Anthraquinones and Anthraquinone Glycosides from the Roots...

2
This work has been digitalized and published in 2013 by Verlag Zeitschrift für Naturforschung in cooperation with the Max Planck Society for the Advancement of Science under a Creative Commons Attribution 4.0 International License. Dieses Werk wurde im Jahr 2013 vom Verlag Zeitschrift für Naturforschung in Zusammenarbeit mit der Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. digitalisiert und unter folgender Lizenz veröffentlicht: Creative Commons Namensnennung 4.0 Lizenz. Anthraquinones and Anthraquinone Glycosides from the Roots of Cassia multijuga* R. D. Tiwari+ and J. Singh Department of Chemistry, University of Allahabad, Allahabad, India Z. Naturforsch. 88b, 1136-1137 (1983); received May 2, 1983 Cassia multijuga, Anthraquinone Glycosides From the roots of Cassia multijuga 1:3-dihydroxy-2-methyl anthraquinone, 1:3:8-tri- hydroxy-6-methoxy-2-methyl anthraquinone, 1:8-dihydroxy-6-methoxy-2-methyl an- thraquinone-3-0-rutinoside and 1:8-dihydroxy-2-methyl anthraquinone-3-0-rutinoside have been isolated and their structures elucidated. Introduction Cassia multijuga is known for its medicinal pro- perties [1]. In the present communication authors describe isolation and characterisation of anthra- quinones and anthraquinone glycosides. Results and Discussion From the ethanolic extract of the roots of Cassia multijuga two anthraquinones C15H10O4 (Qi) and C16H12O6 (Q2) and two anthraquinone glycosides C28H32O15 (Si) and C27H30O14 (S2) have been isolated. Homogeneity and purity of these compounds were established by chromatography. Anthraquinone (Qi) has been identified to be 1:3-dihydroxy-2-methyl anthraquinone (rubiadin) by standard colour reactions [2, 3], spectral data, mass fragmentation pattern, m.p. and m.m.p. Compound (Q2) had one -OMe (4.00 ppm) one C-Me (2.10 ppm) and three phenolic hydroxyl groups (triacetate). The UV absorption maxima (Amax 240, 290 and 430 nm) and mass fragments at m/z 272 (M-CO) and m/z 244 (M-2CO) are typical of anthraquinone skeleton. Isolation of 2-methyl anthracene by zinc dust distillation of Q2 showed it to be a 2-methyl anthraquinone derivative. X NMR spectrum of Q2 showed three aromatic protons, two as meta coupled doublet at 7.67 ppm (C-5, J = 2.5cps) and 6.85 ppm (C-7, J = 2.5cps) and the third as singlet at 7.89 ppm (C-4); the compound is thus a 1:2:3:6:8-penta substituted anthraquinone having methyl group at position-2. * Dedicated to Prof. F. Korte of Munich on the occasion of his 60th birthday - in recognition of his contributions in the field of organic-, Bio- and ecological Chemistry. + Reprint requests to Dr. R. D. Tiwari. 0340-5087/83/0900-1136/S 01.00/0 The absorption maxima at 430 nm is typical of two a-hydroxyl groups which are present at posi- tions 1 and 8 as confirmed by standard colour reactions [2, 4]. The third hydroxyl at position-3 is also confirmed by colour reactions [3, 5]. Since the compound is a 1:2:3:6:8-penta sub- stituted anthraquinone having hydroxyls at 1, 3 and 8 and methyl at 2 the methoxyl group should be at 6. The mass fragmentation (m/z 122) also confirmed that one benzene nucleus has two hydroxyl and one methoxy groups and the other has one hydroxyl and one methoxyl groups. The structure of the compound Q2, therefore, is 1,3,8- trihydroxy-6-methoxy-2-methyl anthraquinone (1). 0H 0 OH 0 1 The compound (Si) C28H32O15 m.p. 270 °C (d) was a glycoside which on acid hydrolysis gave glucose and rhamnose and an aglycone Ci6Hi 2 0 6 m.p.250°, which has been found to be identical with the anthraquinone (Q2) described above. Hence the compound (Si) is a glycoside of the anthraquinone Qa. The attachement of the sugar moiety at position-3 was established by colour reactions [3, 4] and UV spectral data which showed that the two sugars glucose and rhamnose are present as a bioside. The NMR spectrum of the glycoside showed a broad signal at 0.94-0.98 ppm which is typical of rhamnose methyl group. The broad signal at 3.84 ppm which overlapped with methoxyl group at 4.00 ppm, was also due to the sugar protons. The

Transcript of Anthraquinones and Anthraquinone Glycosides from the Roots...

Page 1: Anthraquinones and Anthraquinone Glycosides from the Roots ...zfn.mpdl.mpg.de/data/Reihe_B/38/ZNB-1983-38b-1136.pdf · anthracene by zinc dust distillation of Q2 showed it to be a

This work has been digitalized and published in 2013 by Verlag Zeitschrift für Naturforschung in cooperation with the Max Planck Society for the Advancement of Science under a Creative Commons Attribution4.0 International License.

Dieses Werk wurde im Jahr 2013 vom Verlag Zeitschrift für Naturforschungin Zusammenarbeit mit der Max-Planck-Gesellschaft zur Förderung derWissenschaften e.V. digitalisiert und unter folgender Lizenz veröffentlicht:Creative Commons Namensnennung 4.0 Lizenz.

Anthraquinones and Anthraquinone Glycosides from the Roots of Cassia multijuga*

R. D. Tiwari+ and J. Singh Department of Chemistry, University of Allahabad, Allahabad, India

Z. Naturforsch. 88b, 1136-1137 (1983); received May 2, 1983

Cassia multijuga, Anthraquinone Glycosides

From the roots of Cassia multijuga 1:3-dihydroxy-2-methyl anthraquinone, 1:3:8-tri-hydroxy-6-methoxy-2-methyl anthraquinone, 1:8-dihydroxy-6-methoxy-2-methyl an-thraquinone-3-0-rutinoside and 1:8-dihydroxy-2-methyl anthraquinone-3-0-rutinoside have been isolated and their structures elucidated.

Introduction

Cassia multijuga is known for its medicinal pro-perties [1]. In the present communication authors describe isolation and characterisation of anthra-quinones and anthraquinone glycosides.

Results and Discussion

From the ethanolic extract of the roots of Cassia multijuga two anthraquinones C15H10O4 (Qi) and C16H12O6 (Q2) and two anthraquinone glycosides C28H32O15 (Si) and C27H30O14 (S2) have been isolated. Homogeneity and purity of these compounds were established by chromatography.

Anthraquinone (Qi) has been identified to be 1:3-dihydroxy-2-methyl anthraquinone (rubiadin) by standard colour reactions [2, 3], spectral data, mass fragmentation pattern, m.p. and m.m.p.

Compound (Q2) had one -OMe (4.00 ppm) one C-Me (2.10 ppm) and three phenolic hydroxyl groups (triacetate). The UV absorption maxima (Amax 240, 290 and 430 nm) and mass fragments at m/z 272 (M-CO) and m/z 244 (M-2CO) are typical of anthraquinone skeleton. Isolation of 2-methyl anthracene by zinc dust distillation of Q2 showed it to be a 2-methyl anthraquinone derivative.

XNMR spectrum of Q2 showed three aromatic protons, two as meta coupled doublet at 7.67 ppm (C-5, J = 2.5cps) and 6.85 ppm (C-7, J = 2.5cps) and the third as singlet at 7.89 ppm (C-4); the compound is thus a 1:2 :3 :6 :8-penta substituted anthraquinone having methyl group at position-2.

* Dedicated to Prof. F. Korte of Munich on the occasion of his 60th birthday - in recognition of his contributions in the field of organic-, Bio- and ecological Chemistry.

+ Reprint requests to Dr. R. D. Tiwari. 0340-5087/83/0900-1136/S 01.00/0

The absorption maxima at 430 nm is typical of two a-hydroxyl groups which are present at posi-tions 1 and 8 as confirmed by standard colour reactions [2, 4]. The third hydroxyl at position-3 is also confirmed by colour reactions [3, 5].

Since the compound is a 1 :2 :3 :6 :8-penta sub-stituted anthraquinone having hydroxyls at 1, 3 and 8 and methyl at 2 the methoxyl group should be at 6. The mass fragmentation (m/z 122) also confirmed that one benzene nucleus has two hydroxyl and one methoxy groups and the other has one hydroxyl and one methoxyl groups. The structure of the compound Q2, therefore, is 1,3,8-trihydroxy-6-methoxy-2-methyl anthraquinone (1).

0H 0 OH

0

1

The compound (Si) C28H32O15 m.p. 270 °C (d) was a glycoside which on acid hydrolysis gave glucose and rhamnose and an aglycone Ci6Hi206 m.p.250°, which has been found to be identical with the anthraquinone (Q2) described above. Hence the compound (Si) is a glycoside of the anthraquinone Qa.

The attachement of the sugar moiety at position-3 was established by colour reactions [3, 4] and UV spectral data which showed that the two sugars glucose and rhamnose are present as a bioside.

The NMR spectrum of the glycoside showed a broad signal at 0.94-0.98 ppm which is typical of rhamnose methyl group. The broad signal at 3.84 ppm which overlapped with methoxyl group at 4.00 ppm, was also due to the sugar protons. The

Page 2: Anthraquinones and Anthraquinone Glycosides from the Roots ...zfn.mpdl.mpg.de/data/Reihe_B/38/ZNB-1983-38b-1136.pdf · anthracene by zinc dust distillation of Q2 showed it to be a

R. D. Tiwari-J. Singh • Anthraquinones and Anthraquinone Glycosides 1137

nature of intersugar linkage was deduced by com-parison of rhamnose methyl signal with correspond-ing signals of rutinoside 0.80-0.95 ppm (br) and neohesperidoside 1.20 ppm, (d) to be of the rutinoside type [6, 7]. Thus the glycoside has been identified to be 1:8-dihydroxy-6-methoxy-2-methyl anthraquinone 3-O-rutinoside (2). This glycoside is new, not reported earlier.

OH 0 OH

2 Compound (S2) C27H30O14 m.p. 300° (d) was also a

glycoside and gave characteristic colour reactions of hydroxy anthraquinones. On acid hydrolysis it gave glucose and rhamnose and an aglycone C15H10O5, m.p. 230 °C. The aglycone has been identified to be 1:3:8-trihydroxy-2-methyl anthraquinone [8] by standard colour reactions, spectral data (UV, IR, NMR and mass spectral data). The attachment of sugar moiety at position-3 was established by colour reactions and spectral data [3, 4], which confirmed that the glycoside is a bioside of glucose and rhamnose. NMR spectrum of the compound con-firmed that the bioside is present in the form of rutinoside. The structure of the glycoside is, there-fore, 1:8-dihydroxy-2-methyl anthraquinone 3-O-rutinoside (3). This glycoside is also new not reported earlier from any source.

HO

0 CH2 O ^

HO J—0 i - 0

W HoW OH OH OH

3

[1] R. N. Chopra, I. C. Chopra, K. L. Hande, and L. D. Kapur, Indigenous drugs of India, Dhar and Sons Pvt. Ltd. 98, 499 (1958).

[2] J. Somogyi, Biol. Chem. 19, 195 (1952). [3] S. Sibata, M. Takido, and O. Tonka, J. Am.

Chem. Soc. 72, 2789 (1950). [4] F. Feigl and V. Anger, 'Spot tests in Organic

Analysis', 7th ed., Elsevier, Amsterdam, p. 347 to 349 (1966).

Experimental The roots were extracted with boiling ethanol. The

concentrated ethanolic extract was poured in cold wrater whereby a coloured residue (fraction I) and an aqueous solution (fraction II) were obtained.

Fraction I: The residue was successively extracted, with hexane, benzene and ethyl acetate. Benzene fraction yielded rubiadin and ethyl acetate fraction yielded compound (Q2) m.p. 250 °C.

IR v ™ 3340, 2960, 2800, 1675, 1630, 1180, 1150 cm-1.

UV AEtoH 240, 290, 430 nm. NMR [CDCI3, 90 MHz] 6: 2.10 (S, 3H, CH3), 4.00

(S, 3H, -OCH3), 7.89 (S, IH, C-4), 7.67 (C-5, IH, d, J = 2.5 cps), 6.85 (C-7, I H , d, J = 2.5 cps). Acetate (AcaO/Py) m.p. 213 °C.

/Eton 213, 274 and 337 nm. Methyl ether (Me2S04/K2C03) m.p. 193 °C.

Fraction II: The aqueous solution was concen-trated under reduced pressure and extracted succes-sively with benzene and ethyl acetate. Benzene fraction contained fatty materials. The ethyl acetate fraction wras concentrated, chromatographed over silica gel column and eluted with benzene: methanol (80:20 v/v) and ethyl acetate: methanol (50:50 v/v). Benzene: methanol fraction yielded glycoside Si wrhereas ethyl acetate methanol fraction yielded glycoside S2.

Glycoside Si: m.p. 270 °C (d). Acetate (Ac20/Py) m.p. 240 °C.

IR f£Br 3340, 2950, 2880, 1760, 1730, 1650, 1180, 730-720 cm - 1 .

UV x£aOH 233, 292 and 427 nm. NMR [CDCI3, 90 MHz] <5: 0.94-0.98 (br, rhamnose

methyl), 2.10 (S, 3H, CH3), 4.00 (S, 3H, OCH3), 3.40-3.84(br, sugar protons), 5.00(H-1" rhamnosyl), 5,30 ( H - l " glucosvl), 7.85 (S, IH, C-4), 7.67 (C-5, 1H, d, J = 2.5 cps) and 6.83 (C-7, IB., J = 2.5 cps).

Glycoside S2: m.p. 300 °C (d). Acetate (Ac20/Py) m.p. 275 °C.

IR v ™ 3360, 2955, 1675, 1620,1170, 1150, 1445, 1375, 1010, and 735-720 cm-i.

UV ffiH 242, 285 and 422 nm. NMR [CDCI3, 90 MHz] <5: 0.96 (br, rhamnose

methyl), 2.10 (S, 3H, CH3), 3.40-3.85 (br, sugar protons), 4.95 ( H - l " rhamnosyl), 5.32 ( H - l " glucosyl), 7.88 (S, IH , C-4), 6.90-7.60 (m, 3H, C-5, C-6, C-7).

[5] C. Garebe, Annalen 211, 349 (1906). [6] J. P. Kuteney, W. D. C. Warnock, and B. Gilbert,

Phytochemistry 9, 1877 (1970). [7] R.T. Sherwood and M. Shamma, Phytochemistry

12, 2275 (1973). [8] N. B. Mulchandani and S. A. Hassarjani, Planta

Med. 32, 357 (1977).