• Bovine whey peptides transit the intestinal barrier to reduce oxidative stress in muscle cells

      Corrochano, Alberto R.; Ferraretto, Anita; Arranz, Elena; Stuknytė, Milda; Bottani, Michela; O'Connor, Paula M.; Kelly, Philip; De Noni, Ivano; Buckin, Vitaly; Giblin, Linda; et al. (Elsevier, 2019-03-06)
      Health benefits are routinely attributed to whey proteins, their hydrolysates and peptides based on in vitro chemical and cellular assays. The objective of this study was to track the fate of whey proteins through the upper gastrointestinal tract, their uptake across the intestinal barrier and then assess the physiological impact to downstream target cells. Simulated gastrointestinal digestion (SGID) released a selection of whey peptides some of which were transported across a Caco-2/HT-29 intestinal barrier, inhibited free radical formation in muscle and liver cells. In addition, SGID of β-lactoglobulin resulted in the highest concentration of free amino acids (176 nM) arriving on the basolateral side of the co-culture with notable levels of branched chain and sulphur-containing amino acids. In vitro results indicate that consumption of whey proteins will deliver bioactive peptides to target cells.
    • Comparison of antioxidant activities of bovine whey proteins before and after simulated gastrointestinal digestion

      Corrochano, Alberto R.; Sariçay, Yunus; Arranz, Elena; Kelly, Philip; Buckin, Vitaly; Giblin, Linda; Department of Agriculture, Food and the Marine; Teagasc Walsh Fellowship Programme; 13 F 354-WheyGSH (Elsevier, 2018-10-24)
      Oxidative stress caused by free radicals has been implicated in several human disorders. Dietary antioxidants can help the body to counteract those reactive species and reduce oxidative stress. Antioxidant activity is one of the multiple health-promoting attributes assigned to bovine whey products. The present study investigated whether this activity was retained during upper gut transit using a static simulated in vitro gastrointestinal digestion (SGID) model. The capacity to scavenge free radicals and reduce ferric ion of whey protein isolate (WPI), individual whey proteins, and hydrolysates pre- and post-SGID were measured and compared using various antioxidant assays. In addition, the free AA released from individual protein fractions in physiological gut conditions were characterized. Our results indicated that the antioxidant activity of WPI after exposure to the harsh conditions of the upper gut significantly increased compared with intact WPI. From an antioxidant bioactivity viewpoint, this exposure negates the need for prior hydrolysis of WPI. The whey protein α-lactalbumin showed the highest antioxidant properties post-SGID (oxygen radical absorbance capacity = 1,825.94 ± 50.21 μmol of Trolox equivalents/g of powder) of the 4 major whey proteins tested with the release of the highest amount of the antioxidant AA tryptophan, 6.955 μmol of tryptophan/g of protein. Therefore, α-lactalbumin should be the preferred whey protein in food formulations to boost antioxidant defenses.
    • Delivery of β-carotene to the in vitro intestinal barrier using nanoemulsions with lecithin or sodium caseinate as emulsifiers

      Gasa-Falcon, Ariadna; Arranz, Elena; Odriozola-Serrano, Isabel; Martín-Belloso, Olga; Giblin, Linda; Ministerio de Economía y Competitividad; Enterprise Ireland; European Union; Science Foundation Ireland; Agencia de Gestio d’Ajuts Universitaris I de Recerca; et al. (Elsevier BV, 2021-01)
      To increase the intestinal delivery of dietary β-carotene, there is a need to develop nanostructured food systems to encapsulate this fat soluble bioactive. The aim of this study was to evaluate the bioacessibility and bioavailability across the intestinal barrier of β-carotene-enriched nanoemulsions stabilised with two emulsifiers (lecithin or sodium caseinate) by coupling an in vitro gastrointestinal digestion with two in vitro cell culture models (Caco-2 or co-culture of Caco-2/HT29-MTX). Nanoemulsions stabilised with lecithin had significantly higher β-carotene in the gastrointestinal digested micellar fraction, lower β-carotene in the Caco-2 (and Caco-2/HT29-MTX) apical compartment and significantly higher β-carotene in Caco-2 cellular content compared to β-carotene-enriched nanoemulsions stabilised with sodium caseinate. Finally, to assess anti-inflammatory activity of digested nanoemulsions, lipopolysaccharide stimulated macrophages were exposed to Caco- 2 basolateral samples with levels of TNF-α and IL-β, subsequently quantified. A TNF-α response from stimulated THP-1 macrophages was elicited by basolateral samples, regardless the emulsifier used to formulate nanoemulsions. This study demonstrated that β-carotene permeability is influenced by the food derived emulsifier used for stabilising nanoemulsions, indicating that composition may be a critical factor for β-carotene delivery.
    • Whey proteins: targets of oxidation, or mediators of redox protection.

      Giblin, Linda; Yalçın, A Süha; Biçim, Gökhan; Krämer, Anna C; Chen, Zhifei; Callanan, Michael J; Arranz, Elena; Davies, Michael J; European Cooperation in Science and Technology; Novo Nordisk Foundation; et al. (Taylor and Francis, 2019-01-01)
      Bovine whey proteins are highly valued dairy ingredients. This is primarily due to their amino acid content, digestibility, bioactivities and their processing characteristics. One of the reported bioactivities of whey proteins is antioxidant activity. Numerous dietary intervention trials with humans and animals indicate that consumption of whey products can modulate redox biomarkers to reduce oxidative stress. This bioactivity has in part been assigned to whey peptides using a range of biochemical or cellular assays in vitro. Superimposing whey peptide sequences from gastrointestinal samples, with whey peptides proven to be antioxidant in vitro, allows us to propose peptides from whey likely to exhibit antioxidant activity in the diet. However, whey proteins themselves are targets of oxidation during processing particularly when exposed to high thermal loads and/or extensive processing (e.g. infant formula manufacture). Oxidative damage of whey proteins can be selective with regard to the residues that are modified and are associated with the degree of protein unfolding, with α-Lactalbumin more susceptible than β-Lactoglobulin. Such oxidative damage may have adverse effects on human health. This review summarises how whey proteins can modulate cellular redox pathways and conversely how whey proteins can be oxidised during processing. Given the extensive processing steps that whey proteins are often subjected to, we conclude that oxidation during processing is likely to compromise the positive health attributes associated with whey proteins.