title: Monophosphoryl lipid A analogues with varying 3-O-substitution: synthesis and potent adjuvant activity.
abstract: Structurally defined immunostimulatory adjuvants play important roles in the development of new generation vaccines. Here described are the syntheses of three monophosphoryl lipid A analogues (1-3) with different substitution at 3-O-position of the reducing sugar and their potent immunostimulatory adjuvant activity. The syntheses involve the preparation of glycosylation acceptors benzyl 3,4-di-O-benzyl-2-deoxy-2-[(R)-3-tetradecanoyloxytetradecanamido]-beta-D-glucopyranoside (16) and benzyl 3-O-allyl-4-O-benzyl-2-deoxy-2-[(R)-3-tetradecanoyloxytetradecanamido]-beta-D-glucopyranoside (17). The glycosylation reactions between the donor 4,6-di-O-benzylidene-2-deoxy-2-(2',2',2'-trichloroethoxycarbonylamino)-alpha-d-glucopyranosyl trichloroacetimidate (21) and acceptors 16 and 17 provide the desired beta-(1-->6)-linked disaccharides 22 and 23, respectively. Selective reductive ring opening of the 4,6-di-O-benzylidene group, installation of a phosphate group to the 4'-hydroxyl group, and the final global debenzylation produce the designed monophosphoryl lipid A analogues 1-3. All three synthetic analogues induce antigen specific T-cell proliferation and interferon-gamma (IFN-gamma) production in ex vivo experiments with a totally synthetic liposomal vaccine system. The immunostimulatory potency of compound 1-3 is in the same order of magnitude as that of the detoxified natural lipid A product isolated from Salmonella minnesota R595 (R595 lipid A). The substituent at the 3-O-position of the reducing sugar does not have much effect on the adjuvant activity of monophosphoryl lipid A analogues. The preliminary lethal toxicity study indicates that the 3-O-acylated hepta-acyl monophosphoryl lipid A may not be more toxic than its 3-O-deacylated hexa-acyl analogue.
authors.affiliation: Biomira Inc., 2011-94 Street, Edmonton, Alberta, Canada T6N 1H1. zjiang@lakeheadu.ca
authors.forename: Zi-Hua
authors.initials: ZH
authors.lastname: Jiang
authors.forename: Wladyslaw A
authors.initials: WA
authors.lastname: Budzynski
authors.forename: Dongxu
authors.initials: D
authors.lastname: Qiu
authors.forename: Damayanthi
authors.initials: D
authors.lastname: Yalamati
authors.forename: R Rao
authors.initials: RR
authors.lastname: Koganty
mesh_terms: D000276:Adjuvants, Immunologic / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D002236:Carbohydrate Conformation; D049109:Cell Proliferation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D007371:Interferon-gamma / Q000276:immunology; D008050:Lipid A / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D051379:Mice; D015394:Molecular Structure; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D018675:Toxicity Tests
chemical_list: D000276:Adjuvants, Immunologic; D008050:Lipid A; D007371:Interferon-gamma; C048436:monophosphoryl lipid A