The seeds of Brassica sp. are known to have characteristic sterol composition in containing a larger amount of brassicastero12e72*, and the finding in this study of trans-22-dehydrocholesterol and stigmasta-5,25-dienol, which are regarded indeed as the natural products rather than the artefacts, in B. napus seed oil is of interest from the standpoint of sterol biogenesis.N o m e n c l a t u r e "Campesterol" is a mixture of 24a-and 24fi-methylcholesterol 28, and "campestanol" described here is con-*% W . R. Nes and M . L. McKean, Biochemistry of Steroids and Other Isopentenoids, University Park Press, Baltimore, MA 1977.sidered not 24a-methylcholestanol alone but a mixture of 24a-and 24p-epimers 28; brassicasterol = 24fi-methyltrans-22-dehydrocholesterol; stigmastanol = 24~-ethylcholestanol; sitosterol = 24a-ethylcholesterol; stigmasterol = 24u-ethyl-trans-22-dehydrocholesterol; stigmasta-5,25-dienol = 24~-ethyl-25(27)-dehydrocholesterol; fucosterol = cis-24-ethylidenecholesterol; 28-isofucosterol = trans-24-ethylidenecholesterol.