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the crude residue (CHCl3/MeOH, 100:0 to 95:5 v/v) gave 17
(56.2 mg, 42% overall yield from 3) as a colorless oil.
Hexanoic anhydride: DCC (89 mg, 430 mmol) was added to a solu-
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Lipid A derivative (18): Hexanoic anhydride (92 mg, 429 mmol) and
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(3 mL). The mixture was stirred at RT for 16 h; then it was trans-
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washed with brine. The combined organic layers were dried over
anhydrous Na2SO4, filtered and concentrated. To a solution of the
crude acylated product (25 mg) was added a solution of TBAF
(11 mL, 1m in THF) and the mixture was stirred at RT for 48 h. The
solvent was then removed under reduced pressure. Chromatogra-
phy of the crude residue over silica gel (CHCl3/MeOH, 100:0 to
85:15 v/v) provided lipid A derivative 18 (12 mg, 31% overall yield
over two steps) as a colorless oil.
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Lipid A derivative (19): Under the same conditions reported for
the synthesis of 18, lipid A derivative 19 (12 mg, 9 mmol) was ob-
tained from TBDPS ether 17 (29 mg, 17 mmol) after acylation of the
latter (hexanoic anhydride, 14 mg, 66 mmol; DMAP, 0.2 mg, 2 mmol)
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Immunological assays: Immunological activities were evaluated
by stimulating the human monocytic leukemia cell line THP-
1 (ATCC TIB-202).[19] Briefly, monocytic THP-1 cells (LGC, Promo-
chem, Milan, Italy) were grown in suspension in RPMI 1640
medium supplemented with 10% fetal bovine serum at 378C in
a humidified incubator with a 5% CO2 atmosphere and stimulated
with the lipid A derivatives at 20 mgmLꢀ1. LPS form E. coli O111:B4
(Sigma, Milan, Italy) and MPLA from S. Minnesota R595 (Avanti
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trols. Mabtech’s ELISAPRO kits and Enzo Life Science EIA Kit (BioRad,
Milan, Italy) were used to quantify IL-6, IL-8 and TNF-a production
in tissue-culture supernatants, following manufacturer’s instruc-
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This research was supported by the Ministero dell’Istruzione
dell’Universitꢄ e della Ricerca (MIUR), project PON01_00117
“Antigeni e adiuvanti per vaccini e immunoterapia”. The au-
thors thank BioTekNet for the use of 600 MHz NMR spectrome-
ter.
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Keywords: carbohydrates · glycolipids · immunology · lipids ·
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