ISSUE FOCUS 28 FEED & ADDITIVE MAGAZINE September 2024 POLYPHENOLS IN SELKO AOMIX ARE POTENT ALTERNATIVES TO VITAMIN E Polyphenols are a class of plant chemicals with antioxidant properties. These molecules' basic structure includes a phenol group, which is related to vitamin E. Polyphenols' antioxidant potential has long been recognised, and over a century ago, they were close to being classified as vitamins due to the antioxidant protection they provide. Some polyphenols have more hydroxy groups bonded to benzene rings per unit weight than vitamin E, giving them even more antioxidant activity (Figure 3). However, not all polyphenols can be used as a direct replacement for vitamin E's antioxidant effect. Bioavailability, radical affinity, tissue dispersion, and metabolism must all be considered. In ruminants, bioavailability is directly proportional to three factors: polyphenol susceptibility to fermentation in the rumen; the type of fermentation products produced; and the bioavailability of bypass polyphenols or polyphenol fermentation products. Citrus, for example, contains naringenin, which can skip rumen fermentation and has a high bioavailability in the small intestine. Conversely, proanthocyanidins are too big to digest in the small intestine and must be fermented to produce absorbable antioxidants. Bio-efficacy is affected by both the substrate and the fermentation conditions. Polyphenols for monogastric species must be chosen according to their digestibility and intestine absorption. According to studies, quercetin, rosemarinic acid and resveratrol are highly bioavailable. In contrast, grape-based proanthocyanidins produce almost no useful antioxidants in monogastric species. Together with the low bioavailability of grape polyphenols and proanthocyanidins in poultry, these antioxidants are better suited as an alterHO OH OH O Figure 3. Molecular structure of Naringenin
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