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Meroterpenes from endophytic fungus A1 of mangrove plant Scyphiphora hydrophyllacea.

Mei WL, Zheng B, Zhao YX, Zhong HM, Chen XL, Zeng YB, Dong WH, Huang JL, Proksch P, Dai HF - Mar Drugs (2012)

Bottom Line: Four new meroterpenes, guignardones F-I (1-4), together with two known compounds guignardones A (5) and B (6) were isolated from the endophytic fungus A1 of the mangrove plant Scyphiphora hydrophyllacea.A possible biogenetic pathway of compounds 1-6 was also proposed.All compounds were evaluated for inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agriculture Sciences, Haikou 571101, China. meiwenli@itbb.org.cn

ABSTRACT
Four new meroterpenes, guignardones F-I (1-4), together with two known compounds guignardones A (5) and B (6) were isolated from the endophytic fungus A1 of the mangrove plant Scyphiphora hydrophyllacea. Their structures and relative configurations were elucidated by spectroscopic data and single-crystal X-ray crystallography. A possible biogenetic pathway of compounds 1-6 was also proposed. All compounds were evaluated for inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus.

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Selected ROESY correlations of 2–4.
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marinedrugs-10-01993-f003: Selected ROESY correlations of 2–4.

Mentions: Guignardone G (2) was obtained as a colorless oil. Its molecular formula was determined as C16H22O4 from [M]+ ion peak at m/z 278.1513 in the HREIMS, with six degrees of unsaturation. IR absorptions implied the presence of hydroxyl (3440 cm−1), conjugated carbonyl (1653 cm−1) and double bond (1622 cm−1) groups. The 13C NMR and DEPT spectra (Table 1) revealed 16 carbon signals, including one α,β-unsaturated carbonyl group, one terminal double bond, one oxygenated quaternary carbon, four methines (two oxygenated), four methylenes, and two methyls. Apart from one carbonyl and two double bonds, the remaining degrees of unsaturation indicated that 2 possessed a tricyclic system. Detailed analysis of its 1H NMR and 13C NMR spectra showed that compound 2 was analogous to guignardone A (5) [10], except for the absence of a methylene (C-7), a quaternary carbon (C-6) in 5 and the presence of a methine (C-6) in 2. In addition, the 13C NMR signals of C-4 upshifted from δC 78.5 to δC 66.7 and C-5 from δC 44.0 to δC 36.9. Base on the above evidence, it was supposed that the C-7 of 5 was degraded and the corresponding ring was broken to form the structure of 2, which was confirmed by 2D NMR experiments. The relative configuration of 2 was assigned by a ROESY experiment and comparison with 5. H-9 (δH 1.95) showed correlations to both H3-11 (δH 1.32) and H2-16 (δH 4.64), which indicated that when H-9 and CH3-11 possess α-orientation, H-14 (δH 2.27) will possess β-orientation, as in accordance with the relative configuration of 5 (Figure 3). The α-orientation of H-4 (δH 4.35) was also tentatively established as same as that of 5 for the biogenetic pathway consideration. H-6 (δH 4.48, dd, J = 11.9, 5.4 Hz) exhibited ROESY correlation with H-4, and the large vicinal coupling constant (J = 11.9 Hz) established the pseudoaxial position for H-6. So H-6 was established as α-oriented. Thus, the structure of 2 was established and named guignardone G.


Meroterpenes from endophytic fungus A1 of mangrove plant Scyphiphora hydrophyllacea.

Mei WL, Zheng B, Zhao YX, Zhong HM, Chen XL, Zeng YB, Dong WH, Huang JL, Proksch P, Dai HF - Mar Drugs (2012)

Selected ROESY correlations of 2–4.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475268&req=5

marinedrugs-10-01993-f003: Selected ROESY correlations of 2–4.
Mentions: Guignardone G (2) was obtained as a colorless oil. Its molecular formula was determined as C16H22O4 from [M]+ ion peak at m/z 278.1513 in the HREIMS, with six degrees of unsaturation. IR absorptions implied the presence of hydroxyl (3440 cm−1), conjugated carbonyl (1653 cm−1) and double bond (1622 cm−1) groups. The 13C NMR and DEPT spectra (Table 1) revealed 16 carbon signals, including one α,β-unsaturated carbonyl group, one terminal double bond, one oxygenated quaternary carbon, four methines (two oxygenated), four methylenes, and two methyls. Apart from one carbonyl and two double bonds, the remaining degrees of unsaturation indicated that 2 possessed a tricyclic system. Detailed analysis of its 1H NMR and 13C NMR spectra showed that compound 2 was analogous to guignardone A (5) [10], except for the absence of a methylene (C-7), a quaternary carbon (C-6) in 5 and the presence of a methine (C-6) in 2. In addition, the 13C NMR signals of C-4 upshifted from δC 78.5 to δC 66.7 and C-5 from δC 44.0 to δC 36.9. Base on the above evidence, it was supposed that the C-7 of 5 was degraded and the corresponding ring was broken to form the structure of 2, which was confirmed by 2D NMR experiments. The relative configuration of 2 was assigned by a ROESY experiment and comparison with 5. H-9 (δH 1.95) showed correlations to both H3-11 (δH 1.32) and H2-16 (δH 4.64), which indicated that when H-9 and CH3-11 possess α-orientation, H-14 (δH 2.27) will possess β-orientation, as in accordance with the relative configuration of 5 (Figure 3). The α-orientation of H-4 (δH 4.35) was also tentatively established as same as that of 5 for the biogenetic pathway consideration. H-6 (δH 4.48, dd, J = 11.9, 5.4 Hz) exhibited ROESY correlation with H-4, and the large vicinal coupling constant (J = 11.9 Hz) established the pseudoaxial position for H-6. So H-6 was established as α-oriented. Thus, the structure of 2 was established and named guignardone G.

Bottom Line: Four new meroterpenes, guignardones F-I (1-4), together with two known compounds guignardones A (5) and B (6) were isolated from the endophytic fungus A1 of the mangrove plant Scyphiphora hydrophyllacea.A possible biogenetic pathway of compounds 1-6 was also proposed.All compounds were evaluated for inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agriculture Sciences, Haikou 571101, China. meiwenli@itbb.org.cn

ABSTRACT
Four new meroterpenes, guignardones F-I (1-4), together with two known compounds guignardones A (5) and B (6) were isolated from the endophytic fungus A1 of the mangrove plant Scyphiphora hydrophyllacea. Their structures and relative configurations were elucidated by spectroscopic data and single-crystal X-ray crystallography. A possible biogenetic pathway of compounds 1-6 was also proposed. All compounds were evaluated for inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus.

Show MeSH
Related in: MedlinePlus