A clerodane diterpene and other constituents of Clerodendron inerme

Short Reports

3671

EXPERIMENTAL

Air-dried aerial parts (46Og, voucher Del Vitto 2841, deposited in the Herbario de la Universidad National de San Luis) were extracted with MeOH (24 hr x 3) at room temp and the resulting extract worked-up in the usual fashion. CC silica gel eluted with C,H,-EtOAc mixts, gave the following compounds in order of elution: jaceosidin (&H,-EtOAc) (9: 1), 9-Odesacetylspathulin-2-0-angelate (C,H,-EtOAc) (6: l), nepetin (C,H,-EtOAc) (3: 1) and 2-desoxypleniradin-4-O-a-L-rhamnopiranoside (EtOAc). Complete purification of the compounds was achieved by rechromatography over Sephadex LH-20 for the flavonoids and by crystallization for the lactones, affording 0.21 g, 2.05 g, 0.17 g and 1.65 g respectively. Known compounds were identified by comparison with previously reported data and by comparison with authentic material. 2-Desoxypleniradin-4-0-a-L-rhamnopyranoside (2). MP 163-164”; IR vi:; cm-‘: 3500 (OH), 1765 (y-lactone); MS m/z (rel. int.): 248 [M-CsH,004]+ (2), 231 [CL5H1902]+ (51), 230 [248 -H,O] (lOO),215 (14), 188 (26), 145 (62), 129 (28), 105 (30).

Cali,-=

589 -134.8

578 -138.8

546 - 156.9

(CHCl,; c 1.02)

Acknowledgements-The authors thanks Dr F. H. Guidugli, LEA (UNSL), for MS. The work was supported by a grant from CONICET. REFERENCES 1. Bierner, M. W. (1987) Sida 12, 253. 2. Her4 W., Gast, C. M. and Subramaniam, P. S. (1968) J. Org. Chem. 33, 2780. 3. Gill, S., Dembinska-Migas, W., Sliwinska, E., Daniewski, W. M. and Bohlmann, F. (1980) Phytochemistry 19, 2049. 4. Bohlmann, F., Misra, L. N., Jakupovic, J., King, R. M. and Robinson, H. (1985) Phytochemistry 24, 1315.

Vol. 29,No. 11,pp.3671-3673,1990 Printedin Great Britain.

DITERPENE

-254.3

7(8),9,11(13)-Guaiatrien-Cof-12-oic acid (4). ‘HNMR (60 MHz, CDCI,): 61.18 (3H, s, H-15), 1.74 (3H, br s, H-14), 5.47 (lH,d,5=2Hz),5.60(lH,d,5=2Hz)(H-8andH-9),5.75(1H,s, H-13b), 6.35 (lH, s, H-13a).

0031 9422/90 %3.00+0.00 Pergamon Press plc

Phytochemistry,

A CLERODANE

436 nm

AND OTHER CONSTITUENTS

OF CLERO-

DENDRONINERME BASUDEB ACHARI, CHANDANA CHAUDHURI, CHITTA R. SAHA, PRADEEP K. DUTTA and SATKESH C. PAKRASHI*

Indian Institute of Chemical Biology, Calcutta-700032, India (Received 21 December 1989) Key Word

Index-Clerodendron

inerme; Verbenaceae; clerodane diterpene; clerodermic acid; flavonoids.

Abstract-A new clerodane diterpene clerodermic deduced from spectral data. The known compounds and apigenin were also found.

acid was isolated from Clerodendron inerme and the structure friedelin, S-hydroxy-7,4’-dimethoxyflavone, salvigenin, acacetin

INTRODUCTION

Clerodendron inerme L., like many other species of the genus, is a recognized medicinal plant having alterative and febrifugal properties [ 11. An alcoholic extract of the plant has also been reported to exhibit uterine stimulant activity [2]. Chemical investigations on the leaves and stems have so far shown the presence of a number of common triterpenes [3], a neolignan [4], diterpenoids [3, 51, sterols [3, 63 and flavones [7]. Reinvestigation of the leaves of this plant has now revealed the presence of

*Author to whom correspondence should be addressed.

salvigenin (5-hydroxy-6,7,4’-trimethoxyflavone, 4) and 5hydroxy-7,4’-dimethoxyflavone (3), not reported earlier from any Clerodendron species, in addition to apigenin (6), acacetin (5,7-dihydroxy-4’-methoxyflavone, 5) and friedelin (2) detected in related species and a new diterpene acid, clerodermic acid, the structure determination of which is discussed below. RESULTS AND DISCUSSION

Clerodermic acid (la), mp 161-162”, [a]~‘“---70”, exhibited in its IR spectrum a broad absorption band in the region 3300-2500 cm - ’ together with a strong absorption at 1670 cm- ‘, indicative of a conjugated carboxyl

3672

Short

e

Reports

material chromatographed over a silica gel column. The fraction obtained on elution with CHCl,-petrol (1:3) was further resolved through chromatography on a neutral alumina column to i -* obtain friedelin (2). The earlier fractions obtained from 0 CHCl,-petrol(1 : 1) eluted fraction, when subjected to prep. TLC on silica gel G (solvent: petrol-Et,O-HOAc, 80: 30:3) gave 5hydroxy-7,4’-dimethoxyflavone (3) and the later fractions alTorded la. Elution with CHCl, yielded a fraction which was freed of acidic impurities by washing an ethereal solution with 5% iaR=H NaHCO, and then rechromatographed over a silica gel column b R = Me to afford (24S)-24-ethyl-cholesta-5,22,25-trien-3-fl-o1(4). The 1% MeOH in CHCl, eluents yielded salvigenin (5). Finally, rechromatography of the fraction obtained on elution with 5% MeOH in CHCI, afforded, in solvents of increasing polarity, function. Another prominent peak at 1735 cm- ’ and a less intense one at 1775 cm-‘, could be ascribed to an LX& acacetin (6) and apigenin (7). Clerodermic acid (la). Crystalline solid (70mg) from unsaturated y-lactone moiety because this type of splitCHCl,-petrol; mp 161-162”; IR VT!’ cm-’ 3300-2500, 1775, ting of vc=o is often observed in the IR spectra of such 1735, 1670; [m]p’ -70” (CHCI,; c 0.517). ‘H NMR (CDCI,): 6 compounds due to Fermi resonance with an overtone [S]. The ‘H NMR spectrum of la displayed signals at 6 1.28 6.85(1H,t,J=4Hz),5.85(1H,t,J=2Hz),4.74(2H,d,J=2Hz), (3H, s) and around 60.80 (3H, d, overlapped by a 3H, s) 1.28 (3H, s), 0.80 (3H, d, overlapped with a 3H, s). 13CNMR (CDCl,):6174.0(s,C-13), 172.3(s,C-IS), 171.O(s,C-15), 141.4(s, for three methyl groups besides two downfield triplets at C-4), 139.7 (d, C-3), 114.9 (d, C-14), 73.0 (t, C-16), 46.6 (d, C-IO), 6 6.85 (J =4 Hz) and 5.85 (J = 2 Hz), compatible with the 38.7 (s, C-5), 37.5 (s, C-9), 36.2 (d, C-8), 35.6 (t. C-6), 35.4(t. C-11), chemical shifts of the P-H and the cr-H respectively of two 27.3 (t, C-12), 27.0 (t, C-7), 22.1 (t, C-2), 20.4 (q, C-19). 18.0 (q, Cconjugated carbonyl groups. A 2H doublet at 64.74 (J 299, 286, = 2 Hz) appeared to be allylically coupled to the 6 5.85 20), 17.4 (t, C-l), 15.8 (q, C-17). MS m/z 314 (M-H,O), 271, 221, 203, 189, 175, 165, 125, 111. signal indicating that the c&unsaturated y-lactone Methyl clerodermate (lb). The acid la was treated with CH,N, moiety should be /&substituted. The presence of a conjugin Et,0 to affordOlb as a thick liquid, IR v~~ccm-’ 1770, 1750, ated carboxyl group in la was supported by the spectrum -28” (CHCI,; c 0.1). ‘H NMR (CDCl,): 6 6.56 1715, 1635; [alp of its methyl ester lb, which showed a downfield proton (lH,t,J=4Hz),5.82(1H,t,J=2Hz),4.70(2H,d,J=2Hz),3.66 signal at S 6.76 and a 3H singlet at 6 3.66. 299, 286, 271, 203, 125. The ’ 3C NMR spectrum of la contained signals for 20 (3H, s); MS m/z 314 [M-MeOH], Friedelin (2). Powder (40 mg) from CHCl,-MeOH, mp 260”. carbon atoms. Two of the three most downfield reson‘H NMR (100 MHz, CDCI,): 6 1.18 (3H, s), 1.05 (3H, s), 1.01 (6H, ances (6 174.0-171.0) together with a doublet (in SFORD s), 0.88 (3H, d, J=6 Hz), 0.87 (3H, s), 0.73 (3H, s) spectrum) at 6 114.9 and a triplet at 6 73.0 fully supported 5-Hydroxy-7,4’-dimethoxyflavone (3). Pale yellow crystals the presence of the unsaturated y-lactone moiety. The (100 mg) from petrolCHCl,, mp 170”. ‘H NMR (CDCI,): 5 12.8 other peaks in the spectrum (6 46.6-l 5.8) were consistent (lH,s), 7.84(2H,d,J=9Hz), 7.00(2H,d,J=9Hz), 6.56(lH, s), with three methyl, seven methylene, four methine and two 6.50(1H,d,J=2Hz),6.34(1H,d,J=2Hz),3.90(3H,s),3.88(3H, quaternary carbon signals indicating a molecular fors), MS m/z 298 [Ml’, mula of CZOHz804. The EI mass spectra of la and lb, Saloigenin (4). Greenish yellow crystals (15 mg) from however, did not show any peak for the corresponding CHCl,-petrol, mp 180”. ‘H NMR (CDCI,): 6 12.8 (lH, s), 7.84 molecular ion. Instead, an intense peak was observed at (2H, d, J=9 Hz), 7.02 (2H, d, J=9 Hz), 6.56 (lH, s), 6.52 (lH, s), m/z 3 14 in both the cases, plausibly due to elimination of a 3.96 (3H, s), 3.90 (3H, s), 3.88 (3H, s). MS m/z 328 [Ml+, 313 [M molecule of water or methanol from the parent ion. -Me]. All the above evidence strongly indicated the comAcacetin (5). Pale yellow crystals (90 mg) from CHCl,-MeOH, pound to be a clerodane diterpene, the tram geometry in mp 161”. UV #:F” nm: 267, 300 (sh), 324; ( + NaOAc): 276,294 the A/B ring system of which was evident from the 6 12.8 (1 H, s), 7.82 (2H, absence of any methyl resonance in the 30 ppm region in (sh), 364. ‘H NMR (CDCl, +DMSO-d,): its 13CNMR spectrum, assigned to the 5-Me of the cis 4 J=9 Hz), 7.00 (2H, d, J=9 Hz), 6.52 (lH, s), 6.38 (lH, d, J =2 Hz), 6.18 (lH, d, J=2 Hz), 3.84 (6H, s). series [9]. The complete structure of la including stereoApigenin (6). Pale yellow crystals (80 mg) from CHCl,chemistry of the C-methyl groups at positions 8 and 9 MeOH, mp above 250”. ‘HNMR (DMSO-d,): 6 12.96 (lH, s), could also be concluded by comparison of its 13C and 7.92 (2H, d, J= 10 Hz), 6.92 (2H, d, J= 10 Hz), 6.76 (IH, s), 6.48 ‘H NMR data with those reported [lo, 1 l] for related systems, while the absolute configuration follows from a (lH, d, J=2 Hz), 6.18 (lH, d, J=2Hz).

’

I

0

:

eoof?

comparison hardwickic

of the specific acid [12].

rotation

value with that of Acknowledgement-The authors are grateful to CSIR Delhi) for the award of a research fellowship to C.C.

(New

EXPERIMENTAL

Mp: uncorr. Plant material. A supply was received from M/s United Chemicals and Allied Products, Calcutta, where a voucher specimen is maintained. Extraction and isolation. The air-dried leaves (3.8 kg) of C. inerme were subjected to percolation with MeOH. The methanolic percolate was coned to a small vol. and shaken several times with EtOAc. The EtOAc extract was evapd, and the crude

REFERENCES

Chopra, R. N., Nayer, S. L., Chopra, I. C. (1956) Glossary of Indian Medicinal Plants, p. 71. CSIR, New Delhi. Sharat, A., Aboulezz, A. F., Abdul-Alim, M. A., Goma, N. (1969) Qual. Plan. Mater. Veg. 17, 293; (1970) Gem. Absrr. 72, 99004. Singh, R. and Prakash, L. (1983) Pharmazie 38, 565.

Short Reports 4. Spencer, G. F., Flippen, A. and Judith, L. (1981) Phytochemistry u), 2757. 5. Rogers, D., Unal, G. G,, Williams, D. J., Ley, S. V. Sim, G. A., Joshi, B. S. and Ravindranath, K. R. (1979) J. Chem. Sot.

Chem. Commun.97. Subramanian, S. S., Nair, A. G. R. and Vedantham, T. N. C. (1973) Indian J. Pharm. 35, 191. Vendantham, T. N. C., Subramanian, S. S. and Harborne, J. B. (1977) Phytochemistry 16, 294. Katritzky, A. R. and Ambler, A. P. (1963) in Physical

3673

Methods in Heterocyclic Chemistry Vol. II (Katritzky, A. R., ed.), p. 165. Academic Press, New York. 9. De Rosa, S., Minale, L., Riccio, R. and Sodano, G. (1976) J. Chem. Sot. Perkin I 1408. 10. Kuho, I., Lee, Y. W., Nair, V., Nakanishi, K. and Chapya, A. (1976) J. Chem. Sot. Chem. Commun. 949. 11. Kitagawa, I., Yohihara, M., Tani, T. and Yosioka, I. (1975) Tetrahedron Letters 23. 12. Misra, R., Pandey, R. C. and Dev, S. (1964) Tetrahedron Letters 3751.

Phytochemistry,Vol. 29, No. 11, pp. 3673-3675, 1990 Printed in Great Britain.

0

TAXANES FROM TAXUS ZONGPING Institute of Organic Chemistry,

ZHANG

Lanzhou

003 l-9422/90 $3.00 + 0.00 1990 Pergamon Press plc

YUNNANENSIS

and ZHONGJIAN JIA*

University,

Lanzhou

730000, Gansu, P.R. of China

(Received 16 February 1990) Key Word Index--Taxus

yunnnnensis; Taxaceae; taxane; diterpene; l-dehydroxylbaccatin

III; 5-deacetylbaccatin I;

1-acetylbaccatin IV.

Abstract-Three new taxane diterpenes were isolated from the leaves and stems of Taxus yunnanensis. Their structures were established as 1-dehydroxylbaccatin III, 5-deacetylbaccatin I and 1-acetylbaccatin IV on the basis of spectroscopic analysis.

INTRODUCTION’ Taxus yunnanensis is an evergreen tree or shrub distributed in the wet valley areas of Yunnan Province, China [ 11. In continuation of our research on taxane diterpenes [2], we have recently isolated five taxane diterpenes from the leaves and stems of this plant. Among them are three new taxane diterpenes: 1-dehydroxylbaccatin III (I), 5-deacetylbaccatin I(2) and 1-acetylbaccatin IV (3). The other two were identified as 19-hydroxylbaccatin III (4) and lodeacetylbaccatin III (5). None of these compounds has been found in this species previously. RESULTS AND DISCUSSION

Compound 1, mp 169-171”, [a]i3-45.9” (CHCl,; c 0.75), was isolated as needles. The EI mass spectrum of 1 showed [M-AC]+ at m/z 527.2258 (C,,H,,O,, calcd 527.2281). In the IR spectrum, it showed an absorption at 3458 cm- ’ related to a hydroxyl group. The ‘H NMR spectrum exhibited the presence of tertiary methyl groups of the taxane type: 61.10 (17-H,); 1.26 (16-H,); 1.68 (19-

*Author to whom correspondence

should be addressed.

H,) and 2.00 (18-H,). In the range of 62.2-2.4, there were two methyl signals assignable to acetyl groups. The signalsat64.18(1H,d,J=8 Hz)and4.30(1H,d,J=8 Hz) appeared as an AX system indicating a methylene at C-20. The structural determination of l-dehydroxylbaccatin III (1) was greatly simplified by direct comparison of NMR and mass spectra with those of baccatin III [3,4]. The ‘HNMR spectrum of 1 was remarkably similar to that of baccatin III [3], except that the signal at 61.96, due to the C-l proton, was present. Because the dihedral angle between lb-H and 2/J-H was nearly 90”, a peak for 2-H, which only coupled with 3-H, was observed as a doublet at 65.62 [S]. The 13CNMR spectra were quite comparable, the most significant difference being a strong upfield shift of the C-l signal from 679.2 in baccatin III [4] to 640.8 for 1. The ‘H and “CNMR assignments of 1-dehydroxylbaccatin III are listed in Tables 1 and 2. Compound 2, mp 273-275”, [a]P+ 138.7” (CHCl,; c 0.6), was isolated as needles. The EI mass spectrum of 2 showed a molecular ion at m/z 610. The elemental analysis was confirmed as C30H42013. It showed a UV maximum at 222 nm and IR absorptions at 3571, 2994, 1743 cm-‘. The ‘H NMR spectrum of 2 was very similar to that of 1-acetoxyl-5-deacetyl baccatin I [S], except that the methyl signal at 62.22, due to the 1-acetyl group, was