Triterpenoid levels are reduced during Euphorbia tirucalli L. callus formation

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 CHCl(3)-MeOH (2 : 1, v/v) and subjected to GC-MS analysis. In a plant extract, only two sterol peaks, for campesterol and beta-sitosterol, and at least 11 peaks of the total ion chromatogram (TIC) with a [M(+)] of 426, including peaks for euphol, beta-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, beta-sitosterol, isofucosterol, cycloartenol, and 24-methylenecycloartanol, and two triterpenoids with a molecular weight of 426 (euphol and beta-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.