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Honokiol dimers and magnolol derivatives with new carbon skeletons from the roots of Magnolia officinalis and their inhibitory effects on superoxide anion generation and elastase release.

Shih HC, Hwang TL, Chen HC, Kuo PC, Lee EJ, Lee KH, Wu TS - PLoS ONE (2013)

Bottom Line: Two honokiol dimers, houpulins A and B (1 and 2), and two magnolol derivatives, houpulins C and D (3 and 4), were isolated and characterized from an ethanol extract obtained from the roots of Magnolia officinalis.These four oligomers possess new carbon skeletons postulated to be biosynthesized from the coupling of three or four C6-C3 subunits.In addition, the new oligomers were evaluated for inhibition of superoxide anion generation and elastase release, and houpulin B (2) was identified as a new anti-inflammatory lead compound.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, National Cheng Kung University, Tainan, Taiwan.

ABSTRACT
Two honokiol dimers, houpulins A and B (1 and 2), and two magnolol derivatives, houpulins C and D (3 and 4), were isolated and characterized from an ethanol extract obtained from the roots of Magnolia officinalis. The chemical structures were determined based on spectroscopic and physicochemical analyses, which included 1D and 2D NMR, as well as mass spectrometry data. These four oligomers possess new carbon skeletons postulated to be biosynthesized from the coupling of three or four C6-C3 subunits. In addition, the new oligomers were evaluated for inhibition of superoxide anion generation and elastase release, and houpulin B (2) was identified as a new anti-inflammatory lead compound.

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Related in: MedlinePlus

Structures of 1–4.
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pone-0059502-g001: Structures of 1–4.

Mentions: Repeated silica gel and RP-C18 column chromatography of the dichloromethane-soluble fraction from the ethanol extract obtained from the roots of M. officinalis afforded four novel oligomeric neolignans (1–4) with new carbon skeletons. Compound 1 was obtained as optically active syrup. The positive-mode HR-ESI-MS of 1 showed a sodiated molecular ion peak at m/z 553.2357 ([M+Na]+), corresponding to a molecular formula of C36H34O4 with 20 indices of hydrogen deficiency (IHD). The absorption bands in the IR spectrum indicated the presence of hydroxy (3502 cm−1) and phenyl groups (1639 and 1504 cm−1). Analysis of the 13C NMR, DEPT135 and HMQC spectral data identified 36 carbon signals consistent with four oxygenated quaternary aromatic carbons at δ 155.2, 153.3, 151.9, and 149.6; eleven tertiary aromatic carbons at δ 132.0, 131.4, 131.4, 131.4, 131.3, 131.1, 131.0, 129.4, 128.9, 117.0 and 115.8; nine quaternary aromatic carbons at δ 133.2, 132.2, 131.8, 130.6, 129.1, 128.6, 127.6, 127.2, and 126.9; eight olefinic carbons at δ 139.3, 139.1, 138.1, 138.0, 115.8, 115.7, 115.6, and 115.5; and four aliphatic methylene carbons at δ 40.1, 40.1, 35.6, and 35.1. The 1H NMR spectrum of 1 displayed two sets of ABX-type aromatic signals at δ 6.88 (1H, d, J = 8.1 Hz, H-5), 7.00 (1H, dd, J = 8.1, 2.2 Hz, H-6), and 7.13 (1H, d, J = 2.2 Hz, H-2), as well as 6.91 (1H, d, J = 8.1 Hz, H-5′″), 7.28 (1H, dd, J = 8.1, 2.1 Hz, H-4′″), and 7.32 (1H, d, J = 2.1 Hz, H-2′″). In addition, there were two sets of meta-coupled aromatic protons at δ 7.09 (1H, brs, H-2″) and 7.09 (1H, brs, H-6″) and 7.36 (1H, d, J = 2.2 Hz, H-4′) and 7.37 (1H, d, J = 2.2 Hz, H-6′). Based on the 1H-1H COSY spectrum, four sets of allyl groups were found at δ 3.34 (2H, d, J = 6.7 Hz, H-7), 5.96 (1H, m, H-8), and 5.00 (2H, m, H-9); 3.51 (2H, d, J = 6.7 Hz, H-7′), 6.10 (1H, m, H-8′), and 5.14 (2H, m, H-9′); 3.39 (2H, d, J = 6.9 Hz, H-7″), 6.00 (1H, m, H-8″), and 5.03 (2H, m, H-9″); and 3.43 (2H, d, J = 6.7 Hz, H-7′″), 6.04 (1H, m, H-8′″), and 5.08 (2H, m, H-9′″). From the above spectroscopic data and the proposed biomimetic synthesis in prior studies [17], [18], [19], the chemical structure of 1 should be an o,o-/o,p-linked tetramer containing four C6-C3 subunits (moieties A–D shown in Figure 1). The connections of these moieties were further elucidated via 2D-correlational techniques, including HMBC and NOESY analyses. In the HMBC spectrum, 2J, 3J-correlations from δ 3.34 (H-7) to δ 128.9 (C-6), 131.4 (C-2), and 132.2 (C-1), from δ 3.51 (H-7′) to δ 128.6 (C-1′), 131.1 (C-6′), and 151.9 (C-2′), and from δ 6.88(H-5), 7.36 (H-4′), and 7.37 (H-6′) to δ 129.1 (C-3) indicated that subunits A and B were linked through C-3/C-5′ similarly to honokiol. In addition, the long range HMBC cross-peaks from δ 3.39 (H-7″) to δ 131.4 (C-2″), 131.4 (C-6″), and 133.2 (C-1″); from δ 3.43 (H-7′″) to δ 127.2 (C-1′″), 132.0 (C-2′″) and 155.2 (C-6′″); from δ 7.28 (H-4′″) to δ 131.8 (C-3″); and from δ 7.09 (H-2″) to δ 130.6(C-3′″) revealed that subunits C and D were also connected similarly to honokiol. The NOE correlations of H-2/H-7, H-7/H-6, OH-4/H-5 in subunit A; H-6′/H-7′ in subunit B; H-2″/H-7″, H-7″/H-6″ in subunit C; H-2′″/H-7′″, OH-6′″/H-5′″ in subunit D; H-2/H-4′ between subunits A and B; and H-4′/H-6″ between subunits B and C established the connectivity of the two honokiol fragments to be C-3′/C-5″, and the structure of 1 was determined conclusively, as shown in Figure 1. Compound 1 was named houpulin A.


Honokiol dimers and magnolol derivatives with new carbon skeletons from the roots of Magnolia officinalis and their inhibitory effects on superoxide anion generation and elastase release.

Shih HC, Hwang TL, Chen HC, Kuo PC, Lee EJ, Lee KH, Wu TS - PLoS ONE (2013)

Structures of 1–4.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646836&req=5

pone-0059502-g001: Structures of 1–4.
Mentions: Repeated silica gel and RP-C18 column chromatography of the dichloromethane-soluble fraction from the ethanol extract obtained from the roots of M. officinalis afforded four novel oligomeric neolignans (1–4) with new carbon skeletons. Compound 1 was obtained as optically active syrup. The positive-mode HR-ESI-MS of 1 showed a sodiated molecular ion peak at m/z 553.2357 ([M+Na]+), corresponding to a molecular formula of C36H34O4 with 20 indices of hydrogen deficiency (IHD). The absorption bands in the IR spectrum indicated the presence of hydroxy (3502 cm−1) and phenyl groups (1639 and 1504 cm−1). Analysis of the 13C NMR, DEPT135 and HMQC spectral data identified 36 carbon signals consistent with four oxygenated quaternary aromatic carbons at δ 155.2, 153.3, 151.9, and 149.6; eleven tertiary aromatic carbons at δ 132.0, 131.4, 131.4, 131.4, 131.3, 131.1, 131.0, 129.4, 128.9, 117.0 and 115.8; nine quaternary aromatic carbons at δ 133.2, 132.2, 131.8, 130.6, 129.1, 128.6, 127.6, 127.2, and 126.9; eight olefinic carbons at δ 139.3, 139.1, 138.1, 138.0, 115.8, 115.7, 115.6, and 115.5; and four aliphatic methylene carbons at δ 40.1, 40.1, 35.6, and 35.1. The 1H NMR spectrum of 1 displayed two sets of ABX-type aromatic signals at δ 6.88 (1H, d, J = 8.1 Hz, H-5), 7.00 (1H, dd, J = 8.1, 2.2 Hz, H-6), and 7.13 (1H, d, J = 2.2 Hz, H-2), as well as 6.91 (1H, d, J = 8.1 Hz, H-5′″), 7.28 (1H, dd, J = 8.1, 2.1 Hz, H-4′″), and 7.32 (1H, d, J = 2.1 Hz, H-2′″). In addition, there were two sets of meta-coupled aromatic protons at δ 7.09 (1H, brs, H-2″) and 7.09 (1H, brs, H-6″) and 7.36 (1H, d, J = 2.2 Hz, H-4′) and 7.37 (1H, d, J = 2.2 Hz, H-6′). Based on the 1H-1H COSY spectrum, four sets of allyl groups were found at δ 3.34 (2H, d, J = 6.7 Hz, H-7), 5.96 (1H, m, H-8), and 5.00 (2H, m, H-9); 3.51 (2H, d, J = 6.7 Hz, H-7′), 6.10 (1H, m, H-8′), and 5.14 (2H, m, H-9′); 3.39 (2H, d, J = 6.9 Hz, H-7″), 6.00 (1H, m, H-8″), and 5.03 (2H, m, H-9″); and 3.43 (2H, d, J = 6.7 Hz, H-7′″), 6.04 (1H, m, H-8′″), and 5.08 (2H, m, H-9′″). From the above spectroscopic data and the proposed biomimetic synthesis in prior studies [17], [18], [19], the chemical structure of 1 should be an o,o-/o,p-linked tetramer containing four C6-C3 subunits (moieties A–D shown in Figure 1). The connections of these moieties were further elucidated via 2D-correlational techniques, including HMBC and NOESY analyses. In the HMBC spectrum, 2J, 3J-correlations from δ 3.34 (H-7) to δ 128.9 (C-6), 131.4 (C-2), and 132.2 (C-1), from δ 3.51 (H-7′) to δ 128.6 (C-1′), 131.1 (C-6′), and 151.9 (C-2′), and from δ 6.88(H-5), 7.36 (H-4′), and 7.37 (H-6′) to δ 129.1 (C-3) indicated that subunits A and B were linked through C-3/C-5′ similarly to honokiol. In addition, the long range HMBC cross-peaks from δ 3.39 (H-7″) to δ 131.4 (C-2″), 131.4 (C-6″), and 133.2 (C-1″); from δ 3.43 (H-7′″) to δ 127.2 (C-1′″), 132.0 (C-2′″) and 155.2 (C-6′″); from δ 7.28 (H-4′″) to δ 131.8 (C-3″); and from δ 7.09 (H-2″) to δ 130.6(C-3′″) revealed that subunits C and D were also connected similarly to honokiol. The NOE correlations of H-2/H-7, H-7/H-6, OH-4/H-5 in subunit A; H-6′/H-7′ in subunit B; H-2″/H-7″, H-7″/H-6″ in subunit C; H-2′″/H-7′″, OH-6′″/H-5′″ in subunit D; H-2/H-4′ between subunits A and B; and H-4′/H-6″ between subunits B and C established the connectivity of the two honokiol fragments to be C-3′/C-5″, and the structure of 1 was determined conclusively, as shown in Figure 1. Compound 1 was named houpulin A.

Bottom Line: Two honokiol dimers, houpulins A and B (1 and 2), and two magnolol derivatives, houpulins C and D (3 and 4), were isolated and characterized from an ethanol extract obtained from the roots of Magnolia officinalis.These four oligomers possess new carbon skeletons postulated to be biosynthesized from the coupling of three or four C6-C3 subunits.In addition, the new oligomers were evaluated for inhibition of superoxide anion generation and elastase release, and houpulin B (2) was identified as a new anti-inflammatory lead compound.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, National Cheng Kung University, Tainan, Taiwan.

ABSTRACT
Two honokiol dimers, houpulins A and B (1 and 2), and two magnolol derivatives, houpulins C and D (3 and 4), were isolated and characterized from an ethanol extract obtained from the roots of Magnolia officinalis. The chemical structures were determined based on spectroscopic and physicochemical analyses, which included 1D and 2D NMR, as well as mass spectrometry data. These four oligomers possess new carbon skeletons postulated to be biosynthesized from the coupling of three or four C6-C3 subunits. In addition, the new oligomers were evaluated for inhibition of superoxide anion generation and elastase release, and houpulin B (2) was identified as a new anti-inflammatory lead compound.

Show MeSH
Related in: MedlinePlus