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Cyclopentenylglycines and other constituents from Alangium chinense
Biochemical Systematics and Ecology 37 (2009) 214–217
Contents lists available at ScienceDirect
Biochemical Systematics and Ecology journal homepage: www.elsevier.com/locate/biochemsyseco
Cyclopentenylglycines and other constituents from Alangium chinense Xiao-Hui Zhang, Shan-Shan Liu, Li-Jiang Xuan* State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, 555 Zuchongzhi Road, Zhangjiang Hi-Tech Park, Shanghai 201203, China
a r t i c l e i n f o Article history: Received 6 August 2008 Accepted 21 November 2008 Keywords: Alangium chinense Alangiaceae Cyclopentenylglycines Nonproteinogenic amino acid glycoside
1. Subject and source Alangium chinense (Lour.) Harms (Alangiaceae) is a deciduous shrub indigenous to China, and distributed mainly in the South. As a traditional Chinese medicine, the roots, flowers, and leaves of this plant have been documented for use as a muscle relaxant and analgesic agent (State Administration of Traditional Chinese Medicine of the People’s Republic of China, 1999). The roots of A. chinense were collected from Nanning, Guangxi province of China, in August 2006, and identified by Professor Heming Yang. The voucher specimen (No. AC001) has been deposited in the herbarium of Shanghai Institute of Materia Medica. 2. Previous work Previous studies on A. chinense focused on alkaloids (Hou et al., 1981) and phenolic glycosides (Itoh et al., 1997, 2000, 2001). 3. Present study 3.1. Extraction and isolation The air-dried roots of A. chinense (4 kg) were extracted with 70% acetone (10 L 3, 2 days each) at room temperature. After evaporation in vacuo, the suspended residue was removed by centrifugation. The aqueous solution was chromatographed over a MCI gel CHP-20P column eluted with MeOH–H2O (0%, 100%) to give two fractions (A and B). Both fractions were further subjected to column chromatography on Cosmosil 75 C18-OPN, Amberlite CG-50, and Toyopearl HW-40F repeatedly. Fraction A yielded compounds 1 (42 mg), 2 (20 mg), 3 (1 g), 4 (200 mg), 5 (50 mg), 6 (150 mg), 7 (120 mg), 8 (24 mg), 9 (3 mg), 10 (4 mg), 12 (65 mg), and 13 (56 mg). Compound 11 (24 mg) was afforded from fraction B.
* Corresponding author. Tel./fax: þ86 21 50272221. E-mail address: [email protected] (L.-J. Xuan). 0305-1978/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.bse.2008.11.015
X.-H. Zhang et al. / Biochemical Systematics and Ecology 37 (2009) 214–217 Table 1 1 H (400 MHz) and
13
C (100 MHz) NMR spectral data of 1 and 2 in D2O (d (ppm) (J, Hz)).
1 Atom 1 2 10 20 30 40 50 100 200 300 400 500 600
215
2 1
13
H
C
HMBC (H–C)
175.0 s 68.9 d 49.1 d 130.9 d 138.8 d 34.2 t 27.2 t
3.91 d (4.9) 3.43 m 5.74 dd (2.1, 5.5) 6.11 dd (2.4, 5.3) 2.44 m 2.15 td (8.1, 14.1), 1.77 td (5.9, 14.2) 3.45 m, 3.33 d (13.2)
C-1, 20 , 50 , 100 C-10, 30 , 40 , 50 C-10, 20 , 40 , 50 C-2, 10, 20 , 30 , 40 C-2, 200 , 300
56.1 t 97.8 s 73.1 d 72.0 d 71.5 d 66.5 d
3.83 brd (9.9) 3.93 d (8.0) 4.06 brs 4.08 brd (12.5), 3.81 brd (13.0)
C-200 , 500
1
Atom 1 2 3 4 5 6 7
13
H
C
HMBC (H–C)
C-1, 5 C-2, 6 C-1, 3 C-2, 4 C-1, 2, 100
10 20 30 40 50 60
7.55 d (7.6) 7.21 t (7.7) 7.47 t (7.6) 7.29 d (7.3) 4.94 d (11.9), 5.06 d (11.8) 4.63 d (8.1) 3.70 m 3.46 m 3.58 m 3.67 m 3.79 m, 3.95 m
157.5 s 128.7 s 133.5 d 125.8 d 132.9 d 117.8 d 69.4 t 103.0 d 75.6 d 78.5 d 72.0 d 78.2 d 63.2 t
C-1, 30 , 50 C-40 C-10, 50 C-20 , 60 C-10, 30 C-40
100 200 300 400 500 600
5.20 3.34 3.49 3.43 3.68 3.83
104.2 d 75.8 d 78.7 d 72.3 d 78.4 d 63.4 t
C-7, 300 , 500 C-400 C-100, 500 C-200 , 600 C-100, 300 C-400
d (6.8) m m m m m, 3.99 m
3.2. Identification of constituents Separation and purification of the extract of A. chinense by repetitive chromatography led to the isolation and characterization of a new amino acid glycoside, alanchinin (1), a new phenolic glycoside, 7-O-b-glucopyranosylsalicin (2), and 11 known compounds (3–13). Compounds 3–13 were identified as 2-(20 -cyclopentenyl)glycine (3, Olafsdottir et al., 1989), henryoside (4, Otsuka et al., 1989), salicin 60 -O-b-D-apiofuranoside (5, Tamaki et al., 2000), 600 -O-b-D-glucopyranosylhenryoside (6, Kijima et al., 1997), 5b,6b-dihydroxycyclohex-2-en-1-O-b-glucopyranoside (7, Zhu, 1998), cuneataside D (8, Chang and Case, 2005), 4-cyclohexene-1,2,3-triol (9, Hyldtoft and Madsen, 2000), loganic acid (10, Nakamoto et al., 1988), 4,40 -di-O-methylellagic acid (11, Fukuyama et al., 1983), b-glucogallin (12, Saijo et al., 1990) and edulilic acid (13, Foo et al., 2006), respectively, by comparison of their spectroscopic data with those reported in the literature. The hygroscopic compound 1 was suggested to have the molecular formula of C13H21NO7 by HR-ESIMS (m/z 326.1218, [M þ Na]þ, calc. 326.1261). It displayed a positive ninhydrin reaction (yellowish color), which indicated the presence of an amino acid moiety. The 1H NMR spectrum of 1 (Table 1) showed resonances for a couple of pentacyclic cis-olefin protons [dH 6.11 (dd, J ¼ 2.4, 5.3 Hz) and 5.74 (dd, J ¼ 2.1, 5.5 Hz)], two pairs of methylene protons [dH 2.44 (2H, m) and 2.15 (1H, td, J ¼ 8.1, 14.1 Hz), 1.77 (1H, td, J ¼ 5.9, 14.2 Hz)], and two methine protons [dH 3.91 (d, J ¼ 4.9 Hz) and 3.43 (m)], which supported a 2(20 -cyclopentenyl)glycine architecture. The NMR data of 1 were similar to those of 2-(20 -cyclopentenyl)glycine (3), except for the resonances of one additional sugar unit. Acid hydrolysis of 1 gave the aglycone and fructose, which was identified by direct comparison with authentic samples on TLC. From the coupling constants of H-300 , H-400 , H-600 a, and H-600 b (3J ¼ 9.9 Hz, 2 J ¼ 12.5 Hz), it was determined that the fructose part is present as a pyranose ring system. The purified fructose unit obtained after hydrolysis gave an optical rotation, [a] 128.0B (c 0.12, H2O), indicating that it was in the D-form. In aqueous solution, compound 1 showed mutarotation due to the free hydroxyl group at C-200 . The major signals in the 13C NMR spectrum could be assigned to the b-fructopyranose form (Ro¨per et al., 1983), while other forms (a-furanose, b-furanose or a-pyranose) could OH
OH
OH OH
1''
OH
H N
1 COOH
H
OH O
H
6''
OH
1" 7
1'
O OH
1
O
OH 1' O
4'
OH
O
6
OH
1
2
Fig. 1. Structures of compounds 1 and 2.
OH
216
X.-H. Zhang et al. / Biochemical Systematics and Ecology 37 (2009) 214–217
H N
OH H2N
COOH
COOH
OH
D-glucose pyrosulfite
O
CH3OH : H2O = 1 : 1 reflux
OH OH
Fig. 2. Synthetic study to N-(100 -deoxy-100 -b-D-fructopyranosyl)-2-(20 -cyclopentenyl)glycine.
be observed as minor signals. The glycosidic linkage was determined from the following HMBC correlations: H-100 a [dH 3.45 (m)] and H-100 b [dH 3.33 (d, J ¼ 13.2 Hz)]/C-2 (dC 68.9), and H-2 [dH 3.91 (d, J ¼ 4.9 Hz)]/C-100 (dC 56.1). The aglycone was determined to be (2S,10 R)-2-(20 -cyclopentenyl)glycine by comparing optical rotation ([a] þ120B (c 0.09, MeOH)) and CD data [(MeOH) lmax nm (D3): 202 (þ48.06), 243 (1.91)] of its N-acetyl derivative with published information. On the basis of the above evidence, the structure of compound 1 was established as (2S,10 R)-N-(100 -deoxy-100 -b-D-fructopyranosyl)-2-(20 -cyclopentenyl)glycine, named alanchinin. A synthetic study towards N-(100 -deoxy-100 -b-D-fructopyranosyl)-2-(20 -cyclopentenyl)glycine was carried out by Amadori rearrangement (Figs. 1 and 2). As in the published protocol reference, it was prepared from compound 3 and D-glucopyranose, and it was also deduced that Amadori rearrangement is the biosynthetic pathway to 1. Compound 2 was isolated as a colourless amorphous powder, with the molecular formula C19H28O12, determined from the HR-ESIMS (m/z 471.1089 [M þ Na]þ). Its 1H NMR spectrum exhibited benzylic methylene protons at dH 4.94 and 5.06 (each d, J ¼ 11.8 Hz) and four aromatic protons for the 1,2-disubstituted benzene ring in the dH 7.19–7.55 range, along with the signals arising from two b-glucopyranosyl moieties [dH 4.63 (d, J ¼ 8.1 Hz), 5.20 (d, J ¼ 6.8 Hz)]. These spectral features demonstrated its close similarity to salicin, but with one more b-glucosyl unit. The HMBC correlations of the anomeric proton H-10 (dH 5.20) to C-1 (dC 157.5), and H-100 (dH 4.63) to C-7 (dC 69.4) indicated that the b-glucopyranosyl moieties are located at C-1 and C-7, respectively. Accordingly, compound 2 was deduced to be 7-O-b-glucopyranosylsalicin. 4. Chemotaxonomic significance Alangiaceae belongs to the order Cornales in subclass Rosidae. Compounds 4–7, and 10 have been reported in the family Alangiaceae (Itoh et al., 2000; Tamaki et al., 2000; Zhu, 1998), and compounds 11 and 12 have been mainly found in the subclass Rosidae (Ye et al., 2001; Subeki et al., 2005). Alanchinin (1) and 2-(20 -cyclopentenyl)glycine (3) are nonproteinogenic amino acids. 2-(20 -Cyclopentenyl)glycine (3) was first postulated as a hypothetical precursor for deidaclin (a cyclopentanoid cyanogen, Clapp et al., 1970), and then was demonstrated as the precursor of cyclopentenyl fatty acids in the Flacourtiaceae (Cramer and Spener, 1977). Nowadays, the cyclopentanoid cyanogens and their oxygenated derivatives have been reported to occur in a cluster of closely related species in five families, Passifloraceae (Olafsdottir et al., 1989), Turneraceae (Olafsdottir et al., 1990), Malesherbiaceae (Spencer and Seigler, 1985), Achariaceae (Jensen and Nielsen, 1986), and Flacourtiaceae (Jaroszewski and Olafsdottir, 1987), all in the order Violales (Cronquist, 1981). 2-(20 -Cyclopentenyl)glycine (3) was also distributed both in those five families (Jaroszewski et al., 1988) and Violaceae (Clausen et al., 2002). To our knowledge, this is the first report on the occurrence of 2-(20 -cyclopentenyl)glycine (3) and its new glycoside derivative alanchinin (1) outside the Violales. Compounds 3 and 13, which have similar cyclopentene skeletons, and which co-occur in both A. chinense and Passiflora edulis (Passifloraceae) (Foo et al., 2006) drew our attention. A feasible pathway (Dewick, 2002) from a-carbonyl carboxylic acid to a-amino acid suggested that hydrolysation from compound 13 to 2-(20 -cyclopentenyl)-carbonyl carboxylic acid may be possible. Consequently, edulilic acid (13) could be considered as a hypothetical precursor for 2-(20 -cyclopentenyl)glycine (3), as depicted in Fig. 3.
OH HO
OH O
HO
O O
COOH
COOH
H2N
COOH hydrolyze
PLP
13
3
PLP = pyridoxal phosphate, an aminotransferase coenzyme Fig. 3. Hypothetical biosynthetic pathway from 13 to 3.
X.-H. Zhang et al. / Biochemical Systematics and Ecology 37 (2009) 214–217
217
Finally, from the angiosperm phylogenetic trees (Soltis et al., 2000), the almost parallel positions of orders Cornales and Violales excludes the presumption of hybridization or paternity between A. chinense and the five 2-(20 cyclopentenyl)glycine containing families. However, is it a coincidence that both compounds 3 and 13 co-occur in both A. chinense and P. edulis (Passifloraceae), or a clue that both of the species possessed similar enzymatic systems? So the occurrence of these particular compounds in A. chinense is noteworthy, and may contribute to chemotaxonomic studies of the Alangiaceae family.
References Chang, J., Case, R., 2005. Phytochemistry 66, 2752. Clapp, R.C., Ettlinger, M.G., Long, L., 1970. J. Am. Chem. Soc. 92, 6378. Clausen, V., Frydenvang, K., Koopmann, R., Jorgensen, L., Abbiw, D., Ekpe, P., Jaroszewski, J., 2002. J. Nat. Prod. 65, 542. Cramer, U., Spener, F., 1977. Eur. J. Biochem. 74, 495. Cronquist, A., 1981. An Integrated System of Classification of Flowering Plants. Columbia University Press, New York. Dewick, P.M., 2002. Medicinal Natural Products, a Biosynthetic Approach, second ed. John Wiley & Sons, Ltd. Foo, L.Y., Lu, Y., Watson, R.R., 2006. US Pat. No. US 2006/0222725 A1. Fukuyama, Y., Sato, T., Miura, I., Asakawa, Y., Takemoto, T., 1983. Phytochemistry 22, 549. Hou, L., Chen, M., Zhu, H., 1981. Zhongcaoyao 12, 352. Hyldtoft, L., Madsen, R., 2000. J. Am. Chem. Soc. 122, 8444. Itoh, A., Tanahashi, T., Nagakura, N., 1997. Nat. Med. 51, 173. Itoh, A., Tanahashi, T., Ikejima, S., Inoue, M., Nagakura, N., Inoue, K., Kuwajima, H., Wu, H., 2000. J. Nat. Prod. 63, 95. Itoh, A., Tanahashi, T., Nagakura, N., Inoue, K., Kuwajima, H., Wu, H., 2001. Chem. Pharm. Bull. 49, 1343. Jaroszewski, J.W., Olafsdottir, E.S., 1987. Phytochemistry 26, 3348. Jaroszewski, J.W., Jensen, P.S., Cornett, C., Byberg, J.R., 1988. Biochem. Syst. Ecol. 16, 23. Jensen, S.R., Nielsen, B.J., 1986. Phytochemistry 25, 2349. Kijima, H., Ide, T., Otsuka, H., Ogimi, C., Hirata, E., Takushi, A., Takeda, Y., 1997. Phytochemistry 44, 1551. Nakamoto, K., Otsuka, H., Yamasaki, K., 1988. Phytochemistry 27, 1856. Olafsdottir, E.S., Andersen, J.V., Jaroszewski, J.W., 1989. Phytochemistry 28, 127. Olafsdottir, E.S., Jaroszewski, J.W., Arbo, M.M., 1990. Biochem. Syst. Ecol. 18, 435. Otsuka, H., Yamasaki, K., Yamauchi, T., 1989. Phytochemistry 28, 3197. Ro¨per, H., Ro¨per, S., Heyns, K., 1983. Carbohydr. Res. 116, 183. Saijo, R., Nonaka, G., Nishioka, I., 1990. Phytochemistry 29, 267. Soltis, D.E., Soltis, P.S., Chase, M.W., Mort, M.E., Albach, T.D., Zanis, M., Savolaninen, V., Hahn, W.H., Hoot, S.B., Fay, M.F., Axtell, M., Swensen, S.M., Prince, L.M., Kress, W.J., Nixon, K.C., Farris, J.S., 2000. Bot. J. Linn. Soc. 133, 381. Spencer, K.C., Seigler, D.S., 1985. Biochem. Syst. Ecol. 13, 23. State Administration of Traditional Chinese Medicine of the People’s Republic of China, 1999. ZhongHua BenCao. Shanghai Scientific and Technical Publishers, Shanghai. Subeki, M., Takahashi, K., Yamasaki, M., Yamato, O., Maede, Y., Katakura, K., Kobayashi, S., Chairul, T., 2005. J. Nat. Prod. 68, 537. Tamaki, A., Ide, T., Otsuka, H., 2000. J. Nat. Prod. 63, 1417. Ye, G., Peng, H., Fan, M., Huang, C., 2001. Chem. Nat. Compd. 43, 125. Zhu, M., 1998. Planta Med. 64, 8.
Contents lists available at ScienceDirect
Biochemical Systematics and Ecology journal homepage: www.elsevier.com/locate/biochemsyseco
Cyclopentenylglycines and other constituents from Alangium chinense Xiao-Hui Zhang, Shan-Shan Liu, Li-Jiang Xuan* State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, 555 Zuchongzhi Road, Zhangjiang Hi-Tech Park, Shanghai 201203, China
a r t i c l e i n f o Article history: Received 6 August 2008 Accepted 21 November 2008 Keywords: Alangium chinense Alangiaceae Cyclopentenylglycines Nonproteinogenic amino acid glycoside
1. Subject and source Alangium chinense (Lour.) Harms (Alangiaceae) is a deciduous shrub indigenous to China, and distributed mainly in the South. As a traditional Chinese medicine, the roots, flowers, and leaves of this plant have been documented for use as a muscle relaxant and analgesic agent (State Administration of Traditional Chinese Medicine of the People’s Republic of China, 1999). The roots of A. chinense were collected from Nanning, Guangxi province of China, in August 2006, and identified by Professor Heming Yang. The voucher specimen (No. AC001) has been deposited in the herbarium of Shanghai Institute of Materia Medica. 2. Previous work Previous studies on A. chinense focused on alkaloids (Hou et al., 1981) and phenolic glycosides (Itoh et al., 1997, 2000, 2001). 3. Present study 3.1. Extraction and isolation The air-dried roots of A. chinense (4 kg) were extracted with 70% acetone (10 L 3, 2 days each) at room temperature. After evaporation in vacuo, the suspended residue was removed by centrifugation. The aqueous solution was chromatographed over a MCI gel CHP-20P column eluted with MeOH–H2O (0%, 100%) to give two fractions (A and B). Both fractions were further subjected to column chromatography on Cosmosil 75 C18-OPN, Amberlite CG-50, and Toyopearl HW-40F repeatedly. Fraction A yielded compounds 1 (42 mg), 2 (20 mg), 3 (1 g), 4 (200 mg), 5 (50 mg), 6 (150 mg), 7 (120 mg), 8 (24 mg), 9 (3 mg), 10 (4 mg), 12 (65 mg), and 13 (56 mg). Compound 11 (24 mg) was afforded from fraction B.
* Corresponding author. Tel./fax: þ86 21 50272221. E-mail address: [email protected] (L.-J. Xuan). 0305-1978/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.bse.2008.11.015
X.-H. Zhang et al. / Biochemical Systematics and Ecology 37 (2009) 214–217 Table 1 1 H (400 MHz) and
13
C (100 MHz) NMR spectral data of 1 and 2 in D2O (d (ppm) (J, Hz)).
1 Atom 1 2 10 20 30 40 50 100 200 300 400 500 600
215
2 1
13
H
C
HMBC (H–C)
175.0 s 68.9 d 49.1 d 130.9 d 138.8 d 34.2 t 27.2 t
3.91 d (4.9) 3.43 m 5.74 dd (2.1, 5.5) 6.11 dd (2.4, 5.3) 2.44 m 2.15 td (8.1, 14.1), 1.77 td (5.9, 14.2) 3.45 m, 3.33 d (13.2)
C-1, 20 , 50 , 100 C-10, 30 , 40 , 50 C-10, 20 , 40 , 50 C-2, 10, 20 , 30 , 40 C-2, 200 , 300
56.1 t 97.8 s 73.1 d 72.0 d 71.5 d 66.5 d
3.83 brd (9.9) 3.93 d (8.0) 4.06 brs 4.08 brd (12.5), 3.81 brd (13.0)
C-200 , 500
1
Atom 1 2 3 4 5 6 7
13
H
C
HMBC (H–C)
C-1, 5 C-2, 6 C-1, 3 C-2, 4 C-1, 2, 100
10 20 30 40 50 60
7.55 d (7.6) 7.21 t (7.7) 7.47 t (7.6) 7.29 d (7.3) 4.94 d (11.9), 5.06 d (11.8) 4.63 d (8.1) 3.70 m 3.46 m 3.58 m 3.67 m 3.79 m, 3.95 m
157.5 s 128.7 s 133.5 d 125.8 d 132.9 d 117.8 d 69.4 t 103.0 d 75.6 d 78.5 d 72.0 d 78.2 d 63.2 t
C-1, 30 , 50 C-40 C-10, 50 C-20 , 60 C-10, 30 C-40
100 200 300 400 500 600
5.20 3.34 3.49 3.43 3.68 3.83
104.2 d 75.8 d 78.7 d 72.3 d 78.4 d 63.4 t
C-7, 300 , 500 C-400 C-100, 500 C-200 , 600 C-100, 300 C-400
d (6.8) m m m m m, 3.99 m
3.2. Identification of constituents Separation and purification of the extract of A. chinense by repetitive chromatography led to the isolation and characterization of a new amino acid glycoside, alanchinin (1), a new phenolic glycoside, 7-O-b-glucopyranosylsalicin (2), and 11 known compounds (3–13). Compounds 3–13 were identified as 2-(20 -cyclopentenyl)glycine (3, Olafsdottir et al., 1989), henryoside (4, Otsuka et al., 1989), salicin 60 -O-b-D-apiofuranoside (5, Tamaki et al., 2000), 600 -O-b-D-glucopyranosylhenryoside (6, Kijima et al., 1997), 5b,6b-dihydroxycyclohex-2-en-1-O-b-glucopyranoside (7, Zhu, 1998), cuneataside D (8, Chang and Case, 2005), 4-cyclohexene-1,2,3-triol (9, Hyldtoft and Madsen, 2000), loganic acid (10, Nakamoto et al., 1988), 4,40 -di-O-methylellagic acid (11, Fukuyama et al., 1983), b-glucogallin (12, Saijo et al., 1990) and edulilic acid (13, Foo et al., 2006), respectively, by comparison of their spectroscopic data with those reported in the literature. The hygroscopic compound 1 was suggested to have the molecular formula of C13H21NO7 by HR-ESIMS (m/z 326.1218, [M þ Na]þ, calc. 326.1261). It displayed a positive ninhydrin reaction (yellowish color), which indicated the presence of an amino acid moiety. The 1H NMR spectrum of 1 (Table 1) showed resonances for a couple of pentacyclic cis-olefin protons [dH 6.11 (dd, J ¼ 2.4, 5.3 Hz) and 5.74 (dd, J ¼ 2.1, 5.5 Hz)], two pairs of methylene protons [dH 2.44 (2H, m) and 2.15 (1H, td, J ¼ 8.1, 14.1 Hz), 1.77 (1H, td, J ¼ 5.9, 14.2 Hz)], and two methine protons [dH 3.91 (d, J ¼ 4.9 Hz) and 3.43 (m)], which supported a 2(20 -cyclopentenyl)glycine architecture. The NMR data of 1 were similar to those of 2-(20 -cyclopentenyl)glycine (3), except for the resonances of one additional sugar unit. Acid hydrolysis of 1 gave the aglycone and fructose, which was identified by direct comparison with authentic samples on TLC. From the coupling constants of H-300 , H-400 , H-600 a, and H-600 b (3J ¼ 9.9 Hz, 2 J ¼ 12.5 Hz), it was determined that the fructose part is present as a pyranose ring system. The purified fructose unit obtained after hydrolysis gave an optical rotation, [a] 128.0B (c 0.12, H2O), indicating that it was in the D-form. In aqueous solution, compound 1 showed mutarotation due to the free hydroxyl group at C-200 . The major signals in the 13C NMR spectrum could be assigned to the b-fructopyranose form (Ro¨per et al., 1983), while other forms (a-furanose, b-furanose or a-pyranose) could OH
OH
OH OH
1''
OH
H N
1 COOH
H
OH O
H
6''
OH
1" 7
1'
O OH
1
O
OH 1' O
4'
OH
O
6
OH
1
2
Fig. 1. Structures of compounds 1 and 2.
OH
216
X.-H. Zhang et al. / Biochemical Systematics and Ecology 37 (2009) 214–217
H N
OH H2N
COOH
COOH
OH
D-glucose pyrosulfite
O
CH3OH : H2O = 1 : 1 reflux
OH OH
Fig. 2. Synthetic study to N-(100 -deoxy-100 -b-D-fructopyranosyl)-2-(20 -cyclopentenyl)glycine.
be observed as minor signals. The glycosidic linkage was determined from the following HMBC correlations: H-100 a [dH 3.45 (m)] and H-100 b [dH 3.33 (d, J ¼ 13.2 Hz)]/C-2 (dC 68.9), and H-2 [dH 3.91 (d, J ¼ 4.9 Hz)]/C-100 (dC 56.1). The aglycone was determined to be (2S,10 R)-2-(20 -cyclopentenyl)glycine by comparing optical rotation ([a] þ120B (c 0.09, MeOH)) and CD data [(MeOH) lmax nm (D3): 202 (þ48.06), 243 (1.91)] of its N-acetyl derivative with published information. On the basis of the above evidence, the structure of compound 1 was established as (2S,10 R)-N-(100 -deoxy-100 -b-D-fructopyranosyl)-2-(20 -cyclopentenyl)glycine, named alanchinin. A synthetic study towards N-(100 -deoxy-100 -b-D-fructopyranosyl)-2-(20 -cyclopentenyl)glycine was carried out by Amadori rearrangement (Figs. 1 and 2). As in the published protocol reference, it was prepared from compound 3 and D-glucopyranose, and it was also deduced that Amadori rearrangement is the biosynthetic pathway to 1. Compound 2 was isolated as a colourless amorphous powder, with the molecular formula C19H28O12, determined from the HR-ESIMS (m/z 471.1089 [M þ Na]þ). Its 1H NMR spectrum exhibited benzylic methylene protons at dH 4.94 and 5.06 (each d, J ¼ 11.8 Hz) and four aromatic protons for the 1,2-disubstituted benzene ring in the dH 7.19–7.55 range, along with the signals arising from two b-glucopyranosyl moieties [dH 4.63 (d, J ¼ 8.1 Hz), 5.20 (d, J ¼ 6.8 Hz)]. These spectral features demonstrated its close similarity to salicin, but with one more b-glucosyl unit. The HMBC correlations of the anomeric proton H-10 (dH 5.20) to C-1 (dC 157.5), and H-100 (dH 4.63) to C-7 (dC 69.4) indicated that the b-glucopyranosyl moieties are located at C-1 and C-7, respectively. Accordingly, compound 2 was deduced to be 7-O-b-glucopyranosylsalicin. 4. Chemotaxonomic significance Alangiaceae belongs to the order Cornales in subclass Rosidae. Compounds 4–7, and 10 have been reported in the family Alangiaceae (Itoh et al., 2000; Tamaki et al., 2000; Zhu, 1998), and compounds 11 and 12 have been mainly found in the subclass Rosidae (Ye et al., 2001; Subeki et al., 2005). Alanchinin (1) and 2-(20 -cyclopentenyl)glycine (3) are nonproteinogenic amino acids. 2-(20 -Cyclopentenyl)glycine (3) was first postulated as a hypothetical precursor for deidaclin (a cyclopentanoid cyanogen, Clapp et al., 1970), and then was demonstrated as the precursor of cyclopentenyl fatty acids in the Flacourtiaceae (Cramer and Spener, 1977). Nowadays, the cyclopentanoid cyanogens and their oxygenated derivatives have been reported to occur in a cluster of closely related species in five families, Passifloraceae (Olafsdottir et al., 1989), Turneraceae (Olafsdottir et al., 1990), Malesherbiaceae (Spencer and Seigler, 1985), Achariaceae (Jensen and Nielsen, 1986), and Flacourtiaceae (Jaroszewski and Olafsdottir, 1987), all in the order Violales (Cronquist, 1981). 2-(20 -Cyclopentenyl)glycine (3) was also distributed both in those five families (Jaroszewski et al., 1988) and Violaceae (Clausen et al., 2002). To our knowledge, this is the first report on the occurrence of 2-(20 -cyclopentenyl)glycine (3) and its new glycoside derivative alanchinin (1) outside the Violales. Compounds 3 and 13, which have similar cyclopentene skeletons, and which co-occur in both A. chinense and Passiflora edulis (Passifloraceae) (Foo et al., 2006) drew our attention. A feasible pathway (Dewick, 2002) from a-carbonyl carboxylic acid to a-amino acid suggested that hydrolysation from compound 13 to 2-(20 -cyclopentenyl)-carbonyl carboxylic acid may be possible. Consequently, edulilic acid (13) could be considered as a hypothetical precursor for 2-(20 -cyclopentenyl)glycine (3), as depicted in Fig. 3.
OH HO
OH O
HO
O O
COOH
COOH
H2N
COOH hydrolyze
PLP
13
3
PLP = pyridoxal phosphate, an aminotransferase coenzyme Fig. 3. Hypothetical biosynthetic pathway from 13 to 3.
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Finally, from the angiosperm phylogenetic trees (Soltis et al., 2000), the almost parallel positions of orders Cornales and Violales excludes the presumption of hybridization or paternity between A. chinense and the five 2-(20 cyclopentenyl)glycine containing families. However, is it a coincidence that both compounds 3 and 13 co-occur in both A. chinense and P. edulis (Passifloraceae), or a clue that both of the species possessed similar enzymatic systems? So the occurrence of these particular compounds in A. chinense is noteworthy, and may contribute to chemotaxonomic studies of the Alangiaceae family.
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