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Two pyrrole acids from Berberis koreana
Phytochemistry, Vol. 31, No. 10, pp. 3669-3670, 1992 Printedin Great Britain.
0031-9422/92 $5.00+0.00 Q 1992 PergamonPress Ltd
TWO PYRROLE ACIDS FROM BERBERIS KOREANA DANIELA
KoStkLovti
VERAHROCHOVA,VACLAVSUCH+, MILOS
BUD!%NSKP*
and
KAREL UBIK*
Department of Pharmacognosy and Botany, Faculty of Pharmacy, Comenius University, OdbojLrov 10, 83232 Bratislava, Czechoslovakia; *Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 16610 Praha 6, Czechoslovakia (Received 10 February 1992)
Key Word Index-Berberis koreana; Berberidaceae; lH-pyrrole-2,5-dicarboxylic acid; monomethyl ester of lH-pyrrole-2,3-dicarboxylic acid.
Abstract-An extract from leaves of Berberis koreana afforded lH-pyrrole-2,5-dicarboxylic ester. Their structures were determined by spectroscopic methods.
acid and its monomethyl
INTRODUCTION
Numerous alkaloids with different medicinal importance have been isolated from Berberis species [l, 21. Our preceding papers [3, 4) concerned the isolation of bisbenzylisoquinoline and protoberberine alkaloids from Berberis koreana Palib. We now report the isolation and structure elucidation of two pyrrole acids from the leaves of Berberis koreana. RESULTS AND DISCGSSION
The ethyl acetate extract of the defatted leaves of B. koreana submitted to chromatography over silica gel afforded two compounds. The mass spectra of 1 obtained by high resolution measurement before and after deuterium labelling of the compound (using C,H,OD for replacing active hydrogens with deuterium) indicated a pyrrole skeleton containing two hydroxylic groups and an unsubstituted nitrogen. The molecular ion [M]’ at m/z 155 (C,H,NOJ subsequently eliminated water (m/z 137, C&H,NO,), carbon dioxide (m/z 93, C,H,NO) and carbon monoxide (m/z 65, C,H,N) and on the other hand also water and hydroxyl radical (m/z 120, &H,NO,) and again carbon monoxide (m/z 92, C,H,NO). The mass spectrum of deuterated 1 confirmed the presence of three active hydrogens in the molecule, one active hydrogen in the ion at m/z 137 and no active hydrogens in the other fragments. The mass spectra of natural and deuterated 2 showed a structure similar to that of 1 containing one methoxyl group and two active hydrogens in the molecule. The molecular ion [M] + at m/z 169 eliminated a methoxyl radical (m/z 138) and water (m/z 120). There were also two active hydrogens in the fragment ion at m/z 138 but no active hydrogens in the other ions. The ‘H NMR spectrum of 1 in DMSO-d, showed only three signals (br s at 612.76 and 12.19 and d at 66.74 with 5=2.5 Hz) in the intensity ratio 2: 1:2. The doublet was decoupled by irradiating the signal at 6 12.19, as well as after the addition of D,O, which led to the disappearence of both low field signals. This allows the assignment of the signals to COzH (6 12.76), NH (6 12.19) and -CH= (66.74), respectively. Also the 13C NMR
HO/%sI? N III . 1
2
R H Me
spectrum (see Experimental) contained only three signals thus cont%ming the symmetry of the molecule with two carboxylic groups either in positions C-2, C-5 and/or C-3, C-4 of the pyrrole ring. The .I (NH, CH) value cannot be used for distinguishing between them because of the similar values for the coupling at position C-2 and C-3 [S]. For a final decision on structure 1 the NMR data of 2 proved to be very useful. The ‘H and 13C NMR spectra of 2 (see Experimental) confirmed the presence of one methyl ester and one carboxyl group and the NH proton on a disubstituted pyrrole ring. The pyrrole CH= protons were slightly non-equivalent (doublets of doublets at 66.80 and 6.76). The value of their mutual coupling (3.9 Hz) was compatible only with protons in position C-3 and C-4 [S] while their coupling with the NH proton (2.4 Hz) was not characteristic. The ’ 3C NMR spectrum showed three pairs of slightly non-equivalent signals of C=O, C= and CH= carbons and one methoxyl signal in agreement with the structure of the monomethyl ester of lH-pyrrole-2,5-dicarboxylic acid 2. A close similarity with the 13C NMR data of 1 discussed above clearly proved its structure to be lH-pyrrole-2,5-dicarboxylic acid (1). The natural occurrence of simple pyrrole acids seems to be exceptional. All of those reported are known only from Parietaria oflcinalis (Urticaceae) [6], from some microorganisms [7-91 and as an acyl moiety in quinolizidine alkaloids from the Calpurnia aurea ssp. aurea (Leguminosae) [lo]. Other pyrrole derivatives were described as constituents of Quararibea jimebris (Bombacaceae) [ 111, as volatiles of Hibiscus aesculentus (Malvaceae) [12] and as constituents of Oregon red alga Gracilariopsis lemaneiformis [13]. This is the first report of pyrrole acids from the genus Berberis.
3669
Short Reports
3670 EXPERIMENTAL
Mps: uncorr. EIMS: 70 eV; NMR: ‘H at 500 MHZ i3C at 125.7 MHz. Silica gel Silpearl (Kavalier) 35-60 p, modified according to ref. [lo], Silufol UF,,, and UVss6 sheets were employed for CC and TLC, respectively. Plant material. Leaves of Berberis koreana Palib. were collected in October 1989 from the medicinal plant garden of the Faculty of Pharmacy, Comenius University, Bratislava. Plants were cultivated without any chemical protection. A voucher specimen is deposited at the Laboratory of Botany of our department. Dry leaves (2.4 kg) were crushed, defatted with hexane and extracted with EtOAc. The EtOAc extract (10 g) was separated by CC on silica gel (500 g) using C,H,-Me,CO (10: 1, 1: 1), Me,CO and MeOH as eluents. TLC, which was routinely used to monitor each fraction, was carried out on silica gel Silufol (Kavalier) plates with the solvent system CHCl,-MeOH (15: 1). Compounds were visualized by UV light or spraying with 10% H,SO, in Et,0 following by heating. 186 fractions (each 100 ml) were collected. Frs 2427 after evapn and microsublimation of the amorphous solid afforded 2 (17 mg) as needles, mp 204206”. R, value 0.7 ( x 2). UV E.t$“’ nm: 280,285sh. IR Y::; cm-i: 3440, 3290,2940,2570-2300,1730,1690,1612,1516,1418,1454, 1382, 1320,1269,1245,1203,1176,1115. ‘HNMR(DMSO-d,): 612.80 (lH, br s, CO,H), 12.49 (lH, br s. NH), 6.80 (lH, dd, J=3.9, 24Hz, H-3), 6.76 (lH, dd, J=3.9, 2.4Hz, H-4), 3.77 (3H, s, CO,Me). “C NMR (DMSO-d,+CD,OD, 5: 1):6161.4,160.5 (2 x CO,), 128.1 (C-2). 115.5 (C-4), 115.3 (C-3), 126.2 (C-5), 51.6 (OMe). EIMS (70 eV) m/z (rel. mt.): [Ml” 169 (84), 120 (lOO),93 (28), 138 (27), 121 (14), 92 (14), 101 (13), 84 (lo), 64 (lo), 151 (5). Frs 75-82 after evapn and microsublimation of the amorphous solid afforded 1 (31 mg) as needles, mp 245”. R, value 0.4 (x 2). UV 1:::” nm: 274, 283sh. IR v!$,i: cm-‘: 3440, 3135, 258~2300,1670,1550,1475,1440,1420, 1323, 1255,1115,1072,
964, 880, 828, 761. ‘HNMR (DMSO-I,): 612.76 (2H, br s, 2 xCO,H),12.19(1H,brs,NH),6.74(2H,d,J=2.5Hz,H-3,H-4), i3C NMR (DMSO-I, +CD,OD, 5 : 1): 6162.5 (2 x CO,H), 126.7 (C-2, C-5), 115.9 (C-3, C-4). EIMS (70 eV) m/z (rel. int.): [M] + 155 (lOO),120 (44), 137 (32), 93 (28), 92 (9), 65 (9) 64 (8), 38 (8), 83 (6), 39 (6).
REFERENCES
1. Schiff, P. L. (1991) J. Nat. Prod. 54, 645. 2. Pachaly, P. (1990) Planta Med. 56, 135. 3. KogiilovL, D., Braxdovicovl, B. and Hwang Yang Jin (1982) Farm. Obzor 51, 213. 4. Hrochova, V. and KoStalovl, D. (1987) &skoslov. Farm. 36, 457. 5. Roder, E., Wiedenfeld, H. and Bourael, T. (1987) Liebigs Ann. Chem. 1117. 6. Budzianowski, J. (1990) Phytochemistry 29, 3299. 7. Corpe, W. A. (1963) Agpl. Microbial. 11, 145. 8. HCfle, G. and Wolf, H. (1983) Liebigs Ann. Gem. 835. 9. Komiyama, K., Tronquet, C., Hirokawa, Y., Funayama, S., Santoh, O., Umezawa, I. and Oishi, S. (1986) Jap. J. Antibiot. 39, 746. 10. Asres, K., Phillipson, J. D. and Mascagni, P. (1986) Plnnta Med. 52, 3299.
11. Raffauf, R. F., Zennie, T. M., Onan, K. D. and Le Quesne, P. W. (1984) J. Org. Chem. 49, 2714. 12. Ames, J. M. and MacLeod G. (1990) Phytochemistry 29, 1201. 13. Jiang Zhi, D. and Gerwick, W. H. (1991) J. Nat. Prod. 54,
403. 14. Pitra, J. and Sterba J. (1963) Chem. Listy 57, 389.
0031-9422/92 $5.00+0.00 Q 1992 PergamonPress Ltd
TWO PYRROLE ACIDS FROM BERBERIS KOREANA DANIELA
KoStkLovti
VERAHROCHOVA,VACLAVSUCH+, MILOS
BUD!%NSKP*
and
KAREL UBIK*
Department of Pharmacognosy and Botany, Faculty of Pharmacy, Comenius University, OdbojLrov 10, 83232 Bratislava, Czechoslovakia; *Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 16610 Praha 6, Czechoslovakia (Received 10 February 1992)
Key Word Index-Berberis koreana; Berberidaceae; lH-pyrrole-2,5-dicarboxylic acid; monomethyl ester of lH-pyrrole-2,3-dicarboxylic acid.
Abstract-An extract from leaves of Berberis koreana afforded lH-pyrrole-2,5-dicarboxylic ester. Their structures were determined by spectroscopic methods.
acid and its monomethyl
INTRODUCTION
Numerous alkaloids with different medicinal importance have been isolated from Berberis species [l, 21. Our preceding papers [3, 4) concerned the isolation of bisbenzylisoquinoline and protoberberine alkaloids from Berberis koreana Palib. We now report the isolation and structure elucidation of two pyrrole acids from the leaves of Berberis koreana. RESULTS AND DISCGSSION
The ethyl acetate extract of the defatted leaves of B. koreana submitted to chromatography over silica gel afforded two compounds. The mass spectra of 1 obtained by high resolution measurement before and after deuterium labelling of the compound (using C,H,OD for replacing active hydrogens with deuterium) indicated a pyrrole skeleton containing two hydroxylic groups and an unsubstituted nitrogen. The molecular ion [M]’ at m/z 155 (C,H,NOJ subsequently eliminated water (m/z 137, C&H,NO,), carbon dioxide (m/z 93, C,H,NO) and carbon monoxide (m/z 65, C,H,N) and on the other hand also water and hydroxyl radical (m/z 120, &H,NO,) and again carbon monoxide (m/z 92, C,H,NO). The mass spectrum of deuterated 1 confirmed the presence of three active hydrogens in the molecule, one active hydrogen in the ion at m/z 137 and no active hydrogens in the other fragments. The mass spectra of natural and deuterated 2 showed a structure similar to that of 1 containing one methoxyl group and two active hydrogens in the molecule. The molecular ion [M] + at m/z 169 eliminated a methoxyl radical (m/z 138) and water (m/z 120). There were also two active hydrogens in the fragment ion at m/z 138 but no active hydrogens in the other ions. The ‘H NMR spectrum of 1 in DMSO-d, showed only three signals (br s at 612.76 and 12.19 and d at 66.74 with 5=2.5 Hz) in the intensity ratio 2: 1:2. The doublet was decoupled by irradiating the signal at 6 12.19, as well as after the addition of D,O, which led to the disappearence of both low field signals. This allows the assignment of the signals to COzH (6 12.76), NH (6 12.19) and -CH= (66.74), respectively. Also the 13C NMR
HO/%sI? N III . 1
2
R H Me
spectrum (see Experimental) contained only three signals thus cont%ming the symmetry of the molecule with two carboxylic groups either in positions C-2, C-5 and/or C-3, C-4 of the pyrrole ring. The .I (NH, CH) value cannot be used for distinguishing between them because of the similar values for the coupling at position C-2 and C-3 [S]. For a final decision on structure 1 the NMR data of 2 proved to be very useful. The ‘H and 13C NMR spectra of 2 (see Experimental) confirmed the presence of one methyl ester and one carboxyl group and the NH proton on a disubstituted pyrrole ring. The pyrrole CH= protons were slightly non-equivalent (doublets of doublets at 66.80 and 6.76). The value of their mutual coupling (3.9 Hz) was compatible only with protons in position C-3 and C-4 [S] while their coupling with the NH proton (2.4 Hz) was not characteristic. The ’ 3C NMR spectrum showed three pairs of slightly non-equivalent signals of C=O, C= and CH= carbons and one methoxyl signal in agreement with the structure of the monomethyl ester of lH-pyrrole-2,5-dicarboxylic acid 2. A close similarity with the 13C NMR data of 1 discussed above clearly proved its structure to be lH-pyrrole-2,5-dicarboxylic acid (1). The natural occurrence of simple pyrrole acids seems to be exceptional. All of those reported are known only from Parietaria oflcinalis (Urticaceae) [6], from some microorganisms [7-91 and as an acyl moiety in quinolizidine alkaloids from the Calpurnia aurea ssp. aurea (Leguminosae) [lo]. Other pyrrole derivatives were described as constituents of Quararibea jimebris (Bombacaceae) [ 111, as volatiles of Hibiscus aesculentus (Malvaceae) [12] and as constituents of Oregon red alga Gracilariopsis lemaneiformis [13]. This is the first report of pyrrole acids from the genus Berberis.
3669
Short Reports
3670 EXPERIMENTAL
Mps: uncorr. EIMS: 70 eV; NMR: ‘H at 500 MHZ i3C at 125.7 MHz. Silica gel Silpearl (Kavalier) 35-60 p, modified according to ref. [lo], Silufol UF,,, and UVss6 sheets were employed for CC and TLC, respectively. Plant material. Leaves of Berberis koreana Palib. were collected in October 1989 from the medicinal plant garden of the Faculty of Pharmacy, Comenius University, Bratislava. Plants were cultivated without any chemical protection. A voucher specimen is deposited at the Laboratory of Botany of our department. Dry leaves (2.4 kg) were crushed, defatted with hexane and extracted with EtOAc. The EtOAc extract (10 g) was separated by CC on silica gel (500 g) using C,H,-Me,CO (10: 1, 1: 1), Me,CO and MeOH as eluents. TLC, which was routinely used to monitor each fraction, was carried out on silica gel Silufol (Kavalier) plates with the solvent system CHCl,-MeOH (15: 1). Compounds were visualized by UV light or spraying with 10% H,SO, in Et,0 following by heating. 186 fractions (each 100 ml) were collected. Frs 2427 after evapn and microsublimation of the amorphous solid afforded 2 (17 mg) as needles, mp 204206”. R, value 0.7 ( x 2). UV E.t$“’ nm: 280,285sh. IR Y::; cm-i: 3440, 3290,2940,2570-2300,1730,1690,1612,1516,1418,1454, 1382, 1320,1269,1245,1203,1176,1115. ‘HNMR(DMSO-d,): 612.80 (lH, br s, CO,H), 12.49 (lH, br s. NH), 6.80 (lH, dd, J=3.9, 24Hz, H-3), 6.76 (lH, dd, J=3.9, 2.4Hz, H-4), 3.77 (3H, s, CO,Me). “C NMR (DMSO-d,+CD,OD, 5: 1):6161.4,160.5 (2 x CO,), 128.1 (C-2). 115.5 (C-4), 115.3 (C-3), 126.2 (C-5), 51.6 (OMe). EIMS (70 eV) m/z (rel. mt.): [Ml” 169 (84), 120 (lOO),93 (28), 138 (27), 121 (14), 92 (14), 101 (13), 84 (lo), 64 (lo), 151 (5). Frs 75-82 after evapn and microsublimation of the amorphous solid afforded 1 (31 mg) as needles, mp 245”. R, value 0.4 (x 2). UV 1:::” nm: 274, 283sh. IR v!$,i: cm-‘: 3440, 3135, 258~2300,1670,1550,1475,1440,1420, 1323, 1255,1115,1072,
964, 880, 828, 761. ‘HNMR (DMSO-I,): 612.76 (2H, br s, 2 xCO,H),12.19(1H,brs,NH),6.74(2H,d,J=2.5Hz,H-3,H-4), i3C NMR (DMSO-I, +CD,OD, 5 : 1): 6162.5 (2 x CO,H), 126.7 (C-2, C-5), 115.9 (C-3, C-4). EIMS (70 eV) m/z (rel. int.): [M] + 155 (lOO),120 (44), 137 (32), 93 (28), 92 (9), 65 (9) 64 (8), 38 (8), 83 (6), 39 (6).
REFERENCES
1. Schiff, P. L. (1991) J. Nat. Prod. 54, 645. 2. Pachaly, P. (1990) Planta Med. 56, 135. 3. KogiilovL, D., Braxdovicovl, B. and Hwang Yang Jin (1982) Farm. Obzor 51, 213. 4. Hrochova, V. and KoStalovl, D. (1987) &skoslov. Farm. 36, 457. 5. Roder, E., Wiedenfeld, H. and Bourael, T. (1987) Liebigs Ann. Chem. 1117. 6. Budzianowski, J. (1990) Phytochemistry 29, 3299. 7. Corpe, W. A. (1963) Agpl. Microbial. 11, 145. 8. HCfle, G. and Wolf, H. (1983) Liebigs Ann. Gem. 835. 9. Komiyama, K., Tronquet, C., Hirokawa, Y., Funayama, S., Santoh, O., Umezawa, I. and Oishi, S. (1986) Jap. J. Antibiot. 39, 746. 10. Asres, K., Phillipson, J. D. and Mascagni, P. (1986) Plnnta Med. 52, 3299.
11. Raffauf, R. F., Zennie, T. M., Onan, K. D. and Le Quesne, P. W. (1984) J. Org. Chem. 49, 2714. 12. Ames, J. M. and MacLeod G. (1990) Phytochemistry 29, 1201. 13. Jiang Zhi, D. and Gerwick, W. H. (1991) J. Nat. Prod. 54,
403. 14. Pitra, J. and Sterba J. (1963) Chem. Listy 57, 389.