Collagen Peptides: Production, Bioactivities, and Mechanism of Actions

Collagen peptides are a representative class of bioactive peptides that contain characteristic high amounts of hydroxyproline (60-160 residues/1000 residues). These peptides are typically prepared from animal connective tissues that are largely available as by-products of meat, poultry, and fish processing industry, as well as edible portions of invertebrates like jellyfish and sea cucumber. There are also pioneering patents that explore the production of collagen peptides via the recombinant route using diverse expression systems. Collagen peptides exhibit various bioactivities in the fields of nutraceuticals (e.g., anti-osteoporosis, joint protection, and anti-obesity) and nutricosmetics (e.g., moisture elevation, elasticity improvement, and anti-wrinkling). The material basis for these bioactivities has been focused on the high levels (1–30 μM) of hydroxyproline-containing di-/tripeptides in human blood upon ingestion of collagen peptides. These hydroxyproline-containing di-/tripeptides well survive circulatory peptidase digestion to stimulate skin fibroblast growth, promote hyaluronic acid production in fibroblasts, chondrocytes, and synovium cells, and induce the differentiation of osteoblasts, preadipocytes, myoblasts, chondrocytes, and T-helper cells. They can inhibit the activities of dipeptidyl peptidase-4, angiotensin-converting enzyme, and hypoxia-inducible factor prolyl hydroxylase, which are potential molecular targets of collagen peptides. Advances in chemistry, molecular biology, and bioinformatics are accelerating research in this field.

This Research Topic aims to highlight recent studies on collagen peptides that feature new bioresources and technologies for production, oral and epidermal delivery and bioavailability, new bioactivities and applications, new discoveries of cellular mechanisms, disclosure of new target signaling pathways, and new interpretation of structure-activity relationship. We believe that this Research Topic is a relevant and timely publication, and we look forward to receiving your contributions.

We are seeking original research articles, communications, and reviews that cover the following topics:

• Exploitation of new bioresources to produce bioactive collagen peptides

• Production with novel specific enzymes or non-enzymatic techniques

• Recombinant expressing systems to produce bioactive collagen peptides

• Oral and epidermal delivery via different carriers and/or chemical modifications

• Oral and epidermal bioavailability assessments based on hydroxyproline-containing di-/tripeptides

• Animal studies or clinal trials on the bioactivities of collagen peptides

• Interactions of hydroxyproline-containing di-/tripeptides with molecular targets