was identified in the toluene frs together with several sesquiterpene hydrocarbons by GC-MS analysis.
Glutinone. Crystals from CHCI,-MeOH (50 mg). Mp. 224”. IR v”,f 1705 cm-’ (C=O). ‘H NMR (200 MHz, CDCl,): 0.82, 0.96, 0.99, 1.03, 1.09, 1.16, 1.22 and 1.24 (8 x s, each 3H, 8 x Me), 5.7(1H, br, H-6),2.40(2H, t, J =5 Hz, H-2),0.80-2.01 (m, all other protons). 13C NMR (50 MHz, CDCI,) (C-l-C-30); 21.49, 35.86, 215.29, 49.93, 142.32, 121.23, 23.53, 46.95, 35.03, 50.57, 33.05. 30.25, 38.02, 39.24, 34.05, 35.04, 29.61, 43.04, 35.04, 28.21, 31.83, 38.83, 28.43, 24.29, 15.59, 18.28, 19.27, 32.30, 31.94, 34.45. EIMS 70 eV m/z (rel. int.): 424 [M]’ (25), 409 (15), 274 (lOO), 259 (70), 205 (40), 150 (25). Glutinol. Crystals from CHCl,-MeOH (SO mg). Mp 210” [lit. [8] mp 210”]. ‘HNMR: see ref. [8]. 13CNMR: see ref. [9]. EIMS: see ref. [S]. Taraxerol. Crystals from CHCl,-MeOH (15 mg). Mp 276-277. ‘H NMR (200 MHz, CDCl,): 0.80. 0.82, 0.90 (6H, 2 x Me), 0.92 0.95, 0.97 and 1.07 (7 x s, 8 x Me), 3.2 (lH, m, H-3), 5.53 (lH, dd, H-14) 0.8-2.1 (23H, m). ‘sCNMR: see ref. [lo]. EIMS 70 eV m/z 426 [Ml’, 411 (48), 393 (18). 302 (58). 287 (40). 218 (80), 204 (loo), 189 (SO). /Mttosterol. Identified by direct comparison with an authentic sample. Isodesacetyluvaricin (1). Waxy solid (25 mg). Mp below 30”. IR vzfi cm-‘: 3450, 2940, 2855, 1755. ‘HNMR (Table 1). 13C NMR (Table 2). FABMS (CHCl, + 3-nitrobenzyl alcohol) m/z 629 [M+Na]+, 607 [M+H]+. EIMS (probe) 70eV, m/z (rel. int.): 588 [M- 181’ (3), 570(4), 552 (2), 435 (1 l), 417 (12), 399 (13), 365 (18), 347 (55), 329 (19), 311 (ll), 295 (100). 241 (20), 223 (8). lsodesacetyluvaricin diacetate (la). Oil (10 mg). ‘H NMR (Table 1). ‘sC NMR (50 MHZ, CDCI,): 173.9 (C-l), 134.3 (C-2), 25.2 (C-3), 27.4 (C-4), 30.8 (C-14 and C-25), 75.2 (C-15 and C-24), 80.94 (C-16 and C-23), 79.99 (C-19 and C-20), 31.8 (C-32), 22.6 (C-33), 14.1 (C-34), 148.7 (C-35), 77.3 (C-36). 19.2 (C-37), 29.5, 28.1, 25.4 (C-5-c-13, C-17, C-18, C-21, C-22, C-2&C-31), 21.1 (X 2AcMe), 170.8 (x 3 MeCO-). EIMS (probe) 70 eV, m/z (rel. int.): 630 [M -HOAc]+, 570 (22), 552 (13), 477 (38), 459 (20), 417 (30), 407 (100), 399 (22), 389 (20), 347 (75), 329 (55), 283 (40), 223 (25), 205 (15). Isodesacetyluvaricin TMSi ether. EIMS (probe) 70 eV m/z (rel. int.): 735 [M-15]+ (7). 660 (2), 507 (12), 489 (5), 417 (ll), 367 (lOO), 243 (15). Narumicins I and II (2 and 3). Waxy solid (100 mg). IR vzf; cm-‘: 3450,2920,2855,1755. ‘H NMR (Table 1). “C NMR (Table 2). FABMS 623 [M +H]+. EIMS (probe) 70 eV m/z (rel. int.): 604 [M -HzO]+ (2.4), 586 (3), 568 (3.6), 550(2), 479(15), 461 (lo), 451 (6). 433 (16), 415 (21), 397 (20), 381 (17), 363 (40). 345 (68), 327(10),311(100),293(85),275(10),241(12),223(5).155(15),153 (5). Narumicins I and II triacetate. Oil (20 Mg). ‘HNMR (300 MHz, CDCl,): 7.07 (lH, d, J= 1.5 Hz, H-35), 5.01 (lH, dq, J=6.8 HZ, H-36), 4.854.93 (m. 3H, H-5, H-15 and H-24), 3.98 (2H,m,H-16andH-23), 3,89(2H,m,H-19, H-20),2.30(2H,m,H3), 2.077,2.060, and 2.050 (3 x s, 9H, 3AcMe), 1.5-2.0 (16H. m, H4, H-6, H-14, H-17. H-18, H-21, H-22, H-25), 1.25 (30H, br, H-7-H-13, H-26-H-33), 0.88 (3H, t, .J=6.8 Hz, H-34). 13C NMR (SO MHz, CDCI,): 173.7 (C-l), 170.8 (x 3Me CO-), 149.4 (C-35), 133.1 (C-2), 81.5*, 81.1*, 80.3*, 79.9(C-16, C-19, C-20, C-23 in 2), 80.88, 79.99 (C-16, C-19, C-20, C-23 in l), (*indicates low intensity signals), 77.4 (C-36), 75.1 (C-15 and C-24), 73.1 (C-5), 30.8 (C-14, C-25), 31.4 (C-4), 33.8 (C-6), 25.3,27.5,2&O, 29.4 (C-3, C-7-C-13, C-17, q18, C-21, C-22, C-2&C-31), 31.8 (C-32), 22.5 (C-33), 21.1 (3 x AcMe), 19.0 (C-37), 14.0 (C-34). EIMS (probe) 70 eV m/z (rel. int.): 688 [M - HOAc]’ (20), 628,568,550 (8), 535 (25), 517 (21), 475 (25), 465 (lOO), 415 (23), 405 (50), 387 (22), 353 (27), 345 (70), 327 (27), 293,283 (35), 223 (23). 205 (12), 197 (9) (see Scheme 1).
Acetogenins from Uoaria narum Nnrumicins I and II TMSi ether. EIMS (probe) 70 eV m/z: 823 [M-Me]+ (18), 748 (8), 668 (20), 658 (3), 611 (I), 595 (35), 525 (23), 505 (20), 487 (12), 455 (lOO),415 (28), 397 (20), 383 (IS), 365 (35), 313 (12), 293 (lo), 243 (45), 227 (72) (see Scheme 1). Acknowledgements-A. Hisham is a recipient of a Belgian ASLK grant. L.A.C. Pieters is a senior research assistant of the National Fund for Scientific Research (Belgium). The authors also acknowledge N.F.W.O. for financial support (grant no. 3.0004, 86).
REFERENCES
1. Hisham, A., Pieters, L. A. C., Claeys, M., Esmans, E., Dommisse, R. and Vlietinck, A. J. (1990) Tetrahedron Letters 31, 4649. 2. Hisham, A., Pieters, L. A. C., Claeys, M., Esmans, E.,
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Domrnisse, R. and Vhetinck, A. J. (1990) Phytochemistry 30, 545. 3. Jolad, S. D., Hoffmann, J. J., Cole, J. R., Barry, C. E., Bates, R. B., Linz, G. S. and Konig, W. A. (1985) .I. Nat. Prod. 48, 644. 4. Hoye, T. R. and Suhadolnik, J. C. (1987) J. Am. Chem. Sot. lo!), 4402.
5. Hoye, T. R. and Zhuang, Z. (1988) J. Org. Chem. 53, 5578. 6. Rupprecht, J. K., Hui, Y. H. and McLaughlin, J. L. (1990) J. Nat. Prod. 53, 237. 7. Born, L., Lieb, F., Lorentzen, J. P., Moeschler, H., Nonfon, M., Sollner, R. and Wendisch, D. (1990) PIanta Med. 56,312.
8. Nkunya, M. H. H., Achenbach, H., Renner, C., Waibel, R. and Weenen, H. (1990) Phytochemistry 29, 1261. 9. Gonzalez, A. G., Ferro, E. A. and Ravelo, A. G. (1987) Phytochemistry 26, 2785.
10. Sakurai, N., Yaguchi, Y. and Inoue, T. (1987) Phytochemistry 26, 217.
ACETQGENINS
0
0031-9422/w %3.00+0.00 1991PergamonPress ptc
FROM ROOT BARK OF UVARIA NARUM
A. HISHAM,* L. A. C. P~ETERS,M_ CLAEYS, H, VAN DEN HEUVEL, E. ESMANS,?R. DUMMISSE,J: and A. J. VLIETINCK Department of Pharmaceutical Sciences, University of Antwerp (UIA), Universiteitsplein 1, B-2610, Antwerp, Belgium; *Department of Organic Cbemistry, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2024 Antwerp, Belgium (Received in revised form 30 November 1990)
Key Word Index--Uuaria
narum;
Annonaceae; root bark; acetogenins; isodesacetyluvaricin; narumicins I and Ii.
Abstract-Three new acetogenins, isodesacetyluvaricin, narumicins f. and II were isolated fram hexane and ethyl acetate extracts of the root bark of Uvaria narum, in addition to the known compounds glutinone, glutinol, taraxerol, fi-sitosterol and benzyl benzoate.
INTRODUCTION
Our recent investigations on the root bark of Uuczria narum Bl. (Annonaceae) have led to the isolation of five new acetogenins [11 2f. Further studies on the hexane and ethyl acetate extracts of the root bark of the title plant resulted in the isolation of three more new acetogenins, isodesacetyluvaricin (I), narumicin I (2) and narumicin II (3) in addition to the known compounds glutinone, glutinol, taraxerol, p-sitosterol and benzyl benzoate. Acetugenins 2 and 3 were obtained as an equimixture of two diastereoisomers and could not be resolved by normal chromatographic techniques beoause of their identical R, values. Mass spectrometry established the identical carbon backbones of 2 and 3 in the racemic mixture while NMR spectroscopy including 2D NMR experiments and a thorough comparison of the diagnostic NMR chemical shifts of the similar known compounds led ta the assignments of their relative stereochemistry in the bis-tetrahydrofuranyl part. REsULTs AND DISCU~IUN
The known compounds benzyl benzoate, glutinone, glutinol, taraxerol and /3-sitosterol were eluted in the
OH R
1
H
2 OH 3 OH *Author to whom correspondence should be addressed. PflY
30+7-s
order of their increasing polarity from the hexane extract and identified from comparison of their spectral data and physical constants with those in the literature. Compound I was isolated from the chloroform fractions of the hexane extract whilst 2 and 3 were isulated as a homogeneous mixture from the ethyl acetate extract. Isodesacetyluvaricin (l), a low melting waxy solid, showed a [M +H]’ ion at m/z 607 in the FAB and CI(CH,) mass spectra indicating a M, of 606. The ‘H and 13C NMR spectra (Tables 1 and 2) showed the presence of an ct,@-unsaturated y-la&one, two THF rings, a long ahphatic chain and two hydruxyl groups. Compound I formed a diacetyl and a diTMSi derivative confirming two hydroxyl groups. The EI mass spectral fragmentation pattern of 1 and its derivatives established the carbon skeleton of 1 which was found to be identical with that of clesacetyluvaricin, a compound isolated from the roots of U. accuminata by Jolad et al. [3]. The differences in the ‘H and *3C NMR chemical shifts of the chiral centres in 1 and desacetyluvaricin indicated that they are diastereoisomers. The relative figuration in the bis-THF part in desaeetyluvaricin was previousIy determined as &reo, trans, ghreo, tram, erythro going frum C-15 to C-24 [4,5$ In the 13C NMR spectrum of desacetyluvaricin, C-15, C16, C-I9, C-20, C-23 and C-24 appeared as six distinct signals at 6’74.1 (C-15), 83.2, 82.4, 82.2, 82.9 and 71.6 (C24) (3). However, in the 13C NMR spectrum of 1,these six carbons appeared as only three peaks at S 74.1 (C-l 5 and C-24), 83.2 (C-I 6 and C-23) and 8 1.8 (C-I9 and C-20) as in the case of asimicin [6 and refs cited therein]. In the ‘H NMR spectrum of desacetyluvaricin, H-15 appeared at 63.39 and H-24 appeared between 63.8-3.93 together with the oxymethine protons of the THF rings. In 1, both H-15 and H-24 appeared at 63.40. In order to determine the relative stereochemistry in the bis-THF part in 1 we applied Hoye and Suhadolnik’s proton chemical shift correlation methodology [4, 51. The identical C-15 and C-24 acetyl methyl resonance at 82.077 in the ‘H NMR spectrum of the d&&ate of 1. (la) indicated that the C-15/C-16 and C-23/C-24 stereorelationships in 1 are threu. The chemical shifts of H- 19 and H-20 in la at 6 3.89 and H-16 and H-23 at 63.98 by comparison with the model compounds suggested a brans, threo, tram relationship for the THF rings [4,5]. From these data the relative
2373
A. HISHAM et
2374
al,
Table 1. ‘H NMR data of compounds 1, la, 2 and 3 (300 MHz, CDCI,) H
1
2
3
la
3 4 5 6 7-13 14 15 16 17,18 19,20 21,22 23 24 25 26-33 34 35 36 37 OAc OAc
2.26 t (7.8) 1.5 111 1.25 br 1.25 br 1.2s hr 1.35-1.40 m 3.39 m 3.82-3.87 m 1.5-2.0 m 3.82.-3.87 m 1.5-2.0 m 3.82-3.87 m 3.39 m 1.35-1.40 m 1.25 hr 0.88 t (6.8) 6.99 d (1.4) 4.99 dq (6.8, 1.4) 1.40 d (6.8) ..-
2.40 m 1.65 m 3.59 m 1.35-1.40 m 1.25 br 1.35-1.40 m 3.39 m 3.82-3.87 m 1.5-2.0 m 3.82-3.87 m 1.5-2.0 m 3.82-3.87 m 3.39 m 1.35-1.40 m 1.25 hr 0.88 t (6.8) 7.05 d (1.4) 5.0t dq (4.8, 1.4) 1.40 d (6.8)
2.40 m 1.65 m
2.26 L (7.8) 1.5 m 1.25 br 1.25 br 1.25 hr 1.5m 4.85 m 3.98 m 1.5-2.0 m 3.89 m 1.5-2.0 m 3.98 m 4.85 m 1.5 m 1.25 br 0.88 t (6.8) 6.99 d (1.4) 4.99 dq (6.8, 1.4) 1.40 d (6.8) 2.077 2.077
J (in Hz)
1
1.3.5-1.40 m 1.25 br 1.35-1.40 m 3.39 m 3.82..3.87 m 1.5-2.0 m 3.82-3.87 m 1.5-2.0 m 3.82-3.81 m 3.82-3.87 m 1.35-1.40 m 1.25 br 0.88 t (6.8) 7.05 d (1.5) 5.01 dq (6.8, 1.4) 1.40 d (6.8) -
in parentheses.
Table 2. 13C NMR data of compounds l-3 (75 MHz, CDCl,) C
3.59 m
2
3
1 2 3 4 5 6 7 8--12 13 14 15 16 17,18,21,22
173.9 134.3 25.2 27.2 29.7-29.2 29.7-29.2 29.7F29.2 29.7-29.2 25.7 33.5 74.1 83.2 28.9, 28.3
173.7 133.9 21.4 35.2 70.7 37.4 25.6 29.6-29.1 25.6 33.4 73.99 83.05 28.9, 28.3
173.7 133.9 21.4 35.2 70.7 37.4 25.6 29.6-29.1 25.9” 33.2’” 73KP 83.1eb 28.9,28.3,24.3
19 20 23 24 25 26 27-31 32 33 34 35 36 37
81.8 81.8 83.2 74.1 33.5 25.7 29.7-29.2 31.9 22.7 14.1 148.9 77.3 19.2
81.69 81.69 83.05 73.99 33.4 25.6 29.6-29.1 31.8 22.6 14.0 149.3 77.4 19.0
82.42’ 82.15” 82.6Tb 71.30’6 32.36’” 25.6’ 29.6-29.1 31.8 22.6 14.0 149.3 77.4 19.0
*Indicate low intensity signals. “-“May be reversed within column.
stereochemistry of the bis-THF part in 1 can be ascribed as threo, trans, three, trans, threo. The stereochemistry at C-36 is unknown. Narumicins I (2) and II (3), a stereoisomeric mixture, showed a [M-t-H]’ ion at m/-_ 623 in the FAB mass spectrum indicating a M, of 622. The EI mass spectrum of the product did not show a [M]’ but a series of peaks (m/z 604,586,568,550) arising from the loss of water were observed. The IR spectrum showed absorption bands for hydroxyl groups (3455 cm- ‘) and an a&unsaturated y-lactone (1755 cm I). The ‘H and 13C NMR spectra of the product exhibited typical signals for an cc& unsaturated y-lactone, hydroxyl groups, a long aliphatic chain and THF rings. The mixture formed a triacetate (EIMS m/z 688 (M - HOAc] ‘) and a triTMSi derivative (EIMS m/z 823 [M - Mej+) confirming the presence of three hydroxyl groups. The EIMS fragmentation pattern of the product and its triacetyl and triTMSi derivatives established the identical carbon skeletons of 2 and 3. The diagnostic fragment ions observed in the EI mass spectrum of the mixture and its derivatives are summarized in Scheme 1. The NMR spectral data showed that these two isomers differed only in the relative stereochemistry of the bis-THF portion. The remaining parts of the molecules were found to have identical chemical shifts. The El mass spectral ions at m/z 15.5 (15%) in the underivatized product and the corresponding trimethylsilylated ion at m/z 227 (72%) in the triTMSi derivative formed by the cleavage of the C-4/C-5 bond supported the position of a hydroxyl group at the C-5 position, as in the case of our previously reported compound panalicin [2] isolated from the root bark of U. narum. Even though a peak at m/z 497 was not observed in the EI mass spectrum of the underivatized product formed by the competitive
Acetogenins from Uoarianarum
m/z-
R H TMSi AC
241 313 283
;
; ,
I I I
‘$
TM% 52.5 AC 465
I I
I
0
I
R m/z .J-w TM% 243
R H TMSi AC
353 m/z 451 595 535
R H
m/z ,! 497’
Scheme 1. Diagnostic ions in EI mass spectrum of narumicins I (2) and II (3) and their triTMSi and triacetyl derivatives. *Peak not observed, corresponding peaks formed by consecutive loss of two molecules of water evident.
cleavage of the C-4/C-S bond, the peaks at m/z 479 (15%) [497 -H,O] and 461(10%) [497 - 2H,O] were observed which could be assigned for the ions formed by the C-4/C5 cleavage, followed by the loss of one and two molecules of water (Scheme 1). The presence of a hydroxyl group at the C-5 position was further confirmed by the ‘H-‘H COSY spectrum (3OOMHz, CDCl,) and the lH-13C HETCOR spectrum of the product. The two proton multiplet at 62.40 could obviously be attributed to the H-3 protons. In the ‘H--‘H COSY spectrum, these protons showed correlation with the H-36 proton at 65.01 (lH, dq) in the y-lactone ring. In the ‘H-13C HETCOR spectrum, the H-3 protons correlated with the methylene carbon signal at 621.4. In the ‘H-‘H COSY spectrum, the H-5 proton at 63.59 (lH, m) and the H-3 protons at 6 2.40 showed correlation with a proton multiplet at 61.65 which could clearly be assigned to the protons of the CH, group between C-3 and C-5. Furthermore, the hetero correlations (HETCOR) observed for the atoms in this region [(e.g. 6 1.65 (m) -35.4 (H-4-C4), 3.59 (lH, m)-+70.7 (H-5-&-5), 1.35-1.40 (m)+37.4 (H-6-X-6)] were also in agreement with the position of a hydroxyl group at C-5. Moreover, the ‘H and 13C NMR chemical shifts for the atoms at C-3, C-4, C-5 and C-6 in the narumicin stereoisomeric mixture were found to be different from the NMR chemical shifts reported for these atoms in other common compounds which possess either a hydroxyl group at C-4 or without any hydroxyl substitution in this region. As mentioned above, anomalies in the expected NMR signals as well as in the 13C NMR signal intensities of the chiral centres in the bis-THF portion, that is at C-15, C-16, C-19, C-20, C-23, and C-24, suggested that it was a stereoisomeric mixture of two compounds which differed in the relative configuration in this part. The ‘H and 13CNMR chemical shifts of the remaining parts of the molecules, that is, atoms 1-12, 2634 and 35-37, were quite agreeable with the expected values and were found to be identical for both isomers. A thorough comparison with the diagnostic NMR chemical shifts of the similar reported compounds as well as the application of the Hoye and Suhadolnik proton chemical shift correlation methodology [4, 51 enabled us to interpret the ‘H and
2315
’ 3C NMR spectra of the stereoisomeric mixture and led to the assignment of the relative stereochemistry in the bis-THF part in both isomers. A compilation of the NMR spectral data with the proposed stereochemistry for all the Annonaceous acetogenins reported until 1990 is presented in a recent review article published by Rupprecht et al. [6]. In the “C NMR spectra of the adjacent bis-THF ring-containing acetogenins with a three, trans, threo, trans, erythro (or erythro, trans, threo, trans, three) relative stereochemistry such as in bullatacin, bullatacinone, annonin I, annonin VI, and desacetyluvaricin C-16, C-19, C-20 and C-23 showed four distinct signals between 683.2,82.7,82.1 and 82.4 and the carbinol methine carbons at C-15 and C-24 showed two signals between 673.8-74.3 and 71.3-71.5 with a difference of ca 2.5 ppm. However, in the case of 1 and asimicin [6], two compounds with a three, trans, three, trans, three stereochemistry (which possess pseudosymmeteric stereochemistry), C-16, C-19, C-20 and C-23 showed only two signals at 683.1 (C-16 and C-23) and 81.7 (C-19 and C-20) and C-15 and C-24 also appeared as a single peak at ca 674. In the ‘H NMR of all known bis-THF acetogenins with one three and one erythro relationship for C-15/C-16 and C-23/C-24, one of the protons at either C-15 or C-24 appeared at ca 63.4 and the other proton was found to be merged with oxymethine proton multiplets of the THF rings which usually appear between 63.82 and 3.92. However, in 1 and asimicin, H- 15 and H-24 appeared at ca 6 3.4. These data, as well as the NMR chemical shifts reported for the two synthetic model compounds by Born et al. [7], indicate that a very reliable conclusion could be drawn about the stereorelationships between C-15/C-16 and C-23/C-24 in the adjacent bis-THF acetogenins from the following generalization: a C-15 or C-24 carbon chemical shift at ca 673.8-74.1 and a corresponding proton chemical shift at ca 63.38-3.41 can be ascribed for a three-relationship between the THF ring and the adjacent hydroxyl bearing carbon, and a C-15 or C-24 carbon chemical shift at ca 671.3-71.6 and a corresponding proton chemical shift at ca 63.8-3.9 can be ascribed for an erythro-relationship. This generalization can be validated from the chemical shift data of the mono THF-containing acetogenins cited in the review article [6]_ In the ‘%NMR spectrum of the mixture of 2 and 3, C-16, C-19, C-20 and C-23 showed six signals at 683.14, 83.05, 82.67, 82.42, 82.15 and 82.69 and C-15 and C-24 showed three signals at 673.99,73.90 and 71.30 with high and low intensities. Out of these, four oxymethine carbon signals of the THF rings at 683.14, 82.67, 82.42 and 82.15 and two of the carbinol methine carbon signals at 673.90 and 71.30 were low intensity signals compared with the remaining signals of the THF rings at 683.05 and 81.69 and the carbinol methine signal at 673.90, the signal intensity ratio between the two sets of signals was found to be 1: 2, respectively. In the ‘H NMR spectrum (300 MHz, CDCl,) of the equimixture of 2 and 3 signals of H-16, H-19, H-20 and H-23 in both isomers as well as one of the carbinol methine protons at either H-15 or H-24 in one of the isomers appeared as a multiplet between 63.82 and 3.89 which showed an integration for 4.5 protons. Similarly, the signals of both the H-15 and H-24 protons in one of the isomers as well as one of the protons at either H-15 or H-24 in the second isomer appeared as a multiplet at 63.39 which showed an integration for 1.5 protons. In the
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A. HISHAM et al.
lH-13C HETCOR spectrum of the mixture, all six oxymethine carbon signals which appeared for C-16, C-19, C20 and C-23, and one of the low intensity carbinol methine carbon signals at 671.30 which appeared for C15 or C-24 in one of the isomers showed correlation with the 4.5 proton multiplet as expected. Similarly, the high intensity carbinol methine carbon signal at 673.99 and the low intensity signal at 673.90 showed correlation with the 1.5 proton multiplet at 63.39. The chemical shifts of the low intensity signals of the THF portion in the narumicin stereoisomeric mixture were strikingly similar to those in the adjacent bis-THF acetogenins with a threo, trans, threo, tmns, erythro stereochemistry and the high intensity signals were identical with those in 1 and asimicin which possess a threo, trans, threo, trans, threo stereochemistry. This data led to the conclusion that the mixture contained a threo, trans, threo, trans, erythro isomer and a threo, trans, threo, trans, threo isomer in a 1: 1 ratio. A high field ‘H NMR spectrum (300 MHz, CDCl,) of the acetate of the mixture showed three acetyl methyl singlets at 62.077, 2.06 and 2.05 with considerable differences in their relative intensities (2.077 > 2.06 > 2.05). A two proton multiplet at 6 3.98 (H-16 and H-23) and a two proton multiplet at 63.89 (H-19 and H-20) suggested a trans configuration for both rings and a threo relationship between H-19/H-20 in both isomers according to Hoye and Suhadolnik’s methodology [S, 63. By taking all the above observations into consideration, the ‘H and 13CNMR spectra of the stereoisomeric mixture can be interpreted unambiguously. The isomer named narumitin I (2) was ascribed the relative stereochemistry threo, trans, threo, trans, threo and the second isomer named narumicin II (3) was ascribed threo, trans, threo, trans, erythro or erythro, trams, threo, trans, threo going from C-15 to C-24. The ‘H and 13C chemical shifts assigned for both the isomers are given in Table 1. The stereochemistries at C-36 and C-5 in 2 and 3 are unknown. The diagnostic oxymethine NMR shifts assigned for 2 in the bis-THF part are virtually identical with those signals of compound 1 and asimicin, and the chemical shifts assigned for 3 are identical with those of rolliniastatin II [6]. From the identical diagnostic oxymethine 13C NMR signals of the bis-THF part, it seems that rolliniastatin II, a stereochemically undefined compound, could probably have the identical relative stereochemistry in the bis-THF part to narumicin II.
EXPERIMENTAL
General. Instruments used, plant material, general isolation procedures and derivative preparations were the same as described previously 121. Isolation of benzyl benzoate, glutinone, glutinol, taraxerol and fl-sitosterol. These compounds were isolated from the hexane, toluene, toluene-CHCl, frs of the hexane extract as described in ref. [Z]. Isolation of isodesacetyluvaricin (l), narumicin, I (2) and II (3). Compound 1 was isolated from the initial CHCl, frs and purified by prep. TLC on silica gel using CH,Cl,-EtOAc (3:2). The homogeneous mixt. of 2 and 3 was isolated from the initial CHCl, frs of the EtOAc extract which was purified either by repeated CC or by prep. TLC using CHCl,-MeOH (9: 1). Benzyl benzoate was identified in the toluene frs together with several sesquiterpene hydrocarbons by GC-MS analysis.
Glutinone. Crystals from CHCI,-MeOH (50 mg). Mp. 224”. IR v”,f 1705 cm-’ (C=O). ‘H NMR (200 MHz, CDCl,): 0.82, 0.96, 0.99, 1.03, 1.09, 1.16, 1.22 and 1.24 (8 x s, each 3H, 8 x Me), 5.7(1H, br, H-6),2.40(2H, t, J =5 Hz, H-2),0.80-2.01 (m, all other protons). 13C NMR (50 MHz, CDCI,) (C-l-C-30); 21.49, 35.86, 215.29, 49.93, 142.32, 121.23, 23.53, 46.95, 35.03, 50.57, 33.05. 30.25, 38.02, 39.24, 34.05, 35.04, 29.61, 43.04, 35.04, 28.21, 31.83, 38.83, 28.43, 24.29, 15.59, 18.28, 19.27, 32.30, 31.94, 34.45. EIMS 70 eV m/z (rel. int.): 424 [M]’ (25), 409 (15), 274 (lOO), 259 (70), 205 (40), 150 (25). Glutinol. Crystals from CHCl,-MeOH (SO mg). Mp 210” [lit. [8] mp 210”]. ‘HNMR: see ref. [8]. 13CNMR: see ref. [9]. EIMS: see ref. [S]. Taraxerol. Crystals from CHCl,-MeOH (15 mg). Mp 276-277. ‘H NMR (200 MHz, CDCl,): 0.80. 0.82, 0.90 (6H, 2 x Me), 0.92 0.95, 0.97 and 1.07 (7 x s, 8 x Me), 3.2 (lH, m, H-3), 5.53 (lH, dd, H-14) 0.8-2.1 (23H, m). ‘sCNMR: see ref. [lo]. EIMS 70 eV m/z 426 [Ml’, 411 (48), 393 (18). 302 (58). 287 (40). 218 (80), 204 (loo), 189 (SO). /Mttosterol. Identified by direct comparison with an authentic sample. Isodesacetyluvaricin (1). Waxy solid (25 mg). Mp below 30”. IR vzfi cm-‘: 3450, 2940, 2855, 1755. ‘HNMR (Table 1). 13C NMR (Table 2). FABMS (CHCl, + 3-nitrobenzyl alcohol) m/z 629 [M+Na]+, 607 [M+H]+. EIMS (probe) 70eV, m/z (rel. int.): 588 [M- 181’ (3), 570(4), 552 (2), 435 (1 l), 417 (12), 399 (13), 365 (18), 347 (55), 329 (19), 311 (ll), 295 (100). 241 (20), 223 (8). lsodesacetyluvaricin diacetate (la). Oil (10 mg). ‘H NMR (Table 1). ‘sC NMR (50 MHZ, CDCI,): 173.9 (C-l), 134.3 (C-2), 25.2 (C-3), 27.4 (C-4), 30.8 (C-14 and C-25), 75.2 (C-15 and C-24), 80.94 (C-16 and C-23), 79.99 (C-19 and C-20), 31.8 (C-32), 22.6 (C-33), 14.1 (C-34), 148.7 (C-35), 77.3 (C-36). 19.2 (C-37), 29.5, 28.1, 25.4 (C-5-c-13, C-17, C-18, C-21, C-22, C-2&C-31), 21.1 (X 2AcMe), 170.8 (x 3 MeCO-). EIMS (probe) 70 eV, m/z (rel. int.): 630 [M -HOAc]+, 570 (22), 552 (13), 477 (38), 459 (20), 417 (30), 407 (100), 399 (22), 389 (20), 347 (75), 329 (55), 283 (40), 223 (25), 205 (15). Isodesacetyluvaricin TMSi ether. EIMS (probe) 70 eV m/z (rel. int.): 735 [M-15]+ (7). 660 (2), 507 (12), 489 (5), 417 (ll), 367 (lOO), 243 (15). Narumicins I and II (2 and 3). Waxy solid (100 mg). IR vzf; cm-‘: 3450,2920,2855,1755. ‘H NMR (Table 1). “C NMR (Table 2). FABMS 623 [M +H]+. EIMS (probe) 70 eV m/z (rel. int.): 604 [M -HzO]+ (2.4), 586 (3), 568 (3.6), 550(2), 479(15), 461 (lo), 451 (6). 433 (16), 415 (21), 397 (20), 381 (17), 363 (40). 345 (68), 327(10),311(100),293(85),275(10),241(12),223(5).155(15),153 (5). Narumicins I and II triacetate. Oil (20 Mg). ‘HNMR (300 MHz, CDCl,): 7.07 (lH, d, J= 1.5 Hz, H-35), 5.01 (lH, dq, J=6.8 HZ, H-36), 4.854.93 (m. 3H, H-5, H-15 and H-24), 3.98 (2H,m,H-16andH-23), 3,89(2H,m,H-19, H-20),2.30(2H,m,H3), 2.077,2.060, and 2.050 (3 x s, 9H, 3AcMe), 1.5-2.0 (16H. m, H4, H-6, H-14, H-17. H-18, H-21, H-22, H-25), 1.25 (30H, br, H-7-H-13, H-26-H-33), 0.88 (3H, t, .J=6.8 Hz, H-34). 13C NMR (SO MHz, CDCI,): 173.7 (C-l), 170.8 (x 3Me CO-), 149.4 (C-35), 133.1 (C-2), 81.5*, 81.1*, 80.3*, 79.9(C-16, C-19, C-20, C-23 in 2), 80.88, 79.99 (C-16, C-19, C-20, C-23 in l), (*indicates low intensity signals), 77.4 (C-36), 75.1 (C-15 and C-24), 73.1 (C-5), 30.8 (C-14, C-25), 31.4 (C-4), 33.8 (C-6), 25.3,27.5,2&O, 29.4 (C-3, C-7-C-13, C-17, q18, C-21, C-22, C-2&C-31), 31.8 (C-32), 22.5 (C-33), 21.1 (3 x AcMe), 19.0 (C-37), 14.0 (C-34). EIMS (probe) 70 eV m/z (rel. int.): 688 [M - HOAc]’ (20), 628,568,550 (8), 535 (25), 517 (21), 475 (25), 465 (lOO), 415 (23), 405 (50), 387 (22), 353 (27), 345 (70), 327 (27), 293,283 (35), 223 (23). 205 (12), 197 (9) (see Scheme 1).
Acetogenins from Uoaria narum Nnrumicins I and II TMSi ether. EIMS (probe) 70 eV m/z: 823 [M-Me]+ (18), 748 (8), 668 (20), 658 (3), 611 (I), 595 (35), 525 (23), 505 (20), 487 (12), 455 (lOO),415 (28), 397 (20), 383 (IS), 365 (35), 313 (12), 293 (lo), 243 (45), 227 (72) (see Scheme 1). Acknowledgements-A. Hisham is a recipient of a Belgian ASLK grant. L.A.C. Pieters is a senior research assistant of the National Fund for Scientific Research (Belgium). The authors also acknowledge N.F.W.O. for financial support (grant no. 3.0004, 86).
REFERENCES
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Domrnisse, R. and Vhetinck, A. J. (1990) Phytochemistry 30, 545. 3. Jolad, S. D., Hoffmann, J. J., Cole, J. R., Barry, C. E., Bates, R. B., Linz, G. S. and Konig, W. A. (1985) .I. Nat. Prod. 48, 644. 4. Hoye, T. R. and Suhadolnik, J. C. (1987) J. Am. Chem. Sot. lo!), 4402.
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8. Nkunya, M. H. H., Achenbach, H., Renner, C., Waibel, R. and Weenen, H. (1990) Phytochemistry 29, 1261. 9. Gonzalez, A. G., Ferro, E. A. and Ravelo, A. G. (1987) Phytochemistry 26, 2785.
10. Sakurai, N., Yaguchi, Y. and Inoue, T. (1987) Phytochemistry 26, 217.