Biosynthesis of plant sterols. Conversion of cholesterol to pregnenolone in Digitalis purpurea

Zusammenfassung Der bei der Bestrahlung mit ionisierenden Strahlen auftretende Sättigungseffekt, d.h. die Abweichung von der Linearität des Verhältnisses zwischen der Strahlendosis und der Zahl der geschädigten Molekeln bei höheren Dosisleistungen, wird unter Zugrundelegung eines einfachen Modells, welches sowohl die Erzeugung als auch die Rekombination der Strahlenschäden berücksichtigt, mathematisch beschrieben.     

Effects of plant sterols on cholesterol concentration in the rat small intestine

Summary The effects of feeding single doses of -sitosterol, campesterol and stigmasterol on cholesterol concentration in the rat small intestine was studied to clarify their roles in cholesterol absorption. The different plant sterols affected free and ester cholesterol concentrations differently in the different intestinal segments suggesting that they have different effects on such intestinal processes as uptake, esterification and possibly synthesis of cholesterol and transport of cholesterol esters out of the mucosal cells into the lymphatics.Acknowledgments. Financed by the Emergy Goff Research Award from the American Heart Association-Louisiana, Inc. and the NHLBI research grant HL-08974 from the National Institutes of Health, Bethesda, Maryland.     

Desmosterol as a common intermediate in the conversion of a number of C28 and C29 plant sterols to cholesterol by the tobacco hornworm

Résumé Manduca sexta (Johannson) est capable de transformer 7 phytostérols en cholestérol. Ainsi, cet insecte peut déalcoyler le - et le-méthyl de même que les groupes méthylène et éthylidènes du carbone 24 et peut hydrogéner la double liaison 22, 23. Quand ces stérols sont combinés au 20, 25-diazacholestérol, on a constaté dans tous les cas que la transformation en cholestérol s'effectue par l'intermédiaire commun, le desmostérol.     

The influence of several sterols on the conversion ofβ-sitosterol into cholesterol in the cockroach

Zusammenfassung Die Umwandlung von-Sitosterol in Cholesterol in der SchabeBlattella germanica L. wird durch bestimmte Sterine mit unnatürlichen Seitenketten gehemmt. Anhäufung von zwei verschiedenen Metaboliten wurde festgestellt.

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This work was supported by a grant from the National Council for Agricultural Research TNO.     

In vitro esterification of plant sterols by the esterifying enzyme of the small intestine of rat

Summary The in vitro esterification of plant sterols,-sitosterol, campesterol and stigmasterol, by the esterifying enzyme of the small intestine of rat was studied in the presence of saturated and unsaturated fatty acids. Campesterol esterification was highest, followed by sitosterol and stigmasterol irrespective of the type of fatty acid. Both campesterol and sitosterol esterification was greater with unsaturated fatty acids than with saturated fatty acids.Acknowledgments. Financed by the Emery Goff Research Award from the American Heart Association, Louisiana, Inc. and the USPHS research grant HL-08974 from the National Institutes of Health, Bethesda, Md.     

In vitro esterification of plant sterols by the esterifying enzyme of the small intestine of rat

The in vitro esterification of plant sterols, beta-sitosterol, campesterol and stigmasterol, by the esterifying enzyme of the small intestine of rat was studied in the presence of saturated and unsaturated fatty acids. Campesterol esterification was highest, followed by sitosterol and stigmasterol irrespective of the type of fatty acid. Both campesterol and sitosterol esterification was greater with unsaturated fatty acids than with saturated fatty acids.     

Production of ergotamine by a strain ofClaviceps purpurea (Fr.) Tul.

Riassunto Un ceppo diClaviceps purpurea indicato con la sigla 275 F.I. produce in coltura sommersa 1100–1500g/ml di una miscela di alcaloidi peptidici costituita principalmente da ergotammina (80%). Sono riportati i terreni colturali, le condizioni di coltura e l'andamento di una tipica fermentazione.     

Biosynthesis of alkaloids. on the transformation of tyrosine to 3,4-dihydroxyphenylalanine inPapaver somniferum L. plants

Zusammenfassung In Wurzelpräparaten vonPapaver somniferum L. wurde die enzymatische Umwandlung von Tyrosin in Dioxyphenylalanin bei Anwesenheit oder Abwesenheit vonl-Ascorbinsäure nachgewiesen.     

Non-enzymatic active transport in vitro. Conversion of chemical to osmotic energy]

The active transport of ammonia gas was obtained with an asymmetric composite membrane-model using H+ as carrier and the formation of water as chemical energy source. The experimental molecular pump externally limited by two silicone films permeable to gasses but not to liquids or ions is separated into two liquid layers by a central cation-exchange membrane. The first acid layer produces the aspiration of NH3, due to NH4+ formation, through the inlet silicone film; NH4+ is transferred to the second alkaline layer through the ion exchange membrane, by interdiffusion with K+; there NH4+ reacts with OH-, water is formed and NH3 is expelled throught the oulet silicone film. This new pump enlarges the applicability of in vitro active transport to non-enzymatic systems and energy sources different from ATP.     

The diversity of marine sterols and the role of algal bio-masses; from facts to hypothesis

Summary Modern analytical methods have revealed the great variety of marine sterols, which possess many different side chains and unsaturation patterns. Such biochemical transformations require well-defined mechanistic pathways, and there must be some Raison d'Etre for a situation which has withstood evolution and adaptive changes. However, in this area, insufficient and sometimes not very substantial experimental work has made it difficult to see correlations, and hence to form a solid hypothesis. A review is now presented in which the molecules dissolved in sea water, or found in marine organisms are considered with particular reference to algal production, and to the bio-ecological significance of the main sterols.