Intestinal Absorption and Metabolism of the Tomato Imidazole Alkaloids N-Caprylhistamine-ß-glucoside and N-Caprylhistamine.

Histamine-based imidazole alkaloids N-caprylhistamine (HmC8) and N-caprylhistamine-ß-glucoside (HmC8-Glc) were recently identified as precursors for a tomato biomarker. As studies regarding metabolism and bioavailability are scarce, the present study aimed at the elucidation of intestinal absorption and metabolism using the Caco-2 model and the pig cecum model to mimic human intestinal conditions. The most abundant imidazole alkaloid HmC8-Glc was neither absorbed nor transferred across cellular barriers but extensively metabolized to HmC8 in the pig cecum model, whereas the aglycon HmC8 is subjected to transport and metabolic processes through the Caco-2 monolayer and metabolized to the bioactive neurotransmitter histamine by the intestinal microbiota. Deduced from the combined results of both methods, HmC8-Glc is not absorbed directly via the intestinal epithelium but requires a metabolic cleavage of the glycosidic bond by the gut microbiota. Because of the high bioavailability of the released HmC8 and histamine, HmC8 and its glucoside might also be involved in the intolerance to tomato products by histamine-intolerant consumers.

Simple, Rapid, and Selective Isolation of 2S Albumins from Allergenic Seeds and Nuts.

The 2S albumins belong to the group of seed storage proteins present in different seeds and nuts. Due to their pronounced allergenic potential, which is often associated with severe allergic reactions, this protein family is of special interest in the field of allergen research. Here we present a simple, rapid, and selective method for the purification of 2S albumins directly from allergenic seeds and nuts. We systematically optimized the parameters "buffer system", "extraction temperature", "buffer molarity", and "pH " and were able to achieve 2S albumin purities of about 99% without further purification and demonstrate transferability of this method to nine different allergenic food matrices. Compared to conventional isolation routines, significant reduction of hands-on time and required laboratory equipment is achieved, but nonetheless higher protein yields are obtained. The presented method allows for the rapid purification of different 2S albumins including the corresponding isoforms from natural material.