Quinoa as source of type 1 ribosome inactivating proteins: A novel knowledge for a revision of its consumption

• Published in: Food chemistry Vol. 342; p. 128337
• Main Authors: Landi, Nicola, Ruocco, Maria Rosaria, Ragucci, Sara, Aliotta, Federica, Nasso, Rosarita, Pedone, Paolo V., Di Maro, Antimo
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 16.04.2021
• Subjects: ATP assay; Chenopodium quinoa - enzymology; Chenopodium quinoa Willd; Diet; Humans; Protein purification; Ribosome inactivating proteins; Ribosome Inactivating Proteins, Type 1 - analysis; rRNA N-glycosylase; Seeds - enzymology; ATP assay; Chenopodium quinoa Willd; Protein purification; Ribosome inactivating proteins; rRNA N-glycosylase
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2020.128337

[Display omitted] •Ingestion of quinoa seeds gave intestinal disorders.•These disorders were generally attributed to phytochemicals (e.g.: saponins).•Actually, Quinoa seeds and sprouts contained also a toxic protein, named quinoin.•Quinoin was a type 1 ribosome inactivating protein.•Quinoin was cytotoxic against both human fibroblasts and keratinocytes cells. This study investigates on the presence of toxic proteins in quinoa seeds. To this aim, a plethora of biochemical approaches were adopted for the purification and characterization of quinoin, a type 1 ribosome-inactivating protein (RIP) contained in quinoa seeds. We determined its melting temperature (68.2 ± 0.6 °C) and thermostability (loss of activity after 10-min incubation at 70 °C). Considering that quinoa seeds are used as a food, we found that quinoin is cytotoxic against BJ-5ta (human fibroblasts) and HaCaT (human keratinocytes) in a dose- and time-dependent manner. Moreover, in an in vitro digestive pepsin-trypsin treatment, 30% of quinoin is resistant to enzymatic cleavage. This toxin was found in seeds (0.23 mg/g of seeds) and in sprouted seeds obtained after 24-h (0.12 mg/g of sprout) and 48-h (0.09 mg/g of sprout). We suggest a thermal treatment of quinoa seeds before consumption in order to inactivate the toxin, particularly in sprouts, generally consumed raw.