Antonio Alcaide

Biosynthesis of cholesterol from pollinastanol in the tobacco Nicotiana tabacum

Abstract Pollinastanol (I), tritiated in position 3, is incorporated into cholesterol by leaves of the tobacco Nicotiana tabacum Wisconsin with a 1% yield. As expected, however, C28 and C29 sterols were unlabelled. The significance of these results is discussed.

Nouveaux resultats sur les sterols des algues rouges

Abstract In contrast to preceding results on the sterols of Rhodophytes, C 28 sterols predominate (63 per cent) in the red alga Rytiphlea tinctoria .

Sur la biosynthèse des stérols du tabac Nicotiana tabacum à partir du méthylène-24 cholestérol et du méthylène-24 dihydrolanostérol

Resume Des precurseurs 24-methyleniques ont ete appliques aux feuilles du tabac Nicotiana tabacum Wisconsin. Le methylene-24 dihydrolanosterol 22,23-3H3 est incorpore dans les sterols en C29, essentiellement dans le β-sitosterol. Par contre, le methylene-24 cholesterol 28-14C ne subit pas de seconde methylation, mais est hydrogene en campesterol.

Sur l'origine de la double liaison en position 22,23 des phytostérols

Abstract The radioactivity of the propionate of α-spinasterol-3 3 H (I) is incorporated with a yield of 0·7 per cent in the Δ 5 -sterols of tobacco leaves ( Nicotiana tabacum ). β-Sitosterol (II) is much more radioactive than stigmasterol (III). These results indicate that β-sitosterol is the precursor of stigmasterol, i.e. that the double bond in the 22 position is introduced by desaturation of the side chain.

Triterpenes and sterols of coffee oil

Abstract Samples of triterpenes and sterols previously isolated from coffee oil and reported to contain lanosterol and coffeasterol have been reexamined by TLC and mass spectrometry. The presence of lanosterol is not confirmed; cycloartenol, cycloartanol and probably 24-methylenecycloartanol have been detected. The sterol fraction described as coffeasterol is a mixture of at least six methylsterols.

Incorporation du desmosterol-3-3h dans les sterols du tabac nicotiana tabacum

The propionate of 3‐3H desmosterol has been applied to the leaves of the tobacco Nicotiana tabacum Wisconsin. Radioactivity is incorporated into cholesterol and campesterol with a yield of about 0.5%; the C29 sterols are not labelled in this experiment.