The taste of D- and L-amino acids: In vitro binding assays with cloned human bitter (TAS2Rs) and sweet (TAS1R2/TAS1R3) receptors.

The taste of different enantiomeric forms of amino acids has been deeply investigated because it represents the most impressive case of correlation between stereochemistry and flavour. Herein, we aimed to elucidate the molecular activity of d- and l-amino acids using an in vitro system based on a cellular model overexpressing sweet and bitter receptors, and to analyse the correlation between in vitro and sensory studies. With our work we demonstrated specific enantiomeric activities for several amino acids on TAS1R2-TAS1R3 sweet receptor. Moreover, we proved interaction of tryptophan and phenylalanine with a specific group of TAS2Rs bitter receptors, confirming and improving the results recently obtained in the tasting of amino acids. In addition, we provide the first systematic analysis of l- and d-amino acid actions on the sweet heterodimeric receptor.

Analogues of perillaketone as highly potent agonists of TRPA1 channel.

Transient receptor potential (TRP) channels represent interesting molecular target structures involved in a number of different physiological and pathophysiological systems. In particular, TRPA1 channel is involved in nociception and in sensory perception of many pungent chemesthetic compounds, which are widespread in spices and food plants, including Perilla frutescens. A natural compound from P. frutescens (isoegomaketone) and 16 synthetic derivatives of perillaketone have been prepared and tested in vitro on rTRPA1 expressed in HEK293 cells and their potency, efficacy and desensibilisation activity measured. Most derivatives proved to be high potency agonists of TRPA1, with a potency higher than most natural agonists reported in the literature. These furylketones derivatives, represent a new class of chemical structures active on TRPA1 with many potential applications in the agrifood and pharmaceutical industry.

Formation of N-Nitrosoterbuthylazine and N-Nitrosoterbutryn in a Model System of Soil Water.

The s-triazines terbutryn and terbuthylazine are currently used in Italy for weed control. A possible reaction of these compounds in the environment is N-nitrosation. Experiments performed in 10 mM CaCl(2) as a model of soil water indicated that N-nitrosation is favored only at low pH values and that the N-nitroso derivatives are fairly stable. In the presence of soil either parent compounds or N-nitroso derivatives are strongly adsorbed. These results seem to indicate that the possibility of formation of N-nitrosoterbuthylazine and N-nitrosoterbutryn in common agricultural soil is very remote.

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.