Assessment of chenopodin anti-inflammatory activity for the valorization of quinoa by-products rich in protein

Quinoa (Chenopodium quinoa Willd.) has been cultivated in the Andean Region for several thousand years. Quinoa’s world production has kept increasing because of the nutritional and the techno-functional features of its seed’s components [1]. The major components of quinoa seeds are starch (30 to 70% of the dry matter), mainly contained in the perisperm, and proteins (12–19%), essentially present in the embryo. The starch fraction, because of its physico-chemical properties has been used in the preparation of infant food [2]. In the starch production process, the embryo constitutes a by-product material, giving rise to interesting perspectives concerning its possible upcycling. The present work aims to lay the basis for possible uses of the discarded protein fraction as source for nutraceutical molecules. We were able to separate two different forms of chenopodin, the main quinoa storage protein, indicated as LcC (Low charge Chenopodin, 30% of total chenopodin) and HcC (High charge Chenopodin, 70% of total chenopodin). The biological effects of LcC and HcC were investigated by measuring NF-κB activation and IL-8 expression studies in undifferentiated Caco-2 cells. Inflammation was elicited using IL-1β. The results indicate that LcC and HcC show potential antiinflammatory activities in an intestinal cell model, and that the different forms can act differently, depending on their structural features. Furthermore, the molecular mechanisms of action and the structural/functional relationships of the protein at the basis of the observed bioactivities were investigated using in silico analyses and structural predictions. According to these latter, chenopodins could mimic the agonist effect exerted by Anakinra, a recombinant form of IL-1RA approved for treatment of autoinflammatory disorders. Three regions showed a high level of sequence similarity and were predicted to lie close to each other in the native conformation of chenopodin homo-hexamer suggesting a possible propensity of the inhibition of the local inflammatory effects of IL-1β. Finally, five amino acids are described as crucial for the interaction of IL-1RA with IL-1R. In chenopodins, all these amino acids are located in the regions with the highest similarities and four out of five are either conserved or substituted with similar ones [3]. [1] FAOSTAT (Statistics Division of Food and Agriculture Organization of the United Nations). Available from: http://www.fao.org/faostat/en/#search/quinoa [Accessed on 09 June 2021]. [2] FAO & CIRAD. 2015. State of the Art Report of Quinoa in the World in 2013, by D. Bazile, D. Bertero & C. Nieto, eds. Rome. [3] Capraro J., De Benedetti S., Di Dio M., Bona E., Abate A., Corsetto P.A., Scarafoni A. Biomolecules (2020), 10, 795