The composition of phytosterols in first and second year Digitalis purpurea L

Sterol surfactants: from synthesis to applications

An overview is given of sterol surfactants, including raw material aspects, classification and synthesis routes, physico-chemical behaviour and applications in pharmaceuticals and cosmetics.

Heat stress induces a glycosylation of membrane sterol in myxoamoebae of a true slime mold, Physarum polycephalum

To know the very early events occurring after heat shock, the changes of membrane lipids were examined. Heat stress induced the production of a certain glycolipid in the myxoamoebae of Physarum polycephalum in a few minutes. The purified glycolipid was determined to be a poriferasterol monoglucoside by structural studies that was previously reported to be expressed during the differentiation of Physarum cells from haploid myxoamoebae to diploid plasmodia (Murakami-Murofushi, K., Nakamura, K., Ohta, J., Suzuki, M., Suzuki, A., Murofushi, H., and Yokota, T. (1987) J. Biol. Chem. 262, 16719-16723). The activity of UDP-glucose:poriferasterol glucosyltransferase (Murakami-Murofushi, K., and Ohta, J. (1989) Biochim. Biophys. Acta 992, 412-415) was also expressed rapidly after heat shock. Thus, the activation of sterol glucosyltransferase and the production of sterol-glucoside were considered to be important events that were involved in the signal transduction system to induce some succeeding heat-shock responses, such as the synthesis of heat-shock proteins.

Expression of UDP-glucose: poriferasterol glucosyltransferase in the process of differentiation of a true slime mold, Physarum polycephalum

An expression of UDP-glucose:poriferasterol glucosyltransferase activity associated with differentiation of a true slime mold, Physarum polycephalum, from haploid myxoamoebae to diploid plasmodia was demonstrated. In the haploid cells, this enzyme activity was not detected, but after conjugation of the myxoamoebae, the enzyme activity was expressed and increased definitely. In the plasmodial stage, high enzyme activity was maintained constantly. The enzyme was partially purified (35-fold purification, and 28% yield), and molecular weight of 72,000, pH optimum of 7.0, and some characteristics were demonstrated.

Uptake of [2-(14)C] mevalonic acid by lipid and glycoside sterols

D. L. [2-(14)C] mevalonic acid was fed to Digitalis purpurea flowering plants and the 4-4'-dimethyl and phytosterol fractions isolated at time intervals from the glucoside and lipid portions of the plant extract. The incorporation of mevalonic acid was determined in both the aerial parts and the roots over a period of 35 days. In the aerial parts the uptake of radioactivity was rapid in the cycloartenol and lipid phytosterol fractions, but less so in the glucoside phytosterols. In the roots the glucoside phytosterols incorporation of label was considerably more rapid than in the lipid fraction.

Production of phytosterols by mature Digitalis purpurea L. plants

The relative rates of production by mature Digitalis purpurea plants of cholesterol, campesterol, stigmasterol and sitosterol isolated from the glycoside and lipid fractions of the plant extract, were estimated. Plants were exposed to an atmosphere of (14)CO2 in a growth chamber and the radioactivity of the individual sterols assessed at intervals over 25 days on a gas-liquid radio chemical chromatography (GLRC). Incorporation of (14)CO2 occurred within 12 hours into both fractions of the extract. The 5-ene sterols were produced at a similar rate over a period of 25 days but the lipid fraction was about 100% more radioactive than the glycoside fraction.