In mammals, tetrapyrroles formed following the catabolism of haem (i.e. bilirubin and biliverdin, bile pigments) protect against free radical mediated damage that is induced during inflammation and therefore represent potential therapeutic targets. Recently, novel metabolites of biliverdin were discovered in blood, urine and bile following intraduodenal biliverdin administration(1) indicating a new pathway for biliverdin metabolism had been discovered and required bacteria for biliverdin transformation. These data are important because oral biliverdin administration protects from inflammatory processes, however, based upon the discovery of this new metabolic pathway, biliverdin is unlikely to be responsible for protection. The main aims of this PhD thesis were to identify and characterise the principle novel biliverdin metabolite (bilirubin-10-sulfonate) formed within the gut before investigating the compound's pharmacokinetics and anti-inflammatory effects a clinically relevant animal model of sterile inflammation, thus providing pre-clinical evidence of bilirubin-10-sulfonate's therapeutic potential. [...]