Bioactive peptides bioavailability

Bioactive peptides as products of hydrolysis of diverse marine invertebrate (shellfish, crustacean, rotifer, etc.) proteins are the focus of current research. After much research on these muscles and byproducts, some biologically active peptides were identified and applied to useful compounds for human utilization. This chapter reviews bioactive peptides from marine invertebrates in regarding to their bioactivities. Additionally, specific characteristics of antihypertensive, anti-Alzheimer, antioxidant, antimicrobial peptide enzymatic production, methods to evaluate bioactivity capacity, bioavailability, and safety concerns of peptides are reviewed. 

Water-soluble bioaotives may also be protected from their environment by entrapment within a matrix (e.g., gel) or the use of lipid coats. Most research on delivery of water-soluble bioactives has been on systems for enriching foods with water-soluble vitamins and minerals and more recently on the use of bioactive peptides in food. The delivery of bioavailable iron has been of particular interest because of the widespread problem of iron deficiency. 

As with most bioactive peptides, the delivery of these compounds to the site of action is a major concern when considering the druggability of a conopeptide lead. Improvement in the bioavailability of conotoxins can be achieved with modified peptides with improved potency and lipid solubility. The synthesis of lipo- and liposaccharide conjugates of a-conotoxin, such as MII, " may improve the oral availability and stability of the peptide and facilitate the crossing of the blood-brain barrier, thus improving the pharmaceutical suitability of these compounds. 

Protein 32 g/1 30-40 Essential amino acids, bioactive proteins, peptides. Enhanced bioavailability... 

When considering the addition of a bioactive to food, it is useful to classify them as oil-soluble (e.g., polyunsaturated fatty acids, carotenes, lycopene), water-soluble (e.g., anthocyanins, proteins and peptides), or water/oil dispersible components (e.g., probiotics). Bioactives may be added directly to food if they are in a compatible format with the food matrix and provided their direct addition does not impact negatively on food quality or the bioavailability of the bioactive. When the solubility in a food matrix is limiting, its hydrophilicity/lipophilicity may be modified to enable improved incorporation. An example is the conversion of free plant sterols to fatty acid esters in order to make them more oil-soluble and readily incorporated into spreads (Deckere de and Verschuren 2000). 

Successful oral delivery of protein involves overcoming the barriers of enzymatic degradation, achieving epithelial permeability, and taking steps to conserve bioactivity during formulation processing. The coadministration of enzyme inhibitors and permeation enhancers is an approach used to enhance the bioavailability of oral protein formulations. Chemical modification of peptides and use of polymeric systems as carriers have also been attempted to overcome the inherent barriers. 

Biodegradable polymeric nanoparticles have been prepared and used to enhance the stability of proteins and peptides, control their release and pharmacokinetic parameters, furthermore, to improve their bioavailability. For delivery purposes, the polymeric material needs to meet physicochemical and biological requirements, of which, biocompatibility, safety, and biodegradability into non-toxic metabolites are of cmcial importance. The polymers can be easily functionalised towards off opsoni-sation. They are also known to show reduced toxicity in the peripheral healthy tissues. The selection of polymers depends on the method of administration, the bioactive molecules to be loaded, the desired release profile, the intention to target specific tissues, the desired rate of particle degradation, and the biocompatibility. Table 11.3 outlines some of the natural and synthetic polymers currently used in the fabrication of nanoparticles. 

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