The polyunsaturated fatty acid (PUFA) ω-3 docosahexaenoic acid (DHA) is a precursor for the production of novel sulfido-peptide conjugated mediators with structural similarity to the cysteinyl-leukotrienes and with novel biological properties. They are produced from specialised proresolving mediators (SPMs) in human macrophages and are termed protectin conjugates in tissue regeneration (PCTR), resolvin conjugates in tissue regeneration (RCTR), and maresin conjugates in tissue regeneration (MCTR) because they regulate mechanisms in inflammation resolution as well as tissue regeneration (Dalli et al. 2014, 2015, 2016, Serhan et al. 2017). Their biosynthesis is descibed in this section.