Activated human macrophages and PMNs are able to produce 17-series sulfido-conjugated specialised proresolving mediators (SPMs) that are able to resolve acute inflammation and promote tissue regeneration. The ω-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) is the source of these novel SPMs termed resolvin conjugates in tissue regeneration (RCTR) and protectin conjugates in tissue regeneration (PCTR). protectin conjugate in tissue regeneration PCTR and RCTR are thus named because they share proposed biosynthetic pathways, structural features, and biological actions with the DHA-derived protectins and resolvins (respectively) as well as displaying potent tissue-regenerative actions (Serhan et al. 2014).

The proposed biosynthetic pathways for PCTRs and RCTRs are described here (Dalli et al. 2015, Serhan et al. 2017). Mammalian lipoxygenases insert molecular oxygen predominantly in the S-stereochemistry, so the hydroxy groups at the 7- and 17-positions are presumed to be in the S-configuration. The R-containing diastereomers of these products may also possess biological activity in the resolution of inflammation and tissue regeneration but they are not described here.