David J. Burkhart

PEG modified liposomes containing CRX-601 adjuvant in combination with methylglycol chitosan enhance the murine sublingual immune response to influenza vaccination

The mucosa is the primary point of entry for pathogens making it an important vaccination site to produce a protective mucosal immune response. While the sublingual (SL) mucosa presents several barriers to vaccine penetration, its unique anatomy and physiology makes it one of the best options for mucosal vaccination. Efficient and directed delivery of adjuvants and antigens to appropriate immune mediators in the SL tissue will aid in development of effective SL vaccines against infectious diseases. Herein we demonstrate a robust immune response against influenza antigens co-delivered sublingually with engineered liposomes carrying the synthetic Toll-like receptor-4 agonist, CRX-601. Liposome modification with PEG copolymers (Pluronics), phospholipid-PEG conjugates and chitosan were evaluated for their ability to generate an immune response in a SL murine influenza vaccine model. Phospholipid-PEG conjugates were more effective than Pluronic copolymers in generating stable, surface neutral liposomes. SL vaccination with surface modified liposomes carrying CRX-601 adjuvant generated significant improvements in flu-specific responses compared with unmodified liposomes. Furthermore, the coating of modified liposomes with methylglycol chitosan produced the most effective flu-specific immune response. These results demonstrate efficient SL vaccine delivery utilizing a combination of a muco-adhesive and surface neutral liposomes to achieve a robust mucosal and systemic immune response.

An improved procedure for the lateral lithiation of ethyl 4-acetyl-5-methyl-3-isoxazolyl carboxylate

Abstract Ethyl 4-acetyl-5-methyl-3-isoxazolyl carboxylate was smoothly lithiated at the 5-methyl position, when the 4-acetyl group was protected with a 5,5-dimethyl-1,3-dioxanyl group. The lithio anion was quenched with a variety of electrophiles such as alkyl halides, aldehydes, TMSCl, and Me3SnCl in good to excellent yields. The lithiation of the unprotected compound and the 4-acetyl group protected as 1,3-dioxolanyl both failed. The effects of different bases have been investigated and the addition of LiCl significantly increased yields. Based on variable temperature NMR studies the 5,5-dimethyl-1,3-dioxanyl group appears to occupy a single chair conformation which may facilitate lateral metalation. This represents a facile entry into 5-functionalized 3-isoxazolyl carboxylic acid derivatives as prodrugs for the AMPA glutamate neurotransmitters of the central nervous system.

A new direct synthesis of ACPA and novel AMPA analogues

Abstract A novel synthesis of the potent glutamate neurotransmitter agonist (RS)-2-amino-3-(3-carboxy-5-methyl-4-isoxazolyl) propionic acid (ACPA) provides access to numerous analogues as drug candidates for neurological disorders. The one-pot synthesis of an alpha amino phosphonate from aldehyde 4 was successful using ErCl3 as a catalyst. Molecular modeling of the new amino phosphonic acid with the (RS)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl) propionic acid (AMPA) receptor crystal structure suggests this should be an effective receptor binder.

Synthesis and Biological Characterization of Protease-Activated Prodrugs of Doxazolidine

Doxazolidine (doxaz) is a new anthracycline anticancer agent. While structurally similar to doxorubicin (dox), doxaz acts via a distinct mechanism to selectively enhance anticancer activity over cardiotoxicity, the most significant clinical impediment to successful anthracycline treatment. Here, we describe the synthesis and characterization of a prodrug platform designed for doxaz release mediated by secreted proteolytic activity, a common association with invasiveness and poor prognosis in cancer patients. GaFK-Doxaz is hydrolyzable by the proteases plasmin and cathepsin B, both strongly linked with cancer progression, as well as trypsin. We demonstrate that activation of GaFK-Doxaz releases highly potent doxaz that powerfully inhibits the growth of a wide variety of cancer cells (average IC(50) of 8 nM). GaFK-Doxaz is stable in human plasma and is poorly membrane permeable, thereby limiting activation to locally secreted proteolytic activity and reducing the likelihood of severe side effects.

The structure-based design of novel AMPA bioisosteres

AbstractThe reaction of 4-acetyl-5-methyl-3-isoxazolyl carboxylate with a variety of hydrazines and semicarbazides yielded molecules which are viable antagonist candidates for the AMPA receptor. Molecular modeling studies used in conjunction with the x-ray crystal structures of these derivatives show a close correlation between the hydrogen bonding characteristics of AMPA with that of the hydrazone and semicarbazone isoxazole derivatives. Uncyclized hydrazones and semicarbazones (1–5) were formed by using corresponding hydrazines and semicarbazides containing strong electron withdrawing groups to prevent cyclization with the ethyl ester. The crystals of 1 are orthorhombic with a = 14.2997(3), b = 15.4112(4),c = 16.0153(4) Å, Z = 8, and space group Pbca;2 monoclinic with a = 19.738(2), b = 10.4155(7), c = 15.583(1) Å, β = 92.348(2)°, Z = 8, and space group C2/c;3 triclinic with a = 8.3365(5), b = 8.4930(5), c = 12.2379(7) Å, α = 92.568(2), β = 102.229(2), γ = 104.449(1)°, Z = 2, and space group P

Methods to monitor monocytes-mediated amyloid-beta uptake and phagocytosis in the context of adjuvanted immunotherapies.

\bar 1

Doxorubicin-formaldehyde conjugates targeting alphavbeta3 integrin.

.

Design, Synthesis, and Preliminary Evaluation of Doxazolidine Carbamates as Prodrugs Activated by Carboxylesterases

Influenza is a vaccine-preventable contagious respiratory illness caused by influenza (flu) viruses which can lead to hospitalization and sometimes even death. Current flu vaccines delivered intramuscularly (IM) or intradermally (ID) are less effective at eliciting protective mucosal immune responses and vaccines delivered intranasally (IN) possess potential safety concerns. Sublingual (SL) vaccination is a promising alternative route for vaccine delivery which has been indicated as safe and effective at inducing protective immune responses in both systemic and mucosal compartments. We evaluated the efficacy of methylglycol chitosan (MGC) and a synthetic toll-like receptor 4 agonist (CRX-601), alone or in combination, for improving systemic and mucosal immune responses to a monovalent detergent-split flu virus vaccine delivered SL. SL vaccination of mice with split-flu vaccine formulated with either MGC or CRX-601 resulted in specific serum IgG and mucosal IgA titers that were significantly greater than titers from non-adjuvanted vaccination and equivalent to or greater than titers in mice vaccinated IM. Our results demonstrate that SL vaccination utilizing MGC or CRX-601 as adjuvants is a viable alternative route of vaccination for flu which can elicit systemic immune responses equivalent to or greater than IM vaccination with the added benefit of stimulating a robust specific mucosal immune response.