DIGESTED CHIA PROTEIN IMPROVES LIVER OXIDATIVE STRESS AND INFLAMMATION IN C57BL/6 MICE FED A HIGH-FAT DIET

The increasing consumption of foods with high caloric content, resulting from saturated fats, has been responsible for the increase in the prevalence of overweight and obesity in Brazil and in the world. Increased adiposity is a risk factor for the development of several chronic non-communicable diseases, such as diabetes, cardiovascular disease, and non-alcoholic fatty liver disease. Thus, the search for foods with functional properties, which promote the prevention or improvement of these diseases, is of great interest to the academic community. Among these foods, chia stands out, a protein-rich seed capable of generating bioactive peptides with antioxidant and anti-inflammatory properties. Thus, the present study evaluated the effect of digested total protein (DTP) from chia seed on the antioxidant capacity and improvement of inflammation and oxidative stress in the liver of C57BL/6 mice fed a high-fat diet. For this, 32 male mice were divided into 4 experimental groups: AIN: standard diet (AIN-93M); HF: high fat diet; AIN+DTP: standard diet added of chia seed DTP; HF+DTP: high-fat diet added of chia seed DTP. The animals received their diets for 9 weeks. The animals were euthanized, and the blood and liver were collected. Oxidative stress and lipid peroxidation analyze were performed on liver homogenate, in which malondialdehyde (MDA), superoxide dismutase (SOD) enzyme concentration and catalase enzyme (CAT) activity were analyzed. The total antioxidant capacity (TAC) were evaluated in the plasma. In addition, tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β) were quantified using ELISA kits. The expression of genes for receptors activated by proliferators of peroxisome alpha (PPAR-α), nuclear factor kappa B (NFκB), SOD and IL-1β was quantified, using the real-time PCR technique. Data normality was assessed using the Kolmogorov-Smirnov test and submitted to analysis of variance (ANOVA), followed by Newman-Keuls test at 5% of significance. The MDA analysis showed an increase in lipid peroxidation in the HF group (p<0.05), and DTP consumption was able to reduce its concentration, in the HF+DTP group. There was no difference in SOD between the groups (p>0.05), however the CAT activity was reduced in the groups treated with DTP (p<0.05). TAC was lower in the AIN group compared to the other groups (p<0.05). TNF-α and IL-1β cytokines were reduced in the DTP groups when compared to the HF group (p<0.05). The gene expression of SOD and PPAR-α showed no difference (p>0.05), but the expression of NFκB and IL-1β was reduced in the DTP groups when compared to the HF group (p<0.05). The use of high-fat diets causes the accumulation of fat in the liver, increasing oxidative stress, lipid peroxidation, and inflammation, as observed by the increase in MDA, TNF-α, and IL-1β cytokines. Despite this, due to the peptides with antioxidant capacity present in chia DTP, these effects were reduced, leading to a reduction in MDA and SOD. Furthermore, DTP can reduce the expression and translocation of NFκB, resulting in the decrease of TNF-α and IL-1β. Thus, it was possible to conclude that chia DTP can reduce inflammation and oxidative stress caused by a high-fat diet.