Cordifolisides A, B, C: Norditerpene furan glycosides from Tinospora cordifolia

Pergamon

0031~9422(94)00478-l

CORDIFOLISIDES

A, B, C: NORDITERPENE

PhykxJmkzry. Vol.37,No. 3.pp.781-7861% cOpyri&t0 1994ElsevkrScka Ltd Pnakd inGreatBritain. All rightsrcsmvcd a)31--9422pd 57.00 + 0.00

FURAN GLYCOSIDES

FROM

TINOSPORA CORDIFOLIA VIJAY D. GANGAN,

PADMANAVA

PRADHAN,

ARJUN

T.

SIPAHIMALANI*

and ASOKE BANERJI

Bio-Organic Division, Bhabha Atomic Research Centre, Bombay 400085, India (Received 23 March 1994)

Key Word Index-Tinospora

cordifolia; Menispermaceae;

stem; norditerpene

furan glycosides.

Abstract-Several glycosides were isolated, as polyacetates, from the n-BuOH fraction of the Tinospora cordijoliu stems. The structures of three new norditerpene furan glycosides cordifoliside A, B and C have been established by 1D and 2D NMR spectroscopy.

INTRODUCTION

Tinospora cordifolia Miers is an important medicinal plant, cultivated throughout India, Pakistan, Myanmar and Srilanka. The stems have been used, for centuries. in the Ayurvedic preparations for the treatment ofjaundice, diabetes, skin diseases, anaemia, etc. Cl]. The plant has been shown to possess anti-inflammatory and anti-allergic properties [2]. More recently, the immunostimulatory effects of its aqueous extracts against diverse experimentally induced infections have also been reported [3]. The oral efficacy and relative lack of adverse effects of the aqueous extract of the plant prompted us to investigate its role as an immunomodulator. Chemical investigations of the plant have indicated the presence of several diterpene furan lactones [4], phenolic lignan [S]. phenyl propane glycosides [6] etc. However, the chemical investigations were mainly carried out with non-polar fractions obtained from petrol and CHC13 extracts while the above biological activities were confined to the aqueous extracts. Consequently, this study was targeted to the more polar BuOH fraction.

RESULTS AND DISCUSSION

The methanolic extract of the plant (fresh stems) was successively extracted with petrol, EtOAc and n-BuOH. The BuOH fraction afforded a complex mixture that was difficult to separate. The IR spectra showed the presence of strong OH and C=O adsorptions although acetyl signals were absent. Acetylation followed by exhaustive column, radial and preparative TLC led to the isolation of three compounds as polyacetates. However, in nature these exist as non-acetylated compounds. We report on the characterization and relative configuration of cordifolisides A, B and C as tetraacetates la-3a, respectively. The acetates showed similar R, values on TLC and *Author to whom correspondence should be addressed

similar colour reactions with SbCI,. Their UV absorption spectra were similar C202.227 (sh), 276 (sh)]. The IR spectra of la-3a showed strong broad absorptions in the carbonyl region (1700- 1750 cm - ‘) and around 1230cm-‘, indicating the presence of acetyl carbonyl groups and the possibility of &lactone and/or ester carbonyl. A weak absorption at 1660 cm- ’ indicated their tetra substituted olefinic nature. The presence of a furan ring was deduced from the IR absorptions at 3140, 1508 and 875 cm I. The FAB MS [Na]’ of la, 2a and 3a showed a molecular ion at 713 [M + Na] + thus indicating a M, of 690 [M] + . In view of the spectral evidences and the reported presence of diterpene furan aglycones in the non-polar fraction of the plant [4], it was reasonable to infer that the above compounds could be diterpene furan glycosides, with the molecular formula CJ,H,20, 5 for the tetraacetates and CZ6H3.,0,, for the corresponding parent glycosides. Hydrolysis of all these glycosides afforded glucose which was identified on the basis of TLC and GC comparison with an authentic sample. The ‘H and “C NMR assignments of cordifolisides A, B and C tetraacetate are given in Tables 1-3. The spectra of la-3a showed certain common features. The compounds showed the presence of one angular methyl group (6,sl.O, dc++ 21-24), a carbomethoxyl group (6, z 3.75, 6,5 1.5), four acetyl methyl groups (6, z 1.9-2.2, 6c 20.5) the two z protons (6, ~7.4 and 7.46, 6cl43.7 and 139.6) and one /3 proton (6, a 6.40,6,108.5) of the /l-substituted furan ring and the presence of acetylated sugar protons (6, 3.6-5.2, 6, 60-100). The differences were observed in the region of 6, 1.5-3.5 and dc 15-45. These were attributed to differences in configuration of the closely related methylenes and methines. It was difficult to arrive at any meaningful interpretation on the basis of the ‘H and ’ 3C NMR spectra alone. DEPT in combination with other NMR data indicated the presence of six methyls (1 x -COOMe, 4x -OCOMe, 1 x -Me), six methylene (lx-0-CH,-, 5x-CH,-), 12 methines (7x-0-CH, 3x > C= CH, 2x -CH) and 10 quatemary signals. Of the 781

V. D. GANGAN et al.

782 Table 1. ID and 2DNMR POS. 1

17.0

DEPT

6”

COSY

-CH2

1.63(m H,)

H-10 H-IO, H-3 H-3 H-3

2

28.0

-CH,

3

72.8

-CH-

4 5 6

152.6 126.9 22.3

>c= =C< -CH,

7

28.3

-CH,

8 9 10 II

49.2 38.7 41.8 40.0

-CH>c< -CH-CH,

12

70.8

-CH-

13 14 I5 16 17 18 19 20 COOMe 1’ 2 3 4 5 6 OCOMe MeCO

data of cordifoiiside A tetraacetate (la) in CDCI,

1.95 h Hb) I.50 (m H,) 2.12(m,H,J 4.68 (br s)

H,-1 H-10, H-3, H,-6 H-3, H-10

1.75 (m, H,) 2.37 (m HJ 1.83 (m, H,) 3.16(d, ll.I,H,,) 2.42 (hr s)

H,-7 H,-7 H,-7 H*,,6 H,-7, H-8 H,-7

H,,-7 H,-7 H-20

2.37 (m) 1.8 (m. H,) 2.14 (m, H,,) 5.45 (dd, 12.3.4)

H&t/ 1 H-12 H-12

H-12

H,.,-11 H-16

H-10

6.41 (bt s) 7.45 (br s) 7.40 (br s)

H-15 H-14 H-12

H-15 H-14

>c= -CH = =CH=CH>c=o >C=O

22.5 51.6 101.1

-Me -Me -CH-

O.%(s) 3.76(s) 4.64 (d, 7.43)

H-2

72.8 72.7 68.6 71.2 62.0

-CH-CH-CH-CH-CH,

4.95 (In) 5.15 (t. 9.5) 5.05 (t, 9.5) 3.68 (m) 4.10(dd,12.2,2, H,) 4.21 (dd, 12.2,5, Hb)

H- 1’. H-3 H-2’. H-4 H-3’. H-S H-Q’, H-6 H-S’, Hb6 H-S, H,-6’

2x>c=o 2x>c=o 4x-Me

COLOC

H-20

H&Z H, 1

124.9 fO8.5 139.5 143.7 171.7 168.0

168.8, 169.3 170.2, 170.5 20.5 x 4

NOESY

H-20 H-8, H-20

H-is H-16

H-8, H,-7 3.76 (-OMe) H,1, H-8

H-8

H-2’. H-3’ H-5’ H-l’, H-3 H-I’, H-4 H-3’ H-1’ H,-6 H.-6

H-3

1.96, 1.97,2.0 and 2.07 (all s)

10 quaternary carbons, four could be attributed to four glucosyl acetyl carbonyls (6, 168.8-170.6) one to a 6lactone carbonyl (6,171.2- 173.4) and one to a carbomethoxyl carbonyl (6,168-168.4). The tetrasubstituted olefinic bond accounted for two quaternary carbons (6, 126.9, 152.6). The remaining two quaternary carbons were attributed one each to the &position of the furan ring (6,124-124.9) and at the junctions of rings B and C (Sc 39.0). Further assignments were based on the 2D NMR analysis, 13C-‘H HETCOR, i3C-‘H COLOC, ‘H-‘HCOSY and ‘H-‘H NOESY. The correlations of “C with the corresponding ‘H frequencies, as indicated in the three tables are based on i3C-‘H HETCOR experiments. Based on the biogenetic events leading to the formation of the clerodane type bicyclic diterpenes [7), two angular methyls at C-5, C-9 and two ring junction methines at C-8, C-10 were expected. The ‘H

and i3C NMR spectra of la-3a indicated the presence of two methine protons between 6, 2.27-2.70 and only one angular methyl group (6, 0.86-1.01; 6, 21.4-21.7). The placement of the tetrasubstituted olefinic bond between C-4 and C-5 (6cI52.6.126.9) accounted for the absence of an angular methyl group at C-5. Again on the basis of the same biogenetic scheme, the carbomethoxyl group was placed at the C-4 position. So far the common features of the NMR spectra of la 3a were presented. Further elaboration of the structures of the individual compounds was on the basis of 2D experiments involving i3C-‘H COLOC, ‘H-‘H COSY and ‘H-‘H NOESY. Cord$oliside

A tetraacetate

(la)

The positions of the H-8 angular methine (8” 2.42) and C-17 Slactone carbonyl (S, 171.7) were ascertained on

Norditerpene furan glycosides from Tinospora cordijolia

783

Table 2. ID and 2D NMR data of cordifoliside B tetraacetate (t) in CDCI, Pos.

DEPT

6”

COSY

1.45 (m, H.) 1.58 (m, HJ 1.55 (m, H,) 1.78 (m, Ht.) 4.55 (br s)

H-10 H-10 H-3, H-10 Ht.-2

H,-2

2.15 (m, HJ 3.1 (br d, 11, H,,) 1.63 (m, HJ 1.98 (m, H,,) 2.70 (br d, 1I)

H,-6, H,-7 H,.,-7, H,-6 H,-6, H-8, H,7 H,,,-6, H-8, H,-7 H,.,-7, H-20

H-12,H-10

2.27 (m) 1.86 (m, H.) 2.17 (m, Hb) 5.38 (dd, 11, 5.5)

H,.,-1, H,-2, H-20 H,-11, H-12 H.-l 1, H-12 H,.,-11, H-16

H-8, H,-2 H-20 H-12 H-8, Ht,-I 1

6.39 (br s) 7.43 (br s) 7.39 (br s)

H-15 H-14 H-12

H-15 H-14

0.86 (s) 3.74(s) 4.5 (d, 7.7) 4.87 (m) 5.15(t, 9.5) 5.03 (C,9.5) 3.62 (m) 4.06 (dd, 12.4.4, H,) 4.24 (dd, 12.4.4, H,,)

H-8. H-10

H,-11 H-l’ H-2’. H-3’ H-5’. -0Me H-3’. H-l’ H-l’, H-2’. H-4’. H-5 H-3’ H-l’, H-3 H,-6 H,-6

I

18.1

-CH,

2

26.6

-CH,

3 4 5 6

73.6 145.0 128.9 30.0

-CH>c= =c< -CH,

7

21.9

-CH,

8 9 10 II

47.2 39.0 47.2 43.0

-CH>c< -CH-CH,

12 13 14 15 16 17 18 19 20 COOMe I’ 2 3 4 5 6

70.5 124.0 108.5 139.6 143.7 173.4 168.4

OCOMe

168.9, 169.3 170.2 170.5 20.6 x 4

WC0

21.4 51.5 99.6 71.7 72.9 68.0 71.6 62.0

-CH>c= -CH = =CH=CH>c=o >c=o -Me -Me -CH-CH-CH-CH-CH-CH, 2x>c=D 2x>c=o 4x-Me

the methylene

H-3, H-10

H-2 H-3’. H-l’ H-2, H-4 H-3’, H-5’ H,.,-6’. H-4 H-S, H,-6 H-5’. H,-6

1.95, 1.97, 1.98 and 2.06 (all s)

the basis of COLOC interactions between the angular methyl protons (S, 0.96) and C-8 (6c49.2) and between H8 (6u2.42) and C- 17 @,I7 1.1). H-8, in turn, gave a COSY interaction with the H, methylene proton (6H,1.83, SH,3.16), thus confirming

NOESY

position

at C-7.

The methylene protons (S, 1.75,2.37) were assigned to C6 on the basis of their spin couplings with H-7. H-6 did not show further cross-peaks and was therefore adjacent to quaternary C-5. The placement of the ghrcosyl moiety at C-3 is based on the COLOC interaction between H-3 (6,4.68) and C-4 (6, 152.6). The COSY experiments were also useful in the assignment of 6, 1.50 and 2.12 to C-2 protons, 6ul.63 and 1.95 to C-l protons and 6u2.37 to C10 protons as cross-peaks were observed between H-3 ++ H-2 and H-1 ++ H-10. These assignments were in conformity with the assigned structure la for cordifoliside A tetraacetate. The relative stereochemistry of the compound was fixed on the basis of the ‘H-‘HNOESY spectra. The important NOES observed were between H10 (6, 2.37) ++ H-12 (a, 5.45) and H-8 (6, 2.42) *-* H-20 (6, 0.96). H-10/H-12 did not show any NOE with H-

8/H-20. Thus H-10, H-12 are on the same side of the molecule whereas H-8 and the C-20 methyl are on the opposite side. The other NOESY interactions are as noted in Table 1. Thus, cordifoliside A tetraacetate can be represented by structure la (Scheme 1).

Cordifoliside

B tetraacetate

(2x1)

The assignments of methylenes, methines and glucosyl residue were made on the basis of ZDNMR experiments. The COSY spectral data, unambiguously proved the assignment of glucosyl position at C-3 (6u4.55 for H-3), the two methylenes at C-2 (6, 1.55, 1.78), C-l (6” 1.45, 1.58) and the angular methine at C-10 (6u2.27) as CKSSpeaks were observed between H-10 H H-l and H-2 +P H-

3. The angular methine at C-8 (6, 2.70), the two methylenes at C-7 (6” 1.63, 1.98) and C-6 (6, 2.15, 3.1) were also ascertained on the basis of the spin coupling observed in ‘H-tH COSY spectrum between H-8 w H-7 and H-7 c-) H-6.

784

V. D. GANGAN et al.

Table 3. ID and 2D NMR data of cordifoliside Pos. 1

6, 17.7

DEPT

6,,

-CH,

1.56(m H,)

2

22.2

-CH,

3

28.1

-CH,

4 5 6 7

145.1 128.8 73.0 26.5

>c= =c< -CH-CH,

8 9

49.6 38.5

-CH>c<

10 11

39.3 40.0

-CH-CH,

12

70.1

--CH-

1.84 1.74 2.49 2.08 2.82

(m. HJ (m. H,) (m. Hb) (m, H,) (m, H,,)

C tetraacetate

(3a) in CDCI,

COSY

NOESY

COLOC

H-10, H,-2, H,-I H-10, H,-2, H.-l H,.,-3, H.-l, H,-2 H,,,-3, H,-1, H,-2

H,-1 H.-I

H-10

H..,-2, H,,,-2,

Hb-3 H,-3

I-h-3 H,-3

H,-3 H-10 H,-2 H-10 H-6, H-10

4.57 1.56 1.86 2.37

(hr s) (m, HJ (m. H,,) (m)

H.,,-7 H-6, H-8 H-6, H-8 Ha,,-7

H-20

2.44 (m) 1.91 (m, H,)

K,,- 1

2.25 (m, HJ 5.45 (br d, 11.7)

H-12

H-12 H-15, H-20 Hb-11 H.-l 1 H-10

H-12

H.,,-11

H-20 H-8, H-IO H-20 H-20 H-20

H-16 13 14 15 16 17 18 19 20 COOMe 1’ 2 3’ 4 5 6

124.9 108.4 139.5 143.7 171.2 168.0

OCOMe

168.8, 169.3 170.2, 170.6 20.5x4

MeCO

23.7 51.4 99.3 71.5 72.9 68.3 71.6 62.0

>c= -.CH = =CH=CH>c=o >C=O -Me -Me -CH-CH-CH-CH-CH-CH,

4x-Me

6.42 (br s) 7.50 (hr s) 7.38 (br s)

1.01 (s) 3.74 (s) 4.60 (d, 7.9) 4.9 (I, 8.5) 5.18 (t, 9.5) 5.28 (r, 9.5) 3.66 (m) 4.06 (d, 12.2, H,) 4.12 (dd 12.2.4.25, H,) 2x>c=o 2x>c=o 1.96, 1.99 and 2.07 (all s)

The differences in the vicinal couphng constants of HI2 with the methylene protons at C-l 1 as compared to those ofcordifolisides A and C tetraacetate suggested that cordifoliside B tetraacetate possesses a different stereochemistry at C-12. Further evidence for this and the relative stereochemistry of the rest of the centres in 2a were derived from the ‘H-‘H NOESY spectra. The important NOESY interactions are shown in Table 2. The interactions 6, 5.3865, 2.70 and b, 2.7oU6, 2.27 indicated that the ring junction protons at C-8, C-IO and C12 were all situated on the same side of the molecule. None of these showed any cross-peaks with the angular methyl protons at C-20. Thus, it was on the other side of the molecule. The cross-peaks between H-3 +-+ H,-2 and H,-2 CI H-10 indicted that H-3 is also on the same side as the three protons at C-8, C-10 and C-12. In view of the pposition of H-3. the other three protons are also placed on

H-15 H-14 H-12

H-16 H-14 H-14 H-8 3.74(-OMe)

H,-11

H.-l 1, H-8 H-2 H-l’, H-2’. H-3’. H-4’. H-5’, H-5’.

H-3’ H-4 H-5’ Ha,,-6 H,-6 H,-6

H-2’, H-3’. H-5’ H-l’ H-l’ H-l’ H,-6 H,-6

the P-side while the angular position. Thus cordifoliside-B the structure 2a (Scheme 1).

Cordifoliside

C tetraacetate

H-2’ H-2’ H-3’. H..b-6 H-4

methyl at C-20 is in atetraacetate was assigned

(3a)

The assignment of the structure of 3a was also based on ID and 2D NMR data. Of the two angular methines, the signal at 6, 2.44 was assigned to H-10 on the basis of its COLOC interaction with the two quaternary carbon centres of the tetrasubstituted olefinic bond between C-4 and C-5. The other angular methine at 6, 2.37 was assigned to H-8 on the basis of its COLOC interaction with quaternary C-9 (Sc38.5). The COLOC also fixed the position of lactone carbonyl at C-17 (Sc 171.2) on the basis of its cross-linking with H-8 (6, 2.37). The positions of the methylenes at C-l, C-2 and C-3 were assigned on

Norditerpene furan giycosides from T~no~poracord~~ia

785

Ro,,,,@* gjLjfjzo go 18

o=c

c =o

c=o I

I Me0

I OMe

O?&

2

1

1

- 3

R = @-D-&xo-pyranosyl

la

- 30

R = letre-O-acdyl-P-D-glu~pyranosyi

& 3

Scheme 1. Important NOE interactions observed in la-3s

the basis of the COSY cross-peaks observed between H10 (6n2.44) c* H-l (6,1.56,1.84) and H,-2 (6ml.74) H H3 @,2.08,2.82). The proton at H-8 showed COSY crosspeaks with the methylene protons at Sn(1.56, 1.86) thus ascertaining the position of that methylene at C-7. The methylene protons at C-7, in turn, showed cross-interaction with a downfield methine proton (6u4.57) thus indicating that the glycosidic position should be at C-6. The proton at 6u5.45 was assigned to H-12 on the basis of its long range COSY interaction with the furan proton H16 at 6n7.38. Cordifoliside C tetraacetate was found to have the same relative configuration as cordifoliside A, since NOESY experiment showed cross-peaks between H-8 ++ H-20 and H-10 c, H-12. No NOES were observed between H-8/H-20 and H-10/H-12. Thus, cordifoliside C tetraacetate was assigned the structure 3a (Scheme 1). EXPERIMENTAL

Mps: uncorr.; IR: KBr pellets; UV: MeOH; ‘H and l 3CNMR 200 and 50 MHz respectively. All the 2D experiments were carried out with 0.01 M solns in CD&. For DEFT, signal editings were done by varying the pulse width of the last polarization pulse as 14.5,29 and 43.5. In COLOC, 512 transients were recorded for each t, experiment of 80 increments. It was then zero-filled to 256W. In the W, dimension (i3C) 4K data points were recorded without zero-filling. The delays used in COLOC were: D, = 1 set, D, -0.028 set and D,=0.014 sec. The NOESY and COSY spectra were recorded with following parameters; TD,=256W, SI,=512W and SI=TD= 1K with square sine bell multiplications in both dimensions. For NOESY a mixing time of 1 set was used. Isolation of cordifolisides A, B and C tetraacetates. The plant material (5.8 kg) was collected from Trombay campus, Bhabha Atomic Research Centre, Bombay and identified by Dr V. Abraham of the Nuclear Agriculture Division, BARC. Fresh stems were subjected to cold

extraction, with MeOH, through percolation. The nonpolar compounds were removed by extraction with petrol and EtOAc. It was then extracted with n-BuOH and subjected to CC on silica gel, using increasing amounts of MeOH in CHCI,. The frs. with similar polarities, were pooled together (5 frs). The crude frs 2 and 3 were acetylated using Ac,O and pyridine at room temp. for 48 hr. Further fractionation was achieved by repeated radial chromatography of the acetylated crude frs as well as by prep. TLC. This resulted in the isolation of 3 compounds. They were named as cordifoliside A (I), cordifoliside B (2) and cordifoliside C (3) and were characterized as the tetraacetates la-3a. C~r~~arogra~~~ systems. TLC: silica gel G (Acme, Bombay), CHCl,-MeOH (99:l). Detection was by spraying with 20% SbCI, (CHCl,) and heating (100’ 10 min). For sugars, the solvent system CH,ClzMeOH-HOAc-H,O (20:8: t : 1) was employed. Anisaldehyde/H,SO, spray reagent was used for detection. On heating (lOtI’, 10 mink the sugars developed bluish spots against a violet background. Radial chromatography. Circular glass plates of 1 mm thickness were prepared by using silica gel (PFzs4, E. Merck, 50 g) in cold distilled water (105 ml). For elution, gradually increasing concentrations of MeOH in CHCI, were employed. GC: sugars were detected (FID), as acetates, using 3% OV-17 (glass column, 2 m x 5 mm o.d.). Temp. programming conditions were 180-240” at 4” min- r. The N, flow rate was #ml mitt-‘. Identification of sugars in cordifoliside A, B and C: the hydrolyses of the glycosides were carried out by refluxing with 5% glacial HOAc at 100” for 6 hr. Aglycones were removed by CHCI, extraction and the aq. extract coned under red. pres. The TLC profile of the sugar was compared with that of standard glucose. It was further confirmed by GC (R, of sugar acetate= 10.92 min) comparison with standard glucose acetate (R, = 10.92 min).

786

V. D.

GANGAN et

CordiJoliside A tefraacetate (la). Solid (20 mg); C34H42015;mp 140”;[~]~~= -86.2”(CHCI,;cO.116), IR (KBr) cm- ‘: 3140,2926,2855,1759-1701,1628,1506, 1437, 1367, 1221, 1161, 1064, 1037, 1005, 912, 875, 799, 738 , 693 3 602.7 UViiz” nm: 202, 227 (sh), 280 (sh); ‘HNMR (2OOMHz, CDCI,) and “CNMR (SOMHz, CDCI,): Table 1; FAB MS m/z (rel. int.): 713 [M + Na]’ (3.64),691 [M+H]+ (1.3),685(2.18),673(1.06),653(0.37), 642 (0.26), 535 (0.39), 477 (0.85), 446 (1.06). 408 (6), 343 (17), 331(25),311 (31),217(17), 171 (43), 154(100), 136(91), 107 (52). 89 (57), 77 (73). 56 (67). Cordifoliside B tetraacetate (2a). Solid (20 mg); C34H4L0,5; mp 189’; [z]k’= - 122.14’ (CHCI,; c 0.098), IR (KBr) cm -‘. 3140, 2951, 2874, 1751-1701, 1558,1541,1508,1437,1368,1244,1229,1161,1069,1036, 910, 878, 602; UVJ!$T” nm: 202, 228 (sh), 272 (sh); ‘HNMR (200 MHz, CDCI,) and 13CNMR (50 MHz, CDCI,): Table 2; FAB MS m/z (rel. int.): 713 [M + Na] + (2.6), 691 [M+H]+ (1.24), 685 (l), 466 (0.48). 465 (1.08), 408 (23.9), 391 (10.1). 343 (9.26), 331 (23.53), 311 (22.7), 307 (lo), 289 (8.26), 278 (5.5). 265 (3.12). 249 (4.5), 237 (7.26). 217 (7.9), 187 (5), 169 (34.3). 154 (100). 149 (54). 136 (84). 107 (38). 89 (49). 77 (65). 52 (38). Cordijoliside C tetroacetnte (38). Solid (30 mg); C31H120,5; mp 163”; [a]h5= +26.3” (CHCI,; c 0.113), IR (KBr)cm-‘: 3140,2953,2855,1752--1700,1748,1508, 1437, 1370, 1227, 1163, 1131, 1067, 1047, 934, 910, 876, 777, 691, 602; UV;.z$‘” nm: 202, 224 (sh), 276 (sh); ‘HNMR (2OOMHz, CDCl,) and 13CNMR (50MH2, CDCl,): Table 1; FAB MS m/z (ret. int.): 713 [M + Na] +

al.

(0.32), 691 [M + H] + (0.28), 673 (0.73), 460 (0.6), 430 (0.53), 408 (1 l), 343 (4), 331 (7), 311 (7.1), 307 (15), 297 (2), 289 (9), 279 (1.9), 169 (13), 154 (lOO), 136 (82), 107 (35), 89 (38), 77 (46), 69 (19). 63 (20.25), 52 (29). Acknowledgements-We thank Dr 0. Seligmann and Prof. Dr H. Wagner, Institute of Pharmaceutical Biology, University of Miinchen, Germany, for recording the FAB-MS. One ofthe authors (V.D.G.) thanks the Department of Atomic Energy, for the award of senior research fellowship. REFERENCES

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