Carnosic acid

Chemical standards, including danshensu, caffeic acid, rosmarinic acid, cryptotanshinone, sugiol, carnosic acid, tanshinone IIA, and miltirone, were purchased from Shanghai Yuanye Biotechnology Corporation Ltd. (Shanghai, China). The other chemicals and reagents were purchased as follows: acetonitrile and methanol (HPLC grade), Merck (Darmstadt, Germany); warfarin, Sigma-Aldrich (Madrid, Spain); chloroform, Sinopharm Chemical Reagent (Shanghai, China); leucine encephalin, Waters (Milfor, Massachusetts, USA); pure distilled water, Watsons water (Hong Kong, China); and formic acid (HPLC grade), Fisher Scientific (Fair Lawn, New Jersey, USA).

Spin-trap PBN (purity above 99.5%) for ESR spectroscopy and 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO, 99%) were purchased from Sigma-Aldrich (Steinheim, Germany). PBN was dissolved in anhydrous alcohol, while TEMPO was dissolved in doubly distilled water. TPP (catechin > 98%, Yuanye, Shanghai, China) and a commercial lipid soluble rosemary extract containing 60% carnosic acid (Zelang, Nanjing, China) were used as natural antioxidants. 2-[N-morpholino]ethanesulfonic acid (MES) was supplied by Solarbio (Beijing, China) and dissolved in doubly distilled water. Then, a 1% NaOH water solution was used to adjust the pH value to 5.7.