New Furanones from the Plant Endophytic Fungus Pestalotiopsis besseyi

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 Structures of compounds 1–5.

The fermented material was freeze-dried and extracted with methyl ethyl ketone (3 × 500 mL), and the organic solvent was evaporated to dryness under vacuum to afford 5.0 g of crude extract. The extract was fractionated by silica gel column chromatography (5 × 40 cm) using CHCl₃–CH₃OH gradient elution. The fraction (50 mg) that was eluted with 1% MeOH was further separated by semipreparative reversed-phase HPLC (Kramosil C₁₈ column; 10-µm; 10 × 250 mm, 2 mL/min) to afford pestalafuranone B (2; 1.9 mg, t_R 15.3 min; 50% MeOH in H₂O over 2 min, 50–72% over 10 min, 72–74% over 13 min). The fraction (180 mg) that was eluted with 2% MeOH was then separated by Sephadex LH-20 column chromatography (CH₂Cl₂–n-C₆H₁₄ = 4:1) to afford six fractions. Fraction 3 (60 mg) was successively separated by semipreparative reversed-phase HPLC (32% MeOH in H₂O over 2 min, 32–55% over 60 min) afforded pestalafuranones A (1; 1.6 mg, t_R 25.7 min), C (3; 6.0 mg, t_R 26.6 min), D (4; 1.5 mg, t_R 30.0 min), and E (5; 3.5 mg, t_R 31.5 min).
Pestalafuranone A (1): colorless oil; UV (CH₃OH) λ_max 272 (ε 7800), 265 (ε 6600) nm; IR (Neat) ν_max 2962, 1748, 1717, 1448, 1364 cm⁻¹; ¹H- and ¹³C-NMR data, see Table 1 and Table 2; HRESIMS obsd. m/z 217.0840 [M+Na]⁺ (calcd for C₁₁H₁₄O₃Na, 217.0835).
Pestalafuranone B (2): pale yellow oil; [α]_D −16 (c 0.05, CH₃OH); UV (CH₃OH) λ_max 270 (ε 3300) nm; IR (Neat) ν_max 3403 (br), 2932, 1749, 1446 cm⁻¹; ¹H- and ¹³C-NMR data, see Table 1 and Table 2; HRESIMS obsd. m/z 217.0842 [M+Na]⁺ (calcd for C₁₁H₁₄O₃Na, 217.0835).
Pestalafuranone C (3): pale yellow oil; UV (CH₃OH) λ_max 265 (ε 6600), 235 (ε 4300) nm; IR (Neat) ν_max 2919, 1752, 1717, 1445, 1365 cm⁻¹; ¹H- and ¹³C-NMR data, see Table 1 and Table 2; HRESIMS obsd. m/z 219.0998 [M+Na]⁺ (calcd for C₁₁H₁₆O₃Na, 219.0992).
Pestalafuranone D (4): colorless oil; [α]_D +32 (c 0.05, CH₃OH); UV (CH₃OH) λ_max 275 (ε 4460) nm; IR (Neat) ν_max 2963, 1751, 1450, 1381 cm⁻¹; ¹H- and ¹³C-NMR data, see Table 1 and Table 2; HRESIMS obsd. m/z 217.0846 [M+Na]⁺ (calcd for C₁₁H₁₄O₃Na, 217.0835).
Pestalafuranone D (5): colorless oil; [α]_D +16 (c 0.05, CH₃OH); UV (CH₃OH) λ_max 275 (ε 6270) nm; IR (Neat) ν_max 2931, 1753, 1446, 1346 cm⁻¹; ¹H- and ¹³C-NMR data, see Table 1 and Table 2; HRESIMS obsd. m/z 219.0995 [M+Na]⁺ (calcd for C₁₁H₁₆O₃Na, 219.0992).

Molecules 2012, 17(12), 14015-14021; doi:10.3390/molecules171214015

 New Furanones from the Plant Endophytic Fungus Pestalotiopsis besseyi
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