Absorption, distribution and elimination of carnosic acid, a natural antioxidant from Rosmarinus officinalis, in rats.

The absorption, distribution and elimination of carnosic acid, the main antioxidant found in rosemary was studied, in vivo, in rats. Therefore, carnosic acid was administrated in a single dose, intravenously (20.5 ± 4.2 mg/kg) and orally (64.3 ± 5.8 mg/kg), to four and nine rats, respectively. Blood samples were collected at different time points, and plasma concentrations of carnosic acid were determined using LC-MS. Furthermore, total collection of urine and feces was done during 4 h and 24 h for the intravenous and oral administrations, respectively. After euthanizing the rats, intestinal content, liver and muscle tissue were sampled to determine carnosic acid concentrations. The bioavailability of carnosic acid, after 360 min, was 40.1%. Traces of carnosic acid were found in the rats intestinal content, liver and muscle tissue of abdomen and legs. The recovery of carnosic acid in the feces, 24 h after oral administration, was 15.6 ± 8.2%. Carnosic acid is absorbed into the bloodstream after oral administration in rats and is therefore bioavailable. It was found that carnosic acid in vivo is present in its free form and that its main elimination route is the fecal route.