Rosemary extract antioxidant activity

Common sage and rosemary (see Table 8.32), plants of the Lami-aceae family, contain the diterpenes camosic acid, also known as rosmaricin (8-259), derived from ent-caurene, and bitter carnosol (picrosalvin, 8-260), which are potent antioxidants. Carnosic acid is a major component of fresh rosemary tops (1-2%), but is unstable and is enzymatically transformed into carnosol. These two diterpenoids represent about 15% w/w of plants haulm extracts and exhibit about 90% of extract antioxidant activity. Other transformation products of carnosic acid are rosmanol (7a-hydroxy derivative, 8-261), epirosmanol (7P-isomer, 8-262) and similar compounds. 

CHEN z-Y, WANG L Y, CHAN p T, ZHANG z, CHUNG H Y and LIANG c (1998) Antioxidative activity of green tea catechin extract compared with that of rosemary extract, JAOCS, 75 (9), 1141-5. 

The antioxidant activity of rosemary and sage (leaves and extracts) were most effectively investigated [96,97], Traditional extracts of spices and herbs are obtained by steam distillation (essential oil) or by extracting the botanical with solvents such as alcohol, hexane, or acetone, and removing the solvents by evaporation. The SFE process for production of the inherent natural antioxidants is now the most gentle and effective method [70],... 

In the year 1952, Chipault et al. mentioned that rosemary and sage have the best antioxidant activities, followed by oregano, thyme, clove, allspice and black pepper [28], By using the CO2 extraction the camosolic acid, the most effective substance in this respect, can be enriched to high concentrations. 

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. 

Figure 2. Shows the antioxidant activity of different rosemary extracts in comparison with Butylated Hydroxy Anisole (BHA). Although only 150 ppm of rosemary extract was used to stabilize lard, the antioxidant activity was higher compared to BHA.

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... 

Dapkevicius et al. (1998) compared yields and antioxidant activities of four different extracts from rosemary and sage leaves an acetone, a water extract (both from deodorized plant material), and an acetone and SFC C02 extract (both from nondeodorized plant material). The yields (g per kg dry matter) ranged from 50.2 for the SFC C02 to 90.8 for the water extract from deodorized plant material. High antioxidant activity was found for the SFC C02 and the acetone extracts, but low activity was determined for all water extracts. This emphasizes the importance of camosol and carnosic acid that are extracted from leaves with water-ethanol solvent... 

The accessibility of natural phenolic compounds has opened up the intriguing possibility that one could apply these compounds in foods, cosmetics, and other lipid-containing systems. Rosemary and sage are well known for the highest antioxidant activity among herbs, and their extracts are used in foods because of the strong antioxidant properties. 

Madsen and Bertelsen (1995) reviewed the antioxidant activities of rosemary and sage extracts in meat products (Table 6.3) measured by the inhibition of thiobar-bituric acid reactive substances (TBARS). In lard and meat products, rosemary and sage display the highest activity among other herbs. However, in oil-in-water emulsion, other spices such as clove, mace, turmeric and cinnamon are more effective. 

A wide variety of extracts of plants and spices have also shown antioxidant activity, often comparable with or better than that of 2,6,-di-te/t-butyl-4-methylphenol.33 These include the phenols in extracts of rosemary,34 black pepper,35 buckwheat,36 peanut hulls,37 and others.38... 

In conclusion, in this work we demonstrate the excellent capabilities of using ASE to extract compounds with antioxidant activity from natural sources as rosemary leaves and the microalga Spirulina platemis. ASE shows several advantages compared with traditional extraction processes such as 1) it is faster (IS min vs 2-24h in traditional extraction procedures) 2) it has less solvent volume consumption (13 ml vs 30>S00 mL/lOg) 3) it is more efficient (less dependant on matrix) and 4) it is automatic and allows sequential extraction of samples. The use of in-vitro assays and CE coupled to both, DAD and ESI-MS allows obtaining information about the biological and chemical properties of the ASE extracts. 

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]. 

Table 9.11. Antioxidant activity of a rosemary extract, camosic acid, camosol and rosmarinic acid in stripped com oil and emulsified com oil at 60°C (% inhibition) ...

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. 

Rosemary extracts are also particularly effective in stabilizing dried oats, meat products and roasted nuts. The activities of natural antioxidants are thus very system-dependent and their effectiveness in different real food systems is difficult to predict. 

Cuvelier, M-E., Berset, C. and Richard, H. Use of a new test for determining comparative antioxidative activity of butylated hydroxyanisole, butylated hydroxytoluene, alpha- and gamma-tocopherols and extracts from rosemary and sage. Sci. Aliments 10, 797-806 (1990). 

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). 

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