Screening and purification of bioactive peptides with potential to activate the cholecystokinin receptor type 1

Obesity is a world-wide health problem with tremendous health care costs. Weight maintenance is a complex system in which different mechanisms are involved. One of these mechanisms involves the cholecystokinin receptor type 1 (CCK1R). The CCK1R is a GPCR (G-protein coupled receptor) localized in the gastrointestinal tract that induces a feeling of satiety upon activation by its natural hormone cholecystokinin (CCK). Bioactive peptides, which can be released from food protein, can mimic the effect of CCK and have an influence on satiety. Such peptides could be used as a satiating ingredient in the development of new functional foods for the prevention and treatment of obesity. We set up a cell-based bioassay in 96 well-plates to screen for such bioactive peptides that can activate the CCK1R, based on the fluorescent visualization of a Ca-flux when the receptor is activated. Fluorescence measurements were done using a plate reader and a confocal microscope and the assay was benchmarked with CCK-8S (sulfated octapeptide), JMV-180 and lorglumide. The confocal microscope appeared to be the preferred measuring device when complex samples had to be measured, as measurements with the plate reader could easily be biased by background fluorescence of the sample. Screening of different food protein hydrolysates showed that some food protein hydrolysates , such as soy protein hydrolysates, possess significant CCK1R activity. The peptides in the active soy protein hydrolysates were separated by use of size exclusion chromatography, the CCK1R activity of the resulting fractions was re-evaluated and significant in vitro CCK1R activity was found. The effect on food intake of the active fractions with a physiological relevant molecular weight was evaluated in vivo with rats, but no significant effect could be measured. The amino acid sequences of the peptides present in some promising fractions was identified, however it remained not possible to identify which particular peptide(s) accounted for the CCK1R activity as more than 100 peptides were still present in the fractions. Hence, a highly-selective tool to extract and identify the active peptides was necessary. Therefore, a first onset was made to incorporate the CCK1R into NABBs (nanoscale apo-lipoprotein bound bilayer particles), a unique native-like bilayer membrane system for incorporation of GPCRs, as such nanoparticles could be used as an affinity-selection-mass spectrometry technique to identify CCK1R-binding peptides. Functional incorporation of the CCK1R in NABBs was shown by binding with a fluorescent labeled CCK analog

In Vitro and In Vivo Evaluation of Infestation Deterrents Against Lice

The human head louse is a cosmopolitan ectoparasite and frequently infests many people, particularly school-age children. Due to widespread pyrethroid resistance and the lack of efficient resistance management, there has been a considerable interest in the protection of uninfested people and prevention of reinfestation by disrupting lice transfer. In this study, two nonclinical model systems (in vitro and in vivo) were used to determine the efficacy of the infestation deterrents, Elimax lotion and Elimax shampoo, against human head lice or poultry chewing lice, respectively. With in vitro assessments, female head lice exhibited significantly higher avoidance responses to hair tufts treated with either of the test formulations, which led to significantly higher ovipositional avoidance when compared with female lice on control hair tufts. Additionally, both formulations were determined to be competent infestation deterrents in a competitive avoidance test in the presence of a known attractant (head louse feces extract). In in vivo assessments using a previously validated poultry model, Elimax shampoo was determined to be an efficacious deterrent against poultry chewing lice within Menopon spp. and Menacanthus spp

Protein-derived bioactives affecting CCK-induced satiety: how to detect untargeted compounds and determine their identity

Cholecystokinin (CCK) is a gut hormone that induces a feeling of satiety and therefore plays an important role in weight regulation. In this minireview, different food proteins and protein hydrolysates will be introduced that are able to enhance CCK-mediated satiety. This mechanism can be influenced at three interaction points, namely CCK release, trypsin-sensitive luminal CCK-releasing factors and the CCK receptor. Food components able to affect satiety are very promising ingredients in the development of functional foods that can be used as an aid in the battle against obesity

Bioactive peptides with CCK1-receptor activity as an aid in the battle against obesity

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