Steroids euphorbia

All of the above results refer to rat liver systems. Presumably, the same result also applies to lanosterol (73) preparedby feeding yeast with [2- C,2R- H,3R]mevalonic acid or its (2S)-isomer. However, although steroids are widely distributed in nature (see also Section 13), the first formed triterpenoid in higher plants (with the exception of certain Euphorbia sp. ) is cycloartanol (75). As expected, 2,3-oxidosqualene (71) is incoi porated and the labelling pattern is presumably the same as lanosterol (73) with [2- C,3R,5R- H]mevalonic acid. When [2- C,3R,4R- H]mevalonic acid is fed, six tritium atoms are incorporated [see (75)]. The extra tritium atom is as expected at Cyclo-... 

Sekula B C, Nes W R 1980 The identification of cholesterol and other steroids in Euphorbia pulcherrima. Phytochemistry 19 1509-1512... 

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