Hydroxyproline

Hydroxyproline (DL-Hydroxyproline) is a non-essential amino acid and one of the main components of collagenous tissues. Hydroxyproline acts as a substrate for mitochondrial hydroxyproline oxidase to generate ROS. Hydroxyproline promotes the synthesis of glutathione, DNA, heme and proteins via conversion to Glycine. Hydroxyproline promotes the activation of caspase-9 and apoptosis in cancer cells treated with Doxorubicin. Hydroxyproline serves as a biochemical marker. Hydroxyproline is used in research related to various diseases including colon cancer, diabetes and arthritis ^{[1] [2]}.

In Vivo, Hydroxyproline (oral; dietary supplementation) enhances the growth of young salmon fed plant protein-based diets^[1]. Hydroxyproline (oral; dietary supplementation) enhances the growth performance of turbot fed high plant protein source-based diets^[1].

In Vitro, Hydroxyproline (0.5 mM) inhibits hydroxyl radical generation via the Fenton reaction^[1]. Hydroxyproline (0.1-10 mM) promotes caspase-9 activation and apoptosis in adriamycin-treated human colon carcinoma RKO cells via ROS generation^[1].

References:
[1]. Wu Z, et al. Metabolism, Nutrition, and Redox Signaling of Hydroxyproline. Antioxidants & redox signaling. 2019 Feb 01;30(4):674-682.
[2]. Srivastava AK, et al. Hydroxyproline: A Potential Biochemical Marker and Its Role in the Pathogenesis of Different Diseases. Current protein & peptide science. 2016;17(6):596-602.