Novel monochlorinated metabolites with a 1-benzoxepin skeleton from Mycena galopus

Wijnberg, J. B. P. A.; Veldhuizen, A. van; Swarts, Hans J. M.; Frankland, Juliet C.; Field, Jim A.

doi:10.1016/s0040-4039(99)01074-6

Cited by 44 publications

(29 citation statements)

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“…To date, several 1-benzoxepin and 1-benzoxepinone derivatives have been isolated from Marsamiellus ramealis, 8 Mycena galopus 9 and Pterula species 10,11 as antibiotics or inhibitors of NADH. We evaluated the antimicrobial activity of compounds 1 and 2 by the conventional paper disk (Advantec, Tokyo, Japan; 8 mm in diameter) method 7 at a concentration of 50 mg per disk.…”

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confidence: 99%

Xylarinols A and B, two new 2-benzoxepin derivatives from the fruiting bodies of Xylaria polymorpha

et al. 2009

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Basidiomycetes, as decomposers of forest litter, represent an ecologically important group of organisms in the environment, and are known to produce a large variety of secondary metabolites with unique chemical structures and interesting biological activities. 1 The genus Xylaria has been known to produce a diverse class of bioactive compounds, including cytochalasin analogs with chemokine receptor antagonistic activity and cytotoxicity, 2 multiplolides A, B and xylariamide A with antifungal activity, 3,4 xylarenals A and B with neuropeptide Y receptor antagonistic activity 5 and xyloketals A-E, acetylcholinesterase inhibitors. 6 Earlier, we reported two antifungal substances, xylarinic acids A and B, from the methanolic extract of Xylaria polymorpha. 7 Our ongoing investigation for novel chemical constituents from X. polymorpha has resulted in the isolation of two new 2-benzoxepin derivatives with ABTS (2,2¢-azinobis(3-ethylbenzothiazoline-6-sulfonate)) radical scavenging activity. Benzoxepin is very rare in naturally occurring compounds. In this paper, we describe the isolation and structure determination of xylarinols A (1) and B (2), and their biological activity.Xylarinols were isolated from the fruiting bodies of X. polymorpha, as shown in Figure 1. The collected fruiting bodies were ground and then extracted twice with methanol (MeOH) at room temperature for 2 days. After removal of MeOH under reduced pressure, the concentrate was partitioned between chloroform and water and then ethyl acetate and water. The ethyl acetate-soluble portion was chromatographed on a column of silica gel and eluted with increasing amounts (2.0, 5.0, 10, 20 and 50%, stepwise) of MeOH in CHCl 3 to give two fractions, which exhibited moderate ABTS radical scavenging activity. One was purified by Sephadex LH-20 column chromatography with CHCl 3 -MeOH (1 : 1, v/v), followed by preparative reversed-phase HPLC with 40% aqueous MeOH at a flow rate of 6.0 ml min À1 to yield xylarinol A (1, 1.0 mg). The other fraction was purified by preparative reversed-phase HPLC with 30% aqueous MeOH at a flow rate of 6.0 ml min À1 to provide xylarinol B (2, 1.7 mg).Xylarinol A was isolated as a white powder and showed a molecular ion peak at m/z 176 in the electron impact mass measurement. Its high-resolution electron impact mass measurement provided an accurate mass at m/z 176.0472 [M + , DÀ0.1 mmu], establishing its molecular formula as C 10 H 8 O 3 . The UV spectrum in MeOH exhibited absorption maxima at 205 (log e 4.75), 217 (log e 4.63), 277 (log e 4.43) and 316 (log e 4.07) nm. The IR spectrum suggested the presence of a hydroxyl group (3444 cm À1 ) and an a,b-unsaturated ester group (1651 cm À1 ). The 1 H-NMR spectrum showed signals due to 1,2,3-trisubstituted benzene ring at d 7.28, 6.95 and 6.94, two olefinic methine peaks assigned to a cis-1,2-disubstituted double bond unit at d 7.31 (J¼12.0 Hz) and 6.29 (J¼12.0 Hz), and a methylene peak at d 5.24. In the 13 C-NMR spectrum, an ester carbonyl carbon at d 169.6, an oxygen-bearing sp 2 carbon...

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Xylarinols A and B, two new 2-benzoxepin derivatives from the fruiting bodies of Xylaria polymorpha

et al. 2009

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“…Compound E/Z-1 (0.5 mg), octanoic acid (10 µL) and (CH 3 ) 3 SiCl (2 µL) were heated at 80°C for 3 h. Then, (CH 3 ) 3 SiCl and the excess of octanoic acid were removed at 80°C at 0. (18) Benzyl Stearate: Stearic acid (100 mg), benzyl alcohol (0.5 mL) and (CH 3 ) 3 SiCl (10 µL) were heated at 130°C for 1 h. After removal of the benzyl alcohol in vacuo, the reaction product was purified on a silica gel column (10 ϫ 1 cm) with hexane/AcOEt (4:1) as eluent.…”

Section: Hydrolysis Of the Isolated Benzoxepinementioning

confidence: 99%

“…This Mycena species had already been screened for the presence of bioactive compounds in 1999 by Wijnberg et al, who identified the antifungal benzoxepines (pterulones) E/Z-1 and 3. [3] 6-Hydroxypterulone (3) is structurally closely related to pterulone, which was isolated by Anke et al from submerged cultures of the Pterula species 82168 in 1997.…”

Section: Introductionmentioning

confidence: 99%

Benzoxepine Esters as Precursors of the Wound‐Activated Chemical Defence of Mycena galopus

2008

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The native precursors E/Z‐1a to E/Z‐1e and 2a–2e of the antifungally active benzoxepines E/Z‐1 and 2 have been isolated from intact fruiting bodies of Mycena galopus. These precursors turned out to be fatty acid esters of the benzoxepines (pterulones) E/Z‐1 and 2. Metabolic profiling of ethyl acetate extracts from intact fruiting bodies, from the latex and from mechanically wounded fruiting bodies revealed that the known antifungally active benzoxepines E/Z‐1 and the previously unknown benzoxepines 2 are only present in injured fruiting bodies. Intact fruiting bodies and the latex, however, exclusively contain the corresponding ester derivatives E/Z‐1a to E/Z‐1e and 2a–2e. Unlike the antifungally active benzoxepines E/Z‐1 and 2, the esters E/Z‐1a to E/Z‐1e present in intact fruiting bodies turned out to be inactive. Upon injury the inactive esters E/Z‐1a to E/Z‐1e are cleaved by a putative esterase, and the bioactive benzoxepines E/Z‐1 and 2 are released, suggesting a wound‐activated defence mechanism of M. galopus against yeasts and parasitic fungi. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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“…Similarly, derivatives of oxabenzocycloheptatrienes occur in natural products [21,22] and are used as natural herbicides [23]. Hence, studying tautomerization and inversions of these biologically and pharmacologically interesting compounds provides an opportunity to disclose new aspects of their structural behavior [16][17][18][19][20][21][22][23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Effects of fused benzene rings on tautomerizations and inversions of benzo, azabenzo, and oxabenzocycloheptatrienes at theoretical levels

et al. 2009

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Biologically important bicyclic species, including 6H-, 6H-6-aza-, and 6-oxabenzocycloheptatrienes (in which the benzene moiety is fused meta with respect to the tetrahedral constituents: -CH 2 -, -NH-, and -O-, respectively), show strong shifts of tautomerizations in favor of the corresponding tricyclic benzonorcaradienes In contrast, such shifts are strongly disfavored by the isomeric bicyclic species in which the benzene moieties are fused ortho or para with respect to -CH 2 -, -NH-, and -O-, respectively. Hence for species with ortho benzene rings including 5H-, 5H-5-aza-and 5-oxabenzocycloheptatrienes, tautomerization DH values are 30.76, 31.89, and 25.27 kcal mol -1 , respectively, while for species with para fused benzene moieties including 7H-, 7H-7-aza-, and 7-oxabenzocycloheptatrienes, tautomerization DH values are 24.12, 26.00, and 19.55 kcal mol -1 , respectively. NICS calculations are successfully used to rationalize these results. The calculated energy barriers for inversion of the seven-membered rings of bicyclic species predict a dynamic nature for all the structures except for the virtually planar 6H-6-aza-and 6-oxabenzocycloheptatrienes. Finally, our theoretical data are compared to the experimental results where available.

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Novel monochlorinated metabolites with a 1-benzoxepin skeleton from Mycena galopus

Cited by 44 publications

References 11 publications

Xylarinols A and B, two new 2-benzoxepin derivatives from the fruiting bodies of Xylaria polymorpha

Xylarinols A and B, two new 2-benzoxepin derivatives from the fruiting bodies of Xylaria polymorpha

Benzoxepine Esters as Precursors of the Wound‐Activated Chemical Defence of Mycena galopus

Effects of fused benzene rings on tautomerizations and inversions of benzo, azabenzo, and oxabenzocycloheptatrienes at theoretical levels

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