Gas-phase reaction of phenol with NO3

The fast gas-phase reaction of NO3 radicals with phenol was found to yield 2-nitrophenol as the only relevant nitration product. The yield of this product was high and independent of the concentration of NO2 at the concentrations applied. In the presence of ozone, also significant amounts of 4-nitrophenol and p-benzoquinone were formed. The rate constant of the reaction between NO3 radicals and phenol was determined to be 5.8 x 10(-12) cm3 molecule-1 s-1. The selective formation of 2-nitrophenol (2) is suggested to derive from either the concerted keto-enol tautomerism in the reaction of a phenoxy radical with NO2 or the concerted elimination of nitric acid from a cyclohexa-3,5-diene intermediate.

Toward an in vitro test for the diagnosis of allergy to penicillins. Synthesis, characterization, and use of beta-lactam and beta-lactam metabolite poly-L-lysines which recognize human IgE antibodies

Conjugates of poly-L-lysine (PLL) containing a penicillin or a penicilloyl residue were prepared and characterized by 1H NMR and by size-exclusion (SE) HPLC. These conjugates were used in a radio allergo sorbent tests (RAST) test for the determination of allergy toward beta-lactams. The chemiometric evaluation of the data indicates that allergy to amoxycillin is different from allergy to the other beta-lactams tested. Furthermore, careful chemical characterization of the conjugates appears to be crucial to obtain meaningful information from the RAST data.

Synthesis and characterization of a penicillin-poly(L-lysine) which recognizes human IgE anti-penicillin antibodies

Conjugates of poly(L-lysine) containing a penicillin or a penicilloyl residue were prepared and characterized by 1H NMR and by size-exclusion HPLC. These conjugates and conjugates with human serum albumin were used in radioallergosorbent tests (RAST) for the determination of allergy toward penicillins.

Purification of Phleum pratense pollen extract by immunoaffinity chromatography and high-performance ion-exchange chromatography

Basic allergens of Phleum pratense pollen extract have been purified by either sequence gel filtration-ion-exchange high-performance liquid chromatography (HPIEX) and size-exclusion HPLC or sequence gel filtration-immunoaffinity chromatography and HPIEX. The second procedure seems to be suitable for preparative purposes.

Allergenic fragments in Parietaria judaica pollen extract

High-performance ion-exchange chromatography and immunoaffinity chromatography suggest that Par jI, the principal allergenic component of Parietaria judaica pollen, is a very unstable molecule, which tends to fragment in solution. Several fragments were obtained from Par jI and some of them show positivity toward the anti-Par jI monoclonal antibody, suggesting that they retain the entire structure of the allergenic determinant. These fragments could be the target for sequence and conformation studies.

High-performance liquid chromatographic approach to the separation of antiviral and immunostimulant fractions in Neuramide

Neuramide, a tissue extract having antiviral action against influenza A virus and immunostimulant action, was analyzed by preparative size-exclusion high-performance liquid chromatography (HPLC) and a low-molecular-weight fraction responsible for the antiviral action was isolated after reversed-phase HPLC. Four fractions having immunostimulant activity were also isolated, as evidenced by their potentiating action in the human lymphocyte proliferation induced by phytohaemagglutinin.

Micropreparative-scale enrichment of some allergenic components of Parietaria pollen extract

A preparative-scale enrichment of the allergenic components of the pollen extract of Parietaria judaica, which grow all over the Mediterranean area, has been obtained by high-performance liquid chromatography, operating in the ion-exchange mode at pH 7 with a curvilinear ionic-strength gradient.

Analysis of allergenic components of a Parietaria judaica pollen extract by chromatographic methods for the evaluation of purification procedures

Size-exclusion and ion-exchange high-performance liquid chromatography were used to monitor the presence of polymeric aggregates and of families of allergens of similar isoelectric point in Parietaria judaica pollen extracts. A radio-allergo-sorbent test and chromatofocusing were used for the analysis of individual fractions. This allows the detection of two groups of allergens, having pI of 4.7 and greater than 5.7, respectively, and shows the effect of dialysis or ultrafiltration on the distribution of allergens.

Purification and molecular weight studies on the components of a Parietaria pollen extract

The pollen extract of the allergenic plant Parietaria judaica, growing throughout the Mediterranean region, has been purified by high performance liquid chromatography (HPLC) operating in size-exclusion followed by ion exchange. Molecular weight determination of the components and isoelectrofocusing studies on the enriched material have been performed.

The rate of N-demethylation of N,N-dimethylanilines and N-methylanilines by rat-liver microsomes is related to their first ionization potential, their lipophilicity and to a steric bulk factor

The N-demethylation of a series of 12 p-substituted N,N-dimethylanilines, nine m-substituted N,N-dimethylanilines, one o-substituted N,N-dimethylaniline and four p-substituted N-methylanilines by rat-liver microsomes was studied. For each compound, the apparent Vmax and Km values were determined and these parameters were correlated with their electronic, lipophilicity and steric bulk parameters reported in the literature. Multi-parameter linear regression analysis showed a good correlation between log Vmax and these parameters for the p-substituted N,N,-dimethylanilines. A lower degree of correlation was observed with the meta-substituted N,N-dimethylanilines.

Structure reactivity relationships in the microsomal oxidation of tertiary amines

Apparent kinetic parameters Vmax and KM have been measured for the oxidative N-demethylation of twelve para-substituted N, N-dimethylanilines catalysed by rat liver microsomes. Vmax was enhanced by pretreatment of the rats with phenobarbital, whereas pretreatment with beta-naphthoflavone gave no appreciable enhancement. In the case of phenobarbital pretreatment the kinetic parameters could be expressed in terms of lipophilic and electronic effect of the substituents. Kinetic parameters from control and beta-naphthoflavone microsomes gave no statistically meaningful correlation.

The microbial oxygenation of the benzylisoquinoline alkaloid laudanosine

The microbial transformation of the benzylisoquinoline alkaloid laudanosine by a strain of Pseudomonas putida gives a metabolite in which O-demethylation of 1 methoxyl group of ring C, and introduction of 1 ketonic oxygen at C9 and 1 phenolic oxygen at ring C have occurred. Also, O-methylcoripalline is formed in this transformation.