Chemical constituents of Chirita halongensis Kiew & T.H.Nguyen collected in Ha Long Bay, Quang Ninh province, Viet Nam

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1 , 2018, 56(2), DOI: /vjch Article Chemical constituents of Chirita halongensis Kiew & T.H.Nguyen collected in Ha Long Bay, Quang Ninh province, Viet Nam Khieu Thi Tam 1,3, Nguyen Thi Hoang Anh 1,2*, Nguyen Van Tuan 1,4, Dao Duc Thien 2, Nguyen Thanh Tam 1,2, Tran Duc Quan 2, Le Quoc Thang 5, Trinh Thi Thuy 1,2, Tran Van Sung 1,2 1 Graduate University of Science and Technology, Vietnam Academy of Science and Technology 2 Institute of Chemistry, Vietnam Academy of Science and Technology 3 University of Thai Nguyen, Thai Nguyen, Viet Nam 4 Asean College, Van Lam, Hung Yen, Viet Nam 5 Hue University s College of Educations Received 23 Jan 2018; Accepted for publication March Abstract The chemical investigation of the whole plant of Chirita halongensis Kiew & T.H.Nguyen collected in Ha Long bay, Quang Ninh province led to the isolation and structural elucidation of nine compounds, including one anthraquinone, three triterpenoids and five phenylethanoid glycosides. Three of them: oleanolic acid, decaffeoylacteoside and -hydroxy acteoside have been found for the first time in Chirita genus. Their structures were elucidated by mass, NMR spectroscopies and comparison with published data. It is the first report on chemical constituents of this species. Keywords. Chirita halongensis, anthraquinone, triterpenoid, phenylethanoid glycoside. 1. INTRODUCTION Chirita is the oldest genus of the Gesneriaceae family, distributed in Malaysia, Southeast Asia and south of China. Some Chirita species are used in folk medicine as poultice, hemostasis agents or for treatment of hypertension,... [1] There are about 20 Chirita species in Vietnam. [2] Until now, there have been only a few studies on chemical and biological activities of the Chirita species, but they revealed interesting results. In the previous articles, we reported the chemical constituents as well as toxicity activity of Chirita drakei Burtt. [3-5] In our continuing research on Chirita species growing in Ha Long bay, this paper describes the isolation and structural elucidation of 9 compounds from Chirita halongensis, an endemic species of Ha Long Bay detected in the year [6] The isolated compounds include an anthraquinone (1), three triterpenoids (2-4) and five phenylethanoid glycosides (5-9). Three of them (4, 8 and 9) have been found for the first time in Chirita genus. 2. EXPERIMENTAL 2.1. Equipments and methods IR: Impact 410, Nicolet, Germany; ESI-MS: LC- MSD-Trap-SL, Varian, USA, NMR: Bruker Avance 500, Germany with TMS as internal reference (for 1 H) and solvent signal (for 13 C). CC used silicagel 60G, size mm (Merck), TLC: precoated silica gel G60F254 plates (Merck), spots were detected by spraying with vanillin 1 % in conc. H 2 SO 4 and heating at 110 o C Plant material Chirita halongensis was collected in the islands of Ha Long Bay, Quang Ninh province, Vietnam in October A voucher specimen (VHH.HL ) is deposited in Institute of Chemistry, VAST, Hanoi, Viet Nam. The scientific name was identified by Dr. Tran Thi Phuong Anh, Vietnam National Museum of Nature, VAST, Viet Nam Extraction and isolation The whole plant of C. halongensis (0.64 kg) was 176 Wiley Online Library 2018 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

2 ultrasound extracted with MeOH:H 2 O (95:5) (four times) at room temperature. The methanol extract was concentrated under vacuum and then aqueous solution was extracted with n-hexane, EtOAc and n- BuOH, successively. The solvent was evaporated in vacuum to afford n-hexane (6.0 g), EtOAc (9.1 g) and n-buoh (26.2 g) extracts. The n-hexane extract (6.0 g) was separated by chromatography on silica gel, eluting with gradient n-hexane:etoac to furnish 9 fractions (H1-H9), which were combined according to TLC monitoring. The first fraction H1 (400 mg) was crystallized in methanol to 300 mg of β-sitosterol. The second and third fractions of H2 and H3 (900 mg) were further purified over silica gel column with n- hexane:ch 2 Cl 2 gradient to furnish 4 subfractions. The third subfraction (100 mg) was chromatographed on sephadex LH-20 (CH 2 Cl 2 :MeOH) to yield 12 mg of compound 1. The seventh and eighth fractions of H7 and H8 (750 mg) were subjected on silica gel column, eluting with CH 2 Cl 2 :MeOH gradient to furnish 3 subfractions. The second one (90 mg) was given on sephadex LH- 20 (CH 2 Cl 2 :MeOH) to yield 15 mg of 2. The EtOAc extract (9.0 g) was given on silica gel column, using gradient CH 2 Cl 2 :MeOH to furnish 7 fractions. The results of thin layer chromatographic analysis showed that they contain mainly ursolic acid and oleanolic acid when compared with standard substances. Ursolic acid (330 mg) and oleanolic acid (700 mg) were isolated by crystallization method. The n-buoh extract (26.0 g) was chromatographed over a silica gel column, eluted with a gradient solvent system of CH 2 Cl 2 :MeOH (from 100:0 to 0:100), to give 13 fractions (B1- B13). The fraction B3 (360 mg) was subjected to silica gel column, eluting with gradient of CH 2 Cl 2 :MeOH to yield 18 mg compound 5. The fraction B8 (750 mg) was separated on Sephadex LH-20 (MeOH) to afford 3 subfractions (B8.1- B8.3). The purification of B8.3 (180 mg) on silica gel column with CH 2 Cl 2 :MeOH:H 2 O (4:1:0.5) as eluent to yield 25 mg of compound 6 and 35 mg of 7. The fraction B10 (540 mg) was separated by using sephadex LH-20 column (MeOH) to yield 20 mg of compound 8 and 15 mg of 9. 7-hydroxytectoquinone (1): Yellow needle. 1 H NMR (500 MHz, CD 3 OD): H 8.07 brs (H-1); 7.68 dd, 1.0 & 8.0 (H-3); 8.16 d, 8.0 (H-4); 8.17 d, 8.5 (H-5); 7.21 dd, 2.5 & 8.5 (H-6); 7.59 d, 2.5 (H- 8); 2.54 s (2-CH 3 ). 13 C NMR (125MHz, CD 3 OD): C CH (C- 1), C (C-2), CH (C-3), CH (C- 4), C (C-4a), CH (C-5), CH Nguyen Thi Hoang Anh et al. (C-6), C (C-7), CH (C-8), C (C-8a), C (C-9), C (C-9a), C (C-10), C (C-10a), CH 3 (2-Me). 3,24-dihydroxy-urs-12-ene-28-oic acid (2): Amorphous white powder. 1 H-NMR (500 MHz, CDCl 3 & CD 3 OD) H: 3.83 (br s, H-3); 2.19 (d, J = 11.0 Hz, H-18); 3.70 (d, J = 11.0 Hz, H a -24); 3.46 (d, J = 11.0 Hz, H b -24). 13 C-NMR (125 MHz, CD 3 OD) C: (C-1), (C-3), (C-12), (C-13), (C-18), (C-24), (C-28), (C-29), (C-30). Ursolic acid (3): Amorphous white powder. 13 C NMR (125 MHz, CDCl 3 ): C (C-1), (C-2), (C-3), (C-4), (C-5), (C-6), (C-7), (C-8), (C-9), (C-10), (C-11), (C-12), (C-13), (C-14), (C-15), (C-16), (C- 17), (C-18), (C-19), (C-20), (C-21), (C-22), (C-23), (C-24), (C-25), (C-26), (C-27), (C-28), (C-29), (C-30). Oleanolic acid (4): Amorphous white powder. 13 C NMR (125 MHz, CDCl 3 ): C (C-1); (C-2), (C-3), (C-4), (C-5), (C-6), (C-7), (C-8), (C-9), (C-10), (C-11), (C-12), (C-13), (C-14), (C-15), (C-16), (C- 17), (C-18), (C-19), (C-20), (C-21), (C-22), (C-23), (C-24), (C-25), (C-26), (C-27), (C-28), (C-29), (C-30). 2-(3,4-Dihydroxyphenyl)ethyl- -Dglucopyranoside (5): Amorphous pale yellow powder. 1 H NMR (500 MHz, CD 3 OD): H 6.71 d, 1.5 Hz (H-2); 6.69 d, 8.5 Hz (H-5); 6.57 dd, 1.5 & 8.5 Hz (H-6); 2.80 m (H- ); 3.72 m, 4.05 m (H- ); 4.31 d, 8.0 Hz (Glc-1); 3.20 t, 8.0 Hz (Glc-2); m (Glc-3, 4, 5); 3.68 dd, 5.0 & 12.0 Hz, 3.88 dd, 1.5 & 12.0 Hz (Glc-6). 13 C-NMR (125 MHz, CD 3 OD): C C (C- 1), CH (C-2), C (C-3), C (C- 4), CH (C-5), CH (C-6), CH 2 (C- ), CH 2 (C- ), CH (Glc-1), CH (Glc-2), CH (Glc-3), CH (Glc-4), CH (Glc-5), CH 2 (Glc-6). Acteoside (6): Amorphous powder. 1 H-, 13 C- NMR (500, 125 MHz, CD 3 OD), see table 1. Isoacteoside (7): Amorphous powder. 1 H-, 13 C- NMR (500, 125 MHz, CD 3 OD), see table1. Decaffeoylacteoside (8): Amorphous powder. 1 H-, 13 C-NMR (500, 125 MHz, CD 3 OD), see table 1. -Hydroxyacteoside (9): Amorphous powder. 1 H-, 2018 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 177

3 13 C-NMR (500, 125 MHz, CD 3 OD), see table RESULTS AND DISCUSSION Nine compounds were isolated from n-hexane, ethyl acetate and n-butanol extracts of the whole plant of C. halongensis by repeated column chromatography with the appropriate solvent systems. Their structures were identified as 7-hydroxytectoquinone (1), 3,24-dihydroxy-urs-12-en-28-oic acid (2), ursolic acid (3), oleanolic acid (4), 2-(3,4- dihydroxyphenyl)ethyl- -D-glucopyranoside (5), acteoside (6), isoacteoside (7), decaffeoylacteoside (8) and -hydroxyacteoside (9) by the analysis of their 1D, 2D-NMR, ESI-MS spectra and compared with published data. Compound 1 obtained in the form of yellow needle-shaped crystals. Its 1 H NMR spectrum indicated the characteristic signals of the anthraquinone type, including the signals of the two ABX aromatic rings: 3 protons at δ 8.07 (br s), 7.68 (dd, 1.0 & 8.0 Hz), 8.16 (d, 8.0 Hz) of the first ring and 7.59 (d, 2.5 Hz), 7.21 (dd, 2.5 & 8.5 Hz), 8.17 (d, 8.5 Hz) of the second. Beside these signals, the 13 C NMR spectrum gave the signals of the two carbonyl groups at C ; and a methyl group at C The presence of the hydroxy substituent in 1 was revealed by the quaternary aromatic carbon in the downfield at C The structure of 1 was thus determined to be 7-hydroxytectoquinone when compared to literature. [4] Compound 2 has molecular formula of C 30 H 48 O 4 based on the NMR and positive ESI-MS data (m/z 473 [M+H] + ). The spectroscopic data suggested that 2 belong to the urs-12-en-28-oic acid series. This suggestion confirmed by 1 H-NMR signals at H 2.19 (d, J = 11.0 Hz, H-18), 3.83 br s (H-3) together with 6 methyl groups [ H 0.79, 0.90, 1.06, 1.10 (each 3H, s), 0.86 (d, J = 6.5 Hz), 0.93 (d, J = 5.0 Hz)] and 13 C-NMR signals at C (C-3), (C-12) and (C-13). Besides, a hydroxy-methylene group [( H 3.70 (d, J = 11.0 Hz), 3.46 (d, J = 11.0 Hz), C 65.92)] was observed in NMR spectra of 2. The α configuration of hydroxy group at C-3 was identified by the chemical shift and multiplicity of hydroxy-methine proton. Consequently, 2 was determined as 3,24-dihydroxy-urs-12-en-28-oic acid by comparison with spectroscopic data in literature. [5] The structures of compounds 3 and 4 were elucidated as ursolic acid and oleanolic acid, respectively, by comparison with authentic sample in thin layer chromatography and 13 C NMR spectral data. Chemical constituents of Chirita halongensis Compound 5 was isolated as an amorphous pale yellow powder. Its NMR spectra showed the presence of a phenylethyl alcohol and an - glucopyranose unit in the molecule. The first unit is characterized by the signals of 1,3,4-substituted aromatic ring [δ H 6.71 (d, J = 1.5 Hz); 6.69 (d, J = 8.5 Hz); 6.57 (dd, J = 1.5 & 8.5 Hz)], an oxygenmethylene group at δ H 3.72 m, 4.05 m and a methylene group at δ H 2.80 m. Two aromatic quaternary carbons were shifted in the downfield at C and confirmed two hydroxy groups as substituents. The chemical shift and the coupling constant of anomeric proton at H 4.31 (d, J = 8.0 Hz) verified the presence of -glucopyranose. The spectra of 5 were completely identical with those of 2-(3,4-dihydroxyphenyl)-ethyl- -D-glucopyranoside in literature. [6] Compound 6 was predicted to be a phenylethyl alcohol diglycoside with C6-C3 acid ester from NMR data. Beside the same observed signals of 5, the 1 H-NMR spectrum of 6 appears additional characteristic signals of the -rhamnopyranose sugar: anomeric methine at H 5.22 brs; C and methyl group at H 1.12 (d, J = 6.5 Hz); C and of a caffeoyl unit: three aromatic ABX spin protons at H 7.09 (d, J = 1.5 Hz); 6.81 (d, J = 8.0 Hz); 6.98 (dd, J = 1.5 & 8.0 Hz) and two trans olefinic protons at H 6.30 (d, J = 16.0 Hz); 7.62 (d, J = 16.0 Hz). The structure of 6 is concluded as acteoside when compared with the spectral data in literature. [6,8] The 1 H and 13 C NMR spectra of compound 7 were nearly identical to those of 6 with the only difference being that the caffeoyl moiety is linked to the hydroxy group at C-6 of glucose. The spectroscopic data of 7 were perfectly identical with those of isoacteoside in literature. [7] Acteoside, isoacteoside have been previously isolated from various species such as Cistanche tubulosa, [7] Byblis liniflora. [8] Compound 8, an amorphous powder, revealed a phenylethyl glycoside signals in NMR spectra, when compared to those of 6, but with the absence of the caffeoyl unit. Therefore, the structure of 8 was determined to be decaffeoylacteoside. [9] The NMR spectra of compound 9 were very similar to those of acteoside (6) with the only exception that the CH 2 -β signals at H 2.80 m; C in 6 were replaced by the hydroxy methine signal at H 4.77 m, C CH. The shifting in the downfield of CH 2 -α signal with C = 4.4 ppm as well as the correlations between C- ( C 74.19) and H-2 [ H 6.73 (d, J = 2.0 Hz)], H-6 [ H 6.87 (dd, J = 2.0 & 8.0 Hz)] in the HMBC spectra confirmed the 2018 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 178

4 , 2018, 56(2), DOI: /vjch Table 1: 1 H- and 13 C-NMR (500 and 125 MHz) data of compounds 6-9 (CD 3 OD) Article C 1 H C (d, 2.0) 6.70 (d, 1.5) 6.71 (d, 1.5) 6.73 (d, 2.0) CH C C (d, 8.0) 6.67 (d, 8.0) 6.69 (d, 8.0) 6.76 (d, 8.0) CH (dd, 6.55 (dd, 6.57 (dd, 6.87 (dd, CH & 8.5) 1.5 & 8.0) 2.0 & 8.0) 2.0 & 8.0) α 3.75 m 3.73 m 3.72 m 3.57 m CH , m 4.05 m 4.01 m 4.00 m β 2.81 m 2.80 m 2.80 m 4.77 m CH CH Caffeoyl C (d, 1.5) 7.06 (d, 2.0) (d, 2.0) CH C C (d, 8.0) 6.79 (d, 8.0) (d, 8.0) CH (dd, 1.5 & 8.0) 6.90 (dd, 2.0 & 8.5) (dd, 2.0 & 8.0) CH α C C β 6.30 (d, 6.30 (d, (d, CH γ 7.62 (d, 7.58 (d, (d, 13 C CH Glc (d, 8.0) 4.33 (d, 8.0) 4.31 (d, 8.0) 4.40 (d, 8.0) CH m m m m CH CH (t, 9.0) 4.96 (t, 9.0) CH m m CH (brt, 5.5) 4.52 (dd, 1.5 & 11.5) 3.37 (brt, 9.5) 3.42 (brt, 9.5) 3.42 (brt, 8.5) 3.84 (brt, 9.0) CH Rham brs 5.21 brs 5.17 (d, 1.0) 5.22 brs CH m m m m CH CH CH CH (d, 6.5) 1.28 (d, 6.0) 1.26 (d, 7.0) 1.12 (d, 6.0) CH connection of hydroxyl group at C-β in 9. Finally, the structure of 9 was established as - hydroxyacteoside when compared with the spectral data in literature. [9] This compound was first isolated from Forsythia viridissima in [10] 179 Wiley Online Library 2018 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

5 Chemical constituents of Chirita halongensis The structure of compounds 1-9 Acknowledgments. We would like to thank the National Foundation for Science and Technology Development of Vietnam (NAFOSTED) for financial support (Reference code ). REFERENCES 1. Yao Su, Jun-Long Bi, Yue-Hu Wang, Ying Tan, Jun Yang, Hong-Xin Liu, Wei Gu, Ge-Fen Yin and Chun-Lin Long. Chemical Constituents from Chirita longgangensis var. Hongyao with Inhibitory Activity against Porcine Respiratory and Reproductive Syndrome Virus, J. Braz. Chem. Soc., 2012, 23, Pham Hoang Ho. An Illustrated Flora of Vietnam. Young Publisher, 3, 19-24, N. T. Hoang Anh, N. V. Tuan, D. D. Thien, T. D. Quan, N. T. Tam, G. T. Kim Lien, K. Franke, T. T. Thuy, T. V. Sung. Chemical Constituents of Chirita drakei, Natural Product Communications, 2017, 12, N. T. Hoang Anh, N. V. Tuan, T. D. Quan, D. D. Thien, N. T. Tam, G. T. Kim Lien, T. T. Thuy, T. V. Sung. Chemical constituents of Chirita drakei Burtt collected in Ha Long bay, Quang Ninh province, Viet Nam. Part 1. Compounds isolated from the n-hexane and ethyl acetate extracts, Vietnam Journal of Chemistry, 2017, 55, N. T. Hoang Anh, N. V. Tuan, T. D. Quan, D. D.Thien, N. T. Tam, P. D. Thang, T. T. Thuy, T. V. Sung. Chemical constituents of Chirita drakei Burtt collected in Ha Long Bay, Quang Ninh province, Viet Nam. Part 2. Compounds isolated from the n- butanol extract, Vietnam Journal of Chemistry, 2017, 55, Nguyen Tien Hiep, Kiew R. New and interesting plants from Ha Long Bay, Vietnam. Gardens Bulletin (Singapore), 2000, 52, Kawasaki, Y., Goda Y., Yoshihira K., Noguchi H. A New Anthraquinone from Rubia tinetorum, Shoyakugaku Zasshi, 1990, 44, Deepak M., Handa Sukhdev S. 3,24-Dihydroxy-urs- 12-en-28-oic acid from Verbena officinalis, Phytochemistry, 1998, 49, Shimomura H., Sashida Y., Adachi T. Phenolic glucosides from Prunus grayana, Phytochemistry, 1987, 26, Kobayashi H., Oguchi H., Takizawa N., Miyase T., Ueno A., Usmanghani K., Ahmad M. New phenylethanoid glycosides from Cistanche tubulosa (Schrenk) Hook. f. I., Chem. Pharm. Bull., 1987, 35, Schlauer J., Budzianowski J., Kukulczanka K., Ratajczak L. Acteoside and related phenylethanoid glycosides in Byblis liniflora. Plants propagated in vitro and its systematic significance, Acta Societatis Botanicorum Poloniae, 2004, 73, Nishimura H., Sasaki H., Morota T., Chin M., Mitsuhashi H. Six glycosides from Rehmannia glutinosa var. purpurea., Phytochemistry, 1990, 29, Kitagana S., Tsukamoto H., Hisada S., Nishibe S. Studies on the Chinese Crude Drug Forsythiae Fructus. VII A new cafeoyl glycosides from Forsythia viridissima, Chem. Pharm. Bull., 1984, 32, Corresponding author: Nguyen Thi Hoang Anh Institute of Chemistry, Vietnam Academy of Science and Technology No. 18, Hoang Quoc Viet Street, Cau Giay District, Hanoi, Viet Nam hoanganhvhh@gmail.com Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 180