Triterpene dialcohols

Recently Amelio et al. (7) described a method which may find routine applications and which makes use of SPE for the separation and clean-up of the unsaponifiable from olive oil, from which the aliphatic alcohols are separated by means of HPLC (besides sterols and the two triterpenic dialcohols erythrodiol and uvaol). The alkanols are then derivatized and analyzed by means of HRGC. The use of an autosampler and a fraction collector for use with HPLC permits a considerable automatization of the analysis. (Reprinted from Ref. 1, p. 581, by courtesy of Marcel Dekker Inc.)... 

The method applied consists in a prior, basic hydrolysis (saponification) of the oil sample, followed by thin layer chromatography (TLC) fractionation of the classes of compounds, namely hydrocarbons, tocopherols, long-chain aliphatic alcohols, triterpenic alcohols, methyl sterols, sterols and triterpenic dialcohols. This procedure loses all information about the combination of polycyclic triter-penes with fatty acids. 

Four classes of sterols occur in olive oil common sterols (4-a-desmethylsterols), 4-a-methylsterols, 4,4-dimethylsterols (triterpene alcohols) and triterpene dialcohols. 

The two main triterpene dialcohols in olive oil are erythrodiol (homo-olestranol, 5a-olean-12-ene-3 3,28-diol) and uvaol (A-12-ursen-3(>,28-diol) (Figure 9.7). 

Absolute amounts of erythrodiol plus uvaol range from l-20mg/100g in olive oil and may be as high as 280 mg/100 g in -residue oil. Triterpene dialcohols can be extracted and co-chromatographed with the 4-desmethylsterol fraction. Their relative content in the total fraction as determined by GLC is used as a reliable indicator for distinguishing olive oil from (3-residue oil (Boskou 1996). 

Zarrouk, W., Carrasco-Pancorbo, A., Zarrouk, M., Segura-Carretero, A. and Fernandez-Gutierrez, A. (2009) Multi-component analysis (sterols, tocopherols and triterpenic dialcohols) of the unsaponifiable fraction of vegetable oils by liqnid chromatography-atmospheric pressure chemical ionization-ion trap mass spectrometry. Talanta 80, 924-934. 

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