Bioactivity of protein hydrolysates derived from casein, bovine blood and lung tissues in cultured cells

Bioactive peptides are short amino acid sequences produced from food and food waste-derived proteins and are believed to be capable of exhibiting a variety of physiological functions. Further studies are needed to identify novel bioactive peptides and better understand mechanisms of action. The bioactivities of seven casein hydrolysates generated using different enzymes (mammalian, plant, fungal and bacterial) were compared. All hydrolysates demonstrated significant anti-inflammatory activity; decreasing interleukin (IL)-6 production in RAW264.7 macrophages and Jurkat T cells. There were no differences in bioactivities across the seven samples. Additionally, three of the hydrolysates decreased IL-1β production in RAW264.7 cells. None of the hydrolysates demonstrated antioxidant activity in cells despite showing antioxidant activity in non-cellular assays. Sodium caseinate treatment produced an inflammatory response in 3T3-L1 adipocytes, significantly increasing IL-6 production. This response was not seen when cells were treated with SGID of casein or the casein hydrolysates. The bioactivities of bovine blood and bovine lung protein hydrolysates were also assessed. Papain hydrolysis of blood γ-globulin or fibrinogen generated hydrolysates with significant non-cellular antioxidant activity and these hydrolysates also significantly decreased proliferation in several cancer cell lines, including U937 lymphocytes. Hydrolysates did not demonstrate cellular antioxidant activity. The γ-globulin hydrolysate induced apoptosis in U937 cells, determined by cell morphological changes, DNA fragmentation and flow cytometry analysis. Colony formation in MCF-7 cells was also significantly reduced after hydrolysate treatment. An alcalase hydrolysate from bovine lung demonstrated significant anti-inflammatory activity in RAW264.7 macrophages by decreasing cellular IL-6 and IL-1β production. Bioavailability of bioactive hydrolysates (from casein, bovine blood or bovine lung) was determined in the Caco-2 transwell model and all hydrolysates were transported across the monolayer. In conclusion, casein hydrolysates and novel hydrolysates generated from bovine blood and lung proteins had significant bioactivities and were bioavailable, therefore they show potential as anti-inflammatory and anti-cancer agents