Anthraquinones from the bark of Senna macranthera

Branco, Alexsandro; Pinto, Angelo C.; Schripsema, Jan; Braz-Filho, Raimundo

doi:10.1590/S0001-37652011000400003

Abstracts

2-acetyl physcion (2-acetyl-1,8-dihydroxy-6-methoxy-3-methyl-9,10-anthraquinone, 2), a rare anthraquinone, was isolated from Senna macranthera var. nervosa (Vogel) H.S. Irwin & Barneby (Fabaceae). The chemical structure was elucidated and all ¹H and 13C NMR chemical shifts were assigned by NMR one- (¹HNMR, {¹H}-13CNMR, and APT-13CNMR) and two (COSY, NOESY, HMQC and HMBC) dimensional of this natural compound. Furthermore, the minor anthraquinones chrysophanol (3), chrysophanol-8-methyl ether (4) and physcion (5) were characterized by GC-MS analysis. The occurrence of the anthraquinones 3-5 confirms that S. macranthera is a typical representative of the genus Senna.

anthraquinone; 2-acetyl-physcion; Fabaceae; Senna acranthera

2-acetil-fisciona (2-acetil-1, 8-di-hidróxi-6-metóxi-3-metil-9, 10-antraquinona, 2), uma antraquinona rara, foi isolada de Senna acranthera var. nervosa (Vogel) H.S. Irwin & Barneby (Fabaceae). estrutura química foi elucidada e todos os deslocamentos químicos de RMN ¹H e 13C foram atribuídos através de RMN uni- (RMN¹H, {¹H}-RMN-13C e APT-RMN13C) e bi- (COSY, NOESY, HMQC e HMBC) dimensional deste composto natural. Adicionalmente, as antraquinonas minoritárias crisofanol (3), crisofanol-8-metil éter (4) e fisciona (5) foram caraterizadas pela análise de CG-EM. A ocorrência das antraquinonas 3-5 confirma que S. macranthera é uma típica representante do gênero Senna.

antraquinona; 2-acetil-fisciona; Fabaceae; Senna macranthera

CHEMICAL SCIENCES

Anthraquinones from the bark of Senna macranthera

Alexsandro Branco^I; Angelo C. Pinto^II; Jan Schripsema^III; Raimundo Braz-Filho^IV

^ILaboratório de Fitoquímica, Departamento de Saúde, Universidade Estadual de Feira de Santana, Av. Transnordestina, s/n, Bairro Novo Horizonte, 44036-900 Feira de Santana, BA, Brasil

^IIDepartamento de Química Orgânica, Instituto de Química, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, Bloco A, Cidade Universitária, Ilha do Fundão, 21945-970 Rio de Janeiro, RJ, Brasil

^IIIGrupo Metabolômica, Laboratório de Ciências Químicas, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Av. Alberto Lamego, 2000, Parque Califórnia, 28015-620 Campos dos Goytacazes, RJ, Brasil

^IVSetor de Química de Produtos Naturais, LCQUI-CCT, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Av. Alberto Lamego, 2000, Parque Califórnia, 28015-620 Campos dos Goytacazes, RJ, Brasil

^{Correspondence to} Correspondence to: Alexsandro Branco E-mail: branco@uefs.br

ABSTRACT

2-acetyl physcion (2-acetyl-1,8-dihydroxy-6-methoxy-3-methyl-9,10-anthraquinone, 2), a rare anthraquinone, was isolated from Senna macranthera var. nervosa (Vogel) H.S. Irwin & Barneby (Fabaceae). The chemical structure was elucidated and all ¹H and ¹³C NMR chemical shifts were assigned by NMR one- (¹HNMR, {¹H}-¹³CNMR, and APT-¹³CNMR) and two (COSY, NOESY, HMQC and HMBC) dimensional of this natural compound. Furthermore, the minor anthraquinones chrysophanol (3), chrysophanol-8-methyl ether (4) and physcion (5) were characterized by GC-MS analysis. The occurrence of the anthraquinones 3-5 confirms that S. macranthera is a typical representative of the genus Senna.

Key words: anthraquinone, 2-acetyl-physcion, Fabaceae, Senna acranthera.

RESUMO

2-acetil-fisciona (2-acetil-1, 8-di-hidróxi-6-metóxi-3-metil-9, 10-antraquinona, 2), uma antraquinona rara, foi isolada de Senna acranthera var. nervosa (Vogel) H.S. Irwin & Barneby (Fabaceae). estrutura química foi elucidada e todos os deslocamentos químicos de RMN ¹H e ¹³C foram atribuídos através de RMN uni- (RMN¹H, {¹H}-RMN-¹³C e APT-RMN¹³C) e bi- (COSY, NOESY, HMQC e HMBC) dimensional deste composto natural. Adicionalmente, as antraquinonas minoritárias crisofanol (3), crisofanol-8-metil éter (4) e fisciona (5) foram caraterizadas pela análise de CG-EM. A ocorrência das antraquinonas 3-5 confirma que S. macranthera é uma típica representante do gênero Senna.

Palavras-chave: antraquinona, 2-acetil-fisciona, Fabaceae, Senna macranthera.

INTRODUCTION

The genus Senna is known to produce various classes of aromatic compounds, e.g. quinones, normal (Barba et al. 1992) and dimeric anthraquinones (Koyama et al. 2001), naphthopyrones (Barbosa et al. 2004) and flavonoids (Baez et al. 1999). S. macranthera var. nervosa (Vogel) H.S. Irwin & Barneby (syn. Cassia macranthera), commonly known as "alleluia" (subfamily Papilionoidae, family Fabaceae), is a 6-8 m high tree with a trunk of up to 30 cm of diameter. The leaves are composed of two pairs of opposing leaflets. In Brazil, the tree is found from Ceará in the North down to São Paulo in the South. It is used mainly as an ornamental plant in cities because of lush yellow flowers and rapid growth (Lorenzi 2000). Previous phytochemical studies on the bark of S. acranthera collected in Belo Horizonte, Brazil, revealed the presence of rubrofusarin (1), 6-O-galactosylrubrofusarin, 3,5-dihydroxy-8-isobu-tenyl-2-methyl-7-methoxychromone and -sitosterol (Oliveira et al. 1977). A galactomannan with anticoagulant activity has been isolated from the endosperm of seeds (Pires et al. 2001).

The anthraquinones are traditionally used as pigments and medicines, and are widely distributed in nature, occurring in both free and glycosidic form (Bruneton 1991). Several analytical methods have been used to analyse these compounds, including gas chromatography coupled to mass spectrometry (GC-MS) (Waterman and Mole 1994). This method permits the analysis of non-glycosylated anthraquinones with (Zuo et al. 2008) or without derivatisation (Mueller et al. 1999, Liu et al. 2007).

In this paper we report the identification of 2-acetyl physcion (2) by spectrometric methods, together with the characterisation of others minor anthraquinones (35) (Fig. 1) using GC-MS analysis from S. macranthera.

MATERIALS AND METHODS

GENERAL EXPERIMENTAL PROCEDURES

NMR spectra were recorded in CDCl₃ solution at 400 MHz for ¹H and 100 MHz for ¹³C on a JEOL Eclipse+ 400 spectrometer. Chemical shift values are reported relative to TMS, which was either used as internal standard or by reference to solvent signals: CHO3 at h 7.26 and at c 77.00. GC analyses were recorded on a Hewlett Packard model 5790 A gas chromatograph using glass capillary column (11m x 0.25 m) coated with SE-54 (df = 0.25 m). GC-MS spectra were run at 70 eV on a Shimadzu QP-2000 spectrometer. The data were collected on an HP 3396-II integrator. TLC: silica gel (Merck, Kieselgel 60), spots visualised by UV (254 and 360 nm) and exposure to I₂ vapour. TLC was used to analyse fractions collected from CC.

PLANT MATERIAL

The bark of S. macranthera was collected in Campinas, São Paulo State, Brazil, in September 2000. The identification was performed by Marcia Dias Campos, and a voucher specimen (n. 89281) is deposited at the Herbarium of the State University of Feira de Santana, Brazil.

EXTRACTION AND ISOLATION

The bark (500 g) of S. macranthera was dried at controlled temperature (60 °C). After drying, the bark was shred and extracted with n-hexane (2 L) and dichloromethane (2 L) at room temperature for seven days each, successively. During the evaporation of the hexane under reduced pressure in the rotary evaporator, the formation of a red coloured precipitate was observed, filtered and identified as rubrofusarin 1 (2.0 g) (Branco et al. 2008). The residue, after further drying, yielded the respective hexane extract (9.1 g) that was chromatographed with a gradient of EtOAc in hexane to furnish an additional quantity of 1 (0.8 g). The dichloromethane extract (52.0 g) was also chromatographed on a silica gel column (65.3 g) in the same manner to yield a total of 10 fractions of ca. 100 L each that ere collected and combined on the basis of TLC comparison. Fraction 3 eluted with hexane/EtOAc (3:1), furnished 2 as red crystals (6.5 mg). The fractions 8-9 eluted with EtOAc/EtOH (1:1), were united and analysed by GC-MS (Fig. 2).

2-ACETYL PHYSCION 2

Red solid; IR(KBr) v_maxcm^-1: 3442,1700,1691, 1615, 1598, 1474, 1443, 1208, 1235, 1165; ¹H [400 MHz, CDCl₃]: 7.65 (s, H-4), 7.38 (d, J = 2.6 Hz, H-5), 6.71 (d, J = 2.6 Hz, H-7), 3.95 (s, MeO-6), 2.61 (s, 3H-12), 2.39 (s, 3H-13), 12.48 (s, HO-1), 12.18 (s, HO-8). ¹³CNMR [75 MHz, CDCl₃]: _C: 159.28 (C-1), 136.30 (C-2), 144.59 (C-3), 135.03 (C-4a), 166.88 (C-6), 165.42 (C-8), 110.15 (C-8a), 190.65 (C-9), 114.09 (C-9a), 181.46 (C-10), 133.01 (C-10a), 203.03 (C-11), 122.08 (C-4), 108.75 (C-5), 106.86 (C-7), 56.17 (MeO-6), 31.85 (C-12), 20.13 (C-13). GC-MS (70 eV) m/z (rel. int.): 326 ([M]*+, 68%), 311 (M-Me*, 100), 308 (M-H₂0,15),298(M-CO, 1), 283 (m/z 311-CO,3), 255 (m/z 283-CO, 2), 227 (m/z 255-CO, 9).

GC-MS ANALYSIS

Hydrogen as carrier gas; flow rate of 2 mL/min; injector port was set at 280°C and flame ionization detector (FID) at 290°C. The temperature program for the analysis of mixtures ranged from 260°C to 280°C. The GC-MS interface was at 350°C, and ion source temperature at 300^°C.

RESULTS AND DISCUSSION

The IR spectrum of compound 2 showed bands for two hydroxyl groups (v_max3442 cm^-1), three carbonyl groups (v_max 1700, 1615 and 1598 cm^-1) and aromatic rings (v_max 1550 and 1474 cm^-1). The ¹H NMR spectrum revealed signals corresponding to the presence of two peri-positioned chelated hydroxyl groups (_H 12.48, HO-1, and 12.18, HO-8) (Schripsema and Dag-nino 1996), three aromatic hydrogens [one singlet at _H 7.65 (H-4) and two doublets compatible with two meta-coupled hydrogen atoms at _H 7.38 (d, J = 2.6 Hz) and 6.71 (d, J = 2.6 Hz)], one methoxyl function (_H 3.95) and two methyl groups linked to sp² carbon atoms [_H 2.61 (s, 3H-12) and 2.39 (s, 3H-13)]. These data and comparative analysis of {¹H}- and APT-¹³C NMR spectra [twelve sp² quaternary carbon atoms, including three carbonyl groups at _c 203.03 (C-11), 190.65 (C-9) and 181.46 (C-10)], three sp² methines and three methyl groups at [_c 56.17 (CH₃O), 31.85 (CH₃-12, acetyl function) and 20.13 (CH₃-13)], together with the molecular ion in the mass spectrum at m/z 326 ([M]+, 58%), suggested the structure of this physcion derivative.

Heteronuclear 2D shift-correlated NMR techniques ¹H-¹³C-COSY-¹J_CH (HMQC) and ¹H-¹³C-COSY-ⁿJ_CH (HMBC) were used for the correct ¹H and ¹³CNMR chemical shift assignments of anthraquinone 2. The location of the acetyl group at carbon atom C-2 was confirmed by heteronuclear long-range couplings C-2 (_c 136.30) and HO-1 (_H 12.48, ³J_CH), H-4 (_H 7.65, ³J_CH) and both 3H-12 (_H 2.61, ³J_CH) and 3H-13 (_H 2.39, ³Jch). The ¹H-¹H-NOESY spectrum further confirmed the structure, showing interactions between 3H-13 and H-4, and between the methoxyl group and both H-5 and H-7.

Thus, the structure of 2 was established as 1,8-dihydroxy-2-acetyl-3-methyl-6-methoxy- 9, 10-anthra-quinone (2-acetyl physcion). This is the first report of the antraquinone 2 in a Senna species. All ¹H and ¹³C chemical shifts were unambiguously assigned. This compound has been reported only once in the literature (Wei et al. 2007), and the attributions to the carbons C-4a(_C 135.03) and C-10a(_C 133.01) were corrected.

The fractions of the dichloromethane extract obtained by SiO2 fractionation were analysed by GC-MS to detect other polyketid. Only the fraction 8-9 showed the presence of peaks the typical fragmentation pattern of anthraquinones: intense molecular ion, loss of CO (28 Da) and other fragmentations with weak intensity (Song et al. 2009). Figure 2 and Table I show the chromatogram and mass spectra ofthis fraction, respectively. The peaks corresponding to Tr at 14.6,16.1 and 17.3 min showed molecular ion base peaks ([M]*+, 100%) at m/z 254, 268 and 284, and loss of CO to furnish peaks at mlz 226 (13%), 240 (4%) and 256 (5%), respectively. The molecular mass of 4 ([M]*+, m/z 268) is 14 Da higher than 3 ([M]*+, m/z 254), indicating the presence of an additional methylene unit. This -CH₂- unit was attributed to formation of one methoxyl group at C-8 (C-OHtoC-OCH₃).

Thumbnail

Thus, the GC-MS analyses permitted the identification of chrysophanol (3), chrysophanol-8-methyl ether (4) and physcion (5) in S. macranthera. The occurrence of 3-5 is rather common in species of the genus Senna (Barba et al. 1992). The other hand, the occurrence these compounds in the same plant is common in the nature (Mueller et al. 1999), which can be explain by the biosynthetic route (Dewick 1997). Chrysophanol, chrysophanol-8-methyl ether and physcion present in extracts from plants were thought to be responsible for antimicrobial (Hatano et al. 1999, García-Sosa et al. 2006) and other biological activities (Tewtrakul et al. 2007).

ACKNOWLEDGMENTS

We would like to thank Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ, Brazil), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Brazil), Fundação Universitária José Bonifácio (FUJB, UFRJ, Rio de Janeiro, Brazil) and Programa de Apoio a Núcleos de Excelência (PRONEX) (Grant 4002, Brazil) for financial support.

Manuscript received on March 23, 2010; accepted for publication on March 14, 2011

BARBA B, DÍAZ JG AND HERZ W. 1992. Anthraquinones and others constituents oftwo Senna species. Phytochemistry 31: 4374-4375.
BAEZ DA, VALLEJO LGZ AND JIMENEZ-ESTRADA M. 1999. Phytochemical studies on Senna skinneri and Senna wislizeni. Nat Prod Res 13: 223-228.
BARBOSA FG, OLIVEIRA MCF, BRAZ-FILHO R AND SILVEIRA ER. 2004. Anthraquinones and naphthopyrones from Senna rugosa. Biochem Syst Ecol 32: 363-365.
BRANCO A, PINTO AC, BRAZ-FILHO R, SILVA EF, GRYN-BERG NF AND ECHEVARRIA A. 2008. Rubrofusarina, um policetídeo natural inibidor da topoisomerase II-α humana. Rev Bras Farmacogn 18(suppl): 703-708.
BRUNETON J. 1991. Elementos de fitoquímica y de farmacognosia. Zaragoza: Acribia, 1128 p.
DEWICK PM. 1997. Medicinal Natural Products - A biosynthetic Approach. J Wiley & Sons. England, 466 p.
GARCÍA-SOSA K, VILLAREAL-ALVAREZ N, LUBBEN P AND PENA-RODRIGUEZ LM. 2006. Chrysophanol, an antimicrobial anthraquinone from the root extract of Colubrina greggii. J Mex Chem Soc 50: 76-78.
HATANO T, UEBAYASHI H, ITO H, SHIOTA S, TSUCHIYA T AND YOSHIDA T. 1999. Phenolic constituents of Cassia seeds and antibacterial effect of some naphthalenes and anthraquinones on methicillin-resistent Staphylococcus aureus. Chem Pharm Bull 47: 1121-1127.
KOYAMA J, MORITA I, TAGAHARA K AND AQIL M. 2001. Biantraquinones from Cassia siaea. Phytochemistry 56: 849-851.
LIU S-Y, LO C-T, CHEN C, LIU M-Y, CHEN J-H AND PENG K-C. 2007. Efficient isolation of anthraquinone-derivatives from Trichoderma harzianum ETS 323. J Biochem Biophys Methods 70: 391-395.
LORENZI H. 2000. Árvores Brasileiras - Manual de identificação e cultivo de plantas arbóreas nativas do Brasil. São Paulo: Instituto Plantarum, 352 p.
MUELLER SO, SCHMITT M, DEKANT W, STOPPER H, SCHLATTER J, SCHREIER P AND LUTZ WK. 1999. Occurrence of emoldin, chrysophanol and physion in vegetables, herbs and liquors. Genotoxicity and anti-genotoxicity of the anthraquinones and of the whole plants. Food Chem Toxicol 37: 481-491.
OLIVEIRA AB, FERNANDES MLM, SHAAT VT, VASCONCELOS LA AND GOTTLIEB OR. 1977. Constituents of Cassia species. Rev Latinoamer Quim 8: 82-85.
PIRES L, GORIN PAJ, REICHER F AND SlERAKOWSKI MR. 2001. An active heparinoid obtained by suphation of a galactomannan extracted from the endosperm of Senna macranthera seeds. Carboh Pol 46: 165-169.
SCHRIPSEMA J AND DAGNINO D. 1996. Elucidation of the substitution pattern of 9,10-anthraquinones through the chemical shifts of perihydroxyl protons. Phytochemistry 42: 177-184.
SONG R, LIN H, ZHANG Z, LI Z, XU L, DONG H AND TIAN Y. 2009. Profiling the metabolic differences of anthraquinone derivatives using liquid chromatography/ tandem mass spectrometry with data-dependent acquisition. Rapid Commun Mass Spectrom 23: 537-547.
TEWTRAKUL S, SUBHADHIRASAKUL S, RATTANASUWAN P AND PURIPATTANVONG J. 2007. HIV-1 protease inhibitory substances from Cassia garrettiana. Songklanakarin J Sci Technol 29: 145-149.
WATERMAN PG AND MOLE S. 1994. Analysis of phenolic plants metabolites. London: Blackwell Scientific publications, 238 p.
WEI X, JIANG JS, FENG ZM and ZANG PC. 2007. New anthraquinone derivatives from roots of Berchemia floribunda. Chin Chem Let 18: 412-414.
ZUO Y, WANG C, LIN Y, GUO J AND DENG Y. 2008. Simultaneous determination of anthraquinones in radix Polygony multiflori by gas chromatography coupled with flame ionization and mass spectrometric detection. J Chromatogr A 1200: 43-48.

Correspondence to:

Alexsandro Branco

E-mail:

branco@uefs.br

Publication Dates

Publication in this collection
29 Nov 2011
Date of issue
Dec 2011

History

Accepted
14 Mar 2011
Received
23 Mar 2010

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

[1] BARBA B, DÍAZ JG AND HERZ W. 1992. Anthraquinones and others constituents oftwo Senna species. Phytochemistry 31: 4374-4375.

[2] BAEZ DA, VALLEJO LGZ AND JIMENEZ-ESTRADA M. 1999. Phytochemical studies on Senna skinneri and Senna wislizeni. Nat Prod Res 13: 223-228.

[3] BARBOSA FG, OLIVEIRA MCF, BRAZ-FILHO R AND SILVEIRA ER. 2004. Anthraquinones and naphthopyrones from Senna rugosa. Biochem Syst Ecol 32: 363-365.

[4] BRANCO A, PINTO AC, BRAZ-FILHO R, SILVA EF, GRYN-BERG NF AND ECHEVARRIA A. 2008. Rubrofusarina, um policetídeo natural inibidor da topoisomerase II-α humana. Rev Bras Farmacogn 18(suppl): 703-708.

[5] BRUNETON J. 1991. Elementos de fitoquímica y de farmacognosia. Zaragoza: Acribia, 1128 p.

[6] DEWICK PM. 1997. Medicinal Natural Products - A biosynthetic Approach. J Wiley & Sons. England, 466 p.

[7] GARCÍA-SOSA K, VILLAREAL-ALVAREZ N, LUBBEN P AND PENA-RODRIGUEZ LM. 2006. Chrysophanol, an antimicrobial anthraquinone from the root extract of Colubrina greggii. J Mex Chem Soc 50: 76-78.

[8] HATANO T, UEBAYASHI H, ITO H, SHIOTA S, TSUCHIYA T AND YOSHIDA T. 1999. Phenolic constituents of Cassia seeds and antibacterial effect of some naphthalenes and anthraquinones on methicillin-resistent Staphylococcus aureus. Chem Pharm Bull 47: 1121-1127.

[9] KOYAMA J, MORITA I, TAGAHARA K AND AQIL M. 2001. Biantraquinones from Cassia siaea. Phytochemistry 56: 849-851.

[10] LIU S-Y, LO C-T, CHEN C, LIU M-Y, CHEN J-H AND PENG K-C. 2007. Efficient isolation of anthraquinone-derivatives from Trichoderma harzianum ETS 323. J Biochem Biophys Methods 70: 391-395.

[11] LORENZI H. 2000. Árvores Brasileiras - Manual de identificação e cultivo de plantas arbóreas nativas do Brasil. São Paulo: Instituto Plantarum, 352 p.

[12] MUELLER SO, SCHMITT M, DEKANT W, STOPPER H, SCHLATTER J, SCHREIER P AND LUTZ WK. 1999. Occurrence of emoldin, chrysophanol and physion in vegetables, herbs and liquors. Genotoxicity and anti-genotoxicity of the anthraquinones and of the whole plants. Food Chem Toxicol 37: 481-491.

[13] OLIVEIRA AB, FERNANDES MLM, SHAAT VT, VASCONCELOS LA AND GOTTLIEB OR. 1977. Constituents of Cassia species. Rev Latinoamer Quim 8: 82-85.

[14] PIRES L, GORIN PAJ, REICHER F AND SlERAKOWSKI MR. 2001. An active heparinoid obtained by suphation of a galactomannan extracted from the endosperm of Senna macranthera seeds. Carboh Pol 46: 165-169.

[15] SCHRIPSEMA J AND DAGNINO D. 1996. Elucidation of the substitution pattern of 9,10-anthraquinones through the chemical shifts of perihydroxyl protons. Phytochemistry 42: 177-184.

[16] SONG R, LIN H, ZHANG Z, LI Z, XU L, DONG H AND TIAN Y. 2009. Profiling the metabolic differences of anthraquinone derivatives using liquid chromatography/ tandem mass spectrometry with data-dependent acquisition. Rapid Commun Mass Spectrom 23: 537-547.

[17] TEWTRAKUL S, SUBHADHIRASAKUL S, RATTANASUWAN P AND PURIPATTANVONG J. 2007. HIV-1 protease inhibitory substances from Cassia garrettiana. Songklanakarin J Sci Technol 29: 145-149.

[18] WATERMAN PG AND MOLE S. 1994. Analysis of phenolic plants metabolites. London: Blackwell Scientific publications, 238 p.

[19] WEI X, JIANG JS, FENG ZM and ZANG PC. 2007. New anthraquinone derivatives from roots of Berchemia floribunda. Chin Chem Let 18: 412-414.

[20] ZUO Y, WANG C, LIN Y, GUO J AND DENG Y. 2008. Simultaneous determination of anthraquinones in radix Polygony multiflori by gas chromatography coupled with flame ionization and mass spectrometric detection. J Chromatogr A 1200: 43-48.