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ACCEPTED MANUSCRIPT
3.2. Evaluation of the inhibitory activity of mupirocin H for SbnE
To a solution of 17 (380 mg, 1.48 mmol) in toluene (1 mL)
under N2 was added 14 (100 mg, 0.2 mmol) in toluene (1 mL).
A
modified malachite green assay was employed for
Grubbs’ II catalyst (50 mg) was added to the mixture which was
o
evaluation of the inhibitory activity of mupirocin H against
SbnE,23 a NRPS-independent siderophore synthetase,. To an
Eppendorf tube containing 25 mM HEPES, 5 mM MgCl2, 100
µM ATP, 100 µM sodium citrate, 100 µM L-DAP, and 0.001
U/µL inorganic pyrophosphatase (IPP) was added mupirocin H to
a final concentration of 50 µM (total volume was 100 µL).
DMSO vehicle was used as negative control. The reaction was
initiated by addition of SbnE (20 nM) at 37 ºC. The mixture was
incubated for 1 h before addition of 25 µL of a quenching
solution composed of 50 parts of malachite green solution, 12.5
parts of 7.5% ammonium molybdate, and 1 part of 11% Tween-
20 solution. After incubation at 37 ºC for an additional15 min,
100 µL aliquot of each mixture was loaded in a 96-well clear
bottom plate and the absorbance at 630 nm was measured using a
Hidex Sense microplate reader (Hidex, Finland). A mixture
containing the same components except for SbnE was used as a
positive control. Data were collected in duplicate.
then heated at 110 C for 24 h. The mixture was concentrated
under reduced pressure and the residue was subjected to silica gel
column chromatography to afford compound 18 (125 mg, 95%)
as a colourless liquid. Rf = 0.8 (5% EtOAc/hexane); [α]24D -6.3 (c
1
1.7, CHCl3); IR (KBr): 2958, 2858, 1633, 1254, 1100 cm-1; H
NMR (400 MHz, CDCl3): δ 5.36-5.30 (m, 2H), 4.09-4.03 (m,
1H), 3.94-3.81 (m, 2H), 3.67-3.57 (m, 2H), 3.41 (t, J = 5.4 Hz,
1H), 2.37-2.23 (m, 1H), 2.01-1.91 (m, 1H), 1.85-1.65 (m, 4H),
1.42 (s, 6H), 1.09-1.02 (m, 21H), 0.99 (d, J = 6.9 Hz, 3H), 0.91-
0.87 (m, 27H), 0.09 (d, J = 5.5 Hz, 6H), 0.06 (d, J = 4.5 Hz, 6H);
13C NMR (100 MHz, CDCl3): δ 134.2, 128.9, 98.2, 78.8, 77.9,
77.2, 69.6, 60.0, 44.2, 35.9, 30.1, 29.7, 26.2, 20.6, 19.4, 18.5,
18.2, 16.8, 14.3, -3.5, -3.9; HRMS (ESI): calcd. for
C25H52O4Si2Na [M + Na]+ 723.5211; found 723.5204.
3.1.17.
(4S,5R,6R,10R,11S,E)-6,10-Dimethyldodec-8-ene-
1,3,4,5,11-pentaol (19)
To a solution of 18 (100 mg, 0.15 mmol) in methanol (2 mL)
was added PPTS (200 mg) and the resulting mixture was stirred
for 4 h and concentrated under reduced pressure. The residue was
diluted with EtOAc (5 mL) and washed with water (2 mL) and
brine solution successively, and then extracted with EtOAc (4 × 5
mL). The combined organic layers were dried over MgSO4 and
concentrated under reduced pressure. The residue was subjected
to silica gel column chromatography to afford 19 (30 mg, 85%)
as a sticky colorless oil. Rf = 0.2 (10% MeOH/CHCl3); [α]27D ˗9.6
(c 0.2, CHCl3); IR (KBr): 3451, 2085, 1635, 564 cm-1; 1H NMR
(400 MHz, CDCl3): δ 5.40-5.24 (m, 2H), 3.82-3.77 (m, 1H),
3.71-3.59 (m, 2H), 3.55-3.47 (m, 1H), 3.43 (dd, J = 8.8, 5.0 Hz,
1H), 3.33 (dd, J = 8.8, 2.8 Hz, 1H), 2.24-2.17 (m, 1H), 2.07-2.01
(m, 1H), 1.96-1.87 (m, 1H), 1.86-1.70 (m, 2H), 1.63-1.55 (m,
1H), 0.99 (d, J = 6.2 Hz, 3H), 0.88 (d, J = 6.8 Hz, 3H), 0.87 (d, J
= 6.7 Hz, 3H); 13C NMR (100 MHz, CDCl3): δ 134.4, 131.4, 78.3,
74.9, 72.5, 72.2, 60.3, 45.3, 36.0, 35.1, 34.2, 20.2, 17.2, 16.5;
HRMS (ESI): calcd. for C14H28O5Na [M + Na]+ 299.1834; found
299.1836.
Acknowledgements
This work was supported by Korea Institute of Science and
Technology (KIST), and the KU-KIST Graduate School of
Converging Science and Technology Program, and KRF (Korea
Research Fellowship) program and
2015R1D1A1A01056815) of the National Research Foundation
of Korea.
a
grant (NRF-
References and notes
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2. (a) O’Hanlon, P. J.; Rogers, N. H.; Tyler, J. W. J. Chem. Soc., Perkin
Trans. 1 1983, 2655. (b) Badder, A.; Garre, C. Corresp.-Bl.
Schweiz. Aerzte 1887, 17, 385.
3. El Sayed, A. K.; Hothersall, J.; Cooper, S. M.; Stephens, E.; Simpson,
T. J.; Thomas, C. M. Chem. Biol. 2003, 10, 419. For a recent
review see: Piel, J. Nat. Prod. Rep. 2010, 27, 996.
4. (a) Wu, J.; Cooper, S. M.; Cox, R. J.; Crosby, J.; Hothersall, J.;
Simpson, T. J.; Thomas, C. M.; Willis, C. L. Chem. Commun.
2007, 2040. (b) Cooper, S. M.; Cox, R. J.; Crosby, J.; Crump, M.
P.; Hothersall, J.; Laosripaiboon, W.; Simpson, T. J.; Thomas, C.
M. Chem. Commun. 2005, 1179.
5. (a) Udawant, S. P.; Chakraborty, T. K. J. Org. Chem. 2011, 76, 6331.
(b) Scott, R. W.; Mazzetti, C.; Simpson, T. J.; Willis, C. L. Chem.
Commun. 2012, 48, 2639. (c) Wu, J.; Hothersall, J.; Mazzetti, C.;
O’Connell, Y.; Shields, J. A.; Rahman, A. S.; Cox, R. J.; Crosby,
J.; Simpson, T. J.; Thomas, C. M.; Willis, C. L. ChemBioChem.
2008, 9, 1500. (d) Mckay, C.; Simpson, T. J.; Willis, C. L.;
Forrest, A. K.; O’Hanlon, P. J. Chem. Commun. 2000, 1109. (e)
Zhao, C.; Yuan, Z.; Zhang, Y.; Ma, B.; Li, H.; Tang, S.; Xie, X.;
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Eur. J. Org. Chem. 2014, 5063. (g) Srihari, P.; Hari Krishna, N.;
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37629.
6. (a) Chakraborty, T. K.; Goswami, R. K. Tetrahedron Lett. 2006, 47,
4917. (b) Ireland, R. E.; Highsmith, T. K.; Gegnas, L. D.; Gleason,
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7. (a) Omura, K.; Swern, D. Tetrahedron 1978, 34, 1651. (b) Mancuso,
A. J.; Huang, S. L.; Swern, D. J. Org. Chem. 1978, 43, 2480. (c)
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8. (a) Clark Still, W.; Gennari, C. Tetrahedron Lett. 1983, 24, 41, 4405.
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D.; Hunter, T. J.; O’Doherty, G. A. J. Org. Chem. 2002, 67, 2682.
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2443. d) Yadav, J. S.; Sathaiah, K.; Srinivas, R. Tetrahedron
3.1.18.
(4S,5S)-5-((1R,2R,6R,7S,E)-1,7-Dihydroxy-2,6-
dimethyloct-4-enyl)-4-hydroxydihydrofuran-2(3H)-one
(Mupirocin H)
(1)
To a solution of pentaol 19 (20 mg, 0.07 mmol) in
CH3CN:H2O (3:2, 2 mL) was added BAIB (45 mg, 0.14 mmol)
followed by catalytic TEMPO at room temperature. The mixture
was stirred for 5 h at the same temperature, diluted with EtOAc
(5 mL) and water (5 mL), and then extracted with EtOAc (3 × 10
mL). The combined organic layers were dried over MgSO4 and
concentrated under reduced pressure. The residue was subjected
to silica gel column chromatography to afford mupirocin H (1)
(10 mg, 55%) as a colorless oil. Rf = 0.3 (10% MeOH/CHCl3);
[α]24 +28.7 (c 0.5, CHCl3 (lit. [α]24 +30.5, c 1.3, CHCl3)); IR
D
D
(KBr): 3407, 2960, 2922, 2853, 1742, 1668, 1457, 1376, 1259,
1
1195, 1070 cm-1; H NMR (400 MHz, CDCl3): δ 5.60 (ddd, J =
14.9, 8.4, 6.0 Hz, 1H), 5.38 (dd, J = 15.4, 8.6 Hz, 1H), 4.59 (m,
1H), 4.41 (dd, J = 5.6, 3.4 Hz, 1H), 3.58 (dd, J = 6.6, 6.2 Hz, 1H),
3.51 (m, 1H), 2.93 (dd, J = 18.1, 7.5 Hz, 1H), 2.51 (dd, J = 18.1,
4.4 Hz, 1H), 2.34-2.18 (m, 2H), 2.10-1.99 (m, 1H), 1.93-1.84 (m,
1H), 1.18 (d, J = 6.3 Hz, 3H), 1.03 (d, J = 7.0 Hz, 3H), 0.98 (d, J
= 6.8 Hz, 3H); 13C NMR (100 MHz, CDCl3): δ 175.3, 135.0,
129.5, 87.2, 75.7, 71.5, 68.8, 45.3, 38.2, 35.4, 34.8, 20.7, 16.8,
16.0; HRMS (ESI): calcd. for C14H24O5Na [M + Na]+ 295.1521;
found 295.1535.