Carnosolic acid

Pukl, M., Umek, A., Paris, A., Strukelj, B., Renko, M., Korant, B.D. and Turk, V. 1992. Inhibitory effect of carnosolic acid on HIV-1 protease. Planta Medica. 58 A632. 

Larvae of certain insects, which feed on Pinaceae, ingest and sequester the lipophilic constituents, e.g., the abietic acid, of these plants and use them to repel predators (E 5.1). Carnosolic acid causes the characteristic bitter taste of Labia-tae. Geranylgeraniol, its acetate, and cembrene A are constituents of the pheromones of bees, ants, and termites, respectively. The andromedotoxins, e.g., acetylandromedol, are toxic compounds widespread in Ericaceae. They increase the constancy in pollination (E 5.5.1). 

Extracts and leaves of rosemary and sage have the most effective antioxidant activities, but some are recognized in oregano, clove, thyme, pepper, and allspice. Supercritical CO2 extraction enables enrichment of camosolicacidfromrosemaryup to concentrations of 25 wt%-30 wt%. Figure 8.12 shows that nearly exhaustive extraction of carnosolic acid is possible at elevated pressures. Stability tests on lard (based on peroxide numbers) demonstrated that CO2 extracts had higher lifetimes compared to BHA (butylhydroxyanisole), up to about 2.5 times higher in case of 700 bar extracts. 

Frankel, E.N., Huang, S.W., Aeschbach, R., and Prior, E. 1996 Antioxidant activity of a rosemary extract and its constituents, carnosic acid, carnosol and rosmaric acid in bulk oil and oil-in-water emulsion. J. Agric. Food Chem. 44 131 -136. 

Rosemary (Rosmarinus officinalis, Labiatae) is native to southern Europe. Rosemary acts as a mild analgesic and antimicrobial agent in traditional herbal use [95]. The relative amount of carnosol (Di25) in dried rosemary leaves is 3.8-4.6%. Among the antioxidant compounds in rosemary leaves, 90% of the antioxidant activity can be attributed to Di25 and carnosic acid (ll,12-dihydroxy-8,ll,13-abietatrien-20-oic acid)... 

Extensive studies (139, 140) on rosemary extracts containing carnosol, camosic acid, and rosmarinic acid have shown that the activities of these natural antioxidants are system-dependent and that their effectiveness in different food systems is difficult to predict. In bulk vegetable oils (corn, soybean and peanut) and fish oils, carnosol and camosic acid are effective antioxidants. It has been hypothesized that this... 

One important trend in the food industry is the increased demand for natural food ingredients free of chemicals. Therefore, special attention has been paid to alternative processes directed toward extraction solvents and techniques with both GRAS and GMP labels (Ibanez et al., 1999). Supercritical C02-extraction (SFC C02) has been used (Weinreich, 1989 Nguyen et al., 1991 Nguyen et al., 1994 Ibanez et al., 1999). Tena et al. (1997) noted that extracts from rosemary obtained by SFC C02 (35 bar at 100°C) were the cleanest extracts and provided the highest recovery of carnosic acid compared to solvent extracts (acetone, hexane, dichlor-methane and methanol) after bleaching with active carbon. Bicchi et al. (2000) reported a fractionated SFC C02 method to selectively isolate carnosol and carnosic acid at 250 atm and 60°C in the second fraction. The authors used 5% methanol to modify the dissolution power of SFC C02. 

The use of extracts from rosemary as food preservatives is well established [25] the phenolic compounds obtained from this source have been shown to act as antioxidants in vitro and reduce the oxidation of dietary lipids in a dose-dependant manner [26]. The constituents of rosemary considered responsible for the majority of this antioxidant activity are rosmarinic acid, carnosol, and carnosic acid [14]. 

Aruoma 01, Halliwell B, Aeschbach R, Loligers J. Antioxidant and pro-oxidant properties of active rosemary constituents carnosol and carnosic acid. Xenobiotica 1992 22 257-268. 

In bulk com oil, the rosemary extract, camosic acid, rosmarinic acid and a-tocopherol were significantly more achve than carnosol (Table 9.11). In contrast, in com oil-in-water emulsion, carnosol was significantly more achve than in bulk oil, whereas the rosemary extract and camosic acid were less achve... 

The antioxidant activities of rosemary extracts, carnosol and camosic acid were also significantly influenced by the oil substrates and the type of system tested, bulk oils versus oil-in-water emulsions, the methods used to measure oxidation and the concentration of test compounds. The rosemary extracts, carnosol and camosic acid effectively inhibited hydroperoxide formation in com oil, soybean oil, peanut oil and fish oil, when tested in bulk (Table 9.12). The rosemary extract and pure constituents were more active antioxidants in bulk corn, peanut and fish oils than in bulk soybean oil. This difference may be attributed to the relatively higher concentrations of tocopherols in soybean oil that are known to have a negative effect on the antioxidant activity of rosemary constituents. Test compounds also inhibited hexanal formation in bulk vegetable oils, and propanal and pentenal formation in bulk fish oils. In marked contrast, these test compounds were either inactive or promoted oxidation in the corresponding vegetable oil-in-water emulsions. In fish oil emulsions, however, the rosemary compounds inhibited conjugated diene and pentenal formation, but not propanal. 

Interfacial phenomena may explain these differences in activities. Rosemary extracts, carnosol and camosic acid behaved like other hydrophilic antioxidants such as ascorbic acid and Trolox in being more effective in bulk oil than in oil-in-water emulsion systems. In the bulk oil systems where oil is the main phase, the hydrophilic rosemary antioxidants may be more protective by being oriented in the air-oil interface. In contrast, in the oil-in-water emulsion systems, where water is the main phase, the hydrophilic rosemary antioxidants remain in the water and are less effective in the oil-water interface where oxidation takes place (Chapter 10). The higher antioxidant activities of rosemary antioxidants observed in fish oil emulsions than in vegetable oil emulsions may be explained by their greater affinity toward the more polar oil interface with the water of the fish oil systems. 

Although camosic acid and carnosol are readily oxidized at 60°C and higher temperatures, their antioxidant activities are maintained. The oxidation products formed are apparently active antioxidants at high temperatures and protect oils during frying. They also have carry-over activity by protecting the fried foods. This carry-over activity can be attributed to the formation of various oxidation and isomerization products. Indeed, the radical [2,2 -azobis-(2,4-dimethylvalerate)] initiated or iron-catalysed oxidation of camosic acid in the... 

Frankel, E.N., Huang, S-W., Prior, E. and Aeschbach, R. Evaluation of antioxidant activity of rosemary extracts, carnosol and camosic acid in bulk vegetable oils and fish oil and their emulsions. /. Sci. FoodAgric. 72, 201-208 (1996b). 

Bulk linoleic acid Trolox > a-tocopherol > carnosol > carnosic acid (2)... 

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