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Carnosic acid (CA) and carnosol (CS) are components of rosemary reported to possess antioxidative and peroxisome proliferator-activated receptor gamma (PPARγ) transcriptional activities that are useful for preventing metabolic disorders. The aims of this study were to identify new bioactive compounds in heated rosemary and examine their effects on antioxidative stress and PPARγ activation. In heated rosemary, we found five CA-and CS-related compounds and determined their structures by mass spectrometry and nuclear magnetic resonance analyses. Three compounds were identified as dehydromiltirone (1), miltiodiol (2), and miltirone (4), whereas two compounds (3 and 5) were newly discovered molecules. We examined their antioxidant activities and found that 2 and 3 showed strong activity. Furthermore, in PPARγ−transactivation and adipocyte-differentiation assays, compounds 3 and 5 showed more potent PPARγ agonistic activity than CA.

Miltirone, 1,2-dehydromiltirone, saligerone have been synthesized form carnosic acid. Among them, one step transformation of carnosic acid into miltirone was realized when decarboxylation/aromatization was promoted by Lewis acid. Moreover, 4 derivatives exhibited potent cytotoxic activities against three human cancer lines in vitro.