A new sesquiterpene and lignans from the roots of Kadsura induta

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One new sesquiterpene, (4S,7R,10S)-2-oxo-4,10,11-trihydroxyguaia-1(5)-ene, and five lignans, kadsuralignan J, isovaleroylbinankadsurin A, schizandrin O, futokakadsurin C and arisantetralone were isolated from the roots of Kadsura induta. Their chemical structures were revealed by MS, 1D and 2D NMR spectra in comparison with the reported data. The absolute configuration of compound 1 was determined by calculation of its theoretical ECD spectra and compared with the experimental results.

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Nội dung Text: A new sesquiterpene and lignans from the roots of Kadsura induta

Cite this paper: Vietnam J. Chem., 2023, 61(5), 663-671 Research Article DOI: 10.1002/vjch.202300142 A new sesquiterpene and lignans from the roots of Kadsura induta Truong Thi Thu Hien1, Do Thi Trang2, Tran Thi Phuong Thao3, Ho Ba Ngoc Minh1, Nguyen Ba Hung1, Hoang Dac Thang1, Le Huyen Tram4, Bui Huu Tai2, Tran Thi Thu Ha5, Phan Van Kiem2* 1 Vietnam Military Medical University, 106 Phung Hung, Phuc La, Ha Dong, Hanoi 10000, Viet Nam 2 Institute of Marine Biochemistry, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi 10000, Viet Nam 3 Institute of Chemistry, VAST, 18 Hoang Quoc Viet, Cau Giay, Hanoi 10000, Viet Nam 4 Hanoi University of Science and Technology, 1 Dai Co Viet, Hai Ba Trung, Hanoi 10000, Viet Nam 5 Institute of Forestry and Sustainable Development, Quyet Thang Commune, Thai Nguyen University of Agriculture and Forestry, Thai Nguyen City 24000, Viet Nam Submitted April 13, 2023; Revised June 16, 2023; Accepted July 14, 2023 Abstract One new sesquiterpene, (4S,7R,10S)-2-oxo-4,10,11-trihydroxyguaia-1(5)-ene (1), and five lignans, kadsuralignan J (2), isovaleroylbinankadsurin A (3), schizandrin O (4), futokakadsurin C (5), and arisantetralone (6) were isolated from the roots of Kadsura induta. Their chemical structures were revealed by MS, 1D and 2D NMR spectra in comparison with the reported data. The absolute configuration of compound 1 was determined by calculation of its theoretical ECD spectra and compared with the experimental results. Keywords. Schisandraceae, Kadsura induta, sesquiterpene, (4S,7R,10S)-2-oxo-4,10,11-trihydroxyguaia-1(5)-ene. 1. INTRODUCTION 2.2. Experimental procedures K. induta is a climbing plant that usually grows in All related experimental procedures were described forests and found in the northern Vietnam, such as in details in supporting information. Lao Cai, Ha Giang provinces. The plants belonging to Kadsura have been used to treat enteritis, duodenal 2.3. Extraction and isolation ulcer, stomach pain, or stimulate digestion.[1] The main chemical components of this genus are lignans, The dried sample roots (1.2 kg) were extracted with triterpenes, and sesquiterpenes. Lignans whose main MeOH to yield MeOH extract (37.1 g), which was framework dibenzocyclooctadiene compounds are suspended with H2O and extracted by CH2Cl2 to get the most common feature of this genus.[2-6] The the extract (F1, 17.5 g). The F1 fraction divided on a lignans from Kadsura species showed cytotoxic [3,4] silica gel column eluting with n-hexane/EtOAc (20/1) and nitric oxide inhibition activities.[4-6] This paper to get 5 fractions, F1A-F1E. Fraction F1B (1.5 g) was reported six compounds isolated from the roots of isolated on an YMC RP-18 column eluting by K. induta, including one new sesquiterpene (1) and MeOH/H2O (7/1) to get three fractions, F1B1-F1B3. five known lignans (2-6). F1B2 (121 mg) was purified on the HPLC eluting by 78% ACN to get compound 1 (6.3 mg). F1B3 (213 2. MATERIALS AND METHODS mg) was purified on the HPLC eluting by 81% ACN to get compounds 2 (6.3 mg) and 3 (7.2 mg). Fraction 2.1. Plant materials F1D (2.3 g) was divided on an YMC R18 column eluting by MeOH/H2O (9/1) to get four fractions, The roots of K. induta (NCCT-P149C) were obtained F1D1-F1D4. Compound 4 (5.7 mg) was obtained from Bat Xat, Lao Cai, Vietnam, in October 2022 and from F1D2 (172 mg) by HPLC using 80% ACN. identified by Dr NV Thanh, Institute of Ecology and Compounds 5 (6.8 mg) and 6 (7.4 mg) were obtained Biological Resources, VAST, Hanoi, Viet Nam. from F1D4 by HPLC, eluting with 85% ACN. 663 Wiley Online Library © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH
25728288, 2023, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300142 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vietnam Journal of Chemistry Phan Van Kiem et al. 2.3.1. (4S,7R,10S)-2-Oxo-4,10,11-trihydroxyguaia- 13,5, 2,0 Hz, Hb-6), 2.04 (m, H-7), 1.82 (m, H-8), 4.71 1(5)-ene (1) (s, H-9), 6.48 (s, H-11), 1.02 (d, 7.0 Hz, H-17), 1.17 (d, 7.0 Hz, H-18), 3.78 (s, 2-OCH3), 3.91 (s, 3-OCH3), A white solid. []25D: -27.3 (c 0.06, MeOH). CD 3.82 (s, 14-OCH3), 5.96 and 5.94 (each d, 1.0 Hz, (MeOH, c 0.2 mg/mL) λ (θ: mdeg): 240 (-49.82), 320 O-CH2-O), 2.42 (m, H-2ʹ), 1.45/1.56 (m, H2-3ʹ), 0.82 (+19.60) nm. HR-ESI-MS m/z 269.1747 [M+H]+, (t, 7.0 Hz, H-4ʹ), 0.96 (d, 7.0 Hz, H-5ʹ). 13C NMR data calcd. For [C15H25O4]+: 269.1747 (Δ = 0 ppm); m/z (CD3OD), see table 5. 291.1561 [M+Na]+, calcd. For [C15H24O4Na]+: 291.1567 (Δ = -2.1 ppm); m/z 286.2008 [M+NH4]+, 2.3.3. Isovaleroylbinankadsurin A (3) calcd. For [C15H24O4NH4]+: 286.2013 (Δ = -1.7 ppm); 303.1355 [M+35Cl]-, calcd. For [C15H24O435Cl]-: A white solid. []25D: +42.1 (c 0.1, MeOH). ESI-MS 303.1369 (Δ = -4.6 ppm); m/z 267.1600 [M–H]-, m/z 508.9 [M+Na]+, C27H34O8. 1H NMR (CD3OD): calcd. For [C15H23O4]-: 267.1602 (Δ = -0.8 ppm); 1H 6.39 (s, H-4), 2.63 (m, H-6), 2.05 (m, H-7), 2.03 (m, NMR and 13C NMR data (CD3OD) data, see table 1. H-8), 5.61 (br s, H-9), 6.50 (s, H-11), 0.92 (d, 7.0 Hz, H-17), 1.07 (d, 7.0 Hz, H-18), 5.55 (s, 1-OH), 3.90 (s, 2.3.2. Kadsuralignan J (2) 2-OCH3), 3.89 (s, 3-OCH3), 3.84 (s, 14-OCH3), 5.96 and 5.92 (each, d, 1.5 Hz, OCH2O), 1.71 (m, H-2), A white solid. []25D: −54.3 (c 0.1, MeOH). ESI-MS 1.23 and 1.37 (H2-3), 0,74 (t, 7.0 Hz, H-4), 0,87 (d, m/z 508.9 [M+Na]+, C27H34O8. 1H NMR (CD3OD): 6,5 Hz, H-5). 6.85 (s, H-4), 2.60 (dd, 13,5, 7,0 Hz, Ha-6), 2.72 (dd, 13 C NMR data (CD3OD), see table 5. Figure 1: Chemical structures of 1-7 2.3.4. Schizandrin O (4) 0.86 (t, 7.5 Hz, H-3ʹʹ). 13C NMR data (CD3OD), see table 5. A white solid. ESI-MS: m/z 609.1 [M+H]+, C33H36O11. 1H NMR (CD3OD, 500 MHz) δH: 6.84 (s, 2.3.5. Futokakadsurin C (5) H-4), 5.89 (s, H-6), 2.32 (m, H-8), 5.87 (s, H-9), 6.53 (s, H-11), 5.63 and 5.77 (each, d, 1.5 Hz, O-CH2-O), A white solid. ESI-MS m/z 357.1 [M+H]+, C21H24O5, 1 3.61 (s, 1-OCH3), 3.87 (s, 2-OCH3), 3.95 (s, 3-OCH3), H NMR (CD3OD, 500 MHz): 6.80 (dd, 8.0, 2.0 Hz, 3.32 (s, 14-OCH3), Benzoyl: 7.47 (2H, d, 8.0 Hz, H- H-6), 6.93 (d, 8.0 Hz, H-5), 7.03 (d, 2.0 Hz, H-2), 4.64 2ʹ and H-6ʹ), 7.32 (2H, t, 8.0 Hz, H-3ʹ and H-5ʹ), 7.52 (d, 5.0 Hz, H-7), 2.48 (m, H-8), 0.63 (s, H-9), 6.93 (d, (1H, t, 8.0 Hz, H-4ʹ), Proyl: 1.77/1.89 (m, H2-2ʹʹ), 2.0 Hz, H-2ʹ), 6.96 (d, 8.0 Hz, H-5ʹ), 6.82 (dd, 8.0, 2.0 © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 664
25728288, 2023, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300142 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vietnam Journal of Chemistry A new sesquiterpene and lignans from … Hz, H-6ʹ), 4.64 (d, 5.0 Hz, H-7ʹ), 2.48 (m, H-8ʹ), 0.99 half band was selected at sigma/gamma value of 0.3 (s, H-9ʹ), 3.84 (s, 3ʹ-OCH3), 3.86 (s, 4ʹ-OCH3). 13C eV. The calculated ECD spectrum was blue-shifted NMR data (CD3OD), see table 5. by 8 nm from its UV correction. The calculated ECD spectra of enantiomer 1b were generated by mirror 2.3.6. Arisantetralone (6) image that of calculated ECD curve of 1a. A white solid. ESIMS: m/z 343.2 [M+H]+, C20H22O5. 3. RESULTS AND DISCUSSION 1 H NMR (CD3OD, 500 MHz): 6.43 (s, H-3), 7.62 (s, H-6), 2.77 (m, H-8), 1.11 (d, 7.0 Hz, H-9), 6.55 (s, H- Compound 1 (figure 1) was obtained as a white solid 2ʹ), 6.84 (d, 8.0 Hz, H-5ʹ), 6.54 (d, 8.0 Hz, H-6ʹ), 3.96 and got molecular formula of C15H24O4 as deduced (d, 5.5 Hz, H-7ʹ), 2.40 (m, H-8ʹ), 0.98 (d, 7.0 Hz, H- by HR-ESI-MS and 13C NMR data. The 1H NMR 9ʹ), 3.81 (s, 4-OCH3), 3.80 (s, 3ʹ-OCH3). 13C NMR spectrum of 1 revealed the presence of four methyl data (CD3OD), see table 5. groups at δH 1.20, 1.26 (each 3H, s), and 1.45 (6H, s), which had correlations with the corresponding 2.4. Conformational study carbons at δC 28.1, 25.3, 26.7/26.9 in the HSQC spectrum. Four sp3 methylene groups were identified Conformational study was performed using Spartan by signals at δC/δH: 52.8/2.54, 25.1/ 2.41 and 2.81, Ver.8 software. Chemical structures of compounds 24.3/1.60 and 1.82, 37.7/1.75 and 2.08, and a methine were directly generated by Spartan. Conformational group at δC 48.6/δH 1.72 (m). The 13C NMR spectrum studies were done at gas phase and Merck molecular of 1 exhibited fifteen carbon signals (table 1), force field (MMFF) level. All conformers were including one carbonyl (δC 208.1), one double bond selected by their relative molecule energy lower than (δC 143.8/177.9), three oxygenated quaternary 40 KJ/mol. The presence of each conformer was carbons (δC 73,0, 73.9, 76.9) as evident by the HSQC expressed by their Boltzmann distribution values. spectrum. From the above data, compound 1 was suggested to be a sesquiterpene, similar to the 2.5. Theoretical calculation of ECD spectra compounds isolated from other Kadsura species.[7,8] A set of carbon chemical shifts of δC 52.8 (CH2)/76.9 Theoretical calculation of ECD spectra was (C)/177.9 (C)/143.8 (C)/208.1 (C=O) were very performed through three major steps. Each similar to those of lancilimbnoid C, suggesting enantiomer was generated and performed compound 1 is a guaiane-type sesquiterpenoid.[9] In conformational study using Spartan Ver.18 software. the COSY spectrum, H2-6 correlated with H-7, H-7 Initially selected conformers were then optimized for correlated with H2-8, and H2-8 correlated with H2-9. their structures and calculated ECD spectra using This evidence indicated the structural connection Gaussian Ver.16. Finally, theoretical ECD spectra from C-6 to C-9. In addition, the HMBC correlations were composed using Specdis Ver.171 software. from the methyl group at δH 1.45 to carbon C-4 (δC An enantiomer (4S,7R,10S-1a) was subjected for 78.9), C-3 (δC 52.8), and C-5 (δC 177.9) indicated a conformational analysis at the gas phase and MMFF hydroxy group at C-4, one carbonyl group at C-2, and level. The obtained conformers were re-analyzed with the double bond at C-1/C-5. In addition, HMBC semi-empirical PM3 calculation. The conformers correlations from H-14 (δH 1.45) to C-1 (δC 143.8)/C- displaying their Boltzmann distribution values over 10 (δC 73.0)/C-9 (δC 37.7), from H3-12 and H3-13 to 1% were selected to optimize their structure by C-7 (δC 48.6)/C-11 (δC 73.9) indicated two hydroxy density-functional theory (DFT) method with BLY3P groups attaching to C-10 and C-11 (figure 2). functional calculation and 6-31G(d,p) basic set. Therefore, the planar structure of 1 was suggested as Methanol, a solvent used for ECD measurement, was 2-oxo-4,10,11-trihydroxyguaia-1(5)-ene, which had used to calculate the effect of solvent on the one more hydroxy group at C-10 compared to conformers in IEFPCM model (polarizable lancilimbnoid C (figures S1-S8).[9] continuum model using integral equation formalism The relative configuration of compound 1 was variant). The optimized conformers were then applied determined by NOESY spectrum (figure 2). Because for ECD calculation by TDDFT (time dependent of the flexibility of cycloheptene-ring, density functional theory) method at 30 excited states conformational analysis of backbone structure together with other conditional settings as an (bicyclo[5.3.0]dec-1(5)-en-2-one) of 1 was optimization process. The calculated ECD of 1a was performed. As shown in table 2, there were two most composed from each theoretical ECD of its stable conformations of bicyclo[5.3.0]dec-1(5)-en-2- conformers, weighting factors based on the one. A twist conformation displayed a little higher Boltzmann distribution values of each conformer. A stability (Boltzmann distribution values of 57.2%) © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 665
25728288, 2023, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300142 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vietnam Journal of Chemistry Phan Van Kiem et al. compared to chair conformation (Boltzmann Table 1: NMR data for compound 1 distribution values of 57.2%). In the twist conformation, distances between H-6ax and H-9ax, C δC δH (mult., J in Hz) H-7ax and H-10ax were calculated to be 2.81 Å and 1 143.8 - 2.68 Å, respectively. In contrast, distances between 2 208.1 - H-7ax and H-9ax, H-6ax and H-8ax, H-6ax/H-10ax, and 3 52.8 2.54 (s) H-8ax/H-10ax were calculated to be 2.45, 2.57, 3.47, 4 76.9 - and 2.56 Å, respectively. These pairs of protons are 5 177.9 - close in proximity and hence could have correlations 2.41 (dd, 16.1, 9.6, Hβ) 6 25.1 in the NOESY experiment. The NOESY spectrum of 2.81 (dd, 16.2, 1.8, Hα) 1 observed correlation between H-6β (δH 2.41) and H- 7 48.6 1.72 (m) 9β (δH 2.08), H3-14 (δH 1.45) and H-7 (δH 1.72) 1.60 (m) 8 24.3 indicated that the structural backbone of 1 was in 1.82 (m) twist conformation and H-6β, H-9β, H3-14, H-7 1.75 (m, Hα) assigned to axial positions. Therefore, the hydroxy 9 37.7 2.08 (ddd, 12.0, 12.0, 4.2, Hβ) group at C-10 and isopropyl side chain at C-7 were 10 73.0 - assigned to both β-equatorial positions. The 11 73.9 - β-orientation of the isopropyl side chain was also 12 28.1 1.26 (s) aproved by NOESY corelations between H-6β (2.41) 13 25.3 1.20 (s) and H3-12 (δH 1.20)/H3-13 (δH 1.26). Later, the NOESY corelation between H-6α (δH 2.81) and H3- 14 26.7 1.45 (s) 15 (δH 1.45) indicated α-orientation of H3-15 15 26.9 1.45 (s) (β-orientation of the hydroxy group at C-4). Figure 2: HMBC, COSY and NOESY correlations of 1 Table 2: Conformational analysis of bicyclo[5.3.0]dec-1(5)-en-2-one Stable conformations Boltzmann distribution 57.2 42.8 (%) Distance between H-6ax/H-9ax H-7ax/H-10ax H-7ax/H-9ax H-6ax/H-8ax H-6ax/H-10ax H-8ax/H-10ax protons (Å) 2.81 2.68 2.45 2.57 3.47 2.56 © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 666
25728288, 2023, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300142 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vietnam Journal of Chemistry A new sesquiterpene and lignans from … Table 3: Initial stable conformers of 1a with their Boltzmann distribution values (%) Conf. 1a-1 (13.0%) Conf. 1a-2 (9.4%) Conf. 1a-3 (9.2%) Conf. 1a-4 (8.2%) Conf. 1a-5 (6.5%) Conf. 1a-6 (6.2%) Conf. 1a-7 (5.6%) Conf. 1a-8 (4.2%) Conf. 1a-9 (3.8%) Conf. 1a-10 (3.7%) Conf. 1a-11 (3.1%) Conf. 1a-12 (2.7%) Conf. 1a-13 (2.5%) Conf. 1a-14 (2.3%) Conf. 1a-15 (1.8%) Conf. 1a-16 (1.6%) Conf. 1a-17 (1.5%) Conf. 1a-18 (1.4%) Conf. 1a-19 (1.4%) Conf. 1a-20 (1.2%) Conf. 1a-21 (1.2%) Conf. 1a-22 (1.2%) Conf. 1a-23 (1.1%) © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 667
25728288, 2023, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300142 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vietnam Journal of Chemistry Phan Van Kiem et al. Table 4: The Cartesian coordinates of the two most stable conformers of 1a after optimization and their Boltzmann distribution values (%) Coordinates of optimized conformer Coordinates of optimized conformer (1a-s1, 97.6%) (1a-s2, 2.2%) Center number x y x x y x 1 -2.202406 0.766408 -0.830151 -2.362166 0.443855 -0.735466 2 -1.379420 -0.083862 0.046225 -1.296649 -0.266382 -0.004721 3 -0.357696 0.647287 0.550013 -0.450170 0.645746 0.533898 4 -0.449839 2.129215 0.170323 -0.829974 2.088568 0.176439 5 -1.572548 2.147046 -0.898990 -1.996856 1.912257 -0.824550 6 -1.718633 -1.554109 0.252845 -1.264812 -1.786965 0.124039 7 -0.524770 -2.392530 0.754810 0.142208 -2.360431 -0.152733 8 0.808736 -2.074208 0.056832 1.287961 -2.021640 0.812730 9 0.765564 0.133467 1.400995 0.744131 0.407974 1.416404 10 1.652811 -0.949248 0.715793 1.821899 -0.570495 0.887749 11 2.717596 -0.356549 -0.262479 2.589085 -0.018691 -0.364243 12 3.631005 0.664629 0.425734 3.456764 1.186123 0.025795 13 3.574706 -1.466408 -0.890619 3.472724 -1.089529 -1.019196 14 -0.816169 2.984863 1.391408 -1.258519 2.894501 1.408682 15 -3.210778 0.407867 -1.442885 -3.393115 -0.057752 -1.192477 16 -2.914644 -1.687918 1.213142 -1.813033 -2.213794 1.500028 17 -2.069131 -2.120275 -1.025549 -2.075090 -2.386049 -0.898314 18 0.796065 2.629884 -0.304678 0.295519 2.767907 -0.379948 19 2.077078 0.391405 -1.332502 1.687080 0.515748 -1.370785 20 -1.133368 2.287628 -1.892518 -1.649599 2.129540 -1.840586 21 -2.321976 2.931361 -0.757863 -2.864235 2.548529 -0.628631 22 -0.798510 -3.435103 0.561611 0.398184 -2.093340 -1.185716 23 -0.429679 -2.298319 1.841501 0.020081 -3.450226 -0.160327 24 0.573523 -1.826676 -0.985822 0.982704 -2.299600 1.829019 25 1.416854 -2.982257 0.017816 2.123809 -2.687984 0.577878 26 1.383686 0.965420 1.740447 1.203455 1.371548 1.644672 27 0.338966 -0.312038 2.306102 0.385132 0.010158 2.375221 28 2.229418 -1.408890 1.529006 2.587195 -0.605418 1.674362 29 4.080406 0.236041 1.325967 4.186392 0.906363 0.790356 30 4.435718 0.958632 -0.253998 3.999033 1.547102 -0.852735 31 3.081152 1.566739 0.700544 2.848050 2.010058 0.404687 32 4.329494 -1.021959 -1.545046 4.047745 -0.641219 -1.834017 33 4.087688 -2.047018 -0.117456 4.175869 -1.514709 -0.296135 34 2.975022 -2.158522 -1.488209 2.881519 -1.910161 -1.435770 35 -1.800267 2.713633 1.783315 -2.158262 2.469794 1.862368 36 -0.834170 4.038678 1.097079 -1.472496 3.924147 1.106571 37 -0.074637 2.864904 2.186008 -0.463152 2.917683 2.158090 38 -3.785472 -1.159756 0.814091 -2.849534 -1.878286 1.602693 39 -2.682244 -1.273200 2.199218 -1.239836 -1.793732 2.331503 40 -3.174578 -2.744921 1.330467 -1.795201 -3.305255 1.580342 41 -2.727536 -1.511283 -1.406586 -2.839943 -1.793504 -1.035218 42 1.222842 1.920491 -0.828939 0.780211 2.114655 -0.923217 43 1.576031 -0.223132 -1.887097 1.142174 -0.201545 -1.722345 © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 668
25728288, 2023, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300142 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vietnam Journal of Chemistry A new sesquiterpene and lignans from … Table 5: 13C NMR data for compounds 2-6 2 3 4 5 6 C a b c C d e δC δC δC δC δC δC δC δC δC δC 1 141.7 142.9 146.6 146.6 151.4 151.4 1 136.2 136.9 126.3 126.3 2 138.8 140.0 133.5 133.5 141.1 141.2 2 119.8 120.2 137.9 137.9 3 151.5 153.0 150.4 150.3 151.9 152.0 3 107.9 108.8 111.3 111.4 4 113.0 114.5 107.2 107.2 110.3 110.4 4 147.0 147.9 151.3 151.4 5 134.8 136.2 133.6 133.4 129.6 129.7 5 147.8 148.9 144.7 144.7 6 38.8 39.7 38.7 38.7 85.2 85.3 6 106.8 107.7 111.9 112.0 7 35.1 36.6 35.0 34.9 74.0 74.0 7 87.4 87.2 200.0 200.0 8 43.0 44.4 41.6 41.7 43.2 43.3 8 44.5 44.6 42.6 42.6 9 82.7 84.1 82.5 82.3 83.4 83.4 9 12.7 11.9 11.9 11.9 10 140.0 140.1 135.9 135.8 132.9 132.9 1ʹ 134.8 135.8 135.8 135.8 11 102.5 103.5 102.8 102.9 101.7 101.8 2ʹ 110.0 111.3 111.0 111.1 12 148.8 150.7 148.9 148.9 148.8 148.8 3ʹ 149.1 150.6 146.6 146.7 13 135.0 136.9 136.1 136.1 135.5 135.5 4ʹ 148.6 150.0 144.3 144.3 14 140.8 142.2 141.3 141.2 140.5 140.6 5ʹ 111.3 112.9 114.1 114.2 15 118.3 119.6 119.2 119.3 120.2 120.3 6ʹ 118.6 120.2 121.8 121.8 16 122.8 124.2 117.1 117.0 121.8 121.9 7ʹ 87.4 86.2 50.5 50.5 17 15.3 15.5 14.9 14.9 28.8 28.8 8ʹ 44.4 44.5 42.6 42.6 18 20.1 20.5 19.7 19.7 17.1 17.1 9ʹ 12.8 12.0 15.9 15.9 1-OCH3 - - - - 60.5 60.6 3ʹ-OMe 55.9 56.5 56.0 56.0 2-OCH3 61.1 56.6 60.8 60.8 60.4 60.4 4ʹ-OMe 56.0 56.6 4-OMe 55.9 56.0 3-OCH3 55.9 61.5 55.8 55.8 56.0 56.1 O-CH2-O 100.9 102.2 14-OCH3 59.7 60.0 59.8 59.8 58.6 58.6 O-CH2-O 101.0 102.6 101.2 101.2 100.8 100.8 Isovaleroyl Isovaleroyl Benzoyl 1ʹ 176.4 178.1 172.9 176.0 129.3 129.4 2ʹ 41.4 42.8 33.7 40.4 129.5 129.6 3ʹ 26.7 27.9 24.1 26.7 127.9 127.9 4ʹ 11.5 11.9 31.2 11.4 132.8 132.8 5ʹ 16.7 17.2 13.8 15.6 127.9 127.9 6ʹ 129.5 129.6 7ʹ 164.7 164.7 Proyl 1ʹʹ 172.3 172.4 2ʹʹ 26.9 26.8 3ʹʹ 8.4 8.4 From conformational analysis and NOESY results from NOESY spectral data. Although 23 experiment, compound 1 was established into a pair initial stable conformers were found from of enantiomers (4S,7R,10S)-1a and (4R,7S,10R)-1b conformational analysis. However, it was interesting (figure 3). The absolute configuration of 1 was finally that only two real stable conformers (1a-s1 and 1a- determined by its experimental and comparison with s2) were recognized after structural optimization TD-DFT calculated ECD spectra of enantiomers (1a processes. Of these, the most stable conformer (1a- and 1b). We selected one enantiomer (1a) for s1) achieved 97.6% contribution. The cartesian calculation. After conformational analysis, 23 initial coordinates of the two most stable conformers after conformers of 1a with their Boltzmann distribution optimization as shown in table 4. The two optimized values over 1% (table 3) were obtained and subjected conformers were then subjected to ECD calculation for the next steps structural optimization, and at 30 excited states. The calculated ECD spectra of calculation.[10,11] The conformational analysis also both conformers 1a-s1 and 1a-s2 showed similar indicated all stable conformers of 1a showing the Cotton effects, a negative effect around 240 nm for π- twist conformation which were well agreed with π* transition and a positive effect around 320 nm for © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 669
25728288, 2023, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300142 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vietnam Journal of Chemistry Phan Van Kiem et al. n-π* transition. A final calculation ECD spectrum of The MS and NMR data of 2-6 were compared to 1a was generated from that of 1a-s1 and 1a-s2 with those of kadsuralignan J (2),[12] isovaleroylbinankad- weighting factors based on their Boltzmann surin A (3), [13] schizandrin O (4), [3] futokakadsurin C distribution values (97.6% and 2.2%). The (5), [14] and arisantetralone (6) [15] and found to match. calculation ECD spectrum of enantiomer 1b was composed of a mirror image that ECD curve of 1a. Acknowledgment. This work has been supported by Comparison of experimental ECD spectrum of 1 to NAFOSTED (No: 104.01-2019.22). those of 1a and 1b, indicated a good compatible Cotton effect with 1a (figure 4). Therefore, the Supplemental Material is available online. absolute configuration of 1 was determined and identified to be (4S,7R,10S)-2-oxo-4,10,11- REFERENCES trihydroxyguaia-1(5)-ene. 1. V. V. Chi. Dictionary of Vietnamese Medicinal Plants. Hanoi: Medicine Publishing House, Vol. 2, pp. 192, 201-202, 3263, 2018. 2. Y. Ikeya, H. Kanatani, M. Hakozaki, H. Taguchi, H. Mitsuhashi. The constituents of Schizandra chinensis BAILL. XV. Isolation and structure determination of two new lignans, gomisin S and gomisin T, Chem. Pharm. Bull., 1988, 36(10), 3974-3979. 3. P. T. H. Minh, D. T. Lam, N. Q. Tien, N. N. Tuan, V. P. Nhung, N. V. Hai, P. V. Kiem, N. X. Nhiem, C. V. Minh, S. J. Park, S. H. Kim. New dibenzocyclooctadiene lignan from Kadsura induta and their cytotoxic activities, Bull. Korean Chem. Soc., 2014, 35(6), 1859-1862. 4. J. S. Liu, Y. D. Qi, H. W. Lai, J. Zhang, X. Q. Jia, H. T. Liu, B. G. Zhang, P. G. Xiao. Genus Kadsura, a good source with considerable characteristic chemical constituents and potential bioactivities, Phytomedicine, 2014, 21(8-9), 1092-1097. 5. H. R. Li, Y. L. Feng, Z. G. Yang, J. Wang, A. Daikonya, S. Kitanaka, L. Z. Xu, S. L. Yang. New lignans from Kadsura coccinea and their nitric oxide inhibitory activities, Chem. Pharm. Bull., 2006, Figure 3: Theoretical ECD spectra of the two 54(7), 1022-1025. optimized stable conformers 1a-s1 (top) and 1a-s2 6. B. H. Tai, P. H. Yen, N. H. Hoang, P. T. T. Huong, (bottom) N. V. Dung, B. V. Thanh, N. T. Cuong, N. A. Bang, N. X. Nhiem, P. V. Kiem. New dibenzocyclooctadiene lignans from Kadsura induta with their anti-inflammatory activity, RSC Advanced, 2022, 12, 25433. 7. Y. Yang, Y. Liu, H. Yu, Q. Xie, B. Wang, S. Jiang, W. Su, Y. Mao, B. Li, C. Peng, Y. Jian, W. Wang. Sesquiterpenes from Kadsura coccinea attenuate rheumatoid arthritis-related inflammation by inhibiting the NF-κB and JAK2/STAT3 signal pathways, Phytochemistry, 2022, 194, 113018. 8. L. Cao, N. Shehla, S. Tasneem, M. Cao, W. Sheng, Y. Jian, B. Li, C. Peng, M. I. Choudhary, A. Rahman, D. Liao, W. Wang. New cadinane sesquiterpenes from the stems of Kadsura heteroclita, Molecules, 2019, 24(9), 1164. Figure 4: Comparison between experimental ECD spectrum of 1 and theoretical calculated ECD 9. S. Muhammad, Y. Z. Xiao, S. S. Hassan, X. Xiao, S. spectra of its possible enantiomers (1a and 1b) K. Yan, Y. Q. Guo, X. P. Ma, H. Z. Jin. Three new © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 670
25728288, 2023, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300142 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vietnam Journal of Chemistry A new sesquiterpene and lignans from … guaiane-type sesquiterpenoids and a monoterpenoid Prod., 2007, 70(12), 1999-2002. from Litsea lancilimba Merr, Nat. Prod. Res., 2022, 13. N. Ookawa, Y. Ikeya, H. Taguchi, I. Yosioka. The 36(13), 3271-3279. constituents of Kadsura japonica Dunal. I. The 10. G. Pescitelli, T. Bruhn. Good computational practice structures of three new lignans, acetyl-, angeloyl- and in the assignment of absolute configurations by caproyl-binankadsurin A, Chem. Pharm. Bull., 1981, TDDFT calculations of ECD spectra, Chirality, 2016, 29(1), 123-127. 28(6), 466-474. 14. T. Konishi, T. Konoshima, A. Daikonya, S. Kitanaka. 11. D. T. Trang, D. T. Dung, N. X. Nhiem, N. T. Cuc, P. Neolignans from Piper futokadsura and their H. yen, D. T. T. Hang, T. M. Linh, N. C. Mai, P. T. inhibition of nitric oxide production, Chem. Pharm. T. Huong, B. H. Tai, P. V. Kiem. New tetracyclic and Bull., 2005, 53(1), 121-124. pentacyclic isomalabaricanes from the marine sponge 15. Y. B. Cheng, M. T. Chang, Y. W. Lo, C. J. Ho, Y. C. Rhabdastrella globostellata (Carter, 1883), Kuo, C. T. Chien, C. Y. Chen, S. S. Liou, Y. H. Kuo, Tetrahedron Lett., 2022, 89, 153607. Y. C. Shen. Oxygenated lignans from the roots of 12. H. Li, L. Wang, Z. Yang, S. Kitanaka. Schisandra arisanensis, J. Nat. Prod., 2009, 72(9), Kadsuralignans H-K from Kadsura coccinea and 1663-1668. their nitric oxide production inhibitory effects, J. Nat. Corresponding author: Phan Van Kiem Institute of Marine Biochemistry, Vietnam Academy of Science and Technology 18 Hoang Quoc Viet, Cau Giay, Hanoi 10000, Viet Nam E-mail: phankiem@vast.vn. © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 671