beta-Conglutins' Unique Mobile Arm Is a Key Structural Domain Involved in Molecular Nutraceutical Properties of Narrow-Leafed Lupin (Lupinus angustifolius L.)

Narrow-leafed lupin (NLL; Lupinus angustifolius L.) has multiple nutraceutical properties that may result from unique structural features of beta-conglutin proteins, such as the mobile arm at the N-terminal, a structural domain rich in alpha-helices. A similar domain has not been found in other vicilin proteins of legume species. We used affinity chromatography to purify recombinant complete and truncated (without the mobile arm domain, t beta 5 and t beta 7) forms of NLL beta 5 and beta 7 conglutin proteins. We then used biochemical and molecular biology techniques in ex vivo and in vitro systems to evaluate their anti-inflammatory activity and antioxidant capacity. The complete beta 5 and beta 7 conglutin proteins decreased pro-inflammatory mediator levels (e.g., nitric oxide), mRNA expression levels (iNOS, TNF alpha, IL-1 beta), and the protein levels of pro-inflammatory cytokine TNF-alpha, interleukins (IL-1 beta, IL-2, IL-6, IL-8, IL-12, IL-17, IL-27), and other mediators (INF gamma, MOP, S-TNF-R1/-R2, and TWEAK), and exerted a regulatory oxidative balance effect in cells as demonstrated in glutathione, catalase, and superoxide dismutase assays. The truncated t beta 5 and t beta 7 conglutin proteins did not have these molecular effects. These results suggest that beta 5 and beta 7 conglutins have potential as functional food components due to their anti-inflammatory and oxidative cell state regulatory properties, and that the mobile arm of NLL beta-conglutin proteins is a key domain in the development of nutraceutical properties, making NLL beta 5 and beta 7 excellent innovative candidates as functional foods.