What is L-Hydroxyproline?

L-Hydroxyproline (Hydroxyproline, Hyp) is an important amino acid, accounting for about 13% of the collagen content of amino acids. It is formed by oxidising the carbon at the γ-position of the proline pyrrolidine ring in the presence of prolyl hydroxylase, with ascorbic acid (vitamin C) as a cofactor.Hyp is also an important component of collagen and becomes unstable once lost. It cannot be reused for collagen synthesis. Therefore, it is a classic markers of collagen breakdown and bone resorption.

Applications

L-Hydroxyproline is mainly used as a diagnostic marker for bone turnover and liver fibrosis. Currently, studies have reported the development of a novel sensing material (Poly(Hyp)/BiF/SPGE) for the detection of L-hydroxyproline (Hyp) in humans. The quantification of this Hyp detection sensor was linearly related to the concentration of Hyp in the range of 0.01-5.0 mM with a limit of detection of 9.2 μM under the optimal conditions of the proposed sensor.In addition, other substances detected in biological fluids did not interfered with it based on the calculation of ± 5% error, which indicated that the detection of Hyp had a good selectivity. In practical application, this assay successfully analysed Hyp in human urine samples with recoveries in the acceptable range of 98%-102%.

In addition, Hyp is also used in France as a combination product for the treatment of small superficial wounds. Hyp can also be used as a food additive for the maintenance of bone health and collagen levels in humans.

Supplements and Benefits

Supplementation with L-Hydroxyproline helps accelerate wound healing, reduces collagen loss and has anti-aging effects. In vitro studies showed that the growth performance and feed utilisation of improved triploid crucian carp (Carassius auratus Triploid) (ITCC) were significantly improved with an increase in dietary Hyp content from 0.09% to 0.76%. Muscle texture characteristics increased significantly with the increase of dietary Hyp from 0.09% to 1.53%, and Hyp also significantly increased the content of collagen type I (Col I) and pyridinium crosslinking protein (PYD) in fish muscle. In addition, the addition of appropriate concentrations of Hyp to the bait significantly increased the expression of collagen synthesis genes (col1a1, col1a2, p4hα1, p4hβ, smad4, smad5, smad9 and tgf-β) and muscle growth genes (igf-1, tor, myod, myf5 and myhc). However, the effects of Hyp supplementation on human health remain to be demonstrated.