Rosmarinic acid is a polyphenolic compound and main constituent of Rosmarinus officinalis and has been shown to possess antioxidant and anti-inflammatory properties. We aimed to evaluate the anti-inflammatory properties of rosmarinic acid and of an extract of R. officinalis in local inflammation (carrageenin-induced paw oedema model in the rat), and further evaluate the protective effect of rosmarinic acid in rat models of systemic inflammation: liver ischaemia-reperfusion (I/R) and thermal injury models. In the local inflammation model, rosmarinic acid was administered at 10, 25 and 50 mg/kg (p.o.), and the extract was administered at 10 and 25 mg/kg (equivalent doses to rosmarinic acid groups) to male Wistar rats. Administration of rosmarinic acid and extract at the dose of 25 mg/kg reduced paw oedema at 6 hr by over 60%, exhibiting a dose-response effect, suggesting that rosmarinic was the main contributor to the anti-inflammatory effect. In the liver I/R model, rosmarinic acid was administered at 25 mg/kg (i.v.) 30 min. prior to the induction of ischaemia and led to the significant reduction in the serum concentration of transaminases (AST and ALT) and LDH. In the thermal injury model, rosmarinic acid was administered at 25 mg/ kg (i.v.) 5 min. prior to the induction of injury and significantly reduced multi-organ dysfunction markers (liver, kidney, lung) by modulating NF-jB and metalloproteinase-9. For the first time, the anti-inflammatory potential of rosmarinic acid has been identified, as it causes a substantial reduction in inflammation, and we speculate that it might be useful in the pharmacological modulation of injuries associated to inflammation.Rosmarinus officinalis L., popularly named rosemary, has been used in folk medicine with several pharmacological effects being associated to its consumption, including its antiinflammatory effects [1,2], and rosmarinic acid (RA) is one of its main phenolic compounds [3].Two studies have evaluated the kinetics of rosmarinic acid when administered orally to rats [4,5]. These studies showed that rosmarinic acid was readily absorbed in the gastrointestinal tract (according to Konishi and Kobayashi [6], it crosses intestinal epithelium by passive diffusion) and reaches the peak plasma concentration at 0.5 hr post-administration. Metabolites formed are a result of glucuronidation, sulphation and methylation of rosmarinic acid and are then eliminated in the urine. The effect of R. officinalis and rosmarinic acid on metabolizing enzymes was also studied in Wistar rats [7]. This study demonstrated that the extract of R. officinalis was able to induce the enzymes CYP1A1, CYP2B1/2, CYP2E1, glutathione S-transferase and UDP-glucuronosyl transferase, but this effect was not observed when rosmarinic acid was administered alone. The authors have attributed this effect to the presence of flavones and monoterpenes.It has been widely recognized for many years that certain types of inflammatory tissue injury are mediated by reactive oxygen metabolites and that in ad...