Two New Phenolic Glycosides from the Barks of Hydnocarpus annamensis and their Anti-Inflammatory and Anti-Oxidation Activities

• Abstract
• Materials and Methods
• Acknowledgements
• References

Abstract

Two new phenolic glycosides 1 and 2 were isolated from the barks of Hydnocarpus annamensis, along with eighteen known compounds. The structures of all compounds were deduced using spectroscopic methods. Anti-inflammatory and anti-oxidation activities were evaluated. Among the isolates, compounds 1, 5, 15 and 17 exhibited COX-2 inhibitory activities, with an inhibitory rate of 60.3 - 63.4 % at 10 μM. Compounds 7, 12, 13 and 20 showed anti-oxidation capacities in the DPPH free-radical assay, with a scavenging effect of 60.9 - 69.4 % at 50 μM, and 18.5 - 34.6 % at 10 μM.

Supporting information available online at http://www.thieme-connect.de.accesdistant.sorbonne-universite.fr/ejournals/toc/plantamedica

Hydnocarpus annamensis (Gagnep.) M. Lescot et Sleum. (Flacourtiaceae) is an evergreen tree, mainly distributed in the Guangxi province of P. R. China. It is used in folk medicine for treatment of rheumatoid arthritis and syphilis [1]. The chemical constituents and biological activities of this plant have not been studied. As part of our research on bioactive compounds from Flacourtiaceae plants, we have investigated the barks of H. annamensis and isolated two new phenolic glycosides 1 and 2, along with eighteen known compounds. We describe herein the isolation and structure elucidation of new compounds, as well as the anti-inflammatory and anti-oxidation activities of isolated compounds.

Compound 1 was obtained as an amorphous, light-yellowish powder with a molecular formula of C₂₀H₂₂O₉ as determined by data from positive-ion HR-ESI-MS, showing an [M + Na]⁺ ion at m/z = 429.1150 (calcd. for C₂₀H₂₂O₉Na: 429.1162) and ¹³C-NMR. The IR spectrum showed absorption bands typical of hydroxy groups (3400 cm^-1), ester carbonyl (1712 cm^-1), and aromatic rings (1600, 1491 cm^-1). In the ¹H-NMR spectrum (Table [1]), the presence of an ortho- and meta-substituted phenolic residue [exhibiting the following signal: δ = 6.55 (dd, J = 3.0, 8.5 Hz, H-4), 6.80 (d, J = 3.0 Hz, H-6), 6.96 (d, J = 8.5 Hz, H-3)] and one benzoyl residue (five aromatic protons between δ = 7.53 and 8.01) were observed and suggested a structure similar to that of poliothrysoside (15) [2]. Meanwhile, the ¹³C-NMR spectrum (Table [1]) showed resonances that were readily attributed to β-glucose, one benzoate and one benzyl alcohol. A downfield shift at C-3′ and the upfield shifts at C-2′ and C-4′ in the glucose confirmed that the benzoyl group was attached to C-3′ of the glucose. HMBC correlation of H-3′ and C-7′′ also supported this assignment. On the basis of spectral evidence, mainly 2D-NMR, the structure of compound 1 was elucidated as 2-(3-benzoyl-β-D-glucopyranosyloxy)-5-hydroxybenzyl alcohol.

Compound 2 was obtained as an amorphous, light-yellowish powder. Its HR-ESI-MS exhibited a pseudomolecular ion [M + Na]⁺ at m/z = 429.1152 (calcd. for C₂₀H₂₂O₉Na: 429.1162), compatible with the molecular formula C₂₀H₂₂O₉. Comparison of the IR, ¹H- and ¹³C-NMR data of 2 with those of 1 suggested that the structure of 2 is closely related to that of 1, which contains the same molecular subunits, except for the position of benzoyl group. The downfield chemical shift of C-4′ (δ = 72.9) and the HMBC correlation of H-4′ and C-7′′ revealed that the benzoyl group was attached to C-4′ of the glucosyl moiety. Consequently, compound 2 was identified as 2-(4-benzoyl-β-D-glucopyranosyloxy)-5-hydroxybenzyl alcohol.

Along with the two new compounds, eighteen known compounds were also isolated from the barks of Hydnocarpus annamensis. By comparison of physical and spectroscopic data ([α]_D, ¹H-, ¹³C-NMR and MS data) with those of corresponding authentic samples or literature values, they were identified as: β-sitosterol (3), 4′-hydroxypropiophenone (4) [3], 2,6-dimethoxy-p-benzoquinone (5) [4], coniferaldehyde (6) [5], 5-hydroxy-3-methoxybenzyl alcohol (7) [6], benzoic acid (8), (2S)-3-(4-hydroxy-3-methoxyphenyl)-propane-1,2-diol (9) [7], 3-hydroxy-1-(4-hydroxyphenyl)-propan-1-one (10) [8], daucosterol (11), syringaresinol 4-O-β-D-glucoside (12) [9], threo-1′,2′-guaiacyl glycerol (13) [10], 2-phenylpropane-1,3-diol (14), poliothrysoside (15) [2], junipetrioloside A (16) [11], cremanthodioside (17) [12], salirepin (18) [13], 2,4,6-trimethoxyphenol 1-O-β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside (19) [14], threo-syrigoylglycerol 7-O-β-D-glucopyranoside (20) [15]. Copies of the original spectra are obtainable from the author of correspondence.

Except for compounds 3, 6, 9 and 11, all other isolates were evaluated for their anti-inflammatory and anti-oxidation activities. Compounds 1, 5, 15 and 17 exhibited inhibitory activities on COX-2, with inhibitory rates of 61.7, 60.3, 60.7, 63.4 % at 10 μM, respectively. Celecoxib was used as the positive control with an inhibitory rate of 92.4 % at 1 μM. All compounds (each at 10 μM) failed to significantly inhibit the TNF-α production in murine peritoneal macrophages stimulated with LPS (data not shown). Among the isolates, compounds 7, 12, 13 and 20 showed anti-oxidation capacities in the DPPH free-radical assay, with a scavenging effect of 60.9 - 69.4 % at 50 μM, and 18.5 - 34.6 % at 10 μM (Table [2]).

Materials and Methods

The dried barks (21.4 kg) were extracted three times with 95 % EtOH and concentrated under vacuum to yield a dark residue (320 g). The ethanolic extract was partitioned into a CHCl₃ (17.8 g), an n-BuOH (198.2 g) and an H₂O (104 g) soluble fraction. From the CHCl₃-soluble fraction (17.8 g), compounds 3 (25 mg), 4 (15 mg), 5 (52 mg), 6 (1.8 mg) and 7 (9.1 mg) were obtained. From the n-BuOH-soluble fraction (198.2 g), compounds 1 (22 mg), 2 (17 mg), 8 (31mg), 9 (1.2 mg), 10 (7 mg), 11 (60 mg), 12 (12 mg), 13 (36 mg), 14 (23 mg), 15 (520 mg), 16 (17 mg), 17 (8 mg), 18 (58 mg), 19 (20 mg) and 20 (15 mg) were isolated. For a detailed extraction protocol, see the Supporting Information.

Determination of configuration of D-glucose was carried out by TLC and GC analysis according to the procedure described in the literature [16]. For a detailed protocol and statistical analysis, see the Supporting Information.

The COX-2 assay described by Hu et al. [17] was used for measurement of COX-2 inhibitory activity. The TNF-α assay reported by Li et al. [18] was used for measurement of TNF-α production inhibitory activity. The DPPH radical scavenging inhibitory activity was measured as described by Lee et al. [19]. For a detailed protocol and statistical analysis, see the Supporting Information.

2-(3-Benzoyl-β-D-glucopyranosyloxy)-5-hydroxybenzyl alcohol (1): light yellow amorphous powder; [α]_D ²⁵: -18.3° (c 0.20, CH₃OH); UV (CH₃OH): λ_max (log ε) = 282 (1.01) nm; IR (KBr): ν _max = 3400 (brs), 2932, 1712, 1508, 1430, 1215, 1078 cm^-1; ¹H-NMR and ¹³C -NMR, see Table [1]; HR-ESI-MS: m/z = 429.1150 [M + Na]⁺ (calcd. for C₂₀H₂₂O₉Na: 429.1162).

2-(4-Benzoyl-β-D-glucopyranosyloxy)-5-hydroxybenzyl alcohol (2): light yellow amorphous powder; [α]_D ²⁵: -17.5° (c 0.20, CH₃OH); UV (CH₃OH): λ_max (log ε) = 280 (1.20) nm; IR (KBr): ν _max = 3382 (brs), 2927, 1720, 1498, 1425, 1205, 1046 cm^-1; ¹H-NMR and ¹³C-NMR, see Table [1]; HR-ESI-MS: m/z = 429.1152 [M + Na]⁺ (calcd. for C₂₀H₂₂O₉Na: 429.1162).

Acknowledgements

The authors are grateful to Prof. Gui-Fang Cheng (Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China) for the anti-inflammatory activities experiments.

References

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Prof. Peng-Fei Tu

Department of Natural Medicines

School of Pharmaceutical Sciences

Peking University Health Science Center

No. 38 Xueyuan Road

Haidian District

Beijing 100083

People’s Republic of China

Phone: +86-10-8280-2750

Fax: +86-10-8280-2750

Email: pengfeitu@bjmu.edu.cn

References

• 1 Zhonghuabencao Editorial Board. Zhonghuabencao, Vol. 5. Shanghai; Shanghai Scientific and Technological Press 1999: p 4479-81
  Search in Google Scholar
• 2 Shaari K, Waterman P G. Scoloposides A - E, a series of 2-glucopyranosyloxy-5-hydroxybenzyl alcohol derivatives from Scolopia spinosa .  Phytochemistry. 1994;  36 1021-6
  Thieme ConnectPubMedSearch in Google Scholar
• 3 Regla I, Reyes A, Körber C, Demare P, Estrada O, Juaristi E. Novel applications of Raney nickel/isopropanol: efficient system for the reduction of organic compounds.  Synth Commun. 1997;  27 817-23
  PubMedSearch in Google Scholar
• 4 Inoshiri S, Sasaki M, Hirai Y, Kohda H, Otsuka H, Yamasaki K. Inhibition of mast cell histamine release by 2,6-dimethoxy-p-benzoquinone isolated from Berchemia racemosa .  Chem Pharm Bull. 1986;  34 1333-6
  PubMedSearch in Google Scholar
• 5 Sy L K, Brown G D. Coniferaldehyde derivatives from tissue culture of Artemisia annua and Tanacetum parthenium .  Phytochemistry. 1999;  50 781-5
  CrossrefPubMedSearch in Google Scholar
• 6 Crombie L, Jamieson S V. Dihydrostilbenes of cannabis. synthesis of canniprene.  J Chem Soc Perkin Trans. 1982;  1 1467-75
  PubMedSearch in Google Scholar
• 7 Kikuzaki H, Hara S, Kawai Y, Nakatani N. Antioxidative phenylpropanoids from berries of Pimenta dioica .  Phytochemistry. 1999;  52 1307-12
  CrossrefPubMedSearch in Google Scholar
• 8 Achenbach H, Waibel R, Addae-Mensah I. Lignans and other constituents from Carissa edulis .  Phytochemistry. 1983;  22 749-54
  CrossrefPubMedSearch in Google Scholar
• 9 Wang M A, Wang M K, Peng S L, Ding L S. Chemical constituents from the barks of Pteroceltis tatarinowii .  Nat Prod Res Dev. 2002;  13 5-8
  PubMedSearch in Google Scholar
• 10 Ishikawa T, Fujimatu E, Kitajima J. Water-soluble constituents of anise: new glucosides of anethole glycol and its related compounds.  Chem Pharm Bull. 2002;  50 1460-6
  CrossrefPubMedSearch in Google Scholar
• 11 Comte G, Vercauteren J, Chulia A J, Allais D P, Delage C. Phenylpropanoids from leaves of Juniperus phoenicea .  Phytochemistry. 1997;  45 1679-82
  CrossrefPubMedSearch in Google Scholar
• 12 Wang A X, Zhang Q, Jia Z J. Phenylpropanoids, lignans and other constituents from Cremanthodiium ellisii .  Pharmazie. 2004;  59 889-92
  PubMedSearch in Google Scholar
• 13 Ekabo O A, Farnsworth N R, Santisuk T, Reutrakul V. Phenolic, iridoid and ionyl glycosides from Homalium ceylanicum .  Phytochemistry. 1993;  32 747-54
  CrossrefPubMedSearch in Google Scholar
• 14 Fan G J, He Z S. Studies on the chemical constituents of thinleaf adina (Adina rubella) (III).  Chin Tradit Herb Drugs. 1997;  28 195-8
  PubMedSearch in Google Scholar
• 15 Kijima H, Ide T, Otsuka H, Ogimi C, Hirata E, Takushi A. et al . Water-soluble phenolic glycosides from leaves of Alangium premnifolium .  Phytochemistry. 1997;  44 1551-7
  CrossrefPubMedSearch in Google Scholar
• 16 Tang L, Jiang Y, Chang H T, Zhao M B, Tu P F, Cui J R. et al . Triterpene saponins from the leaves of Ilex kudingcha .  J Nat Prod. 2005;  68 1169-74
  CrossrefPubMedSearch in Google Scholar
• 17 Hu W H, Guo Z R, Chu F M, Bai A P, Yi X, Cheng G F. et al . Synthesis and biological evaluation of substituted 2-sulfonyl-phenyl-3-phenyl-indoles: a new series of selective COX-2 inhibitors.  Bioorg Med Chem. 2003;  11 1153-60
  CrossrefPubMedSearch in Google Scholar
• 18 Li X M, Lin M, Wang Y H, Liu X. Four new stilbenoids from the lianas of Gnetum montanum f. megalocarpum .  Planta Med. 2004;  70 160-5
  Thieme ConnectPubMedSearch in Google Scholar
• 19 Lee Y Y, Jang D S, Jin J L, Yun-Choi H S. Anti-platelet aggregating and anti-oxidative activities of 11-O-(4′-O-methylgalloyl)-bergenin, a new compound isolated from Crassula cv. ‘Himaturi’.  Planta Med. 2005;  71 776-7
  Thieme ConnectPubMedSearch in Google Scholar

Prof. Peng-Fei Tu

Department of Natural Medicines

School of Pharmaceutical Sciences

Peking University Health Science Center

No. 38 Xueyuan Road

Haidian District

Beijing 100083

People’s Republic of China

Phone: +86-10-8280-2750

Fax: +86-10-8280-2750

Email: pengfeitu@bjmu.edu.cn

• Supplementary Material