Emulsification of Simulated Gastric Fluids Protects Wheat α-Amylase Inhibitor 0.19 Epitopes from Digestion

Are Physicochemical Properties Shaping the Allergenic Potency of Plant Allergens?

This review searched for published evidence that could explain how different physicochemical properties impact on the allergenicity of food proteins and if their effects would follow specific patterns among distinct protein families. Owing to the amount and complexity of the collected information, this literature overview was divided in two articles, the current one dedicated to protein families of plant allergens and a second one focused on animal allergens. Our extensive analysis of the available literature revealed that physicochemical characteristics had consistent effects on protein allergenicity for allergens belonging to the same protein family. For example, protein aggregation contributes to increased allergenicity of 2S albumins, while for legumins and cereal prolamins, the same phenomenon leads to a reduction. Molecular stability, related to structural resistance to heat and proteolysis, was identified as the most common feature promoting plant protein allergenicity, although it fails to explain the potency of some unstable allergens (e.g. pollen-related food allergens). Furthermore, data on physicochemical characteristics translating into clinical effects are limited, mainly because most studies are focused on in vitro IgE binding. Clinical data assessing how these parameters affect the development and clinical manifestation of allergies is minimal, with only few reports evaluating the sensitising capacity of modified proteins (addressing different physicochemical properties) in murine allergy models. In vivo testing of modified pure proteins by SPT or DBPCFC is scarce. At this stage, a systematic approach to link the physicochemical properties with clinical plant allergenicity in real-life scenarios is still missing.

Tomato cystine-knot miniproteins possessing anti-angiogenic activity exhibit in vitro gastrointestinal stability, intestinal absorption and resistance to food industrial processing

The cystine-knot miniproteins present in tomato fruit (TCMPs) have been shown to exert anti-angiogenic effects by inhibiting endothelial cell migration and to display resistance to gastrointestinal proteolytic attack. To better define the pharmacological potential of TCMPs, their oral bioavailability and their resistance to industrial processing must be assessed. To explore the intestinal transport of TCMPs we used the differentiated Caco-2 cells model. After 24h incubation, 37.73±9.34% of TCMPs crossed the epithelium, without altering the integrity of the cell layer. To assess the effects of the industrial processing on the biochemical features and the biological activity of TCMPs, we developed a method for purifying the proteins from tomato paste. The tomato-paste purified TCMPs retained the resistance to gastrointestinal digestion and the inhibitory activity towards endothelial cell migration. Our previous and present results collectively demonstrate that TCMPs possess interesting features for drug development.

Metabolite profile analysis of aconitine in rabbit stomach after oral administration by liquid chromatography/electrospray ionization/multiple-stage tandem mass spectrometry

1. Aconitine (AC), an active and highly toxic constituent extracted from aconitum plants, is well known for its excellent effects against rheumatism and rheumatoid arthritis. The metabolism of AC in liver and intestine has been previously reported. However, little is known about the metabolism of AC in stomach. In this study, the metabolite profiling of AC in stomachs of rabbit and rat was performed by liquid chromatography/electrospray ionization/multiple-stage tandem mass spectrometry (LC/ESI/MS(n)), for the first time. 2. The samples were purified by liquid-liquid extraction, separated using an Agilent extended C18 column following a linear gradient elution and then detected by ESI/MS(n) in positive ion mode. Metabolites were identified by comparing their protonated molecules, fragmentation patterns and chromatographic behaviors with those of standard compounds and data from authorized literature works. 3. In conclusion, 14 metabolites were identified in animal stomach after oral administration of AC. The presentation of a large amount of metabolites of AC in stomach suggested that, for aconitum alkaloids, the stomach might play an important role in their metabolism.

Production and characterisation of monoclonal antibodies for the quantification of potentially allergenic xylanase from Aspergillus niger

Xylanase from Aspergillus niger (ANX) is widely used in bakeries as a processing aid since it stabilises and improves dough quality. An association between allergic symptoms among bakery workers and sensitisation to ANX has been reported, indicating that this enzyme is an occupational allergen. The presence of ANX in dough improvers and semi-finished goods is often hidden due to incomplete and unclear labelling. The quantification of microbial enzymes in these products is necessary and the determination of the actual concentration of ANX in workplaces is therefore essential to assess the occupational risk. To this purpose we have developed and characterised monoclonal antibodies to ANX. The monoclonal antibodies do not show any cross-reaction with other commonly used microbial enzymes, and they allow the detection of ANX in complex mixtures by ELISA inhibition assays down to the concentration limit of approximately 10 µg kg(-1). These mAbs are a valuable tool to detect and quantify ANX and to investigate its allergenic potential in the workplace.

Expression of α-amylase inhibitors in diploid Triticum species

The aim of the work was to characterize the expression of various α-amylase inhibitors (αAIs), well known anti-nutritional compounds, for the development of healthier diploid wheat-based functional foods. The salt-soluble protein fractions from the seeds of 53 accessions among Triticum monococcum subsp. monococcum (T.m.), T. monococcum subsp. boeoticum (T.b.) and Triticum urartu (T.u.) were analyzed by immunoblotting after SDS-PAGE and Urea-PAGE using polyclonal antibodies (PABs) raised against 0.19 and 0.28 αAIs expressed in bread-wheat. Reverse zymography with human saliva and Tenebrio molitor α-amylases was used to assay inhibition activity. A great variability of the expression of αAI-related proteins was observed among T.b. and T.u. PABs, and reverse zymography revealed different bands, often not correlating with those present in bread-wheat. Two-dimensional electrophoresis followed by immunoblotting and mass spectrometric analysis identified these proteins as αAIs. Interestingly, no signal was observed within T.m. accessions. This makes T.m. an important candidate for the production of novel functional foods.