Seed lipids of Sesamum indicum and related wild species in Sudan. The sterols

Oil extracted from seeds of different varieties of the cultivated Sesamum indicum L and three related wild species, viz S alatum Thonn, S radiatum Schum & Thonn, and S angustifolium (Oliv) Engl, were analysed for their total unsaponifiables and for the contents and composition of the three sterol fractions (desmethyl, monomethyl and dimethyl sterols). The sterols were analysed after saponification by preparative TLC, capillary GC and GC‐MS of their TMS ethers. Oils from the wild species contained more unsaponifiable material (2.3‐2.4%) compared with the cultivated species (1.1‐1.3%). Considerable differences were observed in the total sterol contents and the relative proportions of the three sterol fractions in the oils from the four species studied. Sitosterol, campesterol, stigmasterol and Δ⁵‐avenasterol were the major desmethyl sterols in all four species. The monomethyl sterol fraction consisted primarily of obtusifoliol, gramisterol, cycloeucalenol and citrostadienol. Cycloartenol and 24‐methylene cycloartanol were the predominant dimethyl sterols. Variations in the composition of the three sterol fractions were observed between S indicum oils traditionally pressed by the camel‐driven expellers and laboratory extracted oils from the same seeds.