Corn Husk Phenolics Modulate Hepatic Antioxidant Response in Nile Tilapia (Oreochromis niloticus) Exposed to Hypoxia.

The hypoxia conditions in intensive farming systems generate oxidative stress related to oxidative damage and mortality of fish. Corn husk meal (CHM), as a source of antioxidants, might modulate the antioxidant response and prevent the damage elicited by hypoxia. This study evaluated CHM's ability to modulate a hepatic response in Nile tilapia exposed to hypoxia. A control and a test diet supplemented with 25 g CHM/kg feed were formulated. Ninety Nile tilapias (5.09 ± 0.55 g initial weight) were fed for 36 days to evaluate growth, feed efficiency, and hepatic antioxidant response (CAT, catalase; SOD, superoxide dismutase, and GPx, glutathione peroxidase) in normal oxygen conditions (normoxia). After the feeding trial (36 days), fish were exposed to hypoxia (1.5 ± 0.2 mg/L dissolved oxygen), and the hepatic antioxidant response was determined. There was no significant effect of CHM on growth and feed efficiency. The CAT activity was significantly increased in tilapias exposed to hypoxia and fed the test diet compared to the control group exposed to hypoxia. The SOD and GPx activities were unchanged in tilapias in normoxia and hypoxia conditions. Results suggest that CHM dietary supplementation promotes the antioxidant response in Nile tilapia exposed to hypoxia through CAT modulation.

Polyphenolic Extracts from Spent Coffee Grounds Prevent H2O2-Induced Oxidative Stress in Centropomus viridis Brain Cells.

Oxidative stress in aquatic organisms might suppress the immune system and propagate infectious diseases. This study aimed to investigate the protective effect of polyphenolic extracts from spent coffee grounds (SCG) against oxidative stress, induced by H2O2, in C. viridis brain cells, through an in vitro model. Hydrophilic extracts from SCG are rich in quinic, ferulic and caffeic acids and showed antioxidant capacity in DPPH, ORAC and FRAP assays. Furthermore, pretreatment of C. viridis brain cells with the polyphenolic extracts from SCG (230 and 460 µg/mL) for 24 h prior to 100 µM H2O2 exposure (1 h) significantly increased antioxidant enzymes activity (superoxide dismutase and catalase) and reduced lipid peroxidation (measured by MDA levels). These results suggest that polyphenols found in SCG extracts exert an antioxidative protective effect against oxidative stress in C. viridis brain cells by stimulating the activity of SOD and CAT.

Exploitation of Agro-Industrial Waste as Potential Source of Bioactive Compounds for Aquaculture.

The agroindustry generates a large amount of waste. In postharvest, food losses can reach up to 50%. This waste represents a source of contamination of soil, air, and bodies of water. This represents a problem for the environment as well as for public health. However, this waste is an important source of bioactive compounds, such as phenolic compounds, terpenes, and ß-glucans, among others. Several biological activities have been attributed to these compounds; for example, antioxidant, antimicrobial, gut microbiota, and immune system modulators. These properties have been associated with improvements in health. Recently, the approach of using these bioactive compounds as food additives for aquaculture have been addressed, where it is sought that organisms, in addition to growing, preserve their health and become disease resistant. The exploitation of agro-industrial waste as a source of bioactive compounds for aquaculture has a triple objective-to provide added value to production chains, reduce pollution, and improve the well-being of organisms through nutrition. However, to make use of the waste, it is necessary to revalue them, mainly by determining their biological effects in aquaculture organisms. The composition of bioactive compounds of agro-industrial wastes, their biological properties, and their application in aquaculture will be addressed here.