OBJECTIVETo establish a HPLC method to determine the carnosic acid in the stomach and intestine of rats and study its tissue distribution characteristics.

METHODAfter intragastric administration of carnosic acid (90 mg x kg(-1)), rats for each time-point were sacrificed by decapitation. After removal of the blood, various tissues were rapidly removed and weighted, all tissues were treated with a series of pretreatment before HPLC. Chromatographic separation was achieved on a Kromasil C18 column (4.6 mm x 150 mm, 5 microm) protected by an ODS guard column at 25 degrees C, using acetonitrile-0.1% phosphoric acid solution (55:45) as mobile phase, at a flow rate of 1 mL x min(-1). The wavelength of the UV detector was set at 210 nm for carnosic acid and internal standard.

RESULTGood linearities were obtained in every tissue over a range of 0.3212-160.6 mg x L(-1). The recovery, intra-day and inter-day precision and accuracy of three concentrations of carnosic acid in tissues met the requirements of methodology. And the stability of the tissue samples were also validated. The results of distribution in stomach and intestine showed that the highest concentration was (307.1 +/- 119.2) microg x g(-1) in stomach and (33.32 +/- 17.70) microg x g(-1) in intestine after intragastric administration of carnosic acid.

CONCLUSIONThe HPLC method was established to determine the concentration of carnosic acid in tissues. This method is quick, precise, and reproducible. It is the first time to study the tissue distribution of carnosic acid in rats after intragastric administration.