Phenolic diterpenes extraction

Bicchi, C., Binello, A., and Rubiolo, P. 2000. Determination of phenolic diterpene antioxidants in Rosemary (Rosmarinus officinalis L.) with different methods of extraction and analysis. Phytochem. Anal. 11, 236-242. 

Selection of a suitable extraction procedure can increase the concentration of phenolic diterpenes relative to the plant material. In addition, undesirable components can be removed prior to adding extracts to foods. For example, chlorophylls present in plant material may reduce the light stability of food during storage. Several extraction techniques have been patented (Nakatani et al., 1984 Aeschbach and Philippossian, 1989) using solvents with different polarity, such as petrol ether, hexane, toluene, acetone, methanol and ethanol. To obtain tailored extracts, the successive use of different solvents has been applied. 

The comparison of six commercial extracts (Figure 6.3) showed that C02 extraction results in the highest proportion of carnosic acid among the phenolic diterpenes (Schwarz and Temes, 1992b). Extraction solvents used for the extracts shown in Figure 6.3 were ethanol (extract 1) hexane and acetone (extract 2) ethanol (extract 3) methanol (extract 4) hexane, ethanol and methanol (extract 5) and super critical C02 (extract 6). 

FIGURE 6.3 The phenolic diterpene composition of commercial extracts from rosemary and sage (for extraction solvents used, see text). Data taken from Schwarz et al. (1992). 

Since the ancient times, spices have been added to different types of food to improve their flavor and to enhance their storage stability. The intake of herbs and spices is regulated by themselves by means of the flavor intensity of the essential oil. However, antioxidant extracts with high contents of phenolic diterpenes do not necessarily contain essential oils. Particularly, plant material from essential oil production for cosmetic or pharmaceutical products is an interesting side product to be used for the preparation of antioxidative extracts. However, data published by Richheimer et al. (1996) indicated that the deoiled biomass contains markedly less camosic acid than the dried, nondeoiled plant material. 

FIGURE 6.4 HPLC chromatogram of phenolic diterpenes in commercial rosemary extracts (ISO isorosmanol ROS rosmanol CAR camosic acid CA camosol DMIR dimethyl -isorosmanol and MCA 12-O-methylcamosic acid). 

Schwarz, K., Ternes, W. and Schmauderer, E. 1992. Antioxidative constituents of Rosmarinus officinalis and Salvia officinalis. III. Stability of phenolic diterpenes of rosemary extracts under thermal stress as required for technological processes. Z. Lebensm. unters. Forsch. 195 104-107. 

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. 

Diterpenes are a large group of C20 compounds. Their main structural types are acyclic compounds, cyclic compounds, bicyclic diterpenes and tri- and tetra-cyclic diterpenes. The cosmetic use of this group of compounds is restricted to the antioxidant properties of the phenolic diterpenes extracted from rosemary and sage. 

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... 

Centered in South America, the approximately four hundred perennial herbaceous or shrubby Baccharis species extend in their range into North America 292). Their closest relatives most likely include Archibaccharis and Conyza (A. Cronquist, pers. commun.). The dominant lipophilic constituents of the leaf extracts from 54 taxa are diterpenes, triterpenes, sesquiterpenes, flavonoids, and other phenolics (Table 8 [pp. 443-446] Figure 22 [pp. 467-468]). Although ew/-clerodanes are the most frequently reported diterpene components, labdanes and tetracyclic /-kaurenes and ew/-stachanes are common (Figure 22). 

The molecular compositions of rosemary Rosmarinus officinalis L.) extracts and their dependence on extraction solvents, seasons, and drying processes were characterized using NMR spectroscopy and multivariate data analysis. The rosemary metabonome was dominated by 33 metabolites including sugars, amino acids, organic acids, poly-phenolic acids, and diterpenes. ... 

---