Triterpenoid levels are reduced during Euphorbia tirucalli L. callus formation

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In order to compare the profiles of hydrophobic secondary metabolites between the calli and plants of Euphorbia tirucalli, we analyzed their free sterol and free triterpenoid contents by GC-MS. We obtained the calli by culturing E. tirucalli internodes successively on solidified B5 medium containing hormones. The aerial parts of the plants or calli were extracted with CHCl3-MeOH (2 : 1, v/v) and subjected to GC-MS analysis. In a plant extract, only two sterol peaks, for campesterol and β-sitosterol, and at least 11 peaks of the total ion chromatogram (TIC) with a [M+] of 426, including peaks for euphol, β-amyrin, and glutinol, were detected. The ratio of triterpenoid- and triterpenoid-like-peaks of TIC with a [M+] of 426 to the total of all peaks detected was ca. 86% (n=3) in the plant extract. In a callus extract, 6 sterols, campesterol, stigmasterol, β-sitosterol, isofucosterol, cycloartenol, and 24-methylenecycloartanol, and two triterpenoids with a molecular weight of 426 (euphol and β-amyrin) were detected. The ratio of triterpenoid- and triterpenoid-like peaks of TIC with a [M+] of 426 to the total of all peaks detected was only ca. 6.3% (n=3) in the callus extract. These results indicate that the ratio of free triterpenoids and free triterpenoid-like compounds (MW: 426) to free sterols is lower in the calli than in the plants of E. tirucalli.
2010-03-25