(B) synthesis of guanidine calixarene derivatives and and main amine calixarene derivative and to the oxygenated carbon, rotation of the larger tail of the ring through the core is too sluggish to be of result.36 In this respect, those calixarene compounds that we synthesized to be amphipathic, remain so and do not interconvert. Initially, we screened our topomimetic library in vitro for the ability of compounds to neutralize E. we identified several compounds that neutralize LPS in the 10?8 M range, Acitretin Acitretin making them as effective as bactericidal/permeability increasing (BPI) protein and polymyxin B. In an endotoxemia mouse model, three of the most effective topomimetics are shown to be at least partially protective against challenges of LPS from different bacterial species. NMR studies provide mechanistic insight by suggesting the site of molecular conversation between topomimetics and the lipid A component of LPS, with binding being mediated by electrostatic and hydrophobic interactions. This research contributes to the development of pharmaceutical brokers against endotoxemia and septic shock. Introduction A number of diseases result from Gram unfavorable bacterial infection and subsequent release of lipopolysaccharide (LPS) endotoxins from their membranes.1,2 Sepsis and septic shock are systemic complications generally associated with increased levels of LPS in the blood stream. An inflammatory response involving various cell receptors3 (e.gs CD144, the Toll-like receptor 4-MD-2 receptor complex5 and non-CD14 expressing endothelial cells6) and plasma components like cytokines, lipid mediators and reactive oxygen species,7 occurs on exposure to LPS, and this may initiate the cascade to septic shock, organ failure, and ultimately death.8 Standard clinical approaches to this problem Rabbit polyclonal to THIC are generally aimed at combating the bacterial infection itself via treatment with antibacterial agents, but these themselves may lead to disruption of the very bacterial membranes that release LPS. More recent clinical strategies against sepsis have been focused at targeting specific mediators, primarily cytokines; however, this approach has failed in clinical trials.9 Acitretin A therapeutic approach that quells LPS stimulation of the inflammatory response at the onset, rather than one that inhibits any individual intermediary mediator or molecular event, may actually be the most effective way to halt the septic shock cascade. In this regard, a therapeutic agent that can bind to and neutralize LPS directly would be highly useful in the clinic. While some Acitretin bactericidal brokers also can neutralize LPS, most are not that active against the endotoxin More effective LPS neutralizing brokers are clearly needed. LPS is an integral component of the outer membrane of Gram unfavorable bacteria.10,11 As such, it is composed of hydrophobic, acyl chains at one end, and hydrophilic and negatively charged groups at the other end. Because the chemical structure of LPS is usually highly variable among species of bacteria,10,12 a generic structure of LPS is usually illustrated in Physique 1. The lipid A group, which is the most conserved a part of LPS from any Gram unfavorable species of bacteria, consists of a poly iron uptake receptor protein FhuA in complex with an LPS molecule, Ferguson et Acitretin al33 found a precise spatial arrangement of cationic side chains from a three-stranded antiparallel -sheet was crucial to bind this LPS. Using NMR spectroscopy, Pristovsek & Kidric34 decided the structure of PmxB in a LPS bound state and concluded that a phenylalanine (F6) side chain and two positively charged, ,-diaminobutyric acid groups (Dab 1 and Dab 5) were crucial to binding LPS. From another NMR structural study, Japelj et al25 found that peptide LF11 in the presence of LPS from serotype 055:B5, folded in a T-shaped arrangement of a hydrophobic core and two clusters of basic residues that match the distance between the two phosphate groups of the lipid A moiety. All three of these structural studies demonstrate the importance to LPS binding of some specific spatial relationships among both cationic and hydrophobic groups on these peptides. The present study capitalizes on this recurring theme and uses the NMR structures of pep peptides22,23 and dodecapeptide SC424 to design a series of non-peptide, calixarene-based compounds that mimic the overall structure of a small unit of helix or -sheet. This design essentially captures the molecular dimensions and amphipathic surface topology common to all LPS binding peptides. These novel, sheet/helix topomimetics present hydrophobic and positively charged residues in a manner that allows.