Phenolic diterpenes antioxidant activity

The effectiveness of the two natural antioxidants rosemary and sage increases with the content of the active phenolic diterpenes [2-3]. New and improved extraction techniques based on supercritical C02-extraction (see chapter 2.1.2) resulted not only in concentrated and very active, but also in well desodourized and almost neutral tasting antioxidants. 

The strong antioxidant activity of plant material from rosemary and sage leaves compared to other herbs was already recognized by Chipault et al. (1952). The antioxidant properties of rosemary and sage are extensively documented and well related to the phenolic diterpenes. 

Richheimer, S.L., Bernart, M.W., King, G.A., Kent, M.C. and Bailey, D.T. 1996. Antioxidant activity of lipid-soluble phenolic diterpenes from rosemary. J. Am. Oil Chem. Soc. 73 507-514. 

Schwarz, K. and Temes, W. 1992a. Antioxidative constituents of Rosmarinus officinalis and Salvia officinalis I. Determination of phenolic diterpenes with antioxidative activity amongst tocochromanols using HPLC. Z. Lebensm.-unters. Forsch. 195 95-98. 

Del Bano, M.J., Lorente, J., Castillo, J., Benavente-Garcia, O., del Rio, J.A., and Ortuno, A. 2003. Phenolic diterpenes, flavones, and rosmarinic acid distribution during the development of leaves, flowers, stems, and roots of Rosmarinus officinalis. Antioxidant activity. Journal of Agricultural and Food Chemistry. 2003. 51, 4247-4253. 

The antioxidant activity of rosemary has been well documented over the past 50 years. The active constituents include phenolic acids, diterpenes, and flavonoids. Cuppett and HaU (1998), Ho et al. (2000) and Yanishlieva and Heinonen (2(X)1) have completed thorough reviews on rosemary antioxidants, and readers should consult these for additional information. Three prominent compounds - camosic acid, camosol, and rosmarinic acid (Figure 3) - have received the most attention. Camosic acid and camosol account for 1.7-5.5%... 

Cuvelier et al. (1996) assessed the antioxidant activity of 24 pilot-plant and commercial rosemary extracts and identified 22 different compounds for investigation. These included diterpenes, flavonoids, and phenolic acids. There was no apparent correlation between antioxidant activity and extract composition but the most effective extracts contained camosol, rosmarinic acid, and camosic acid and, to a lesser extent, caffeic acid, rosmanol, rosmadial, cirsimaritin, and genkwanin. Camosol was a component of all 24 extracts while rosmarinic and camosic acids were found in 83% and 71% of the extracts, respectively (Cuvelier et al, 1996). Richheimer et al. (1996) also evaluated the antioxidant components in a variety of plant and commercial rosemary products. In the commercial products, camosol and camosic acid were the predominant forms with low levels of methyl camosate. No clear relationship between the type of commercial rosemary extract and antioxidant composition was established. These investigators found that 7-methoxy-rosmanol was present in the commercial extracts but not in extracts obtained... 

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