Analysis and correlations of the protein content and selected 'antinutrients' of faba beans (Vicia faba) in a German sample set of the cultivation years 2016, 2017, and 2018.

BACKGROUND: Faba beans (Vicia faba) experienced a significant revival in cultivation in Western Europe in the last decade. In this study, potential correlations between protein content (PC), trypsin inhibitory activity (TIA), and tannin content were investigated in a large German sample set with bean samples obtained from 50 different farms present in 11 German federal states. Three consecutive cultivation years (2016, 2017, and 2018) were included. RESULTS: The faba bean samples were grown under real cultivation conditions without any specific experimental design and finally marketed by the farmers. This enabled researchers to identify the relationship and extent of the three quality parameters towards the varying cultivation conditions and practices. Moreover, the correlations observed between the parameters were brought into the context of well-known theoretical plant hypotheses such as the carbon-nutrient balance hypothesis (CNBH), the growth-differentiation balance hypothesis (GDBH), as well as the protein competition model (PCM) for evaluating the potential for use in predictions. The study showed a significant negative correlation between PC and tannin content in faba beans over each cultivation year, whereas a positive correlation between TIA and tannin content was found. No clear correlation was observed between PC and TIA. CONCLUSION: The three plant hypotheses (CNBH, GDBH, and PCM) seem to be not fully valid. Nonetheless, these findings might be a useful guideline for predicting the composition of selected compounds, and sustainable recommendations about cultivation and exploitation for the feed and food sector can be derived. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Immunological analysis of food proteins using high-performance thin-layer chromatography-immunostaining.

The chromatographic analysis of intact proteins is still challenging, especially when biological functions as antigenicity of proteins or peptides are in the focus. Traditional immunoassays provide information about the entirety of antigenic proteins/peptides, e.g., in ELISA assays. On the other hand, when focusing on the investigation of (cross) reactivity of antibodies, Western blot following gel-electrophoresis represents the method of choice. However, gel-electrophoresis is limited by the molecular weight and therefore, not suitable for peptides ≤3kDa or proteins ≥250kDa. Furthermore, for gaining detailed information about the protein sequence (e.g., via mass spectrometric analysis), a so called in-gel digest needs to be performed following electrophoretic separation and is therefore elaborate and accompanied by a significant loss of structural, and even more severe, conformational information. Here, protein analysis using HPTLC seems to be a promising alternative due to the high level of variability regarding the chromatographic system (multiple mobile and stationary phases, even mixed) and manifold detection as well as hyphenation possibilities. This study exemplarily focused on the immunological investigation of proteins in milk following thin-layer chromatographic separation. The detection of these antigens is mandatory, as they might trigger allergenic reactions in sensitized people. Besides the proof of its applicability on different stationary phase materials, the newly developed immunoassay can be used as an approach for semi-quantitative estimation of antigenic proteins. In addition to the analysis of intact food allergens, also analyzing peptides thereof is worth considering which can be realized using HPTLC-immunostaining as well.

Free radicals induced by sunlight in different spectral regions - in vivo versus ex vivo study.

Sunlight represents an exogenous factor stimulating formation of free radicals which can induce cell damage. To assess the effect of the different spectral solar regions on the development of free radicals in skin, in vivo electron paramagnetic resonance (EPR) investigations with human volunteers and ex vivo studies on excised human and porcine skin were carried out. For all skin probes, the ultraviolet (UV) spectral region stimulates the most intensive radical formation, followed by the visible (VIS) and the near infrared (NIR) regions. A comparison between the different skin models shows that for UV light, the fastest and highest production of free radicals could be detected in vivo, followed by excised porcine and human skin. The same distribution pattern was found for the VIS/NIR spectral regions, whereby the differences in radical formation between in vivo and ex vivo were less pronounced. An analysis of lipid composition in vivo before and after exposure to UV light clearly showed modifications in several skin lipid components; a decrease of ceramide subclass [AP2] and an increase of ceramide subclass [NP2], sodium cholesterol sulphate and squalene (SQ) were detectable. In contrast, VIS/NIR irradiation led to an increase of ceramides [AP2] and SCS, and a decrease of SQ. These results, which are largely comparable for the different skin models investigated in vivo and ex vivo, indicate that radiation exposure in different spectral regions strongly influences radical production in skin and also results in changes in skin lipid composition, which is essential for barrier function.

Hetero analogues of the antimicrobial alkaloids cleistopholine and sampangine.

Hetero analogues of the alkaloids cleistopholine and sampangine were prepared in order to investigate the significance of the (aza)quinoid partial structures for antimicrobial activity. Several analogues containing amino or sulfone groups showed high antimicrobial activities, indicating that the (aza)quinoid partial structures of the alkaloids are not an indispensable requisite for antimicrobial activity.