Letter - spectral assignment Received: 19 June 2014
Revised: 26 August 2014
Accepted: 28 August 2014
Published online in Wiley Online Library
(wileyonlinelibrary.com) DOI 10.1002/mrc.4150
1H
and 13C NMR assignments of tricanguinas A–B, coumarin monoterpenes from Trichosanthes anguina L Nguyen Xuan Nhiem,a,b Hoang Thi Yen,b Phan Van Kiem,b Chau Van Minh,b Bui Huu Tai,b Hoang Le Tuan Anh,b SeonJu Park,a Nanyoung Kima and Seung Hyun Kima* Introduction The Trichsanthes, a genus of tropical and subtropical vines, belongs to Cucurbitaceae family. The plant Trichosanthes anguina L. is cultivated as vegetable crop in Vietnam. T. anguina is often used to treat sore throat and skin diseases.[1] There are few reports about chemical constituents such as isoflavone glycoside[2] and trichoanguin[3] of this plants. In addition, trichoanguin showed antitumor and antiHIV-1 activities.[3] This study deals with the isolation and structure identification of two novel coumarin monoterpenes from the leaves of T. anguina (Fig. 1).
Results and discussion
Magn. Reson. Chem. (2014)
* Correspondence to: Seung Hyun Kim, College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 406-840, Republic of Korea. E-mail: [email protected] a College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 406-840, Republic of Korea b Institute of Marine Biochemistry, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Caugiay, Hanoi, Vietnam
Copyright © 2014 John Wiley & Sons, Ltd.
1
Compound 1 was obtained as a colorless amorphous powder, and its molecular formula was determined to be C21H24O7 by HR ESI MS at m/z 389.1578 [M + H]+ (calcd C21H25O7 for 389.1595). The 1H NNR spectrum showed one olefinic proton at δH 6.15 (s), three aromatic protons at δH 6.36 (d, J = 9.6 Hz), 7.00 (s), and 7.89 (d, J = 9.6 Hz), two methoxy groups at δH 3.89 (s) and 3.99 (s), two quaternary methyl groups at δH 1.90 (s), 2.09 (s), and one secondary methyl group at δH 1.15 (d, J = 6.4 Hz). The 13C NMR and DEPT spectra of 1 displayed three carbonyls at δC 162.82, 200.70, and 211.57, six quaternary at δC 116.45, 141.85, 144.09, 145.74, 151.42, and 157.41, five methine at δC 38.65, 105.92, 115.73, 124.28, and 146.04, two methylene at δC 48.52 and 77.67, and five methyl carbons at δC 16.84, 21.00, 27.79, 57.02, and 62.95. Analysis of the 1H and 13C NMR data (Table 1) of 1 indicated the presence of a coumarin and monoterpene moieties. The 1H and 13C NMR data of 1 were similar to those of 8-(2,3-dihydroxy-3-methylbutoxy)-6,7-dimethoxycoumarin except for monoterpene moiety at C-8.[4] The HMBC correlations from two methoxy groups (δH 3.89 and 3.99) to C-6 (δC 151.42) and C-7 (δC 141.85), respectively, confirmed the presence of two methoxy groups at C-6 and C-7 (Fig. 2). In addition, COSY correlations were observed between H-3 (δH 6.36)/H-4 (δH 7.89). These suggested the coumarin moiety to be 6,7-dimethoxy-8-hydroxycoumarin. The HMBC correlations between H-1′ (δH 4.98) and C-2′ (δC 211.57)/C-3′ (δC 38.65); between H-10′ (δH 1.15) and C-2′ (δC 211.57)/C-3′ (δC 38.65)/C-4′ (δC 48.52) suggested the carbonyl and methyl groups at C-2′ and C-3′, respectively. In addition, the HMBC correlations from H-8′ (δH 1.90)/H-9′ (δH 2.09) to C-6′ (δC 124.28)/C-7′ (δC 157.41); from H-6′ (δH 6.15) to C-5′/C-7′/C-8′/C-9′ confirmed the
carbonyl and double bond at C-5′ and C-6′/C-7′, respectively (Fig. 2). Moreover, the C-1′ of monoterpene moiety was linked to C-8 of coumarin via oxygen bridge, proved by the HMBC correlations between H-1′ (δH 4.98) and C-8 (δC 145.74). The positive Cotton effect λ = 278 nm (Δε: + 8.05) (Fig. 3) in the CD spectrum of 1 proved the configuration at C-3 to be R by comparison with those of similar structure: (S)-3-methylhexane-2,5-dione (a negative Cotton effect at λ = 280 nm).[5] Based on the above evidence, the structure of 1 was elucidated as 8-((3R)-3,7-dimethyloct-6-en-2,5-dione-1-oxy)6,7-dimethoxycoumarin, a new compound named tricanguina A. Compound 2 was obtained as a colorless amorphous powder, and its molecular formula was deduced as C21H22O8, by the HR ESI MS ion [M + H]+ at m/z 403.1372 (calcd for C21H23O8, 403.1387). The 1H and 13C NMR analyses indicated that the structure of 2 contained a coumarin and a monoterpene with spiroring. The coumarin moiety was similar to those in 1, confirmed by HSQC, HMBC, and COSY spectra. Carefully comparing 13C NMR data of monoterpene moiety in 2 with those of spiro-ring (C-20–C27) in firmanolide as well as 23-epi-firmanolide confirmed the presence of spiro-ring in monoterpene moiety.[6] The HMBC correlations between H-2′ (δH 4.56) and C-1′ (δC 74.66), C-3′ (δC 36.00), C-4′ (δC 43.84), C-5′ (δC 114.56), and C-10′ (δC 13.74) confirmed that the methyl group was at C-3′ and epoxy group at C-2′/C-5′. In addition, the HMBC correlations between H-9′ (δH 1.89) and C-6′ (δC 147.58)/C-7′ (δC 133.53), and C-8′ (δC 173.65); between H-6′ (δH 7.00) and C-4′ (δC 43.84) and C-5′ (δC 114.56) confirmed the remaining part of spiro-ring. The monoterpene moiety was linked to C-8 of coumarin by HMBC correlations from H-1′ (δH 4.21 and 4.28) to C-8 (δC 146.36). Based on the above evidence, the constitution of 2 was established. To our knowledge, compound 2 was the biogenetic derivative of 1, maybe the result of oxidation of C-8 and epoxydation at C-2′/C-5′ and C-5′/C-8′ of 1.[7] For this reason, the stereochemistry of the
N. X. Nhiem et al.
Figure 1. Structures of 1–2.
methyl group at C-3′ of 2 was deduced the same as those in 1. The important ROESY correlations were shown in Fig. 2. The ROESY correlations between H-2′ (δH 4.56) and H-3′ (δH 2.92); H10′ (δH 1.28) and H-1′ (δH 4.21 and 4.28)/Hα-4′ (δH 2.33); Hα-4′ (δH 2.33) and H-6′ (δH 7.00) proved the configuration of spiro-ring, shown in Fig. 2. Therefore, the novel structure 2 was determined as 8-((2S,3R,5S)-2,5,5,7-diepoxy-3,7-dimethyloct-6-en-8-one-1-oxy)-6,7dimethoxycoumarin, and named tricanguina B.
Figure 2. Key HMBC, COSY, and ROE correlations of 1–2.
Experimental General experimental procedures Chemical shifts are reported in parts per million from TMS. All NMR spectra were recorded on an Agilent 400-MR-NMR Spectrometer operated at 400 and 100 MHz for hydrogen and carbon, respectively. NMR measurements, including 1H, 13C, HSQC, HMBC ROESY, and COSY experiments, were carried out using 5-mm probe tubes at a temperature of 22.2 °C in CD3OD solutions, with TMS as the internal standard. The pulse conditions were as follows: for the 1H spectrum, spectrometer frequency (SF) = 399.99 MHz, acquisition time (AQ) = 2.5559 s, spectral width (SW) = 6410.3 Hz, and digital
Figure 3. Circular dichroism spectra of 1.
Table 1. The NMR spectral data of compounds 1 and 2 in CD3OD Pos.
1 δCa
2 3 4 5 6 7 8 9 10 6-OCH3 7-OCH3 1’ 2’ 3’ 4’ 5’ 6’ 7’ 8’ 9’ 10’
162.8`2 115.73 146.04 105.92 151.42 141.85 145.74 144.09 116.45 57.02 62.95 77.67 211.57 38.65 48.52 200.70 124.28 157.41 27.79 21.00 16.84
2 δHb
(mult., J in Hz)
– 6.36 (d, 9.6) 7.89 (d, 9.6) 7.00 (s) –
3.89 (s) 3.99 (s) 4.98 (s) – 3.25 (m) 2.62 (dd, 4.4, 17.6)/3.00 (dd, 9.2, 17.6) – 6.15 (s) – 1.90 (s) 2.09 (s) 1.15 (d, 6.4)
δCa 162.82 115.63 146.06 106.00 151.71 142.09 146.36 144.29 116.38 56.91 62.61 74.66 84.35 36.00 43.84 114.56 147.58 133.53 173.65 10.50 13.74
δHb (mult., J in Hz) – 6.34 (d, 9.6) 7.88 (d, 9.6) 6.99 (s) –
3.91 (s) 4.01 (s) 4.21 (dd, 3.2, 10.8)/4.28 (dd, 3.2, 10.8) 4.56 (s) 2.92 (m) 2.18 (β, dd, 7.6, 12.8)/2.33 (α, d, 12.8) – 7.00 (s) – 1.89 (s) 1.28 (d, 6.5)
2
a
100 MHz. 400 MHz. Assignments were done by HMQC, HMBC, COSY, and ROESY experiments.
b
wileyonlinelibrary.com/journal/mrc
Copyright © 2014 John Wiley & Sons, Ltd.
Magn. Reson. Chem. (2014)
Two novel coumarin monoterpenes from Trichosanthes anguina L resolution (DR) = 0.391 Hz; for the 13C spectrum, SF = 100.59 MHz, AQ = 1.5 s, SW = 25 000.0 Hz, and DR = 0.666 Hz; for the COSY spectrum, AQ = 0.500 s, RD = 1.5 s, SW = 6410.3 Hz, number of points (NP) = 4096, and number of increments (NI) = 128; for the ROESY spectrum, AQ = 0.500 s, RD = 1.5 s, SW = 6410.3 Hz, NP = 4096, NI = 256, and mixing time 0.5 s; for the HSQC spectrum, observation frequency 399.99 MHz, AQ = 0.300 s, RD = 1.5 s, SW = 6410.3 (1H) and 20 115.7 (13C) Hz, NP = 1923, NI = 96; for the HMBC spectrum, observation frequency 399.99 MHz, an evolution delay for long range coupling 8 Hz, AQ = 0.300 s, RD = 1.5 s, SW = 6410.3 (1H) and 24 140.0 (13C) Hz, NP = 1923, NI = 200. Data processing was carried out with the MestReNova v6.0.2 program. The HR-ESI-MS was obtained on an AGILENT 6550 iFunnel Q-TOF LC/MS spectrometer. Optical rotations were determined on a Jasco DIP-370 automatic polarimeter. Circular dichroism spectrums were determined on a ChirascanTM CD spectrometer. Preparative HPLC was carried out using an AGILENT 1200 HPLC system. Column chromatography was performed using a silica-gel (Kieselgel 60, 70– 230 mesh and 230–400 mesh, Merck) or YMC RP-18 resins (30– 50 μm, Fujisilisa Chemical Ltd.), thin layer chromatography (TLC) using a pre-coated silica-gel 60 F254 (0.25 mm, Merck), and RP-18 F254S plates (0.25 mm, Merck). Plant material The leaves T. anguina were collected in Hoabinh, Vietnam during August, 2013, and identified by Dr. Ninh Khac Ban, Institute of Marine Biochemistry, VAST, Vietnam. A voucher specimen (TA1308) was deposited at the Institute of Marine Biochemistry, VAST, Vietnam Extraction and isolation The leaves of T. anguina (4.0 kg) were extracted with MeOH three times under reflux for 15 h to yield 150.0 g of a dark solid extract, which was then suspended in water and successively partitioned with chloroform (CHCl3) and ethyl acetate (EtOAc) to obtain CHCl3 (TA1, 70.0 g), EtOAc (TA2, 30.0 g), and water (TA3, 50.0 g) layers after removal of the solvents in vacuo. The TA1 fraction was chromatographed on a silica gel column eluting with gradient of n-hexane–acetone (100:1 → 1:1, v/v) to give five smaller fractions, TA1A (20.0 g), TA1B (15.0 g), TA1C (10.0 g), TA1D (8.0 g), and TA1E (6.0 g). The TA1C fraction was chromatographed on a silica gel column eluting with chloroform–acetone (6:1, v/v) to give four fractions, TA1C1 (1.5 g), TA1C2 (2.0 g), TA1C3 (2.4 g), and TA1C4 (2.0 g). The TA1C3 fraction was chromatographed on HPLC using
J’sphere ODS H-80 (250 mm × 20 mm, 4 μm, 8 nm) column eluting with 50% acetonitrile in aqueous at a flow rate of 3 ml/min to yield 1 (8.0 mg, tR 27.2 min) and 2 (6.0 mg, tR 25.0 min). Tricanguina A (1): A yellow powder, ½α25 D : +30.1 (c = 0.1 in MeOH); UV (CH3OH) λmax: 246.5, 299.9, 337.0 nm; IR (KBr) νmax: 2927, 2363, 1730, 1407 cm-1; C21H24O7, HR-ESI-MS found m/z: 389.1578 [M + H]+ (Calcd. C21H25O7 for 389.1595) and 411.1383 [M + Na]+ (calcd. C21H24O7Na for 411.1414); CD (c = 5 × 10-4 M) +8.05 (278 nm): see Fig. 3; 1H and 13C NMR: see Table 1. Tricanguina B (2): A yellow powder, ½α25 D : +43.3 (c = 0.1 in MeOH); UV (CH3OH) λmax 231.2, 296.2, 337.6 nm; IR (KBr) νmax 2930, 2359, 1730, 1409, 1125 cm-1; C21H22O8, HR-ESI-MS found m/z: 403.1372 [M + H]+ (Calcd. C21H23O8 for 403.1387); 1H and 13 C NMR: see Table 1.
Declaration of interest The authors report no conflicts of interest. Acknowledgements This research was supported by the Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 104.01-2011.23 and the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF-2011-0025129).
References [1] V. V. Chi, The Dictionary of Medicinal Plants in Vietnam, vol. 1, Medical Publishing House, Hanoi, 2012, pp. 186–187. [2] R. N. Yadava, Y. Syeda. Phytochemistry 1994, 36, 1519. [3] L. P. Chow, M. H. Chou, C. Y. Ho, C. C. Chuang, F. M. Pan, S. H. Wu, J. Y. Lin. Biochem. J. 1999, 338, 211. [4] C. A. N. Catalan, M. I. Vega, M. E. Lopez, M. Cuenca del R, T. E. Gedris, W. Herz. Biochem. Syst. Ecol. 2003, 31, 417. [5] N. Kosaka, K. Nozaki, T. Hiyama, M. Fujiki, N. Tamai, T. Matsumoto. Macromolecules 2003, 36, 6884. [6] S. Hasegawa, N. Kaneko, Y. Hirose. Phytochemistry 1987, 26, 1095. [7] O. A. Carter, R. J. Peters, R. Croteau. Phytochemistry 2003, 64, 425.
Supporting information Additional supporting information may be found in the online version of this article at the publisher’s web site.
3
Magn. Reson. Chem. (2014)
Copyright © 2014 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/mrc
Revised: 26 August 2014
Accepted: 28 August 2014
Published online in Wiley Online Library
(wileyonlinelibrary.com) DOI 10.1002/mrc.4150
1H
and 13C NMR assignments of tricanguinas A–B, coumarin monoterpenes from Trichosanthes anguina L Nguyen Xuan Nhiem,a,b Hoang Thi Yen,b Phan Van Kiem,b Chau Van Minh,b Bui Huu Tai,b Hoang Le Tuan Anh,b SeonJu Park,a Nanyoung Kima and Seung Hyun Kima* Introduction The Trichsanthes, a genus of tropical and subtropical vines, belongs to Cucurbitaceae family. The plant Trichosanthes anguina L. is cultivated as vegetable crop in Vietnam. T. anguina is often used to treat sore throat and skin diseases.[1] There are few reports about chemical constituents such as isoflavone glycoside[2] and trichoanguin[3] of this plants. In addition, trichoanguin showed antitumor and antiHIV-1 activities.[3] This study deals with the isolation and structure identification of two novel coumarin monoterpenes from the leaves of T. anguina (Fig. 1).
Results and discussion
Magn. Reson. Chem. (2014)
* Correspondence to: Seung Hyun Kim, College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 406-840, Republic of Korea. E-mail: [email protected] a College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 406-840, Republic of Korea b Institute of Marine Biochemistry, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Caugiay, Hanoi, Vietnam
Copyright © 2014 John Wiley & Sons, Ltd.
1
Compound 1 was obtained as a colorless amorphous powder, and its molecular formula was determined to be C21H24O7 by HR ESI MS at m/z 389.1578 [M + H]+ (calcd C21H25O7 for 389.1595). The 1H NNR spectrum showed one olefinic proton at δH 6.15 (s), three aromatic protons at δH 6.36 (d, J = 9.6 Hz), 7.00 (s), and 7.89 (d, J = 9.6 Hz), two methoxy groups at δH 3.89 (s) and 3.99 (s), two quaternary methyl groups at δH 1.90 (s), 2.09 (s), and one secondary methyl group at δH 1.15 (d, J = 6.4 Hz). The 13C NMR and DEPT spectra of 1 displayed three carbonyls at δC 162.82, 200.70, and 211.57, six quaternary at δC 116.45, 141.85, 144.09, 145.74, 151.42, and 157.41, five methine at δC 38.65, 105.92, 115.73, 124.28, and 146.04, two methylene at δC 48.52 and 77.67, and five methyl carbons at δC 16.84, 21.00, 27.79, 57.02, and 62.95. Analysis of the 1H and 13C NMR data (Table 1) of 1 indicated the presence of a coumarin and monoterpene moieties. The 1H and 13C NMR data of 1 were similar to those of 8-(2,3-dihydroxy-3-methylbutoxy)-6,7-dimethoxycoumarin except for monoterpene moiety at C-8.[4] The HMBC correlations from two methoxy groups (δH 3.89 and 3.99) to C-6 (δC 151.42) and C-7 (δC 141.85), respectively, confirmed the presence of two methoxy groups at C-6 and C-7 (Fig. 2). In addition, COSY correlations were observed between H-3 (δH 6.36)/H-4 (δH 7.89). These suggested the coumarin moiety to be 6,7-dimethoxy-8-hydroxycoumarin. The HMBC correlations between H-1′ (δH 4.98) and C-2′ (δC 211.57)/C-3′ (δC 38.65); between H-10′ (δH 1.15) and C-2′ (δC 211.57)/C-3′ (δC 38.65)/C-4′ (δC 48.52) suggested the carbonyl and methyl groups at C-2′ and C-3′, respectively. In addition, the HMBC correlations from H-8′ (δH 1.90)/H-9′ (δH 2.09) to C-6′ (δC 124.28)/C-7′ (δC 157.41); from H-6′ (δH 6.15) to C-5′/C-7′/C-8′/C-9′ confirmed the
carbonyl and double bond at C-5′ and C-6′/C-7′, respectively (Fig. 2). Moreover, the C-1′ of monoterpene moiety was linked to C-8 of coumarin via oxygen bridge, proved by the HMBC correlations between H-1′ (δH 4.98) and C-8 (δC 145.74). The positive Cotton effect λ = 278 nm (Δε: + 8.05) (Fig. 3) in the CD spectrum of 1 proved the configuration at C-3 to be R by comparison with those of similar structure: (S)-3-methylhexane-2,5-dione (a negative Cotton effect at λ = 280 nm).[5] Based on the above evidence, the structure of 1 was elucidated as 8-((3R)-3,7-dimethyloct-6-en-2,5-dione-1-oxy)6,7-dimethoxycoumarin, a new compound named tricanguina A. Compound 2 was obtained as a colorless amorphous powder, and its molecular formula was deduced as C21H22O8, by the HR ESI MS ion [M + H]+ at m/z 403.1372 (calcd for C21H23O8, 403.1387). The 1H and 13C NMR analyses indicated that the structure of 2 contained a coumarin and a monoterpene with spiroring. The coumarin moiety was similar to those in 1, confirmed by HSQC, HMBC, and COSY spectra. Carefully comparing 13C NMR data of monoterpene moiety in 2 with those of spiro-ring (C-20–C27) in firmanolide as well as 23-epi-firmanolide confirmed the presence of spiro-ring in monoterpene moiety.[6] The HMBC correlations between H-2′ (δH 4.56) and C-1′ (δC 74.66), C-3′ (δC 36.00), C-4′ (δC 43.84), C-5′ (δC 114.56), and C-10′ (δC 13.74) confirmed that the methyl group was at C-3′ and epoxy group at C-2′/C-5′. In addition, the HMBC correlations between H-9′ (δH 1.89) and C-6′ (δC 147.58)/C-7′ (δC 133.53), and C-8′ (δC 173.65); between H-6′ (δH 7.00) and C-4′ (δC 43.84) and C-5′ (δC 114.56) confirmed the remaining part of spiro-ring. The monoterpene moiety was linked to C-8 of coumarin by HMBC correlations from H-1′ (δH 4.21 and 4.28) to C-8 (δC 146.36). Based on the above evidence, the constitution of 2 was established. To our knowledge, compound 2 was the biogenetic derivative of 1, maybe the result of oxidation of C-8 and epoxydation at C-2′/C-5′ and C-5′/C-8′ of 1.[7] For this reason, the stereochemistry of the
N. X. Nhiem et al.
Figure 1. Structures of 1–2.
methyl group at C-3′ of 2 was deduced the same as those in 1. The important ROESY correlations were shown in Fig. 2. The ROESY correlations between H-2′ (δH 4.56) and H-3′ (δH 2.92); H10′ (δH 1.28) and H-1′ (δH 4.21 and 4.28)/Hα-4′ (δH 2.33); Hα-4′ (δH 2.33) and H-6′ (δH 7.00) proved the configuration of spiro-ring, shown in Fig. 2. Therefore, the novel structure 2 was determined as 8-((2S,3R,5S)-2,5,5,7-diepoxy-3,7-dimethyloct-6-en-8-one-1-oxy)-6,7dimethoxycoumarin, and named tricanguina B.
Figure 2. Key HMBC, COSY, and ROE correlations of 1–2.
Experimental General experimental procedures Chemical shifts are reported in parts per million from TMS. All NMR spectra were recorded on an Agilent 400-MR-NMR Spectrometer operated at 400 and 100 MHz for hydrogen and carbon, respectively. NMR measurements, including 1H, 13C, HSQC, HMBC ROESY, and COSY experiments, were carried out using 5-mm probe tubes at a temperature of 22.2 °C in CD3OD solutions, with TMS as the internal standard. The pulse conditions were as follows: for the 1H spectrum, spectrometer frequency (SF) = 399.99 MHz, acquisition time (AQ) = 2.5559 s, spectral width (SW) = 6410.3 Hz, and digital
Figure 3. Circular dichroism spectra of 1.
Table 1. The NMR spectral data of compounds 1 and 2 in CD3OD Pos.
1 δCa
2 3 4 5 6 7 8 9 10 6-OCH3 7-OCH3 1’ 2’ 3’ 4’ 5’ 6’ 7’ 8’ 9’ 10’
162.8`2 115.73 146.04 105.92 151.42 141.85 145.74 144.09 116.45 57.02 62.95 77.67 211.57 38.65 48.52 200.70 124.28 157.41 27.79 21.00 16.84
2 δHb
(mult., J in Hz)
– 6.36 (d, 9.6) 7.89 (d, 9.6) 7.00 (s) –
3.89 (s) 3.99 (s) 4.98 (s) – 3.25 (m) 2.62 (dd, 4.4, 17.6)/3.00 (dd, 9.2, 17.6) – 6.15 (s) – 1.90 (s) 2.09 (s) 1.15 (d, 6.4)
δCa 162.82 115.63 146.06 106.00 151.71 142.09 146.36 144.29 116.38 56.91 62.61 74.66 84.35 36.00 43.84 114.56 147.58 133.53 173.65 10.50 13.74
δHb (mult., J in Hz) – 6.34 (d, 9.6) 7.88 (d, 9.6) 6.99 (s) –
3.91 (s) 4.01 (s) 4.21 (dd, 3.2, 10.8)/4.28 (dd, 3.2, 10.8) 4.56 (s) 2.92 (m) 2.18 (β, dd, 7.6, 12.8)/2.33 (α, d, 12.8) – 7.00 (s) – 1.89 (s) 1.28 (d, 6.5)
2
a
100 MHz. 400 MHz. Assignments were done by HMQC, HMBC, COSY, and ROESY experiments.
b
wileyonlinelibrary.com/journal/mrc
Copyright © 2014 John Wiley & Sons, Ltd.
Magn. Reson. Chem. (2014)
Two novel coumarin monoterpenes from Trichosanthes anguina L resolution (DR) = 0.391 Hz; for the 13C spectrum, SF = 100.59 MHz, AQ = 1.5 s, SW = 25 000.0 Hz, and DR = 0.666 Hz; for the COSY spectrum, AQ = 0.500 s, RD = 1.5 s, SW = 6410.3 Hz, number of points (NP) = 4096, and number of increments (NI) = 128; for the ROESY spectrum, AQ = 0.500 s, RD = 1.5 s, SW = 6410.3 Hz, NP = 4096, NI = 256, and mixing time 0.5 s; for the HSQC spectrum, observation frequency 399.99 MHz, AQ = 0.300 s, RD = 1.5 s, SW = 6410.3 (1H) and 20 115.7 (13C) Hz, NP = 1923, NI = 96; for the HMBC spectrum, observation frequency 399.99 MHz, an evolution delay for long range coupling 8 Hz, AQ = 0.300 s, RD = 1.5 s, SW = 6410.3 (1H) and 24 140.0 (13C) Hz, NP = 1923, NI = 200. Data processing was carried out with the MestReNova v6.0.2 program. The HR-ESI-MS was obtained on an AGILENT 6550 iFunnel Q-TOF LC/MS spectrometer. Optical rotations were determined on a Jasco DIP-370 automatic polarimeter. Circular dichroism spectrums were determined on a ChirascanTM CD spectrometer. Preparative HPLC was carried out using an AGILENT 1200 HPLC system. Column chromatography was performed using a silica-gel (Kieselgel 60, 70– 230 mesh and 230–400 mesh, Merck) or YMC RP-18 resins (30– 50 μm, Fujisilisa Chemical Ltd.), thin layer chromatography (TLC) using a pre-coated silica-gel 60 F254 (0.25 mm, Merck), and RP-18 F254S plates (0.25 mm, Merck). Plant material The leaves T. anguina were collected in Hoabinh, Vietnam during August, 2013, and identified by Dr. Ninh Khac Ban, Institute of Marine Biochemistry, VAST, Vietnam. A voucher specimen (TA1308) was deposited at the Institute of Marine Biochemistry, VAST, Vietnam Extraction and isolation The leaves of T. anguina (4.0 kg) were extracted with MeOH three times under reflux for 15 h to yield 150.0 g of a dark solid extract, which was then suspended in water and successively partitioned with chloroform (CHCl3) and ethyl acetate (EtOAc) to obtain CHCl3 (TA1, 70.0 g), EtOAc (TA2, 30.0 g), and water (TA3, 50.0 g) layers after removal of the solvents in vacuo. The TA1 fraction was chromatographed on a silica gel column eluting with gradient of n-hexane–acetone (100:1 → 1:1, v/v) to give five smaller fractions, TA1A (20.0 g), TA1B (15.0 g), TA1C (10.0 g), TA1D (8.0 g), and TA1E (6.0 g). The TA1C fraction was chromatographed on a silica gel column eluting with chloroform–acetone (6:1, v/v) to give four fractions, TA1C1 (1.5 g), TA1C2 (2.0 g), TA1C3 (2.4 g), and TA1C4 (2.0 g). The TA1C3 fraction was chromatographed on HPLC using
J’sphere ODS H-80 (250 mm × 20 mm, 4 μm, 8 nm) column eluting with 50% acetonitrile in aqueous at a flow rate of 3 ml/min to yield 1 (8.0 mg, tR 27.2 min) and 2 (6.0 mg, tR 25.0 min). Tricanguina A (1): A yellow powder, ½α25 D : +30.1 (c = 0.1 in MeOH); UV (CH3OH) λmax: 246.5, 299.9, 337.0 nm; IR (KBr) νmax: 2927, 2363, 1730, 1407 cm-1; C21H24O7, HR-ESI-MS found m/z: 389.1578 [M + H]+ (Calcd. C21H25O7 for 389.1595) and 411.1383 [M + Na]+ (calcd. C21H24O7Na for 411.1414); CD (c = 5 × 10-4 M) +8.05 (278 nm): see Fig. 3; 1H and 13C NMR: see Table 1. Tricanguina B (2): A yellow powder, ½α25 D : +43.3 (c = 0.1 in MeOH); UV (CH3OH) λmax 231.2, 296.2, 337.6 nm; IR (KBr) νmax 2930, 2359, 1730, 1409, 1125 cm-1; C21H22O8, HR-ESI-MS found m/z: 403.1372 [M + H]+ (Calcd. C21H23O8 for 403.1387); 1H and 13 C NMR: see Table 1.
Declaration of interest The authors report no conflicts of interest. Acknowledgements This research was supported by the Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 104.01-2011.23 and the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF-2011-0025129).
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Magn. Reson. Chem. (2014)
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