Catalytic antibodies.

Monoclonal antibodies elicited to haptens that are analogs of the transition state for hydrolysis of carboxylic esters behaved as enzymic catalysts with the appropriate substrates. These substrates are distinguished by the structural congruence of both hydrolysis products with haptenic fragments. The haptens were potent inhibitors of this esterolytic activity, in agreement with their classification as transition state analogs. Mechanisms are proposed to account for the different chemical behavior of these antibodies with two types of ester substrates. The generation of an artificial enzyme through transition state stabilization by antibodies was thus demonstrated. These studies indicate a potentially general approach to catalyst design.

Reactive immunization.

For almost 200 years inert antigens have been used for initiating the process of immunization. A procedure is now described in which the antigen used is so highly reactive that a chemical reaction occurs in the antibody combining site during immunization. An organophosphorus diester hapten was used to illustrate this concept coined "reactive immunization." The organophosphonate recruited chemical potential from the immune response that resembled the way these compounds recruit the catalytic power of the serine hydrolases. During this recruitment, a large proportion of the isolated antibodies catalyzed the formation and cleavage of phosphonylated intermediates and subsequent ester hydrolysis. Reactive immunization can augment traditional immunization and enhance the scope of catalytic antibody chemistry. Among the compounds anticipated to be effective are those that contain appropriate reactive functionalities or those that are latently reactive, as in the mechanism-based inhibitors of enzymes.

Carbohydrate fatty acid monosulphate esters are safe and effective adjuvants for humoral responses.

Carbohydrate fatty acid sulphate esters (CFASEs) formulated in a squalane-in-water emulsion are effective adjuvants for humoral responses to a wide range of antigens in various animal species but rise in body temperature and local reactions albeit mild or minimal hampers application in humans. In rabbits, body temperature increased 1°C one day after intramuscular (IM) injection, which returned to normal during the next day. The effect increased with increasing dose of CFASE but not with the number of injections (up to 5). Antigen enhanced the rise in body temperature after booster immunization (P<0.01) but not after priming. Synthetic CFASEs are mixtures of derivatives containing no sulphate, one or multiple sulphate groups and the monosulphate derivatives (CMS) were isolated, incorporated in a squalane in-water emulsion and investigated. In contrast to CFASE, CMS adjuvant did not generate rise in body temperature or local reactions in rabbits immunized with a purified, recombinant malaria chimeric antigen R0.10C. In comparison to alum, CMS adjuvant revealed approximately 30-fold higher antibody titres after the first and >100-fold after the second immunization. In ferrets immunized with 7.5µg of inactivated influenza virus A/H7N9, CMS adjuvant gave 100-fold increase in HAI antibody titres after the first and 25-fold after the second immunisation, which were 10-20-fold higher than with the MF59-like AddaVax adjuvant. In both models, a single immunisation with CMS adjuvant revealed similar or higher titres than two immunisations with either benchmark, without detectable systemic and local adverse effects. Despite striking chemical similarities with monophospholipid A (MPL), CMS adjuvant did not activate human TLR4 expressed on HEK cells. We concluded that the synthetic CMS adjuvant is a promising candidate for poor immunogens and single-shot vaccines and that rise in body temperature, local reactions or activation of TLR4 is not a pre-requisite for high adjuvanticity.

Synthesis of alpha,alpha-trehalose 2,3- and 2,3'-diesters with palmitic and stearic acid: potential immunoreactants for the serodiagnosis of tuberculosis.

Regioselective monoacylation, by the stannylation method, of 4,6:4',6'-di-O-benzylidene-alpha,alpha-trehalose with palmitoyl or stearoyl chloride afforded the 2-palmitate and 2-stearate of the diacetal, whereas partial diacylation led to the corresponding 2,3'-dipalmitate and 2,3'-distearate. Protection of the monoesters in the 2',3' positions by cyclizing silylation with 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane, followed by acylation of the silyl ethers, gave the fully protected 2,3-dipalmitate, 2,3-distearate, and 2-palmitate-3-stearate. Small proportions of other isomers and triesters were also produced in these reactions. Desilylation and debenzylidenation of the diesters finally furnished 2,3- and 2,3'-di-O-palmitoyl-2,3- and 2,3'-di-O-stearoyl-, and 2-O-palmitoyl-3-O-stearoyl-alpha,alpha-trehalose.

Propolis specimens from different locations of central Italy: chemical profiling and gas chromatography-mass spectrometry (GC-MS) quantitative analysis of the allergenic esters benzyl cinnamate and benzyl salicylate.

Propolis is a beehive product popular in natural medicine thanks to its noteworthy properties. Propolis is non-toxic but is responsible for allergic reactions in sensitive individuals. In this paper, we propose a new gas chromatography-mass spectrometry (GC-MS) analytical methodology for the quantitative analysis of two allergenic esters in propolis specimens, benzyl salicylate and benzyl cinnamate, and test it on specimens from different locations of central Italy. We also present the results obtained in the chemical characterization of the same specimens. The characterization showed that the resin fractions of all of the specimens are of poplar origin.

Neutrophils are a key component of the antitumor efficacy of topical chemotherapy with ingenol-3-angelate.

Harnessing neutrophils for the eradication of cancer cells remains an attractive but still controversial notion. In this study, we provide evidence that neutrophils are required to prevent relapse of skin tumors following topical treatment with a new anticancer agent, ingenol-3-angelate (PEP005). Topical PEP005 treatment induces primary necrosis of tumor cells, potently activates protein kinase C, and was associated with an acute T cell-independent inflammatory response characterized by a pronounced neutrophil infiltrate. In Foxn1(nu) mice depleted of neutrophils and in CD18-deficient mice (in which neutrophil extravasation is severely impaired) PEP005 treatment was associated with a >70% increase in tumor relapse rates. NK cell or monocyte/macrophage deficiency had no effect on relapse rates. Both in vitro and in mice, PEP005 induced MIP-2/IL-8, TNF-alpha, and IL-1beta, all mediators of neutrophil recruitment and activation. In vitro, PEP005 activated human endothelial cells resulting in neutrophil adhesion and also induced human neutrophils to generate tumoricidal-reactive oxygen intermediates. Treatment of tumors with PEP005 significantly elevated the level of anticancer Abs, which were able to promote neutrophil-mediated Ab-dependent cellular cytotoxicity (ADCC) in vitro. PEP005 treatment of tumors grown in SCID mice was also associated with >70% increase in tumor relapse rates. Taken together, these data suggest a central role for neutrophil-mediated ADCC in preventing relapse. PEP005-mediated cure of tumors therefore appears to involve initial chemoablation followed by a neutrophil-dependent ADCC-mediated eradication of residual disease, illustrating that neutrophils can be induced to mediate important anticancer activity with specific chemotherapeutic agents.

Immunogenicity of aryl esters of salicylic or acetylsalicylic acid in guinea pigs.

A variety of derivatives of acetylsalicylic and salicylic acid have been investigated for their immunogenic properties in guinea pigs including salicylsalicylic acid (SSA), acetylsalicylsalicylic acid (ASSA), disalicylide (DI), trisalicylide (TRI), acetylsalicylic acid paracetamol ester (ASPE) and acetylsalicylic acid guajacol ester (ASGE). Contact sensitivity could be elicited by the sensitizing agent, however, with acetylsalicylic acid anhydride (ASAN) a more pronounced contact reaction could consistently be observed. Systemic anaphylactic reactions elicited by intravenous injection of N-salicyloyl bovine serum albumin could only be induced by ASAN, DI, TRI and ASSA, whereas SSA, ASPE and ASGE did not induce an anaphylactic state at a comparable dose level. From these results it is anticipated that all aryl esters of acetylsalicylic or salicylic acid are immunogenic when applied intradermally, leading to a N-salicyloyl specific immune response.

Preparation of monoclonal antibodies specific for methyl esters of gibberellins A7 and A4.

According to the heterogeneity of the immunogen of GA3-3-O-HSA, which contained other components such as GA3-7-CONH-HSA, two kinds of monoclonal antibodies (MAbs) against different antigen determinants of GA3 were prepared in a single process using a two-step screening assay for hybridomas. The results from a cross-reactivity experiment showed that MAb BG2 was specific for GA7/4 methyl esters (GA7/4me) with high affinity. Its affinity for GA7me was over 100 and 200 times higher than for GA3me and GA1me, respectively. Methylation of the 7-oic acid significantly increased the binding of MAb BG2 with GAs. On the contrary, the absence of a double bond or 3beta-OH in ring A and the breakdown of 19,10-gamma-lactone as well as the presence of 13-OH in ring D greatly reduced the binding of MAb BG2 with GAs. This antibody with high specificity can be used effectively to quantify and localize the main active GA7 and GA4 from the early non-hydroxylation pathway of GAs metabolism. Using this antibody, enzyme immunoassays with high sensitivity were developed which displayed linear ranges from 1.0 x 10(-14) to 1.0 x 10(-12) mol for GA4me and from 2.0 x 10(-15) to 2.0 x 10(-13) mol for GA7me.

Alkyl-esters of polyacrylic acid as vaccine adjuvants.

Previously, we demonstrated that polyacrylic acid (PAA) augmented significantly the immune response to inactivated Newcastle disease virus (iNDV) in chickens, but that efficacy was insufficient to replace the water-in-mineral oil (W/O) adjuvant applied for boosting primed animals. Attempting to improve its adjuvanticity, PAA with weight-average molecular weight (Mw) of 450 kDa was grafted with alkyl-chains by esterifying the carboxylic groups with octanol and butanol. The butyl-PAA and octyl-PAA esters obtained varied in degree of esterification between 10% and 92%. Adjuvant activity of water-soluble esters for humoral responses to iNDV was examined in chickens primed previously with iNDV without adjuvant. The alkyl-PAA esters exhibited significantly higher responses than unmodified PAA and titres increased with increasing dose of adjuvant. At doses of 2 mg per animal, octyl- and butyl-PAA esters with a substitution rate of 16% (octyl16-PAA and butyl16-PAA, respectively) gave similar titres as W/O. In aged animals primed with live NDV at early age, butyl16-PAA and W/O elicited comparable antibody responses. Butyl16-PAA was also more effective than PAA in stimulating primary immune responses in mice which was accompanied by stronger local reaction determined by monitoring swelling at the site of injection. Reactogenicity of butyl16-PAA was less than of W/O. We concluded that alkyl-PAA esters are strong adjuvants for primary and secondary responses and that they are promising alternatives to the mineral oil-based adjuvants presently used in various veterinary vaccines.

Further studies on the adjuvanticity of stearyl tyrosine and ester analogues.

A new family of immunoadjuvants, long-chain stearyl esters of amino acids and peptides, are described and examined with bacterial and viral vaccines. The parent compound, stearyl tyrosine, displayed significant adjuvant activity with these vaccines. Stearyl glycyl glycine displayed superior activity with viral vaccines. A number of analogues of stearyl tyrosine were adjuvant-active. Further, these adjuvants were able to elicit a neutralizing antibody response. Stearyl tyrosine and stearyl ester analogues represent promising adjuvants for human vaccines.

Toward selective covalent inactivation of pathogenic antibodies: a phosphate diester analog of vasoactive intestinal peptide that inactivates catalytic autoantibodies.

We report the selective inactivation of proteolytic antibodies (Abs) to an autoantigen, the neuropeptide vasoactive intestinal peptide (VIP), by a covalently reactive analog (CRA) of VIP containing an electrophilic phosphonate diester at the Lys(20) residue. The VIP-CRA was bound irreversibly by a monoclonal Ab that catalyzes the hydrolysis of VIP. The reaction with the VIP-CRA proceeded more rapidly than with a hapten CRA devoid of the VIP sequence. The covalent binding occurred preferentially at the light chain subunit of the Ab. Covalent VIP-CRA binding was inhibited by VIP devoid of the phosphonate diester group. These results indicate the importance of noncovalent VIP recognition in guiding Ab nucleophilic attack on the phosphonate group. Consistent with the covalent binding data, the VIP-CRA inhibited catalysis by the recombinant light chain of this Ab with potency greater than the hapten-CRA. Catalytic hydrolysis of VIP by a polyclonal VIPase autoantibody preparation that cleaves multiple peptide bonds located between residues 7 and 22 essentially was inhibited completely by the VIP-CRA, suggesting that the electrophilic phosphonate at Lys(20) enjoys sufficient conformational freedom to react covalently with Abs that cleave different peptide bonds in VIP. These results suggest a novel route to antigen-specific covalent targeting of pathogenic Abs.

Una nueva aproximación a la optimización terapéutica del diclofenaco / A novel approach towards therapeutic optimization of diclofenac

Con objeto de obtener compuestos con menor toxicidad gástrica que el diclofenaco, se sintetizaron y evaluaron cinco ésteres derivados aminoetílicos N,N-sustituidos derivados del diclofenaco. Estos ésteres se diseñaron para satisfacer el requisito estructural de disponer de una actividad anticolinérgica intacta antes de la separación. Además de bloquear el grupo carboxilo ácido mediante esterificación, esta actividad se incorporó a los ésteres sintetizados, con el beneficio adicional esperado de la reducción de la secreción de ácido gástrico y la consecuente eliminación de la irritación local mediante un mecanismo dual. En este estudio se describen la síntesis, la cinética de la hidrólisis y la actividad biológica de estos ésteres. Todos los derivados de éster permanecieron estables en tampones de pH 2,0 y 7,4 durante un período de tiempo suficiente, lo que aseguró su absorción en estado intacto y la eliminación de la irritación gástrica local producida por el fármaco principal. Se observó una rápida hidrólisis enzimática de todos los derivados en un 80% de suero humano combinado. Se descubrió que los ésteres sintetizados poseían la actividad anticolinérgica propuesta. Se mantuvo la actividad antiinflamatoria en la mayoría de los compuestos y se logró una significativa reducción del potencial ulcerogénico en comparación con el diclofenaco

In an effort for obtaining compounds with lower gastric toxicity than diclofenac, five different N,Ndisubstitutedaminoethyl ester derivatives of diclofenac were synthesized and evaluated. These esters were designed so as to satisfy the structural requirement for them to possess the anticholinergic activity in intact form before cleavage. Besides blocking the acidic carboxyl group by esterification this activity was incorporated into the synthesized esters with an expected additional benefit of having reduced gastric acid secretion and thereby abolishing the local irritation by a dual mechanism. This report describes the synthesis, hydrolysis kinetics and the biological activity of these esters. All the ester derivatives were found to be stable in buffers (pH 2.0 and 7.4) for sufficient time period, assuring them to be absorbed intact and to successfully overcome the local gastric irritation of the parent drug. A fast enzymatic hydrolysis was observed for all the derivatives in 80% pooled human serum. The synthesized esters were found to possess the proposed anticholinergic activity. The anti-inflammatory activity for most of the compounds was retained with a significant reduction in the ulcerogenic potential compared to diclofenac