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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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The ORTEP view of compound 1.
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marinedrugs-10-01993-f004: The ORTEP view of compound 1.

Mentions: Guignardone F (1) was isolated as colorless needle crystals, and possessed a molecular formula of C17H24O5 as established by HREIMS (m/z 308.1625 [M]+), indicating six degrees of unsaturation. The IR spectrum displayed hydroxyl (3463 cm−1), conjugated carbonyl (1657 cm−1) and double bond (1606 cm−1) absorptions. In the 13C NMR and DEPT spectra (Table 1), a total of 17 carbon resonances were found and classified into three methyls, five methylenes (one oxygenated), three methines (one oxygenated), and six quaternary carbons (one α,β-unsaturated carbonyl unit, three oxygenated). In the HMBC spectrum (Figure 2), the correlations from H2-8 (δH 3.03, 1.92) to C-1 (δC 200.2), C-2 (δC 114.7), and C-3 (δC 173.9), from H-4 (δH 4.46) to C-2 and C-6 (δC 81.8), from H2-5 (δH 2.31, 1.91) to C-1 and C-3, and from H2-7 (δH 3.80, 3.45) to C-4 (δC 81.3), C-5 (δC 42.5), and C-6 were found and led to the establishment of partial structure 1a, which was identical to that of guignardone B (6) [10]. In the 1H-1H COSY spectrum, a proton spin system (H-8/H-9/H-14/H-13/H-12) was found as drawn with bond lines in Figure 2. In addition, the HMBC cross-peaks from H3-11 (δH 1.35) to C-9 (δC 46.1), C-10 (δC 80.5), and C-12 (δC 39.3), and from both H3-16 (δH 1.17) and H3-17 (δH 1.45) to C-14 (δC 54.1) and C-15 (δC 86.9) determined the establishment of substructure 1b. Careful comparison of the 13C NMR data of 1 with those of 6, the upfield shift of C-10 (Δ −10.2 ppm) and the downfield shift of C-15 (Δ +14.0 ppm) were observed. So it was proposed that C-3 connected with C-15 via an ether bond to form a seven-membered ring in 1, instead of the C-3 connected with C-10 via an ether bond to form a six-membered ring in 6. This also gave a good explanation for the obvious difference (Δ 10.8 ppm) of chemical shifts between the 16-CH3 and the 17-CH3, since their stereochemistry circumstance was quite different in the structure of 1. Thus, the gross structure of 1 was elucidated and further confirmed by X-ray crystallography which also established its relative configuration (Chart 1). Therefore, the structure of 1 was established as shown in Figure 1, named Guignardone F (1).


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)

The ORTEP view of compound 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

marinedrugs-10-01993-f004: The ORTEP view of compound 1.
Mentions: Guignardone F (1) was isolated as colorless needle crystals, and possessed a molecular formula of C17H24O5 as established by HREIMS (m/z 308.1625 [M]+), indicating six degrees of unsaturation. The IR spectrum displayed hydroxyl (3463 cm−1), conjugated carbonyl (1657 cm−1) and double bond (1606 cm−1) absorptions. In the 13C NMR and DEPT spectra (Table 1), a total of 17 carbon resonances were found and classified into three methyls, five methylenes (one oxygenated), three methines (one oxygenated), and six quaternary carbons (one α,β-unsaturated carbonyl unit, three oxygenated). In the HMBC spectrum (Figure 2), the correlations from H2-8 (δH 3.03, 1.92) to C-1 (δC 200.2), C-2 (δC 114.7), and C-3 (δC 173.9), from H-4 (δH 4.46) to C-2 and C-6 (δC 81.8), from H2-5 (δH 2.31, 1.91) to C-1 and C-3, and from H2-7 (δH 3.80, 3.45) to C-4 (δC 81.3), C-5 (δC 42.5), and C-6 were found and led to the establishment of partial structure 1a, which was identical to that of guignardone B (6) [10]. In the 1H-1H COSY spectrum, a proton spin system (H-8/H-9/H-14/H-13/H-12) was found as drawn with bond lines in Figure 2. In addition, the HMBC cross-peaks from H3-11 (δH 1.35) to C-9 (δC 46.1), C-10 (δC 80.5), and C-12 (δC 39.3), and from both H3-16 (δH 1.17) and H3-17 (δH 1.45) to C-14 (δC 54.1) and C-15 (δC 86.9) determined the establishment of substructure 1b. Careful comparison of the 13C NMR data of 1 with those of 6, the upfield shift of C-10 (Δ −10.2 ppm) and the downfield shift of C-15 (Δ +14.0 ppm) were observed. So it was proposed that C-3 connected with C-15 via an ether bond to form a seven-membered ring in 1, instead of the C-3 connected with C-10 via an ether bond to form a six-membered ring in 6. This also gave a good explanation for the obvious difference (Δ 10.8 ppm) of chemical shifts between the 16-CH3 and the 17-CH3, since their stereochemistry circumstance was quite different in the structure of 1. Thus, the gross structure of 1 was elucidated and further confirmed by X-ray crystallography which also established its relative configuration (Chart 1). Therefore, the structure of 1 was established as shown in Figure 1, named Guignardone F (1).

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