Diversity of sterol composition in the family chenopodiaceae

The predominant 4‐desmethylsterols from the leaves of 13 species in eight genera of the family Chenopodiaceae are 24α‐ethylsterols. In four species, Chenopodium ambrosioides L., C. rubrum L., Salicornia europaea L. and S. bigelovii Torr., the C‐22(23) double bond is introduced into more than 70% of the 24α‐ethylsterols producing spinasterol (24α‐ethylcholesta‐7,22E‐dien‐3β‐ol) in the first two species and mixtures of spinasterol and stigmasterol (24α‐ethylcholesta‐5,22E‐dien‐3β‐ol) in the latter species. The saturated side chain analogues predominate with more than 70% of the 24α‐ethylsterols in eight species. Salsola kali L., Suaeda linearis (Ell.) Moq., Kochia scoparia (L.) Roth., and Bassia hirsute (L.) Aschers. synthesize sitosterol (24α‐ethylcholest‐5‐en‐3β‐ol), and Atriplex arenaria Nutt., C. album L., C. urbicum L. and C. leptophyllum Nutt. possess mixtures of sitosterol and 22‐dihydrospinasterol (24α‐ethylcholest‐7‐en‐3β‐ol). Sitostanol (24α‐ethyl‐5α‐cholestan‐3β‐ol) was isolated from Suaeda linearis as an 18% component of the total 4‐desmethylsterol and in lesser amounts from four other species. In all species synthesizing 24‐ethyl‐Δ 5 ‐sterols, a 24ξ‐methylcholest‐5‐en‐3β‐ol was also present at 1.0–20% of the total 4‐desmethylsterol. Avenasterol [24‐ethylcholesta‐7,24(28)Z‐dien‐3β‐ol], isofucosterol [24‐ethylcholesta‐5,24(28)Z‐dien‐3β‐ol), cholesterol (cholest‐5‐en‐3β‐ol) and 24ξ‐methyl‐5α‐cholestan‐3β‐ol also were isolated from several species. Species in the family Chenopodiaceae and the type genus Chenopodium may be categorized into one of three groups based on sterol biosynthesis: the Δ 7 ‐sterol producers; the Δ 5 ‐sterol producers, and those producing mixtures of both Δ 7 ‐ and Δ 5 ‐sterols in relatively fixed percentage compositions.