Cirrhopetalin, a phenanthrene derivative from Cirrhopetalum andersonii

Short Reports

1002 REFERENCES

1. Kitanaka, S. and Takido, M. (1981) Phytochemistry 20, 1951. 2. Takido, M., Takahashi, S., Masuda, K. and Yasukawa, K.

4. Harada, N. and Nakanishi, K. (1972) Ace. Chem. Res. 5, 257. 5. Harada, N., Chen, S. L. and Nakanishi. K. (1975) J. Am. Chem. sot. 97, 5345. 6. Harada, N., Tamura, Y. and Uda, H. (1976) J. Am. Chem. Sot.

(1977) L[oydia 40, 191. 3. Noguchi, H., Sankawa, U. and Iidaka, Y. (1978) Acta Cryst. 834. 3273.

98, 5408. 7. Harada, N., Tamura, 100, 4029.

Y. and Uda, H. (1978) J. .4m. Chem. Sot.

003 I 9422:90 $3.00 + 0.00 Press plc

Phytochemisrr~, Vol. 29. No. 3, pp. lo02 1004, 1990. Printed in Great Britam

,(’ 1990 Pergamon

CIRRHOPETALIN, A PHENANTHRENE DERIVATIVE CIRRHOPETALUM ANDERSONII P. L. MAJUMDER* Department

of Chemistry,

University

College of Science, 92 Acharya (Receiwd

Key Word Index-~ Cirrhopetalum dioxy phenanthrene.

adersonii;

Abstract-Cirrhopetalin, a new phenolic be 7-hydroxy-4-methoxy-2,3_methylenedioxy

in revised,form

Prafulla

4 Auyust

Chandra

Road. Calcutta

700009,

India

1989)

7-hydroxy-4-methoxy-2,3-methylene

compound, isolated from the orchid Cirrhopetalurn andersonii was shown to phenanthrene mainly from spectroscopic evidence.

Our continued search for new phytochemicals from Indian orchids has resulted in the isolation of a new phenanthrene derivative, designated as cirrhopetalin, from Cirrhopetalum andersonii. It was shown to have the structure la. RESULTS AND DISCUSSION

Cirrhopetalin, C,,H , 20, ([M] + rnjz 268), mp 142’, showed UV absorptions, I max E’oH206,258,284 and 344 nm (log c 4.40, 4.89, 4.29 and 2.95) typical of phenanthrene derivatives [l&6]. The presence of a phenolic hydroxyl group was indicated by its characteristic colour reactions, alkali induced bathochromic shifts of its UV maxima ;.~~“-“.’ MNaoH 217, 239, 270 and 305 nm (log E 4.37, 4.48, 4.90 and 4.19), its IR band at v,,, 3185 cm-‘, and was confirmed by the formation of a monoacetyl derivative, C,,HI,O, (CMI’ m/z310), mp 139 , with acetic anhydride and pyridine. The ‘HNMR spectrum of cirrhopetalin showed signals for a phenolic hydroxyl group (fi5.06, lH, s; deuterium exchangeable), an aromatic methoxyl (64.11, 3H. s), a methylenedioxy function (fi6.08, 2H, s) and six should

BASAK

Orchidaceae; cirrhopetalin;

INTRODUCTION

*Author to whom correspondence

and MALJWW

FROM

be addressed.

aromatic protons. Of the signals for the aromatic protons the pair of one-proton doublets at 67.46 (J = 8.82 Hz) and 7.53 (5=8.82 Hz) is reminiscent of H-9 and H-10 of phenanthrene derivatives [l--5. 7,8], and the one-proton doublet at 69.41 (J=9.06 Hz) is typical of H-S or H-4 of such compounds [I. 4,5.7,8]. Assignment of the latter signal to H-5 implied that while C-4 and C-7 of the compound must contain an oxygen substituent, its C-6 was unsubstituted. The one-proton doublet of the doublet at 67.14 (J, =9.05 Hz and J,=2.87 Hz) may then be assigned to H-6 which coupled with both H-5 and H-8. The one-proton doublet at (i7.18 (J =2.87 Hz) may thus be attributed to H-8. The remaining aromatic proton signal at 67.01 (lH, s) was then assigned to H-l, bearing oxygen substituents at C-2, C-3 and C-4. In the ‘H NMR spectrum of cirrhopetalin acetate only the signals at 67.14 and 7.18 corresponding to H-6 and H-8 of the parent compound showed downfield shifts of 0.16 and 0.36 ppm respectively, while that at ii7.01 remained almost unchanged, and the signals for H-Y and H-10 collapsed to a singlet at 67.57. Thus H-6 and H-8 of cirrhopetalin must be flanked by the lone hydroxyl group at C-7. and ruled out the placement of the hydroxyl function at either C-2 or C-4. The absence of a hydroxyl group at C-4 was also indicated by the fact that its signal for H-5 showed a slight downfield shift (0.12 ppm) in the spectrum of its acetate, which, instead, would have been shifted upfield by

Short Reports

R’O

OR3

la

Rr =

H, R* = Me, R’, R4 = CHZ

lb 1~

R’ = R’ =

AC, R2 = Me, R3,R4 = CH, R4 = H, R’ = Ra = Me

Id

RI = R4 =

AC. R* = R3 = Me

ppm had there been a hydroxyl group at C-4 [6,8]. The compound is thus a 7-hydroxyphenanthrene derivative containing a methoxy and a methylenedioxy function distributed between C-2, C-3 and C-4. The complete structure was finally established by 13C NMR spectral data of the compound and its acetate. The degree of protonation of each carbon atom was determined by DEPT experiments. The assignments of the carbon chemical shifts of the two compounds (Table 1) were made by comparison with the 6, values of structurally similar compounds [l-5,7] taking into consideration the known additive parameters of the functional groups in the benzenoid system; these are in excellent agreement with the structures la and b for the two compounds. Thus, the signals for C-4b, C-5, C-6, C-7, C-8 and C-8a of cirrhopetalin acetate appeared essentially at the same positions as those for the corresponding carbon atoms of nudol diacetate (Id) [l] indicating an identical structure for their A-ring. The placement of the hydroxyl group at C-7 was also corroborated by the fact that the carbon resonances of cirrhopetalin and its acetate are essentially the same except for those of C-4b, C-6, C-7 and C-8. While the C4b, C-6 and C-8 resonances showed upfield shifts by 4.71, 7.77 and 4.01 ppm, respectively, compared to those of the corresponding carbon atoms of the acetate, that of its C-7 is shifted downfield by 5.14 ppm. Both C-9 and C-10 resonances of the two compounds appeared almost at the normal region (6, 125-128) of the corresponding carbon 0.546

Table Chemical

1. Carbon

chemical

1003

atoms of phenanthrene derivatives bearing no substituent at either C-l or C-8 [l-3]. This would imply that the methoxy and methylenedioxy functions must be distributed between C-2, C-3 and C-4. The strongest evidence in support of the placement of the methoxy group at C-4 and the methylenedioxy function at C-2 and C-3 was provided by the chemical shifts of its methoxyl carbon (6, 59.85), which required that the methoxyl group be Banked by two ortho substituents [see, e.g. 1,2,4,5,9]. The only other alternative 7-hydroxy-2-methoxy-3,4-methylenedioxy phenanthrene formulation [phenanthrenes of such distribution of methoxy and methylenedioxy functions have earlier been reported by Aquino et al. [lo]] for cirrhopetalin would have caused the carbon atom of its methoxy group (having an ortho- hydrogen at C-l) to resonate in the normal region (6, 55.56) [see, e.g. 3,7,9]. as 7-hydroxyCirrhopetalin is thus represented 4-methoxy-2,3-methylenedioxy phenanthrene (la). EXPERIMENTAL

Mps: uncorr. Silica gel (6~100 mesh) was used for CC and gel G for TLC. UV spectra were measured in 9.5% aldehyde-freeEtOH, IR spectra in KBr discs. ‘H and ‘%NMR silica

were measured at 250 and 300 MHz, and 75 MHz, respectively, in CDCI,, using TMS as int. standard. Chemical shifts are expressed in 6 values. MS were recorded with a direct inlet system at 70 eV. All analytical samples were routinely dried over P,O, for 24 hr in t~acuo and were tested for purity by TLC and MS. Dry Na,SO, was used for drying organic solvents and the petrol had bp 6&80”. Isolation ofcirrhopetalin (la). Air-dried powdered whole plant of C. andersonii (2 kg) was kept soaked in MeOH (5 1)for 3 weeks. The MeOH ext was then drained out and coned under red. pres. to ca 100 ml, diluted with H,O (750 ml) and extracted with Et,O. The Et,0 ext was fractionated into acidic and non-acidic frs with 2 M aq. NaOH soln. The aq. alkaline soln was acidified in the cold with cone HCl and the liberated solid was extracted with Et,O, washed with H,O, dried and the solvent removed. The residue was chromatographed. The petrol-EtOAc (20: 1) eluate gave la (O.l2g), crystallized from petrol-EtOAc, mp 142”. (Found C, 71.59; H, 4.51. C,,H,,O, requires: C, 71.64; H, 4.47%). IR Y,,, cm-‘: 3185 (OH), 1630, 1608, 1492, 860, 847, 827, 800 and 780 (aromatic nucleus); MS m/z (rel. int.): 268

shifts of compounds Chemical

shifts (6values)*

la and b shifts (avalues)*

C

la

lb

C

la

lb

1 2 3 4 4a 4b 5 6 7

101.85 140.93 138.66 147.24 120.03 124.89 128.99 111.41 152.95

101.75 141.16 138.57 147.81 119.54 129.60 128.49 119.18” 147.81

8 8a 9 10 10a OCH,O OMe OCOMe -

116.21 133.78 127.59b 125.36b 128.77 101.50 59.85 -

120.22” 132.94 127.57’ 125.68’ 128.14 101.52 59.81 169.62 21.16

*The values are in ppm downfield “-‘Values are interchangeable.

from TMS: 6,r,s, = &,c,,,

+ 76.9 ppm.

1004

Short Reports

([Ml’, IOO),252 (S), 239 (7), 222 (1 l), 223 (61), 197 (7), 199 (6),

REFERENCES

167 (20) and 139 (25). Compound la was acetylated with Ac,O-pyridine in the usual manner to give lb, crystallized from petrol-EtOAc, mp 139” (Found: C, 69.59; H, 4.60. C,,H,,OS requires: C, 69.67; H, 4.51%). UV &n,, nm: 257 and 340 (log E 4.56 and 2.72); IR vm,,cm-‘: 1260 and 1768 (OAc), 1640, 1625, 1608, 890, 852, 838, 811, 790 and 770 (aromatic nucleus); ‘H NMR: 69.53 (lH, d, J=9.40 Hz; H-5), 7.57 (2H, s; H-9 and H-lo), 7.54 (lH, cl. J=2.6 Hz; H-S), 7.30(1H,dd, J,=9.4Hzand J,=2.6Hz;H-6),7,04(1H,s;H-l), 6.12 (2H, s; -0-CH,-0-), 4.12 (3H, s; ArOMe) and 2.37 (3H, s; OAc); MS m/z (rel. int.): 310 ([Ml’. 38), 268 (100). 223 (34), 167 (1 I), 138 (22) and 43 (39).

1. Bandari, S. R., Kapadi, A. H., Majumder, P. L., Joardar, M. and Shoolery, J. N. (1985) Phytochemistry 24, 801. 2. Majumder, P. L., Kar, A. and Shoolery, J. N. (1985) Phytochemistry 24, 2083. 3. Majumder, P. L. and Sen, R. C. (1987) Indian J. Chem. 26B, 18. 4. Majumder, P. L. and Kar, A. (1987) Phytochemistry 26,1127. 5. Majumder. P. L. and Banerjee, S. (1988) Phytochemistry 27, 245. 6. Letcher, R. M. and Nhamo, L. R. M. (1971) J. Chem. Sot.(C) 3070. 7. Majumder, P. L., Pal, A. and Joardar, M. (1990) Phytochemistry, 29 (in press). 8. Letcher, R. M. and Wong. K,M. (1978) J. Chem. Sot. Perkin Trans I 3070. 9. Wenkert, E., Gottlieb, H. E., Gottlieb, 0. R., Pereira Das, M. 0. and Formiga, M.D. (1976) Phytochemistry 15, 1547. 10. Aquino, R., Behar, I., De Simone, F., Pizza, C. and Senatore, F. (1985) Blochem. Sysr. Ecol. 13, 251.

AcknowledyemenrsWe thank Dr J. M. Wilson (University of Manchester, U.K.) for MS, Prof. W. Kraus and Dr M. Bokel (University of Hohenheim, Stuttgart, F.R.G.) for the ‘H and 13CNMR of cirrhopetalin, and Dr A. K. Sarkar (University of Cambridge, U.K.) for ‘HNMR of cirrhopetalin acetate. The work was supported by CSIR. New Delhi, India.

Phytochemisrry. Vol. 29, No. 3, pp. 1004~~1007,1990. Printed in Great Britain.

CHROMONE

GLYCOSIDES

PIERRE Department

of Organic

c

FROM

SCHUMANNIOPH

TANE, JOHNSON F. AYAFOR, B. Luc Chemistry,

University

SONDENGAM

YTON MAGNIFICUM

and JOSEPH D. CONNOLLY*

of Yaounde, Box 812, Yaounde, Cameroon; Glasgow, Glasgow Cl2 SQQ, U.K. (Received

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

*Department

of Chemistry.

University

of

10 July 1989)

Key Word IndexpSchumanniophyton magnijicum; Rubiaceae; root bark; schumaniofiosides A and B; 2-methyl-5,7dihydroxychromone 5-O-D-D-glucopyranoside; 2-methyl-5,7-dihydroxychromone 7-O-p-I>-glucopyranosyl-(I +2)apiofuranoside.

Abstract-Two

glycosides, schumanniofiosides A and B have been isolated and their structures shown to be 2-methyl-5,7-dihydroxychromone anoside and 2-methyl-5,7-dihydroxychromone 7-O-~-D-gluCOpyranOSyl-( l-+2)-apiofuranoside, structures were elucidated by a combination of spectral data and chemical degradation.

Schumanniophyton

new chromone magnijicum

from the root bark of 5-O-P-D-ghXOpyr-

respectively.

The

INTRODUCTION

RESULTSANDDISCUSSION

Schumanniophyton magn$cum is a small tree which grows

The ethanol extract of the dried powdered root bark of S. magntjicum collected at Bafia in the Central Province of Cameroon, was subjected to silica gel column chromatography with solvents of increasing polarity. Examination of the polar fractions resulted in the isolation of compounds 1 and 2. Schumaniofioside A (l), was obtained as granules, mp 162-163” from methanol and analysed for C 16H 180 9 It gave a violet ferric reaction and a positive Molish test. Strong IR absorptions at 345&3000 and 1645 cm-’

in the tropical zone of West and Central Africa. In Cameroon, the bark decoction is known as a remedy for dysentery and used in an enema. Other tribes use it after circumcision Cl]. Previous work on this plant revealed a number of alkaloids [2-4] while neutral components attracted little attention. Continuing studies on Cameroonian medicinal plants [S, 61, we re-examined the root bark of S. magnijicum and we now report on the neutral constituents of this plant.