The leaves of the plant Rosmarinus officinalis L. are best known as a spice and flavoring agent but they are also reported as a herbal remedy with antioxidant, anti-inflammatory, anticarcinogenic, antidiuretic, and hepatotoxic protective properties (1-3). Crude and refined extracts of R. officinalis L. are commercially available in the form of powders and liquids at different concentrations of the active components (e.g., Robertet S.A., Grasse, France; LycoRed Natural Products Industries, Beer Sheva, Israel; Kalsec Inc., Michigan, USA).
To overcome the problem of odor, color, and taste associated with rosemary components, refined rosemary extracts are prepared. Manufacturing procedures generally involve two steps. In the first step, the essential oils of rosemary are removed by steam distillation or selective solvent extraction. The residue (dried leaves) is extracted with different solvents, such as hexane, methanol, ethanol, and acetone (4-8), or, alternatively, by supercritical fluid processing with carbon dioxide (9). The final preparation is almost without odor and color and has a high antioxidant capacity, similar to the synthetic antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT).
The composition of rosemary extracts varies according to their extraction procedure. A large number of antioxidant components have been identified (5,6,10-14). The most potent antioxidant components are the diterpenes carnosol and carnosic acid, which account for 90% of the antioxidant potential in certain extracts (15). Interestingly, in the plant, carnosic acid is localized to subcellular compartments and its function is to protect chloro-plasts against oxidative stress (16). Other phenolics and minor constituents such as rosmanol, isorosmanol, rosmaridiphenol, and rosmariquinone also have antioxidant activity (11-14). Some components of rosemary extracts that do not have strong antioxidant activity but may be involved in the
anticarcinogenic activity include the triterpenic acids ursolic acid, oleanolic acid, and betulinic acid (17-19).
Analysis of a commercially available water-soluble extract (Robertet S.A., France) showed a high content of rosmarinic acid (1.2%), flavones (glycoside and glucuronide of 6-hydroxyluteolin and aglyones derived from apigenin and chrysin, around 3%), and some monoterpenes (verbenone, a-terpineol, 1,8-cineole, camphor, and limonene) (20). A dichloromethane extract contained mainly flavonoids and phenolic diterpenes (21). Two flavones were identified as cirsimaritin and genkwanin. Phenolic diterpenes were carnosic acid and its derivatives, carnosol, rosmanol, epirosmanol methyl ether, and traces of epirosmanol. The triterpene ursolic acid was not detected. Glucuronides of the flavonoid luteolin, together with hesperedin, were isolated from 50% aqueous methanol extract of rosemary leaves (22).
The essential oil of rosemary is obtained primarily from the apical part of the plant and the leaves (23). Around 50 constituents have been identified but the essential oil is principally rich in monoterpenes and sesquiterpene hydrocarbons, which vary according to the geographic origin (24). Spanish oils were found to be rich in a-pinene, 1,8-cineole, and camphor while the French oils possessed a-pinene, 1,8 cineole, and bornyl acetate and Moroccan oils were typically rich in 1,8-cineole. Some minor constituents include h-pinene, h-caryophylene, camphene, limonene, myrcene, camphor, borneol, a-terpineol, and terpinen-4-ol (21,24)(Fig. 1).
Was this article helpful?