Thymosin-like peptides as potential immunostimulants. Synthesis via the polymeric-reagent method

Plant-Derived Proteins and Peptides as Potential Immunomodulators

The immune response of humans may be modulated by certain biopeptides. The present study aimed to determine the immunomodulatory potential of plant-derived food proteins and hydrolysates obtained from these proteins via monocatalytic in silico hydrolysis (using ficin, stem bromelainm or pepsin (pH > 2)). The scope of this study included determinations of the profiles of select bioactivities of proteins before and after hydrolysis and computations of the frequency of occurrence of selected bioactive fragments in proteins (parameter A), frequency/relative frequency of the release of biopeptides (parameters AE, W) and the theoretical degree of hydrolysis (DHt), by means of the resources and programs available in the BIOPEP-UWM database. The immunomodulating (ImmD)/immunostimulating (ImmS) peptides deposited in the database were characterized as well (ProtParam tool). Among the analyzed proteins of cereals and legumes, the best precursors of ImmD immunopeptides (YG, YGG, GLF, TPRK) turned out to be rice and garden pea proteins, whereas the best precursors of ImmS peptides appeared to be buckwheat (GVM, GFL, EAE) and broad bean (LLY, EAE) proteins. The highest number of YG sequences was released by stem bromelain upon the simulated hydrolysis of rice proteins (AE = 0.0010-0.0820, W = 0.1994-1.0000, DHt = 45-82%). However, antibacterial peptides (IAK) were released by ficin only from rice, oat, and garden pea proteins (DHt = 41-46%). Biopeptides (YG, IAK) identified in protein hydrolysates are potential immunomodulators, nutraceuticals, and components of functional food that may modulate the activity of the human immune system. Stem bromelain and ficin are also active components that are primed to release peptide immunomodulators from plant-derived food proteins.

A Comparison of Immobilised Triphenylphosphine and 1-Hydroxybenzotriazole as Mediators of Catch-and-Release Acylation Under Flow Conditions

Described herein is a comparative study of immobilised triphenylphosphine (PS-PPh3) and 1-hydroxybenzotriazole (PS-HOBt) to mediate amide couplings under continuous flow. Compared to Appel-type amidations (PS-PPh3), the developed 'catch-and-release' approach (PS-HOBt) afforded near-quantitative amide conversions. Utilising this strategy, sulfonyl chloride amenability enabled facile access to an expanded library of sulfonate and sulfonamides. Post-constructional peptide modification was also demonstrated, affording two Nβ-functionalised pentapeptides in high yields and purities. In contrast to frequently utilised coupling agents, the PS-HOBt resin could be recycled six times without a reduction in efficacy or regeneration requirements.

Immobilized coupling reagents: synthesis of amides/peptides

The primary idea of using immobilized reagents in organic synthetic chemistry is to simplify the downstream process, product workup and isolation, and therefore avoiding time-consuming and expensive chromatographic separations, which are intrinsic to every synthetic process. Numerous polymer-bounded reagents are commercially available and applicable to almost all kinds of synthetic chemistry conversions. Herein, we have covered all known supported-coupling reagents and bases which have had a great impact in amide/peptide bond formation. These coupling reagents have been used for the activation of a carboxyl moiety; thus generating an active acylating species that is ready to couple with an amine nucleophile liberating the amide/peptide and polymeric support which can be regenerated for reuse. This also addresses a large variety of anchored coupling reagents, additives, and bases that have only been employed in amide/peptide syntheses during the last six decades.

Modulation of cytokine production by carnitine

The ability of carnitine congeners to modulate cytokine production by human peripheral blood mononuclear cells (PBMC) was investigated. Modulation of cytokine production by PBMC of young (30 years of age or younger) and old (70 years of age or older) normal donors was first compared. The PBMC were collected over Ficoll–Hypaque and incubated in the presence of various concentrations of acetyl L-carnitine for 24 h. Subsequently the supernatants were collected and examined for cytokine production. The presence of cytokines in tissue culture supernatants was examined by ELISA. The cytokines measured included IL-1α, IL-1β, IL-2, IL-4, IL-6, TNFα, GM–CSF, and IFNγ. The results showed that at 50 μg/ml of acetyl L-carnitine the most significant response was obtained for TNFα. In this regard four of five young donors responded, but only one of five old donors responded. More recently these studies were expanded to examine the ability of L-carnitine to modulate cytokine production at higher doses, 200 and 400 μg/ml, in young donors. The results of these studies showed that in addition to TNFα, significant production of IL-1β and IL-6 was observed. These preliminary studies provide evidence that carnitine may modulate immune functions through the production of selected cytokines.

Solid-phase development of a L-hydroxybenzotriazole linker for heterocycle synthesis using analytical constructs

The development of a 1-hydroxybenzotriazole linker for the synthesis of heterocyclic derivatives is described, utilizing analytical construct methodology to facilitate the analysis of resin samples. A UV-chromophore-containing analytical construct enabled the accurate determination of resin loading and the automated monitoring of key reactions using only small quantities of resin. The syntheses of an array of isoxazole derivatives are reported.

Versatile Acylation of N-Nucleophiles Using a New Polymer-Supported 1-Hydroxybenzotriazole Derivative

The synthesis of a new polymer-supported coupling reagent derived from 1-hydroxybenzotriazole is described. An aminomethylated polystyrene was functionalized by reaction with 3-nitro-4-chlorobenzenesulfonyl chloride (2) followed by treatement with hydrazine hydrate, to give the polymeric N-benzyl-1-hydroxybenzotriazole-6-sulfonamide (4).The polymeric reagent 4 was shown to be highly efficient for the synthesis of amides. The efficiency of 4 could be attributed to its high acidity, conferred by the sulfonyl moiety. The procedure for amide synthesis involves the formation of an activated ester on the derivatized polymer followed, in a second step, by treatment with an amine to generate the amide in solution. Simple filtration allows the separation of the product from the polymeric reagent which in this case plays the role of leaving group. An optimization study of this two-step procedure was performed. As amides are obtained in solution free of reaction byproducts, this method can be used in an automated procedure to recover them directly into a 96 well plate, ready to be used in high throughput screening assays. Thus 4 was shown to be particularly suitable for the high throughput parallel synthesis of amides libraries.

Peptidyl aminosteroids as potential new antiarrhythmic agents

The synthesis of peptidyl derivatives of the aminosteroid, amafalone (Am), is described. Six analogs were synthesized: the hydrochloride salts of Gly-Am (2) Ala-Gly-Am (3), D-Ala-Gly-Am (4), Pro-Am (6), Pro-Pro-Am (7), and D-Ala-Pro-Am (8). The peptide bonds were formed by the polymeric reagent method using polymeric hydroxybenzotriazole as the activating polymer. Peptidyl aminosteroids 2, 6, 7, and 8, when administered to rats intravenously, had protective antiarrhythmic effects similar to those of amafalone. By the oral route, less marked protection, in comparison to amafalone, was observed with 6, while 7 and 8 were disappointingly inactive.